[apple/xnu.git] / osfmk / vm / vm_pageout.c

/*
 * Copyright (c) 2000-2009 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */
/*
 *      File:   vm/vm_pageout.c
 *      Author: Avadis Tevanian, Jr., Michael Wayne Young
 *      Date:   1985
 *
 *      The proverbial page-out daemon.
 */

#include <stdint.h>

#include <debug.h>
#include <mach_pagemap.h>
#include <mach_cluster_stats.h>
#include <mach_kdb.h>
#include <advisory_pageout.h>

#include <mach/mach_types.h>
#include <mach/memory_object.h>
#include <mach/memory_object_default.h>
#include <mach/memory_object_control_server.h>
#include <mach/mach_host_server.h>
#include <mach/upl.h>
#include <mach/vm_map.h>
#include <mach/vm_param.h>
#include <mach/vm_statistics.h>
#include <mach/sdt.h>

#include <kern/kern_types.h>
#include <kern/counters.h>
#include <kern/host_statistics.h>
#include <kern/machine.h>
#include <kern/misc_protos.h>
#include <kern/sched.h>
#include <kern/thread.h>
#include <kern/xpr.h>
#include <kern/kalloc.h>

#include <machine/vm_tuning.h>
#include <machine/commpage.h>

#include <sys/kern_memorystatus.h>

#include <vm/pmap.h>
#include <vm/vm_fault.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_protos.h> /* must be last */
#include <vm/memory_object.h>
#include <vm/vm_purgeable_internal.h>
#include <vm/vm_shared_region.h>
/*
 * ENCRYPTED SWAP:
 */
#include <../bsd/crypto/aes/aes.h>
extern u_int32_t random(void);  /* from <libkern/libkern.h> */

#if UPL_DEBUG
#include <libkern/OSDebug.h>
#endif

extern void consider_pressure_events(void);

#ifndef VM_PAGEOUT_BURST_ACTIVE_THROTTLE   /* maximum iterations of the active queue to move pages to inactive */
#define VM_PAGEOUT_BURST_ACTIVE_THROTTLE  100
#endif

#ifndef VM_PAGEOUT_BURST_INACTIVE_THROTTLE  /* maximum iterations of the inactive queue w/o stealing/cleaning a page */
#ifdef  CONFIG_EMBEDDED
#define VM_PAGEOUT_BURST_INACTIVE_THROTTLE 1024
#else
#define VM_PAGEOUT_BURST_INACTIVE_THROTTLE 4096
#endif
#endif

#ifndef VM_PAGEOUT_DEADLOCK_RELIEF
#define VM_PAGEOUT_DEADLOCK_RELIEF 100  /* number of pages to move to break deadlock */
#endif

#ifndef VM_PAGEOUT_INACTIVE_RELIEF
#define VM_PAGEOUT_INACTIVE_RELIEF 50   /* minimum number of pages to move to the inactive q */
#endif

#ifndef VM_PAGE_LAUNDRY_MAX
#define VM_PAGE_LAUNDRY_MAX     128UL   /* maximum pageouts on a given pageout queue */
#endif  /* VM_PAGEOUT_LAUNDRY_MAX */

#ifndef VM_PAGEOUT_BURST_WAIT
#define VM_PAGEOUT_BURST_WAIT   30      /* milliseconds */
#endif  /* VM_PAGEOUT_BURST_WAIT */

#ifndef VM_PAGEOUT_EMPTY_WAIT
#define VM_PAGEOUT_EMPTY_WAIT   200     /* milliseconds */
#endif  /* VM_PAGEOUT_EMPTY_WAIT */

#ifndef VM_PAGEOUT_DEADLOCK_WAIT
#define VM_PAGEOUT_DEADLOCK_WAIT        300     /* milliseconds */
#endif  /* VM_PAGEOUT_DEADLOCK_WAIT */

#ifndef VM_PAGEOUT_IDLE_WAIT
#define VM_PAGEOUT_IDLE_WAIT    10      /* milliseconds */
#endif  /* VM_PAGEOUT_IDLE_WAIT */

unsigned int    vm_page_speculative_q_age_ms = VM_PAGE_SPECULATIVE_Q_AGE_MS;
unsigned int    vm_page_speculative_percentage = 5;

#ifndef VM_PAGE_SPECULATIVE_TARGET
#define VM_PAGE_SPECULATIVE_TARGET(total) ((total) * 1 / (100 / vm_page_speculative_percentage))
#endif /* VM_PAGE_SPECULATIVE_TARGET */


#ifndef VM_PAGE_INACTIVE_HEALTHY_LIMIT
#define VM_PAGE_INACTIVE_HEALTHY_LIMIT(total) ((total) * 1 / 200)
#endif /* VM_PAGE_INACTIVE_HEALTHY_LIMIT */


/*
 *      To obtain a reasonable LRU approximation, the inactive queue
 *      needs to be large enough to give pages on it a chance to be
 *      referenced a second time.  This macro defines the fraction
 *      of active+inactive pages that should be inactive.
 *      The pageout daemon uses it to update vm_page_inactive_target.
 *
 *      If vm_page_free_count falls below vm_page_free_target and
 *      vm_page_inactive_count is below vm_page_inactive_target,
 *      then the pageout daemon starts running.
 */

#ifndef VM_PAGE_INACTIVE_TARGET
#define VM_PAGE_INACTIVE_TARGET(avail)  ((avail) * 1 / 3)
#endif  /* VM_PAGE_INACTIVE_TARGET */

/*
 *      Once the pageout daemon starts running, it keeps going
 *      until vm_page_free_count meets or exceeds vm_page_free_target.
 */

#ifndef VM_PAGE_FREE_TARGET
#ifdef  CONFIG_EMBEDDED
#define VM_PAGE_FREE_TARGET(free)       (15 + (free) / 100)
#else
#define VM_PAGE_FREE_TARGET(free)       (15 + (free) / 80)
#endif
#endif  /* VM_PAGE_FREE_TARGET */

/*
 *      The pageout daemon always starts running once vm_page_free_count
 *      falls below vm_page_free_min.
 */

#ifndef VM_PAGE_FREE_MIN
#ifdef  CONFIG_EMBEDDED
#define VM_PAGE_FREE_MIN(free)          (10 + (free) / 200)
#else
#define VM_PAGE_FREE_MIN(free)          (10 + (free) / 100)
#endif
#endif  /* VM_PAGE_FREE_MIN */

#define VM_PAGE_FREE_RESERVED_LIMIT     100
#define VM_PAGE_FREE_MIN_LIMIT          1500
#define VM_PAGE_FREE_TARGET_LIMIT       2000


/*
 *      When vm_page_free_count falls below vm_page_free_reserved,
 *      only vm-privileged threads can allocate pages.  vm-privilege
 *      allows the pageout daemon and default pager (and any other
 *      associated threads needed for default pageout) to continue
 *      operation by dipping into the reserved pool of pages.
 */

#ifndef VM_PAGE_FREE_RESERVED
#define VM_PAGE_FREE_RESERVED(n)        \
        ((unsigned) (6 * VM_PAGE_LAUNDRY_MAX) + (n))
#endif  /* VM_PAGE_FREE_RESERVED */

/*
 *      When we dequeue pages from the inactive list, they are
 *      reactivated (ie, put back on the active queue) if referenced.
 *      However, it is possible to starve the free list if other
 *      processors are referencing pages faster than we can turn off
 *      the referenced bit.  So we limit the number of reactivations
 *      we will make per call of vm_pageout_scan().
 */
#define VM_PAGE_REACTIVATE_LIMIT_MAX 20000
#ifndef VM_PAGE_REACTIVATE_LIMIT
#ifdef  CONFIG_EMBEDDED
#define VM_PAGE_REACTIVATE_LIMIT(avail) (VM_PAGE_INACTIVE_TARGET(avail) / 2)
#else
#define VM_PAGE_REACTIVATE_LIMIT(avail) (MAX((avail) * 1 / 20,VM_PAGE_REACTIVATE_LIMIT_MAX))
#endif
#endif  /* VM_PAGE_REACTIVATE_LIMIT */
#define VM_PAGEOUT_INACTIVE_FORCE_RECLAIM       100


/*
 * Exported variable used to broadcast the activation of the pageout scan
 * Working Set uses this to throttle its use of pmap removes.  In this
 * way, code which runs within memory in an uncontested context does
 * not keep encountering soft faults.
 */

unsigned int    vm_pageout_scan_event_counter = 0;

/*
 * Forward declarations for internal routines.
 */

static void vm_pageout_garbage_collect(int);
static void vm_pageout_iothread_continue(struct vm_pageout_queue *);
static void vm_pageout_iothread_external(void);
static void vm_pageout_iothread_internal(void);

extern void vm_pageout_continue(void);
extern void vm_pageout_scan(void);

static thread_t vm_pageout_external_iothread = THREAD_NULL;
static thread_t vm_pageout_internal_iothread = THREAD_NULL;

unsigned int vm_pageout_reserved_internal = 0;
unsigned int vm_pageout_reserved_really = 0;

unsigned int vm_pageout_idle_wait = 0;          /* milliseconds */
unsigned int vm_pageout_empty_wait = 0;         /* milliseconds */
unsigned int vm_pageout_burst_wait = 0;         /* milliseconds */
unsigned int vm_pageout_deadlock_wait = 0;      /* milliseconds */
unsigned int vm_pageout_deadlock_relief = 0;
unsigned int vm_pageout_inactive_relief = 0;
unsigned int vm_pageout_burst_active_throttle = 0;
unsigned int vm_pageout_burst_inactive_throttle = 0;

int     vm_upl_wait_for_pages = 0;

/*
 *      Protection against zero fill flushing live working sets derived
 *      from existing backing store and files
 */
unsigned int vm_accellerate_zf_pageout_trigger = 400;
unsigned int zf_queue_min_count = 100;
unsigned int vm_zf_queue_count = 0;

uint64_t vm_zf_count __attribute__((aligned(8))) = 0;

/*
 *      These variables record the pageout daemon's actions:
 *      how many pages it looks at and what happens to those pages.
 *      No locking needed because only one thread modifies the variables.
 */

unsigned int vm_pageout_active = 0;             /* debugging */
unsigned int vm_pageout_active_busy = 0;        /* debugging */
unsigned int vm_pageout_inactive = 0;           /* debugging */
unsigned int vm_pageout_inactive_throttled = 0; /* debugging */
unsigned int vm_pageout_inactive_forced = 0;    /* debugging */
unsigned int vm_pageout_inactive_nolock = 0;    /* debugging */
unsigned int vm_pageout_inactive_avoid = 0;     /* debugging */
unsigned int vm_pageout_inactive_busy = 0;      /* debugging */
unsigned int vm_pageout_inactive_error = 0;     /* debugging */
unsigned int vm_pageout_inactive_absent = 0;    /* debugging */
unsigned int vm_pageout_inactive_notalive = 0;  /* debugging */
unsigned int vm_pageout_inactive_used = 0;      /* debugging */
unsigned int vm_pageout_cache_evicted = 0;      /* debugging */
unsigned int vm_pageout_inactive_clean = 0;     /* debugging */
unsigned int vm_pageout_speculative_clean = 0;  /* debugging */
unsigned int vm_pageout_inactive_dirty_internal = 0;    /* debugging */
unsigned int vm_pageout_inactive_dirty_external = 0;    /* debugging */
unsigned int vm_pageout_inactive_deactivated = 0;       /* debugging */
unsigned int vm_pageout_inactive_zf = 0;        /* debugging */
unsigned int vm_pageout_dirty_no_pager = 0;     /* debugging */
unsigned int vm_pageout_purged_objects = 0;     /* debugging */
unsigned int vm_stat_discard = 0;               /* debugging */
unsigned int vm_stat_discard_sent = 0;          /* debugging */
unsigned int vm_stat_discard_failure = 0;       /* debugging */
unsigned int vm_stat_discard_throttle = 0;      /* debugging */
unsigned int vm_pageout_reactivation_limit_exceeded = 0;        /* debugging */
unsigned int vm_pageout_catch_ups = 0;                          /* debugging */
unsigned int vm_pageout_inactive_force_reclaim = 0;     /* debugging */

unsigned int vm_pageout_scan_reclaimed_throttled = 0;
unsigned int vm_pageout_scan_active_throttled = 0;
unsigned int vm_pageout_scan_inactive_throttled_internal = 0;
unsigned int vm_pageout_scan_inactive_throttled_external = 0;
unsigned int vm_pageout_scan_throttle = 0;                      /* debugging */
unsigned int vm_pageout_scan_throttle_aborted = 0;              /* debugging */
unsigned int vm_pageout_scan_burst_throttle = 0;                /* debugging */
unsigned int vm_pageout_scan_empty_throttle = 0;                /* debugging */
unsigned int vm_pageout_scan_deadlock_detected = 0;             /* debugging */
unsigned int vm_pageout_scan_active_throttle_success = 0;       /* debugging */
unsigned int vm_pageout_scan_inactive_throttle_success = 0;     /* debugging */
unsigned int vm_pageout_inactive_external_forced_reactivate_count = 0; /* debugging */
unsigned int vm_page_speculative_count_drifts = 0;
unsigned int vm_page_speculative_count_drift_max = 0;

/*
 * Backing store throttle when BS is exhausted
 */
unsigned int    vm_backing_store_low = 0;

unsigned int vm_pageout_out_of_line  = 0;
unsigned int vm_pageout_in_place  = 0;

unsigned int vm_page_steal_pageout_page = 0;

/*
 * ENCRYPTED SWAP:
 * counters and statistics...
 */
unsigned long vm_page_decrypt_counter = 0;
unsigned long vm_page_decrypt_for_upl_counter = 0;
unsigned long vm_page_encrypt_counter = 0;
unsigned long vm_page_encrypt_abort_counter = 0;
unsigned long vm_page_encrypt_already_encrypted_counter = 0;
boolean_t vm_pages_encrypted = FALSE; /* are there encrypted pages ? */

struct  vm_pageout_queue vm_pageout_queue_internal;
struct  vm_pageout_queue vm_pageout_queue_external;

unsigned int vm_page_speculative_target = 0;

vm_object_t     vm_pageout_scan_wants_object = VM_OBJECT_NULL;

boolean_t (* volatile consider_buffer_cache_collect)(int) = NULL;

#if DEVELOPMENT || DEBUG
unsigned long vm_cs_validated_resets = 0;
#endif

int     vm_debug_events = 0;


/*
 *      Routine:        vm_backing_store_disable
 *      Purpose:
 *              Suspend non-privileged threads wishing to extend
 *              backing store when we are low on backing store
 *              (Synchronized by caller)
 */
void
vm_backing_store_disable(
        boolean_t       disable)
{
        if(disable) {
                vm_backing_store_low = 1;
        } else {
                if(vm_backing_store_low) {
                        vm_backing_store_low = 0;
                        thread_wakeup((event_t) &vm_backing_store_low);
                }
        }
}


#if MACH_CLUSTER_STATS
unsigned long vm_pageout_cluster_dirtied = 0;
unsigned long vm_pageout_cluster_cleaned = 0;
unsigned long vm_pageout_cluster_collisions = 0;
unsigned long vm_pageout_cluster_clusters = 0;
unsigned long vm_pageout_cluster_conversions = 0;
unsigned long vm_pageout_target_collisions = 0;
unsigned long vm_pageout_target_page_dirtied = 0;
unsigned long vm_pageout_target_page_freed = 0;
#define CLUSTER_STAT(clause)    clause
#else   /* MACH_CLUSTER_STATS */
#define CLUSTER_STAT(clause)
#endif  /* MACH_CLUSTER_STATS */

/* 
 *      Routine:        vm_pageout_object_terminate
 *      Purpose:
 *              Destroy the pageout_object, and perform all of the
 *              required cleanup actions.
 * 
 *      In/Out conditions:
 *              The object must be locked, and will be returned locked.
 */
void
vm_pageout_object_terminate(
        vm_object_t     object)
{
        vm_object_t     shadow_object;

        /*
         * Deal with the deallocation (last reference) of a pageout object
         * (used for cleaning-in-place) by dropping the paging references/
         * freeing pages in the original object.
         */

        assert(object->pageout);
        shadow_object = object->shadow;
        vm_object_lock(shadow_object);

        while (!queue_empty(&object->memq)) {
                vm_page_t               p, m;
                vm_object_offset_t      offset;

                p = (vm_page_t) queue_first(&object->memq);

                assert(p->private);
                assert(p->pageout);
                p->pageout = FALSE;
                assert(!p->cleaning);

                offset = p->offset;
                VM_PAGE_FREE(p);
                p = VM_PAGE_NULL;

                m = vm_page_lookup(shadow_object,
                        offset + object->vo_shadow_offset);

                if(m == VM_PAGE_NULL)
                        continue;
                assert(m->cleaning);
                /* used as a trigger on upl_commit etc to recognize the */
                /* pageout daemon's subseqent desire to pageout a cleaning */
                /* page.  When the bit is on the upl commit code will   */
                /* respect the pageout bit in the target page over the  */
                /* caller's page list indication */
                m->dump_cleaning = FALSE;

                assert((m->dirty) || (m->precious) ||
                                (m->busy && m->cleaning));

                /*
                 * Handle the trusted pager throttle.
                 * Also decrement the burst throttle (if external).
                 */
                vm_page_lock_queues();
                if (m->laundry) {
                        vm_pageout_throttle_up(m);
                }

                /*
                 * Handle the "target" page(s). These pages are to be freed if
                 * successfully cleaned. Target pages are always busy, and are
                 * wired exactly once. The initial target pages are not mapped,
                 * (so cannot be referenced or modified) but converted target
                 * pages may have been modified between the selection as an
                 * adjacent page and conversion to a target.
                 */
                if (m->pageout) {
                        assert(m->busy);
                        assert(m->wire_count == 1);
                        m->cleaning = FALSE;
                        m->encrypted_cleaning = FALSE;
                        m->pageout = FALSE;
#if MACH_CLUSTER_STATS
                        if (m->wanted) vm_pageout_target_collisions++;
#endif
                        /*
                         * Revoke all access to the page. Since the object is
                         * locked, and the page is busy, this prevents the page
                         * from being dirtied after the pmap_disconnect() call
                         * returns.
                         *
                         * Since the page is left "dirty" but "not modifed", we
                         * can detect whether the page was redirtied during
                         * pageout by checking the modify state.
                         */
                        if (pmap_disconnect(m->phys_page) & VM_MEM_MODIFIED)
                              m->dirty = TRUE;
                        else
                              m->dirty = FALSE;

                        if (m->dirty) {
                                CLUSTER_STAT(vm_pageout_target_page_dirtied++;)
                                vm_page_unwire(m, TRUE);        /* reactivates */
                                VM_STAT_INCR(reactivations);
                                PAGE_WAKEUP_DONE(m);
                        } else {
                                CLUSTER_STAT(vm_pageout_target_page_freed++;)
                                vm_page_free(m);/* clears busy, etc. */
                        }
                        vm_page_unlock_queues();
                        continue;
                }
                /*
                 * Handle the "adjacent" pages. These pages were cleaned in
                 * place, and should be left alone.
                 * If prep_pin_count is nonzero, then someone is using the
                 * page, so make it active.
                 */
                if (!m->active && !m->inactive && !m->throttled && !m->private) {
                        if (m->reference)
                                vm_page_activate(m);
                        else
                                vm_page_deactivate(m);
                }
                if (m->overwriting) {
                        /*
                         * the (COPY_OUT_FROM == FALSE) request_page_list case
                         */
                        if (m->busy) {
                                /*
                                 * We do not re-set m->dirty !
                                 * The page was busy so no extraneous activity
                                 * could have occurred. COPY_INTO is a read into the
                                 * new pages. CLEAN_IN_PLACE does actually write
                                 * out the pages but handling outside of this code
                                 * will take care of resetting dirty. We clear the
                                 * modify however for the Programmed I/O case.
                                 */
                                pmap_clear_modify(m->phys_page);

                                m->busy = FALSE;
                                m->absent = FALSE;
                        } else {
                                /*
                                 * alternate (COPY_OUT_FROM == FALSE) request_page_list case
                                 * Occurs when the original page was wired
                                 * at the time of the list request
                                 */
                                 assert(VM_PAGE_WIRED(m));
                                 vm_page_unwire(m, TRUE);       /* reactivates */
                        }
                        m->overwriting = FALSE;
                } else {
                        /*
                         * Set the dirty state according to whether or not the page was
                         * modified during the pageout. Note that we purposefully do
                         * NOT call pmap_clear_modify since the page is still mapped.
                         * If the page were to be dirtied between the 2 calls, this
                         * this fact would be lost. This code is only necessary to
                         * maintain statistics, since the pmap module is always
                         * consulted if m->dirty is false.
                         */
#if MACH_CLUSTER_STATS
                        m->dirty = pmap_is_modified(m->phys_page);

                        if (m->dirty)   vm_pageout_cluster_dirtied++;
                        else            vm_pageout_cluster_cleaned++;
                        if (m->wanted)  vm_pageout_cluster_collisions++;
#else
                        m->dirty = 0;
#endif
                }
                if (m->encrypted_cleaning == TRUE) {
                        m->encrypted_cleaning = FALSE;
                        m->busy = FALSE;
                }
                m->cleaning = FALSE;

                /*
                 * Wakeup any thread waiting for the page to be un-cleaning.
                 */
                PAGE_WAKEUP(m);
                vm_page_unlock_queues();
        }
        /*
         * Account for the paging reference taken in vm_paging_object_allocate.
         */
        vm_object_activity_end(shadow_object);
        vm_object_unlock(shadow_object);

        assert(object->ref_count == 0);
        assert(object->paging_in_progress == 0);
        assert(object->activity_in_progress == 0);
        assert(object->resident_page_count == 0);
        return;
}

/*
 * Routine:     vm_pageclean_setup
 *
 * Purpose:     setup a page to be cleaned (made non-dirty), but not
 *              necessarily flushed from the VM page cache.
 *              This is accomplished by cleaning in place.
 *
 *              The page must not be busy, and new_object
 *              must be locked.
 *
 */
void
vm_pageclean_setup(
        vm_page_t               m,
        vm_page_t               new_m,
        vm_object_t             new_object,
        vm_object_offset_t      new_offset)
{
        assert(!m->busy);
#if 0
        assert(!m->cleaning);
#endif

        XPR(XPR_VM_PAGEOUT,
    "vm_pageclean_setup, obj 0x%X off 0x%X page 0x%X new 0x%X new_off 0x%X\n",
                m->object, m->offset, m, 
                new_m, new_offset);

        pmap_clear_modify(m->phys_page);

        /*
         * Mark original page as cleaning in place.
         */
        m->cleaning = TRUE;
        m->dirty = TRUE;
        m->precious = FALSE;

        /*
         * Convert the fictitious page to a private shadow of
         * the real page.
         */
        assert(new_m->fictitious);
        assert(new_m->phys_page == vm_page_fictitious_addr);
        new_m->fictitious = FALSE;
        new_m->private = TRUE;
        new_m->pageout = TRUE;
        new_m->phys_page = m->phys_page;

        vm_page_lockspin_queues();
        vm_page_wire(new_m);
        vm_page_unlock_queues();

        vm_page_insert(new_m, new_object, new_offset);
        assert(!new_m->wanted);
        new_m->busy = FALSE;
}

/*
 *      Routine:        vm_pageout_initialize_page
 *      Purpose:
 *              Causes the specified page to be initialized in
 *              the appropriate memory object. This routine is used to push
 *              pages into a copy-object when they are modified in the
 *              permanent object.
 *
 *              The page is moved to a temporary object and paged out.
 *
 *      In/out conditions:
 *              The page in question must not be on any pageout queues.
 *              The object to which it belongs must be locked.
 *              The page must be busy, but not hold a paging reference.
 *
 *      Implementation:
 *              Move this page to a completely new object.
 */
void    
vm_pageout_initialize_page(
        vm_page_t       m)
{
        vm_object_t             object;
        vm_object_offset_t      paging_offset;
        vm_page_t               holding_page;
        memory_object_t         pager;

        XPR(XPR_VM_PAGEOUT,
                "vm_pageout_initialize_page, page 0x%X\n",
                m, 0, 0, 0, 0);
        assert(m->busy);

        /*
         *      Verify that we really want to clean this page
         */
        assert(!m->absent);
        assert(!m->error);
        assert(m->dirty);

        /*
         *      Create a paging reference to let us play with the object.
         */
        object = m->object;
        paging_offset = m->offset + object->paging_offset;

        if (m->absent || m->error || m->restart || (!m->dirty && !m->precious)) {
                VM_PAGE_FREE(m);
                panic("reservation without pageout?"); /* alan */
                vm_object_unlock(object);

                return;
        }

        /*
         * If there's no pager, then we can't clean the page.  This should 
         * never happen since this should be a copy object and therefore not
         * an external object, so the pager should always be there.
         */

        pager = object->pager;

        if (pager == MEMORY_OBJECT_NULL) {
                VM_PAGE_FREE(m);
                panic("missing pager for copy object");
                return;
        }

        /* set the page for future call to vm_fault_list_request */
        vm_object_paging_begin(object);
        holding_page = NULL;

        pmap_clear_modify(m->phys_page);
        m->dirty = TRUE;
        m->busy = TRUE;
        m->list_req_pending = TRUE;
        m->cleaning = TRUE;
        m->pageout = TRUE;

        vm_page_lockspin_queues();
        vm_page_wire(m);
        vm_page_unlock_queues();

        vm_object_unlock(object);

        /*
         *      Write the data to its pager.
         *      Note that the data is passed by naming the new object,
         *      not a virtual address; the pager interface has been
         *      manipulated to use the "internal memory" data type.
         *      [The object reference from its allocation is donated
         *      to the eventual recipient.]
         */
        memory_object_data_initialize(pager, paging_offset, PAGE_SIZE);

        vm_object_lock(object);
        vm_object_paging_end(object);
}

#if     MACH_CLUSTER_STATS
#define MAXCLUSTERPAGES 16
struct {
        unsigned long pages_in_cluster;
        unsigned long pages_at_higher_offsets;
        unsigned long pages_at_lower_offsets;
} cluster_stats[MAXCLUSTERPAGES];
#endif  /* MACH_CLUSTER_STATS */


/*
 * vm_pageout_cluster:
 *
 * Given a page, queue it to the appropriate I/O thread,
 * which will page it out and attempt to clean adjacent pages
 * in the same operation.
 *
 * The page must be busy, and the object and queues locked. We will take a
 * paging reference to prevent deallocation or collapse when we
 * release the object lock back at the call site.  The I/O thread
 * is responsible for consuming this reference
 *
 * The page must not be on any pageout queue.
 */

void
vm_pageout_cluster(vm_page_t m)
{
        vm_object_t     object = m->object;
        struct          vm_pageout_queue *q;


        XPR(XPR_VM_PAGEOUT,
                "vm_pageout_cluster, object 0x%X offset 0x%X page 0x%X\n",
                object, m->offset, m, 0, 0);

        VM_PAGE_CHECK(m);
#if DEBUG
        lck_mtx_assert(&vm_page_queue_lock, LCK_MTX_ASSERT_OWNED);
#endif
        vm_object_lock_assert_exclusive(object);

        /*
         * Only a certain kind of page is appreciated here.
         */
        assert(m->busy && (m->dirty || m->precious) && (!VM_PAGE_WIRED(m)));
        assert(!m->cleaning && !m->pageout);
#ifndef CONFIG_FREEZE
        assert(!m->inactive && !m->active);
        assert(!m->throttled);
#endif

        /*
         * protect the object from collapse - 
         * locking in the object's paging_offset.
         */
        vm_object_paging_begin(object);

        /*
         * set the page for future call to vm_fault_list_request
         * page should already be marked busy
         */
        vm_page_wire(m);
        m->list_req_pending = TRUE;
        m->cleaning = TRUE;
        m->pageout = TRUE;

        if (object->internal == TRUE)
                q = &vm_pageout_queue_internal;
        else
                q = &vm_pageout_queue_external;

        /* 
         * pgo_laundry count is tied to the laundry bit
         */
        m->laundry = TRUE;
        q->pgo_laundry++;

        m->pageout_queue = TRUE;
        queue_enter(&q->pgo_pending, m, vm_page_t, pageq);
        
        if (q->pgo_idle == TRUE) {
                q->pgo_idle = FALSE;
                thread_wakeup((event_t) &q->pgo_pending);
        }

        VM_PAGE_CHECK(m);
}


unsigned long vm_pageout_throttle_up_count = 0;

/*
 * A page is back from laundry or we are stealing it back from 
 * the laundering state.  See if there are some pages waiting to
 * go to laundry and if we can let some of them go now.
 *
 * Object and page queues must be locked.
 */
void
vm_pageout_throttle_up(
       vm_page_t       m)
{
       struct vm_pageout_queue *q;

       assert(m->object != VM_OBJECT_NULL);
       assert(m->object != kernel_object);

       vm_pageout_throttle_up_count++;

       if (m->object->internal == TRUE)
               q = &vm_pageout_queue_internal;
       else
               q = &vm_pageout_queue_external;

       if (m->pageout_queue == TRUE) {

               queue_remove(&q->pgo_pending, m, vm_page_t, pageq);
               m->pageout_queue = FALSE;

               m->pageq.next = NULL;
               m->pageq.prev = NULL;

               vm_object_paging_end(m->object);
       }

       if ( m->laundry == TRUE ) {

               m->laundry = FALSE;
               q->pgo_laundry--;

               if (q->pgo_throttled == TRUE) {
                       q->pgo_throttled = FALSE;
                       thread_wakeup((event_t) &q->pgo_laundry);
               }
               if (q->pgo_draining == TRUE && q->pgo_laundry == 0) {
                       q->pgo_draining = FALSE;
                       thread_wakeup((event_t) (&q->pgo_laundry+1));
               }
        }
}


/*
 * VM memory pressure monitoring.
 *
 * vm_pageout_scan() keeps track of the number of pages it considers and
 * reclaims, in the currently active vm_pageout_stat[vm_pageout_stat_now].
 *
 * compute_memory_pressure() is called every second from compute_averages()
 * and moves "vm_pageout_stat_now" forward, to start accumulating the number
 * of recalimed pages in a new vm_pageout_stat[] bucket.
 *
 * mach_vm_pressure_monitor() collects past statistics about memory pressure.
 * The caller provides the number of seconds ("nsecs") worth of statistics
 * it wants, up to 30 seconds.
 * It computes the number of pages reclaimed in the past "nsecs" seconds and
 * also returns the number of pages the system still needs to reclaim at this
 * moment in time.
 */
#define VM_PAGEOUT_STAT_SIZE    31
struct vm_pageout_stat {
        unsigned int considered;
        unsigned int reclaimed;
} vm_pageout_stats[VM_PAGEOUT_STAT_SIZE] = {{0,0}, };
unsigned int vm_pageout_stat_now = 0;
unsigned int vm_memory_pressure = 0;

#define VM_PAGEOUT_STAT_BEFORE(i) \
        (((i) == 0) ? VM_PAGEOUT_STAT_SIZE - 1 : (i) - 1)
#define VM_PAGEOUT_STAT_AFTER(i) \
        (((i) == VM_PAGEOUT_STAT_SIZE - 1) ? 0 : (i) + 1)

/*
 * Called from compute_averages().
 */
void
compute_memory_pressure(
        __unused void *arg)
{
        unsigned int vm_pageout_next;

        vm_memory_pressure =
                vm_pageout_stats[VM_PAGEOUT_STAT_BEFORE(vm_pageout_stat_now)].reclaimed;

        commpage_set_memory_pressure( vm_memory_pressure );

        /* move "now" forward */
        vm_pageout_next = VM_PAGEOUT_STAT_AFTER(vm_pageout_stat_now);
        vm_pageout_stats[vm_pageout_next].considered = 0;
        vm_pageout_stats[vm_pageout_next].reclaimed = 0;
        vm_pageout_stat_now = vm_pageout_next;
}

unsigned int
mach_vm_ctl_page_free_wanted(void)
{
        unsigned int page_free_target, page_free_count, page_free_wanted;

        page_free_target = vm_page_free_target;
        page_free_count = vm_page_free_count;
        if (page_free_target > page_free_count) {
                page_free_wanted = page_free_target - page_free_count;
        } else {
                page_free_wanted = 0;
        }

        return page_free_wanted;
}

kern_return_t
mach_vm_pressure_monitor(
        boolean_t       wait_for_pressure,
        unsigned int    nsecs_monitored,
        unsigned int    *pages_reclaimed_p,
        unsigned int    *pages_wanted_p)
{
        wait_result_t   wr;
        unsigned int    vm_pageout_then, vm_pageout_now;
        unsigned int    pages_reclaimed;

        /*
         * We don't take the vm_page_queue_lock here because we don't want
         * vm_pressure_monitor() to get in the way of the vm_pageout_scan()
         * thread when it's trying to reclaim memory.  We don't need fully
         * accurate monitoring anyway...
         */

        if (wait_for_pressure) {
                /* wait until there's memory pressure */
                while (vm_page_free_count >= vm_page_free_target) {
                        wr = assert_wait((event_t) &vm_page_free_wanted,
                                         THREAD_INTERRUPTIBLE);
                        if (wr == THREAD_WAITING) {
                                wr = thread_block(THREAD_CONTINUE_NULL);
                        }
                        if (wr == THREAD_INTERRUPTED) {
                                return KERN_ABORTED;
                        }
                        if (wr == THREAD_AWAKENED) {
                                /*
                                 * The memory pressure might have already
                                 * been relieved but let's not block again
                                 * and let's report that there was memory
                                 * pressure at some point.
                                 */
                                break;
                        }
                }
        }

        /* provide the number of pages the system wants to reclaim */
        if (pages_wanted_p != NULL) {
                *pages_wanted_p = mach_vm_ctl_page_free_wanted();
        }

        if (pages_reclaimed_p == NULL) {
                return KERN_SUCCESS;
        }

        /* provide number of pages reclaimed in the last "nsecs_monitored" */
        do {
                vm_pageout_now = vm_pageout_stat_now;
                pages_reclaimed = 0;
                for (vm_pageout_then =
                             VM_PAGEOUT_STAT_BEFORE(vm_pageout_now);
                     vm_pageout_then != vm_pageout_now &&
                             nsecs_monitored-- != 0;
                     vm_pageout_then =
                             VM_PAGEOUT_STAT_BEFORE(vm_pageout_then)) {
                        pages_reclaimed += vm_pageout_stats[vm_pageout_then].reclaimed;
                }
        } while (vm_pageout_now != vm_pageout_stat_now);
        *pages_reclaimed_p = pages_reclaimed;

        return KERN_SUCCESS;
}

/* Page States: Used below to maintain the page state
   before it's removed from it's Q. This saved state
   helps us do the right accounting in certain cases
*/

#define PAGE_STATE_SPECULATIVE          1
#define PAGE_STATE_ZEROFILL             2
#define PAGE_STATE_INACTIVE             3
#define PAGE_STATE_INACTIVE_FIRST       4

#define VM_PAGEOUT_SCAN_HANDLE_REUSABLE_PAGE(m)                         \
        MACRO_BEGIN                                                     \
        /*                                                              \
         * If a "reusable" page somehow made it back into               \
         * the active queue, it's been re-used and is not               \
         * quite re-usable.                                             \
         * If the VM object was "all_reusable", consider it             \
         * as "all re-used" instead of converting it to                 \
         * "partially re-used", which could be expensive.               \
         */                                                             \
        if ((m)->reusable ||                                            \
            (m)->object->all_reusable) {                                \
                vm_object_reuse_pages((m)->object,                      \
                                      (m)->offset,                      \
                                      (m)->offset + PAGE_SIZE_64,       \
                                      FALSE);                           \
        }                                                               \
        MACRO_END


#define VM_PAGEOUT_DELAYED_UNLOCK_LIMIT         128
#define VM_PAGEOUT_DELAYED_UNLOCK_LIMIT_MAX     1024

#define FCS_IDLE                0
#define FCS_DELAYED             1
#define FCS_DEADLOCK_DETECTED   2

struct flow_control {
        int             state;
        mach_timespec_t ts;
};


/*
 *      vm_pageout_scan does the dirty work for the pageout daemon.
 *      It returns with vm_page_queue_free_lock held and
 *      vm_page_free_wanted == 0.
 */
void
vm_pageout_scan(void)
{
        unsigned int loop_count = 0;
        unsigned int inactive_burst_count = 0;
        unsigned int active_burst_count = 0;
        unsigned int reactivated_this_call;
        unsigned int reactivate_limit;
        vm_page_t   local_freeq = NULL;
        int         local_freed = 0;
        int         delayed_unlock;
        int         delayed_unlock_limit = 0;
        int         refmod_state = 0;
        int     vm_pageout_deadlock_target = 0;
        struct  vm_pageout_queue *iq;
        struct  vm_pageout_queue *eq;
        struct  vm_speculative_age_q *sq;
        struct  flow_control    flow_control = { 0, { 0, 0 } };
        boolean_t inactive_throttled = FALSE;
        boolean_t try_failed;
        mach_timespec_t ts;
        unsigned        int msecs = 0;
        vm_object_t     object;
        vm_object_t     last_object_tried;
        uint64_t        zf_ratio;
        uint64_t        zf_run_count;
        uint32_t        catch_up_count = 0;
        uint32_t        inactive_reclaim_run;
        boolean_t       forced_reclaim;
        int             page_prev_state = 0;
        int             cache_evict_throttle = 0;
        uint32_t        vm_pageout_inactive_external_forced_reactivate_limit = 0;

        VM_DEBUG_EVENT(vm_pageout_scan, VM_PAGEOUT_SCAN, DBG_FUNC_START,
                       vm_pageout_speculative_clean, vm_pageout_inactive_clean,
                       vm_pageout_inactive_dirty_internal, vm_pageout_inactive_dirty_external);

        flow_control.state = FCS_IDLE;
        iq = &vm_pageout_queue_internal;
        eq = &vm_pageout_queue_external;
        sq = &vm_page_queue_speculative[VM_PAGE_SPECULATIVE_AGED_Q];


        XPR(XPR_VM_PAGEOUT, "vm_pageout_scan\n", 0, 0, 0, 0, 0);

        
        vm_page_lock_queues();
        delayed_unlock = 1;     /* must be nonzero if Qs are locked, 0 if unlocked */

        /*
         *      Calculate the max number of referenced pages on the inactive
         *      queue that we will reactivate.
         */
        reactivated_this_call = 0;
        reactivate_limit = VM_PAGE_REACTIVATE_LIMIT(vm_page_active_count +
                                                    vm_page_inactive_count);
        inactive_reclaim_run = 0;


        /*
         *      We want to gradually dribble pages from the active queue
         *      to the inactive queue.  If we let the inactive queue get
         *      very small, and then suddenly dump many pages into it,
         *      those pages won't get a sufficient chance to be referenced
         *      before we start taking them from the inactive queue.
         *
         *      We must limit the rate at which we send pages to the pagers
         *      so that we don't tie up too many pages in the I/O queues.
         *      We implement a throttling mechanism using the laundry count
         *      to limit the number of pages outstanding to the default
         *      and external pagers.  We can bypass the throttles and look
         *      for clean pages if the pageout queues don't drain in a timely
         *      fashion since this may indicate that the pageout paths are
         *      stalled waiting for memory, which only we can provide.
         */


Restart:
        assert(delayed_unlock!=0);
        
        /*
         *      A page is "zero-filled" if it was not paged in from somewhere,
         *      and it belongs to an object at least VM_ZF_OBJECT_SIZE_THRESHOLD big.
         *      Recalculate the zero-filled page ratio.  We use this to apportion
         *      victimized pages between the normal and zero-filled inactive
         *      queues according to their relative abundance in memory.  Thus if a task
         *      is flooding memory with zf pages, we begin to hunt them down.
         *      It would be better to throttle greedy tasks at a higher level,
         *      but at the moment mach vm cannot do this.
         */
        {
                uint64_t  total  = vm_page_active_count + vm_page_inactive_count;
                uint64_t  normal = total - vm_zf_count;

                /* zf_ratio is the number of zf pages we victimize per normal page */
                
                if (vm_zf_count < vm_accellerate_zf_pageout_trigger)
                        zf_ratio = 0;
                else if ((vm_zf_count <= normal) || (normal == 0))
                        zf_ratio = 1;
                else 
                        zf_ratio = vm_zf_count / normal;
                        
                zf_run_count = 0;
        }
        
        /*
         *      Recalculate vm_page_inactivate_target.
         */
        vm_page_inactive_target = VM_PAGE_INACTIVE_TARGET(vm_page_active_count +
                                                          vm_page_inactive_count +
                                                          vm_page_speculative_count);
        /*
         * don't want to wake the pageout_scan thread up everytime we fall below
         * the targets... set a low water mark at 0.25% below the target
         */
        vm_page_inactive_min = vm_page_inactive_target - (vm_page_inactive_target / 400);

        if (vm_page_speculative_percentage > 50)
                vm_page_speculative_percentage = 50;
        else if (vm_page_speculative_percentage <= 0)
                vm_page_speculative_percentage = 1;

        vm_page_speculative_target = VM_PAGE_SPECULATIVE_TARGET(vm_page_active_count +
                                                                vm_page_inactive_count);

        vm_pageout_inactive_external_forced_reactivate_limit = vm_page_active_count + vm_page_inactive_count;

        object = NULL;
        last_object_tried = NULL;
        try_failed = FALSE;
        
        if ((vm_page_inactive_count + vm_page_speculative_count) < VM_PAGE_INACTIVE_HEALTHY_LIMIT(vm_page_active_count))
                catch_up_count = vm_page_inactive_count + vm_page_speculative_count;
        else
                catch_up_count = 0;
                    
        for (;;) {
                vm_page_t m;

                DTRACE_VM2(rev, int, 1, (uint64_t *), NULL);

                if (delayed_unlock == 0) {
                        vm_page_lock_queues();
                        delayed_unlock = 1;
                }
                if (vm_upl_wait_for_pages < 0)
                        vm_upl_wait_for_pages = 0;

                delayed_unlock_limit = VM_PAGEOUT_DELAYED_UNLOCK_LIMIT + vm_upl_wait_for_pages;

                if (delayed_unlock_limit > VM_PAGEOUT_DELAYED_UNLOCK_LIMIT_MAX)
                        delayed_unlock_limit = VM_PAGEOUT_DELAYED_UNLOCK_LIMIT_MAX;

                /*
                 * Move pages from active to inactive if we're below the target
                 */
                if ((vm_page_inactive_count + vm_page_speculative_count) >= vm_page_inactive_target)
                        goto done_moving_active_pages;

                if (object != NULL) {
                        vm_object_unlock(object);
                        object = NULL;
                        vm_pageout_scan_wants_object = VM_OBJECT_NULL;
                }
                /*
                 * Don't sweep through active queue more than the throttle
                 * which should be kept relatively low
                 */
                active_burst_count = MIN(vm_pageout_burst_active_throttle,
                                         vm_page_active_count);

                VM_DEBUG_EVENT(vm_pageout_balance, VM_PAGEOUT_BALANCE, DBG_FUNC_START,
                               vm_pageout_inactive, vm_pageout_inactive_used, vm_page_free_count, local_freed);

                VM_DEBUG_EVENT(vm_pageout_balance, VM_PAGEOUT_BALANCE, DBG_FUNC_NONE,
                               vm_pageout_speculative_clean, vm_pageout_inactive_clean,
                               vm_pageout_inactive_dirty_internal, vm_pageout_inactive_dirty_external);

                while (!queue_empty(&vm_page_queue_active) && active_burst_count--) {

                        vm_pageout_active++;

                        m = (vm_page_t) queue_first(&vm_page_queue_active);

                        assert(m->active && !m->inactive);
                        assert(!m->laundry);
                        assert(m->object != kernel_object);
                        assert(m->phys_page != vm_page_guard_addr);

                        DTRACE_VM2(scan, int, 1, (uint64_t *), NULL);

                        /*
                         * The page might be absent or busy,
                         * but vm_page_deactivate can handle that.
                         */
                        vm_page_deactivate(m);

                        if (delayed_unlock++ > delayed_unlock_limit) {

                                if (local_freeq) {
                                        vm_page_unlock_queues();
                                        
                                        VM_DEBUG_EVENT(vm_pageout_freelist, VM_PAGEOUT_FREELIST, DBG_FUNC_START,
                                                       vm_page_free_count, local_freed, delayed_unlock_limit, 1);

                                        vm_page_free_list(local_freeq, TRUE);
                                        
                                        VM_DEBUG_EVENT(vm_pageout_freelist, VM_PAGEOUT_FREELIST, DBG_FUNC_END,
                                                       vm_page_free_count, 0, 0, 1);

                                        local_freeq = NULL;
                                        local_freed = 0;
                                        vm_page_lock_queues();
                                } else
                                        lck_mtx_yield(&vm_page_queue_lock);

                                delayed_unlock = 1;

                                /*
                                 * continue the while loop processing
                                 * the active queue... need to hold
                                 * the page queues lock
                                 */
                        }
                }

                VM_DEBUG_EVENT(vm_pageout_balance, VM_PAGEOUT_BALANCE, DBG_FUNC_END,
                               vm_page_active_count, vm_page_inactive_count, vm_page_speculative_count, vm_page_inactive_target);


                /**********************************************************************
                 * above this point we're playing with the active queue
                 * below this point we're playing with the throttling mechanisms
                 * and the inactive queue
                 **********************************************************************/

done_moving_active_pages:

                if (vm_page_free_count + local_freed >= vm_page_free_target) {
                        if (object != NULL) {
                                vm_object_unlock(object);
                                object = NULL;
                        }
                        vm_pageout_scan_wants_object = VM_OBJECT_NULL;

                        if (local_freeq) {
                                vm_page_unlock_queues();
                                        
                                VM_DEBUG_EVENT(vm_pageout_freelist, VM_PAGEOUT_FREELIST, DBG_FUNC_START,
                                               vm_page_free_count, local_freed, delayed_unlock_limit, 2);

                                vm_page_free_list(local_freeq, TRUE);
                                        
                                VM_DEBUG_EVENT(vm_pageout_freelist, VM_PAGEOUT_FREELIST, DBG_FUNC_END,
                                               vm_page_free_count, local_freed, 0, 2);

                                local_freeq = NULL;
                                local_freed = 0;
                                vm_page_lock_queues();
                        }
                        /*
                         * recalculate vm_page_inactivate_target
                         */
                        vm_page_inactive_target = VM_PAGE_INACTIVE_TARGET(vm_page_active_count +
                                                                          vm_page_inactive_count +
                                                                          vm_page_speculative_count);
#ifndef CONFIG_EMBEDDED
                        if (((vm_page_inactive_count + vm_page_speculative_count) < vm_page_inactive_target) &&
                            !queue_empty(&vm_page_queue_active)) {
                                /*
                                 * inactive target still not met... keep going
                                 * until we get the queues balanced...
                                 */
                                continue;
                        }
#endif
                        lck_mtx_lock(&vm_page_queue_free_lock);

                        if ((vm_page_free_count >= vm_page_free_target) &&
                            (vm_page_free_wanted == 0) && (vm_page_free_wanted_privileged == 0)) {
                                /*
                                 * done - we have met our target *and*
                                 * there is no one waiting for a page.
                                 */
                                vm_page_unlock_queues();

                                thread_wakeup((event_t) &vm_pageout_garbage_collect);

                                assert(vm_pageout_scan_wants_object == VM_OBJECT_NULL);

                                VM_DEBUG_EVENT(vm_pageout_scan, VM_PAGEOUT_SCAN, DBG_FUNC_NONE,
                                               vm_pageout_inactive, vm_pageout_inactive_used, 0, 0);
                                VM_DEBUG_EVENT(vm_pageout_scan, VM_PAGEOUT_SCAN, DBG_FUNC_END,
                                               vm_pageout_speculative_clean, vm_pageout_inactive_clean,
                                               vm_pageout_inactive_dirty_internal, vm_pageout_inactive_dirty_external);

                                return;
                        }
                        lck_mtx_unlock(&vm_page_queue_free_lock);
                }
                
                /*
                 * Before anything, we check if we have any ripe volatile 
                 * objects around. If so, try to purge the first object.
                 * If the purge fails, fall through to reclaim a page instead.
                 * If the purge succeeds, go back to the top and reevalute
                 * the new memory situation.
                 */
                assert (available_for_purge>=0);
                if (available_for_purge)
                {
                        if (object != NULL) {
                                vm_object_unlock(object);
                                object = NULL;
                        }

                        VM_DEBUG_EVENT(vm_pageout_purgeone, VM_PAGEOUT_PURGEONE, DBG_FUNC_START, vm_page_free_count, 0, 0, 0);

                        if (TRUE == vm_purgeable_object_purge_one()) {

                                VM_DEBUG_EVENT(vm_pageout_purgeone, VM_PAGEOUT_PURGEONE, DBG_FUNC_END, vm_page_free_count, 0, 0, 0);

                                continue;
                        }
                        VM_DEBUG_EVENT(vm_pageout_purgeone, VM_PAGEOUT_PURGEONE, DBG_FUNC_END, 0, 0, 0, -1);
                }
                if (queue_empty(&sq->age_q) && vm_page_speculative_count) {
                        /*
                         * try to pull pages from the aging bins...
                         * see vm_page.h for an explanation of how
                         * this mechanism works
                         */
                        struct vm_speculative_age_q     *aq;
                        mach_timespec_t ts_fully_aged;
                        boolean_t       can_steal = FALSE;
                        int num_scanned_queues;
                       
                        aq = &vm_page_queue_speculative[speculative_steal_index];

                        num_scanned_queues = 0;
                        while (queue_empty(&aq->age_q) &&
                               num_scanned_queues++ != VM_PAGE_MAX_SPECULATIVE_AGE_Q) {

                                speculative_steal_index++;

                                if (speculative_steal_index > VM_PAGE_MAX_SPECULATIVE_AGE_Q)
                                        speculative_steal_index = VM_PAGE_MIN_SPECULATIVE_AGE_Q;
                                
                                aq = &vm_page_queue_speculative[speculative_steal_index];
                        }

                        if (num_scanned_queues == VM_PAGE_MAX_SPECULATIVE_AGE_Q + 1) {
                                /*
                                 * XXX We've scanned all the speculative
                                 * queues but still haven't found one
                                 * that is not empty, even though
                                 * vm_page_speculative_count is not 0.
                                 *
                                 * report the anomaly...
                                 */
                                printf("vm_pageout_scan: "
                                       "all speculative queues empty "
                                       "but count=%d.  Re-adjusting.\n",
                                       vm_page_speculative_count);
                                if (vm_page_speculative_count > vm_page_speculative_count_drift_max)
                                        vm_page_speculative_count_drift_max = vm_page_speculative_count;
                                vm_page_speculative_count_drifts++;
#if 6553678
                                Debugger("vm_pageout_scan: no speculative pages");
#endif
                                /* readjust... */
                                vm_page_speculative_count = 0;
                                /* ... and continue */
                                continue;
                        }

                        if (vm_page_speculative_count > vm_page_speculative_target)
                                can_steal = TRUE;
                        else {
                                ts_fully_aged.tv_sec = (VM_PAGE_MAX_SPECULATIVE_AGE_Q * vm_page_speculative_q_age_ms) / 1000;
                                ts_fully_aged.tv_nsec = ((VM_PAGE_MAX_SPECULATIVE_AGE_Q * vm_page_speculative_q_age_ms) % 1000)
                                                      * 1000 * NSEC_PER_USEC;

                                ADD_MACH_TIMESPEC(&ts_fully_aged, &aq->age_ts);

                                clock_sec_t sec;
                                clock_nsec_t nsec;
                                clock_get_system_nanotime(&sec, &nsec);
                                ts.tv_sec = (unsigned int) sec;
                                ts.tv_nsec = nsec;

                                if (CMP_MACH_TIMESPEC(&ts, &ts_fully_aged) >= 0)
                                        can_steal = TRUE;
                        }
                        if (can_steal == TRUE)
                                vm_page_speculate_ageit(aq);
                }
                if (queue_empty(&sq->age_q) && cache_evict_throttle == 0) {
                        int     pages_evicted;

                        if (object != NULL) {
                                vm_object_unlock(object);
                                object = NULL;
                        }
                        pages_evicted = vm_object_cache_evict(100, 10);

                        if (pages_evicted) {

                                vm_pageout_cache_evicted += pages_evicted;

                                VM_DEBUG_EVENT(vm_pageout_cache_evict, VM_PAGEOUT_CACHE_EVICT, DBG_FUNC_NONE,
                                               vm_page_free_count, pages_evicted, vm_pageout_cache_evicted, 0);

                                /*
                                 * we just freed up to 100 pages,
                                 * so go back to the top of the main loop
                                 * and re-evaulate the memory situation
                                 */
                                continue;
                        } else
                                cache_evict_throttle = 100;
                }
                if  (cache_evict_throttle)
                        cache_evict_throttle--;


                /*
                 * Sometimes we have to pause:
                 *      1) No inactive pages - nothing to do.
                 *      2) Flow control - default pageout queue is full
                 *      3) Loop control - no acceptable pages found on the inactive queue
                 *         within the last vm_pageout_burst_inactive_throttle iterations
                 */
                if (queue_empty(&vm_page_queue_inactive) && queue_empty(&vm_page_queue_zf) && queue_empty(&sq->age_q)) {
                        vm_pageout_scan_empty_throttle++;
                        msecs = vm_pageout_empty_wait;
                        goto vm_pageout_scan_delay;

                } else if (inactive_burst_count >= 
                           MIN(vm_pageout_burst_inactive_throttle,
                               (vm_page_inactive_count +
                                vm_page_speculative_count))) {
                        vm_pageout_scan_burst_throttle++;
                        msecs = vm_pageout_burst_wait;
                        goto vm_pageout_scan_delay;

                } else if (VM_PAGE_Q_THROTTLED(iq) && 
                                  VM_DYNAMIC_PAGING_ENABLED(memory_manager_default)) {
                        clock_sec_t sec;
                        clock_nsec_t nsec;

                        switch (flow_control.state) {

                        case FCS_IDLE:
reset_deadlock_timer:
                                ts.tv_sec = vm_pageout_deadlock_wait / 1000;
                                ts.tv_nsec = (vm_pageout_deadlock_wait % 1000) * 1000 * NSEC_PER_USEC;
                                clock_get_system_nanotime(&sec, &nsec);
                                flow_control.ts.tv_sec = (unsigned int) sec;
                                flow_control.ts.tv_nsec = nsec;
                                ADD_MACH_TIMESPEC(&flow_control.ts, &ts);
                                
                                flow_control.state = FCS_DELAYED;
                                msecs = vm_pageout_deadlock_wait;

                                break;
                                        
                        case FCS_DELAYED:
                                clock_get_system_nanotime(&sec, &nsec);
                                ts.tv_sec = (unsigned int) sec;
                                ts.tv_nsec = nsec;

                                if (CMP_MACH_TIMESPEC(&ts, &flow_control.ts) >= 0) {
                                        /*
                                         * the pageout thread for the default pager is potentially
                                         * deadlocked since the 
                                         * default pager queue has been throttled for more than the
                                         * allowable time... we need to move some clean pages or dirty
                                         * pages belonging to the external pagers if they aren't throttled
                                         * vm_page_free_wanted represents the number of threads currently
                                         * blocked waiting for pages... we'll move one page for each of
                                         * these plus a fixed amount to break the logjam... once we're done
                                         * moving this number of pages, we'll re-enter the FSC_DELAYED state
                                         * with a new timeout target since we have no way of knowing 
                                         * whether we've broken the deadlock except through observation
                                         * of the queue associated with the default pager... we need to
                                         * stop moving pages and allow the system to run to see what
                                         * state it settles into.
                                         */
                                        vm_pageout_deadlock_target = vm_pageout_deadlock_relief + vm_page_free_wanted + vm_page_free_wanted_privileged;
                                        vm_pageout_scan_deadlock_detected++;
                                        flow_control.state = FCS_DEADLOCK_DETECTED;

                                        thread_wakeup((event_t) &vm_pageout_garbage_collect);
                                        goto consider_inactive;
                                }
                                /*
                                 * just resniff instead of trying
                                 * to compute a new delay time... we're going to be
                                 * awakened immediately upon a laundry completion,
                                 * so we won't wait any longer than necessary
                                 */
                                msecs = vm_pageout_idle_wait;
                                break;

                        case FCS_DEADLOCK_DETECTED:
                                if (vm_pageout_deadlock_target)
                                        goto consider_inactive;
                                goto reset_deadlock_timer;

                        }
                        vm_pageout_scan_throttle++;
                        iq->pgo_throttled = TRUE;
vm_pageout_scan_delay:
                        if (object != NULL) {
                                vm_object_unlock(object);
                                object = NULL;
                        }
                        vm_pageout_scan_wants_object = VM_OBJECT_NULL;

                        if (local_freeq) {
                                vm_page_unlock_queues();

                                VM_DEBUG_EVENT(vm_pageout_freelist, VM_PAGEOUT_FREELIST, DBG_FUNC_START,
                                               vm_page_free_count, local_freed, delayed_unlock_limit, 3);

                                vm_page_free_list(local_freeq, TRUE);
                                        
                                VM_DEBUG_EVENT(vm_pageout_freelist, VM_PAGEOUT_FREELIST, DBG_FUNC_END,
                                               vm_page_free_count, local_freed, 0, 3);

                                local_freeq = NULL;
                                local_freed = 0;
                                vm_page_lock_queues();

                                if (flow_control.state == FCS_DELAYED &&
                                    !VM_PAGE_Q_THROTTLED(iq)) {
                                        flow_control.state = FCS_IDLE;
                                        vm_pageout_scan_throttle_aborted++;
                                        goto consider_inactive;
                                }
                        }

                        VM_CHECK_MEMORYSTATUS;

                        assert_wait_timeout((event_t) &iq->pgo_laundry, THREAD_INTERRUPTIBLE, msecs, 1000*NSEC_PER_USEC);
                        counter(c_vm_pageout_scan_block++);

                        vm_page_unlock_queues();

                        assert(vm_pageout_scan_wants_object == VM_OBJECT_NULL);

                        VM_DEBUG_EVENT(vm_pageout_thread_block, VM_PAGEOUT_THREAD_BLOCK, DBG_FUNC_START, 
                                       iq->pgo_laundry, iq->pgo_maxlaundry, msecs, 0);

                        thread_block(THREAD_CONTINUE_NULL);

                        VM_DEBUG_EVENT(vm_pageout_thread_block, VM_PAGEOUT_THREAD_BLOCK, DBG_FUNC_END,
                                       iq->pgo_laundry, iq->pgo_maxlaundry, msecs, 0);

                        vm_page_lock_queues();
                        delayed_unlock = 1;

                        iq->pgo_throttled = FALSE;

                        if (loop_count >= vm_page_inactive_count)
                                loop_count = 0;
                        inactive_burst_count = 0;

                        goto Restart;
                        /*NOTREACHED*/
                }


                flow_control.state = FCS_IDLE;
consider_inactive:
                vm_pageout_inactive_external_forced_reactivate_limit = MIN((vm_page_active_count + vm_page_inactive_count), 
                                                                            vm_pageout_inactive_external_forced_reactivate_limit);
                loop_count++;
                inactive_burst_count++;
                vm_pageout_inactive++;

                /* Choose a victim. */
                
                while (1) {     
                        m = NULL;
                        
                        if (VM_DYNAMIC_PAGING_ENABLED(memory_manager_default)) {
                                assert(vm_page_throttled_count == 0);
                                assert(queue_empty(&vm_page_queue_throttled));
                        }

                        /*
                         * The most eligible pages are ones we paged in speculatively,
                         * but which have not yet been touched.
                         */
                        if ( !queue_empty(&sq->age_q) ) {
                                m = (vm_page_t) queue_first(&sq->age_q);

                                page_prev_state = PAGE_STATE_SPECULATIVE;
                                break;
                        }
                        /*
                         * Time for a zero-filled inactive page?
                         */
                        if ( ((zf_run_count < zf_ratio) && vm_zf_queue_count >= zf_queue_min_count) ||
                             queue_empty(&vm_page_queue_inactive)) {
                                if ( !queue_empty(&vm_page_queue_zf) ) {
                                        m = (vm_page_t) queue_first(&vm_page_queue_zf);

                                        page_prev_state = PAGE_STATE_ZEROFILL;
                                        zf_run_count++;
                                        break;
                                }
                        }
                        /*
                         * It's either a normal inactive page or nothing.
                         */
                        if ( !queue_empty(&vm_page_queue_inactive) ) {
                                m = (vm_page_t) queue_first(&vm_page_queue_inactive);
                                
                                page_prev_state = PAGE_STATE_INACTIVE;
                                zf_run_count = 0;
                                break;
                        }

                        panic("vm_pageout: no victim");
                }
                VM_PAGE_QUEUES_REMOVE(m);

                assert(!m->laundry);
                assert(!m->private);
                assert(!m->fictitious);
                assert(m->object != kernel_object);
                assert(m->phys_page != vm_page_guard_addr);


                if (page_prev_state != PAGE_STATE_SPECULATIVE)
                        vm_pageout_stats[vm_pageout_stat_now].considered++;

                DTRACE_VM2(scan, int, 1, (uint64_t *), NULL);

                /*
                 * check to see if we currently are working
                 * with the same object... if so, we've
                 * already got the lock
                 */
                if (m->object != object) {
                        /*
                         * the object associated with candidate page is 
                         * different from the one we were just working
                         * with... dump the lock if we still own it
                         */
                        if (object != NULL) {
                                vm_object_unlock(object);
                                object = NULL;
                                vm_pageout_scan_wants_object = VM_OBJECT_NULL;
                        }
                        /*
                         * Try to lock object; since we've alread got the
                         * page queues lock, we can only 'try' for this one.
                         * if the 'try' fails, we need to do a mutex_pause
                         * to allow the owner of the object lock a chance to
                         * run... otherwise, we're likely to trip over this
                         * object in the same state as we work our way through
                         * the queue... clumps of pages associated with the same
                         * object are fairly typical on the inactive and active queues
                         */
                        if (!vm_object_lock_try_scan(m->object)) {
                                vm_page_t m_want = NULL;

                                vm_pageout_inactive_nolock++;

                                if (page_prev_state == PAGE_STATE_SPECULATIVE)
                                        page_prev_state = PAGE_STATE_INACTIVE_FIRST;

                                pmap_clear_reference(m->phys_page);
                                m->reference = FALSE;

                                /*
                                 * m->object must be stable since we hold the page queues lock...
                                 * we can update the scan_collisions field sans the object lock
                                 * since it is a separate field and this is the only spot that does
                                 * a read-modify-write operation and it is never executed concurrently...
                                 * we can asynchronously set this field to 0 when creating a UPL, so it
                                 * is possible for the value to be a bit non-determistic, but that's ok
                                 * since it's only used as a hint
                                 */
                                m->object->scan_collisions++;

                                if ( !queue_empty(&sq->age_q) )
                                        m_want = (vm_page_t) queue_first(&sq->age_q);
                                else if ( ((zf_run_count < zf_ratio) && vm_zf_queue_count >= zf_queue_min_count) ||
                                          queue_empty(&vm_page_queue_inactive)) {
                                        if ( !queue_empty(&vm_page_queue_zf) )
                                                m_want = (vm_page_t) queue_first(&vm_page_queue_zf);
                                } else if ( !queue_empty(&vm_page_queue_inactive) ) {
                                        m_want = (vm_page_t) queue_first(&vm_page_queue_inactive);
                                }
                                /*
                                 * this is the next object we're going to be interested in
                                 * try to make sure its available after the mutex_yield
                                 * returns control
                                 */
                                if (m_want)
                                        vm_pageout_scan_wants_object = m_want->object;

                                /*
                                 * force us to dump any collected free pages
                                 * and to pause before moving on
                                 */
                                try_failed = TRUE;

                                goto requeue_page;
                        }
                        object = m->object;
                        vm_pageout_scan_wants_object = VM_OBJECT_NULL;

                        try_failed = FALSE;
                }
                if (catch_up_count)
                        catch_up_count--;

                if (m->busy) {
                        if (m->encrypted_cleaning) {
                                /*
                                 * ENCRYPTED SWAP:
                                 * if this page has already been picked up as
                                 * part of a page-out cluster, it will be busy 
                                 * because it is being encrypted (see
                                 * vm_object_upl_request()).  But we still
                                 * want to demote it from "clean-in-place"
                                 * (aka "adjacent") to "clean-and-free" (aka
                                 * "target"), so let's ignore its "busy" bit
                                 * here and proceed to check for "cleaning" a
                                 * little bit below...
                                 *
                                 * CAUTION CAUTION:
                                 * A "busy" page should still be left alone for
                                 * most purposes, so we have to be very careful
                                 * not to process that page too much.
                                 */
                                assert(m->cleaning);
                                goto consider_inactive_page;
                        }

                        /*
                         *      Somebody is already playing with this page.
                         *      Put it back on the appropriate queue
                         *
                         */
                        vm_pageout_inactive_busy++;
requeue_page:
                        switch (page_prev_state) {

                        case PAGE_STATE_SPECULATIVE:
                                vm_page_speculate(m, FALSE);
                                break;

                        case PAGE_STATE_ZEROFILL:
                                m->zero_fill = TRUE;
                                /*
                                 * fall through to add in the
                                 * inactive state
                                 */
                        case PAGE_STATE_INACTIVE:
                                VM_PAGE_ENQUEUE_INACTIVE(m, FALSE);
                                break;

                        case PAGE_STATE_INACTIVE_FIRST:
                                VM_PAGE_ENQUEUE_INACTIVE(m, TRUE);
                                break;
                        }
                        goto done_with_inactivepage;
                }


                /*
                 *      If it's absent, in error or the object is no longer alive,
                 *      we can reclaim the page... in the no longer alive case,
                 *      there are 2 states the page can be in that preclude us
                 *      from reclaiming it - busy or cleaning - that we've already
                 *      dealt with
                 */
                if (m->absent || m->error || !object->alive) {

                        if (m->absent)
                                vm_pageout_inactive_absent++;
                        else if (!object->alive)
                                vm_pageout_inactive_notalive++;
                        else
                                vm_pageout_inactive_error++;
reclaim_page:
                        if (vm_pageout_deadlock_target) {
                                vm_pageout_scan_inactive_throttle_success++;
                                vm_pageout_deadlock_target--;
                        }

                        DTRACE_VM2(dfree, int, 1, (uint64_t *), NULL);

                        if (object->internal) {
                                DTRACE_VM2(anonfree, int, 1, (uint64_t *), NULL);
                        } else {
                                DTRACE_VM2(fsfree, int, 1, (uint64_t *), NULL);
                        }
                        vm_page_free_prepare_queues(m);

                        /*
                         * remove page from object here since we're already
                         * behind the object lock... defer the rest of the work
                         * we'd normally do in vm_page_free_prepare_object
                         * until 'vm_page_free_list' is called
                         */
                        if (m->tabled)
                                vm_page_remove(m, TRUE);

                        assert(m->pageq.next == NULL &&
                               m->pageq.prev == NULL);
                        m->pageq.next = (queue_entry_t)local_freeq;
                        local_freeq = m;
                        local_freed++;

                        inactive_burst_count = 0;

                        if (page_prev_state != PAGE_STATE_SPECULATIVE)
                                vm_pageout_stats[vm_pageout_stat_now].reclaimed++;

                        goto done_with_inactivepage;
                }
                /*
                 * If the object is empty, the page must be reclaimed even
                 * if dirty or used.
                 * If the page belongs to a volatile object, we stick it back
                 * on.
                 */
                if (object->copy == VM_OBJECT_NULL) {
                        if (object->purgable == VM_PURGABLE_EMPTY) {
                                m->busy = TRUE;
                                if (m->pmapped == TRUE) {
                                        /* unmap the page */
                                        refmod_state = pmap_disconnect(m->phys_page);
                                        if (refmod_state & VM_MEM_MODIFIED) {
                                                m->dirty = TRUE;
                                        }
                                }
                                if (m->dirty || m->precious) {
                                        /* we saved the cost of cleaning this page ! */
                                        vm_page_purged_count++;
                                }
                                goto reclaim_page;
                        }
                        if (object->purgable == VM_PURGABLE_VOLATILE) {
                                /* if it's wired, we can't put it on our queue */
                                assert(!VM_PAGE_WIRED(m));

                                /* just stick it back on! */
                                reactivated_this_call++;
                                goto reactivate_page;
                        }
                }

        consider_inactive_page:
                if (m->busy) {
                        /*
                         * CAUTION CAUTION:
                         * A "busy" page should always be left alone, except...
                         */
                        if (m->cleaning && m->encrypted_cleaning) {
                                /*
                                 * ENCRYPTED_SWAP:
                                 * We could get here with a "busy" page 
                                 * if it's being encrypted during a
                                 * "clean-in-place" operation.  We'll deal
                                 * with it right away by testing if it has been
                                 * referenced and either reactivating it or
                                 * promoting it from "clean-in-place" to
                                 * "clean-and-free".
                                 */
                        } else {
                                panic("\"busy\" page considered for pageout\n");
                        }
                }

                /*
                 *      If it's being used, reactivate.
                 *      (Fictitious pages are either busy or absent.)
                 *      First, update the reference and dirty bits
                 *      to make sure the page is unreferenced.
                 */
                refmod_state = -1;

                if (m->reference == FALSE && m->pmapped == TRUE) {
                        refmod_state = pmap_get_refmod(m->phys_page);
                  
                        if (refmod_state & VM_MEM_REFERENCED)
                                m->reference = TRUE;
                        if (refmod_state & VM_MEM_MODIFIED)
                                m->dirty = TRUE;
                }

                /*
                 *      If already cleaning this page in place and it hasn't
                 *      been recently referenced, convert from
                 *      "adjacent" to "target". We can leave the page mapped,
                 *      and upl_commit_range will determine whether
                 *      to free or reactivate.
                 *
                 *      note: if m->encrypted_cleaning == TRUE, then
                 *              m->cleaning == TRUE
                 *      and we'll handle it here
                 */
                if (m->cleaning) {
                        
                        if (m->reference == TRUE) {
                                reactivated_this_call++;
                                goto reactivate_page;
                        }
                        m->busy = TRUE;
                        m->pageout = TRUE;
                        m->dump_cleaning = TRUE;
                        vm_page_wire(m);

                        CLUSTER_STAT(vm_pageout_cluster_conversions++);

                        inactive_burst_count = 0;

                        goto done_with_inactivepage;
                }

                if (m->reference || m->dirty) {
                        /* deal with a rogue "reusable" page */
                        VM_PAGEOUT_SCAN_HANDLE_REUSABLE_PAGE(m);
                }

                if (m->reference && !m->no_cache) {
                        /*
                         * The page we pulled off the inactive list has
                         * been referenced.  It is possible for other
                         * processors to be touching pages faster than we
                         * can clear the referenced bit and traverse the
                         * inactive queue, so we limit the number of
                         * reactivations.
                         */
                        if (++reactivated_this_call >= reactivate_limit) {
                                vm_pageout_reactivation_limit_exceeded++;
                        } else if (catch_up_count) {
                                vm_pageout_catch_ups++;
                        } else if (++inactive_reclaim_run >= VM_PAGEOUT_INACTIVE_FORCE_RECLAIM) {
                                vm_pageout_inactive_force_reclaim++;
                        } else {
                                uint32_t isinuse;
reactivate_page:
                                if ( !object->internal && object->pager != MEMORY_OBJECT_NULL &&
                                     vnode_pager_get_isinuse(object->pager, &isinuse) == KERN_SUCCESS && !isinuse) {
                                        /*
                                         * no explict mappings of this object exist
                                         * and it's not open via the filesystem
                                         */
                                        vm_page_deactivate(m);
                                        vm_pageout_inactive_deactivated++;
                                } else {
                                        /*
                                         * The page was/is being used, so put back on active list.
                                         */
                                        vm_page_activate(m);
                                        VM_STAT_INCR(reactivations);
                                }
                                vm_pageout_inactive_used++;
                                inactive_burst_count = 0;

                                goto done_with_inactivepage;
                        }
                        /* 
                         * Make sure we call pmap_get_refmod() if it
                         * wasn't already called just above, to update
                         * the dirty bit.
                         */
                        if ((refmod_state == -1) && !m->dirty && m->pmapped) {
                                refmod_state = pmap_get_refmod(m->phys_page);
                                if (refmod_state & VM_MEM_MODIFIED)
                                        m->dirty = TRUE;
                        }
                        forced_reclaim = TRUE;
                } else {
                        forced_reclaim = FALSE;
                }

                XPR(XPR_VM_PAGEOUT,
                "vm_pageout_scan, replace object 0x%X offset 0x%X page 0x%X\n",
                object, m->offset, m, 0,0);

                /*
                 * we've got a candidate page to steal...
                 *
                 * m->dirty is up to date courtesy of the
                 * preceding check for m->reference... if 
                 * we get here, then m->reference had to be
                 * FALSE (or possibly "reactivate_limit" was
                 * exceeded), but in either case we called
                 * pmap_get_refmod() and updated both
                 * m->reference and m->dirty
                 *
                 * if it's dirty or precious we need to
                 * see if the target queue is throtttled
                 * it if is, we need to skip over it by moving it back
                 * to the end of the inactive queue
                 */

                inactive_throttled = FALSE;

                if (m->dirty || m->precious) {
                        if (object->internal) {
                                if (VM_PAGE_Q_THROTTLED(iq))
                                        inactive_throttled = TRUE;
                        } else if (VM_PAGE_Q_THROTTLED(eq)) {
                                inactive_throttled = TRUE;
                        }
                }
throttle_inactive:
                if (!VM_DYNAMIC_PAGING_ENABLED(memory_manager_default) &&
                    object->internal && m->dirty &&
                    (object->purgable == VM_PURGABLE_DENY ||
                     object->purgable == VM_PURGABLE_NONVOLATILE ||
                     object->purgable == VM_PURGABLE_VOLATILE)) {
                        queue_enter(&vm_page_queue_throttled, m,
                                    vm_page_t, pageq);
                        m->throttled = TRUE;
                        vm_page_throttled_count++;

                        vm_pageout_scan_reclaimed_throttled++;

                        goto done_with_inactivepage;
                }
                if (inactive_throttled == TRUE) {

                        if (object->internal)
                                vm_pageout_scan_inactive_throttled_internal++;
                        else
                                vm_pageout_scan_inactive_throttled_external++;                  

                        if (page_prev_state == PAGE_STATE_SPECULATIVE)
                                page_prev_state = PAGE_STATE_INACTIVE;

                        if (!VM_DYNAMIC_PAGING_ENABLED(memory_manager_default) && object->internal == FALSE) {
                                /*
                                 * a) The external pageout queue is throttled
                                 * b) We're done with the active queue and moved on to the inactive queue
                                 * c) We start noticing dirty pages and usually we would put them at the end of the inactive queue, but,
                                 * d) We don't have a default pager, and so,
                                 * e) We push these onto the active queue in an effort to cause a re-evaluation of the active queue 
                                 *    and get back some, possibly clean, pages.
                                 *
                                 * We also keep a count of the pages of this kind, since, these will be a good indicator of us being in a deadlock
                                 * on systems without a dynamic pager, where: 
                                 * a) The external pageout thread is stuck on the truncate lock for a file that is being extended i.e. written.
                                 * b) The thread doing the writing is waiting for pages while holding the truncate lock
                                 * c) Most of the pages in the inactive queue belong to this file.
                                 */
                                
                                vm_page_activate(m);
                                vm_pageout_inactive_external_forced_reactivate_count++;
                                vm_pageout_inactive_external_forced_reactivate_limit--;

                                if (vm_pageout_inactive_external_forced_reactivate_limit <= 0){
                                        vm_pageout_inactive_external_forced_reactivate_limit = vm_page_active_count + vm_page_inactive_count;
#if CONFIG_EMBEDDED
                                        /*
                                         * Possible deadlock scenario so request jetsam action
                                         */
                                        assert(object);
                                        vm_object_unlock(object);
                                        object = VM_OBJECT_NULL;
                                        vm_page_unlock_queues();

                                        if (jetsam_kill_top_proc(TRUE, kJetsamFlagsKilledVM) < 0){
                                                panic("vm_pageout_scan: Jetsam request failed\n");      
                                        }

                                        vm_page_lock_queues();  
                                        delayed_unlock = 1;
#endif
                                }
                                inactive_burst_count = 0;
                                goto done_with_inactivepage;
                        } else {
                                goto requeue_page;
                        }
                }

                /*
                 * we've got a page that we can steal...
                 * eliminate all mappings and make sure
                 * we have the up-to-date modified state
                 * first take the page BUSY, so that no new
                 * mappings can be made
                 */
                m->busy = TRUE;
                
                /*
                 * if we need to do a pmap_disconnect then we
                 * need to re-evaluate m->dirty since the pmap_disconnect
                 * provides the true state atomically... the 
                 * page was still mapped up to the pmap_disconnect
                 * and may have been dirtied at the last microsecond
                 *
                 * we also check for the page being referenced 'late'
                 * if it was, we first need to do a WAKEUP_DONE on it
                 * since we already set m->busy = TRUE, before 
                 * going off to reactivate it
                 *
                 * Note that if 'pmapped' is FALSE then the page is not
                 * and has not been in any map, so there is no point calling
                 * pmap_disconnect().  m->dirty and/or m->reference could
                 * have been set in anticipation of likely usage of the page.
                 */
                if (m->pmapped == TRUE) {
                        refmod_state = pmap_disconnect(m->phys_page);

                        if (refmod_state & VM_MEM_MODIFIED)
                                m->dirty = TRUE;
                        if (refmod_state & VM_MEM_REFERENCED) {
                                
                                /* If m->reference is already set, this page must have
                                 * already failed the reactivate_limit test, so don't
                                 * bump the counts twice.
                                 */
                                if ( ! m->reference ) {
                                        m->reference = TRUE;
                                        if (forced_reclaim ||
                                            ++reactivated_this_call >= reactivate_limit)
                                                vm_pageout_reactivation_limit_exceeded++;
                                        else {
                                                PAGE_WAKEUP_DONE(m);
                                                goto reactivate_page;
                                        }
                                }
                        }
                }
                /*
                 * reset our count of pages that have been reclaimed 
                 * since the last page was 'stolen'
                 */
                inactive_reclaim_run = 0;

                /*
                 *      If it's clean and not precious, we can free the page.
                 */
                if (!m->dirty && !m->precious) {

                        if (page_prev_state == PAGE_STATE_SPECULATIVE)
                                vm_pageout_speculative_clean++;
                        else {
                                if (page_prev_state == PAGE_STATE_ZEROFILL)
                                        vm_pageout_inactive_zf++;
                                vm_pageout_inactive_clean++;
                        }
                        goto reclaim_page;
                }

                /*
                 * The page may have been dirtied since the last check
                 * for a throttled target queue (which may have been skipped
                 * if the page was clean then).  With the dirty page
                 * disconnected here, we can make one final check.
                 */
                if (object->internal) {
                        if (VM_PAGE_Q_THROTTLED(iq))
                                inactive_throttled = TRUE;
                } else if (VM_PAGE_Q_THROTTLED(eq)) {
                        inactive_throttled = TRUE;
                }

                if (inactive_throttled == TRUE) {
                        /*
                         * we set busy before issuing the pmap_disconnect,
                         * so clear it and wakeup anyone that happened upon
                         * it in that state
                         */
                        PAGE_WAKEUP_DONE(m);
                        goto throttle_inactive;
                }

                vm_pageout_stats[vm_pageout_stat_now].reclaimed++;

                vm_pageout_cluster(m);

                if (page_prev_state == PAGE_STATE_ZEROFILL)
                        vm_pageout_inactive_zf++;
                if (object->internal)
                        vm_pageout_inactive_dirty_internal++;
                else
                        vm_pageout_inactive_dirty_external++;
        
                inactive_burst_count = 0;

done_with_inactivepage:
                if (delayed_unlock++ > delayed_unlock_limit || try_failed == TRUE) {

                        if (object != NULL) {
                                vm_pageout_scan_wants_object = VM_OBJECT_NULL;
                                vm_object_unlock(object);
                                object = NULL;
                        }
                        if (local_freeq) {
                                vm_page_unlock_queues();

                                VM_DEBUG_EVENT(vm_pageout_freelist, VM_PAGEOUT_FREELIST, DBG_FUNC_START,
                                               vm_page_free_count, local_freed, delayed_unlock_limit, 4);

                                vm_page_free_list(local_freeq, TRUE);
                                
                                VM_DEBUG_EVENT(vm_pageout_freelist, VM_PAGEOUT_FREELIST, DBG_FUNC_END,
                                               vm_page_free_count, local_freed, 0, 4);

                                local_freeq = NULL;
                                local_freed = 0;
                                vm_page_lock_queues();
                        } else
                                lck_mtx_yield(&vm_page_queue_lock);

                        delayed_unlock = 1;
                }
                /*
                 * back to top of pageout scan loop
                 */
        }
}


int vm_page_free_count_init;

void
vm_page_free_reserve(
        int pages)
{
        int             free_after_reserve;

        vm_page_free_reserved += pages;

        if (vm_page_free_reserved > VM_PAGE_FREE_RESERVED_LIMIT)
                vm_page_free_reserved = VM_PAGE_FREE_RESERVED_LIMIT;

        free_after_reserve = vm_page_free_count_init - vm_page_free_reserved;

        vm_page_free_min = vm_page_free_reserved +
                VM_PAGE_FREE_MIN(free_after_reserve);

        if (vm_page_free_min > VM_PAGE_FREE_MIN_LIMIT)
                vm_page_free_min = VM_PAGE_FREE_MIN_LIMIT;

        vm_page_free_target = vm_page_free_reserved +
                VM_PAGE_FREE_TARGET(free_after_reserve);

        if (vm_page_free_target > VM_PAGE_FREE_TARGET_LIMIT)
                vm_page_free_target = VM_PAGE_FREE_TARGET_LIMIT;

        if (vm_page_free_target < vm_page_free_min + 5)
                vm_page_free_target = vm_page_free_min + 5;

        vm_page_throttle_limit = vm_page_free_target - (vm_page_free_target / 3);
        vm_page_creation_throttle = vm_page_free_target / 2;
}

/*
 *      vm_pageout is the high level pageout daemon.
 */

void
vm_pageout_continue(void)
{
        DTRACE_VM2(pgrrun, int, 1, (uint64_t *), NULL);
        vm_pageout_scan_event_counter++;
        vm_pageout_scan();
        /* we hold vm_page_queue_free_lock now */
        assert(vm_page_free_wanted == 0);
        assert(vm_page_free_wanted_privileged == 0);
        assert_wait((event_t) &vm_page_free_wanted, THREAD_UNINT);
        lck_mtx_unlock(&vm_page_queue_free_lock);

        counter(c_vm_pageout_block++);
        thread_block((thread_continue_t)vm_pageout_continue);
        /*NOTREACHED*/
}


#ifdef FAKE_DEADLOCK

#define FAKE_COUNT      5000

int internal_count = 0;
int fake_deadlock = 0;

#endif

static void
vm_pageout_iothread_continue(struct vm_pageout_queue *q)
{
        vm_page_t       m = NULL;
        vm_object_t     object;
        memory_object_t pager;
        thread_t        self = current_thread();

        if ((vm_pageout_internal_iothread != THREAD_NULL)
            && (self == vm_pageout_external_iothread )
            && (self->options & TH_OPT_VMPRIV))
                self->options &= ~TH_OPT_VMPRIV;

        vm_page_lockspin_queues();

        while ( !queue_empty(&q->pgo_pending) ) {

                   q->pgo_busy = TRUE;
                   queue_remove_first(&q->pgo_pending, m, vm_page_t, pageq);
                   if (m->object == slide_info.slide_object) {
                           panic("slid page %p not allowed on this path\n", m);
                   }
                   VM_PAGE_CHECK(m);
                   m->pageout_queue = FALSE;
                   m->pageq.next = NULL;
                   m->pageq.prev = NULL;
                   vm_page_unlock_queues();

#ifdef FAKE_DEADLOCK
                   if (q == &vm_pageout_queue_internal) {
                           vm_offset_t addr;
                           int  pg_count;

                           internal_count++;

                           if ((internal_count == FAKE_COUNT)) {

                                   pg_count = vm_page_free_count + vm_page_free_reserved;

                                   if (kmem_alloc(kernel_map, &addr, PAGE_SIZE * pg_count) == KERN_SUCCESS) {
                                           kmem_free(kernel_map, addr, PAGE_SIZE * pg_count);
                                   }
                                   internal_count = 0;
                                   fake_deadlock++;
                           }
                   }
#endif
                   object = m->object;

                   vm_object_lock(object);

                   if (!object->pager_initialized) {

                           /*
                            *   If there is no memory object for the page, create
                            *   one and hand it to the default pager.
                            */

                           if (!object->pager_initialized)
                                   vm_object_collapse(object,
                                                      (vm_object_offset_t) 0,
                                                      TRUE);
                           if (!object->pager_initialized)
                                   vm_object_pager_create(object);
                           if (!object->pager_initialized) {
                                   /*
                                    *   Still no pager for the object.
                                    *   Reactivate the page.
                                    *
                                    *   Should only happen if there is no
                                    *   default pager.
                                    */
                                   vm_page_lockspin_queues();

                                   vm_pageout_queue_steal(m, TRUE);
                                   vm_page_activate(m);
                                   vm_pageout_dirty_no_pager++;

                                   vm_page_unlock_queues();

                                   /*
                                    *   And we are done with it.
                                    */
                                   PAGE_WAKEUP_DONE(m);

                                   vm_object_paging_end(object);
                                   vm_object_unlock(object);

                                   vm_page_lockspin_queues();
                                   continue;
                           }
                   }
                   pager = object->pager;
                   if (pager == MEMORY_OBJECT_NULL) {
                           /*
                            * This pager has been destroyed by either
                            * memory_object_destroy or vm_object_destroy, and
                            * so there is nowhere for the page to go.
                            */
                           if (m->pageout) {
                                   /*
                                    * Just free the page... VM_PAGE_FREE takes
                                    * care of cleaning up all the state...
                                    * including doing the vm_pageout_throttle_up
                                    */
                                   VM_PAGE_FREE(m);
                           } else {
                                   vm_page_lockspin_queues();

                                   vm_pageout_queue_steal(m, TRUE);
                                   vm_page_activate(m);
                                   
                                   vm_page_unlock_queues();

                                   /*
                                    *   And we are done with it.
                                    */
                                   PAGE_WAKEUP_DONE(m);
                           }
                           vm_object_paging_end(object);
                           vm_object_unlock(object);

                           vm_page_lockspin_queues();
                           continue;
                   }
                   VM_PAGE_CHECK(m);
                   vm_object_unlock(object);
                   /*
                    * we expect the paging_in_progress reference to have
                    * already been taken on the object before it was added
                    * to the appropriate pageout I/O queue... this will
                    * keep the object from being terminated and/or the 
                    * paging_offset from changing until the I/O has 
                    * completed... therefore no need to lock the object to
                    * pull the paging_offset from it.
                    *
                    * Send the data to the pager.
                    * any pageout clustering happens there
                    */
                   memory_object_data_return(pager,
                                             m->offset + object->paging_offset,
                                             PAGE_SIZE,
                                             NULL,
                                             NULL,
                                             FALSE,
                                             FALSE,
                                             0);

                   vm_object_lock(object);
                   vm_object_paging_end(object);
                   vm_object_unlock(object);

                   vm_page_lockspin_queues();
        }
        assert_wait((event_t) q, THREAD_UNINT);

        if (q->pgo_throttled == TRUE && !VM_PAGE_Q_THROTTLED(q)) {
                q->pgo_throttled = FALSE;
                thread_wakeup((event_t) &q->pgo_laundry);
        }
        if (q->pgo_draining == TRUE && q->pgo_laundry == 0) {
                q->pgo_draining = FALSE;
                thread_wakeup((event_t) (&q->pgo_laundry+1));
        }
        q->pgo_busy = FALSE;
        q->pgo_idle = TRUE;
        vm_page_unlock_queues();

        thread_block_parameter((thread_continue_t)vm_pageout_iothread_continue, (void *) &q->pgo_pending);
        /*NOTREACHED*/
}


static void
vm_pageout_iothread_external(void)
{
        thread_t        self = current_thread();

        self->options |= TH_OPT_VMPRIV;

        vm_pageout_iothread_continue(&vm_pageout_queue_external);
        /*NOTREACHED*/
}


static void
vm_pageout_iothread_internal(void)
{
        thread_t        self = current_thread();

        self->options |= TH_OPT_VMPRIV;

        vm_pageout_iothread_continue(&vm_pageout_queue_internal);
        /*NOTREACHED*/
}

kern_return_t
vm_set_buffer_cleanup_callout(boolean_t (*func)(int)) 
{
        if (OSCompareAndSwapPtr(NULL, func, (void * volatile *) &consider_buffer_cache_collect)) {
                return KERN_SUCCESS;
        } else {
                return KERN_FAILURE; /* Already set */
        }
}

static void
vm_pageout_garbage_collect(int collect)
{
        if (collect) {
                boolean_t buf_large_zfree = FALSE;
                stack_collect();

                /*
                 * consider_zone_gc should be last, because the other operations
                 * might return memory to zones.
                 */
                consider_machine_collect();
                if (consider_buffer_cache_collect != NULL) {
                        buf_large_zfree = (*consider_buffer_cache_collect)(0);
                }
                consider_zone_gc(buf_large_zfree);

                consider_machine_adjust();
                consider_pressure_events();
                
        }

        assert_wait((event_t) &vm_pageout_garbage_collect, THREAD_UNINT);

        thread_block_parameter((thread_continue_t) vm_pageout_garbage_collect, (void *)1);
        /*NOTREACHED*/
}



void
vm_pageout(void)
{
        thread_t        self = current_thread();
        thread_t        thread;
        kern_return_t   result;
        spl_t           s;

        /*
         * Set thread privileges.
         */
        s = splsched();
        thread_lock(self);
        self->priority = BASEPRI_PREEMPT - 1;
        set_sched_pri(self, self->priority);
        thread_unlock(self);

        if (!self->reserved_stack)
                self->reserved_stack = self->kernel_stack;

        splx(s);

        /*
         *      Initialize some paging parameters.
         */

        if (vm_pageout_idle_wait == 0)
                vm_pageout_idle_wait = VM_PAGEOUT_IDLE_WAIT;

        if (vm_pageout_burst_wait == 0)
                vm_pageout_burst_wait = VM_PAGEOUT_BURST_WAIT;

        if (vm_pageout_empty_wait == 0)
                vm_pageout_empty_wait = VM_PAGEOUT_EMPTY_WAIT;

        if (vm_pageout_deadlock_wait == 0)
                vm_pageout_deadlock_wait = VM_PAGEOUT_DEADLOCK_WAIT;

        if (vm_pageout_deadlock_relief == 0)
                vm_pageout_deadlock_relief = VM_PAGEOUT_DEADLOCK_RELIEF;

        if (vm_pageout_inactive_relief == 0)
                vm_pageout_inactive_relief = VM_PAGEOUT_INACTIVE_RELIEF;

        if (vm_pageout_burst_active_throttle == 0)
                vm_pageout_burst_active_throttle = VM_PAGEOUT_BURST_ACTIVE_THROTTLE;

        if (vm_pageout_burst_inactive_throttle == 0)
                vm_pageout_burst_inactive_throttle = VM_PAGEOUT_BURST_INACTIVE_THROTTLE;

        /*
         * Set kernel task to low backing store privileged 
         * status
         */
        task_lock(kernel_task);
        kernel_task->priv_flags |= VM_BACKING_STORE_PRIV;
        task_unlock(kernel_task);

        vm_page_free_count_init = vm_page_free_count;

        /*
         * even if we've already called vm_page_free_reserve
         * call it again here to insure that the targets are
         * accurately calculated (it uses vm_page_free_count_init)
         * calling it with an arg of 0 will not change the reserve
         * but will re-calculate free_min and free_target
         */
        if (vm_page_free_reserved < VM_PAGE_FREE_RESERVED(processor_count)) {
                vm_page_free_reserve((VM_PAGE_FREE_RESERVED(processor_count)) - vm_page_free_reserved);
        } else
                vm_page_free_reserve(0);


        queue_init(&vm_pageout_queue_external.pgo_pending);
        vm_pageout_queue_external.pgo_maxlaundry = VM_PAGE_LAUNDRY_MAX;
        vm_pageout_queue_external.pgo_laundry = 0;
        vm_pageout_queue_external.pgo_idle = FALSE;
        vm_pageout_queue_external.pgo_busy = FALSE;
        vm_pageout_queue_external.pgo_throttled = FALSE;
        vm_pageout_queue_external.pgo_draining = FALSE;

        queue_init(&vm_pageout_queue_internal.pgo_pending);
        vm_pageout_queue_internal.pgo_maxlaundry = 0;
        vm_pageout_queue_internal.pgo_laundry = 0;
        vm_pageout_queue_internal.pgo_idle = FALSE;
        vm_pageout_queue_internal.pgo_busy = FALSE;
        vm_pageout_queue_internal.pgo_throttled = FALSE;
        vm_pageout_queue_internal.pgo_draining = FALSE;


        /* internal pageout thread started when default pager registered first time */
        /* external pageout and garbage collection threads started here */

        result = kernel_thread_start_priority((thread_continue_t)vm_pageout_iothread_external, NULL, 
                                              BASEPRI_PREEMPT - 1, 
                                              &vm_pageout_external_iothread);
        if (result != KERN_SUCCESS)
                panic("vm_pageout_iothread_external: create failed");

        thread_deallocate(vm_pageout_external_iothread);

        result = kernel_thread_start_priority((thread_continue_t)vm_pageout_garbage_collect, NULL,
                                              MINPRI_KERNEL, 
                                              &thread);
        if (result != KERN_SUCCESS)
                panic("vm_pageout_garbage_collect: create failed");

        thread_deallocate(thread);

        vm_object_reaper_init();


        vm_pageout_continue();

        /*
         * Unreached code!
         *
         * The vm_pageout_continue() call above never returns, so the code below is never
         * executed.  We take advantage of this to declare several DTrace VM related probe
         * points that our kernel doesn't have an analog for.  These are probe points that
         * exist in Solaris and are in the DTrace documentation, so people may have written
         * scripts that use them.  Declaring the probe points here means their scripts will
         * compile and execute which we want for portability of the scripts, but since this
         * section of code is never reached, the probe points will simply never fire.  Yes,
         * this is basically a hack.  The problem is the DTrace probe points were chosen with
         * Solaris specific VM events in mind, not portability to different VM implementations.
         */

        DTRACE_VM2(execfree, int, 1, (uint64_t *), NULL);
        DTRACE_VM2(execpgin, int, 1, (uint64_t *), NULL);
        DTRACE_VM2(execpgout, int, 1, (uint64_t *), NULL);
        DTRACE_VM2(pgswapin, int, 1, (uint64_t *), NULL);
        DTRACE_VM2(pgswapout, int, 1, (uint64_t *), NULL);
        DTRACE_VM2(swapin, int, 1, (uint64_t *), NULL);
        DTRACE_VM2(swapout, int, 1, (uint64_t *), NULL);
        /*NOTREACHED*/
}

kern_return_t
vm_pageout_internal_start(void)
{
        kern_return_t result;

        vm_pageout_queue_internal.pgo_maxlaundry = VM_PAGE_LAUNDRY_MAX;
        result = kernel_thread_start_priority((thread_continue_t)vm_pageout_iothread_internal, NULL, BASEPRI_PREEMPT - 1, &vm_pageout_internal_iothread);
        if (result == KERN_SUCCESS)
                thread_deallocate(vm_pageout_internal_iothread);
        return result;
}


static upl_t
upl_create(int type, int flags, upl_size_t size)
{
        upl_t   upl;
        int     page_field_size = 0;
        int     upl_flags = 0;
        int     upl_size  = sizeof(struct upl);

        size = round_page_32(size);

        if (type & UPL_CREATE_LITE) {
                page_field_size = (atop(size) + 7) >> 3;
                page_field_size = (page_field_size + 3) & 0xFFFFFFFC;

                upl_flags |= UPL_LITE;
        }
        if (type & UPL_CREATE_INTERNAL) {
                upl_size += (int) sizeof(struct upl_page_info) * atop(size);

                upl_flags |= UPL_INTERNAL;
        }
        upl = (upl_t)kalloc(upl_size + page_field_size);

        if (page_field_size)
                bzero((char *)upl + upl_size, page_field_size);

        upl->flags = upl_flags | flags;
        upl->src_object = NULL;
        upl->kaddr = (vm_offset_t)0;
        upl->size = 0;
        upl->map_object = NULL;
        upl->ref_count = 1;
        upl->ext_ref_count = 0;
        upl->highest_page = 0;
        upl_lock_init(upl);
        upl->vector_upl = NULL;
#if UPL_DEBUG
        upl->ubc_alias1 = 0;
        upl->ubc_alias2 = 0;

        upl->upl_creator = current_thread();
        upl->upl_state = 0;
        upl->upl_commit_index = 0;
        bzero(&upl->upl_commit_records[0], sizeof(upl->upl_commit_records));

        (void) OSBacktrace(&upl->upl_create_retaddr[0], UPL_DEBUG_STACK_FRAMES);
#endif /* UPL_DEBUG */

        return(upl);
}

static void
upl_destroy(upl_t upl)
{
        int     page_field_size;  /* bit field in word size buf */
        int     size;

        if (upl->ext_ref_count) {
                panic("upl(%p) ext_ref_count", upl);
        }

#if UPL_DEBUG
        {
                vm_object_t     object;

                if (upl->flags & UPL_SHADOWED) {
                        object = upl->map_object->shadow;
                } else {
                        object = upl->map_object;
                }
                vm_object_lock(object);
                queue_remove(&object->uplq, upl, upl_t, uplq);
                vm_object_unlock(object);
        }
#endif /* UPL_DEBUG */
        /*
         * drop a reference on the map_object whether or
         * not a pageout object is inserted
         */
        if (upl->flags & UPL_SHADOWED)
                vm_object_deallocate(upl->map_object);

        if (upl->flags & UPL_DEVICE_MEMORY)
                size = PAGE_SIZE;
        else
                size = upl->size;
        page_field_size = 0;

        if (upl->flags & UPL_LITE) {
                page_field_size = ((size/PAGE_SIZE) + 7) >> 3;
                page_field_size = (page_field_size + 3) & 0xFFFFFFFC;
        }
        upl_lock_destroy(upl);
        upl->vector_upl = (vector_upl_t) 0xfeedbeef;
        if (upl->flags & UPL_INTERNAL) {
                kfree(upl,
                      sizeof(struct upl) + 
                      (sizeof(struct upl_page_info) * (size/PAGE_SIZE))
                      + page_field_size);
        } else {
                kfree(upl, sizeof(struct upl) + page_field_size);
        }
}

void
upl_deallocate(upl_t upl)
{
        if (--upl->ref_count == 0) {
                if(vector_upl_is_valid(upl))
                        vector_upl_deallocate(upl);
                upl_destroy(upl);
        }
}

#if DEVELOPMENT || DEBUG
/*/*
 * Statistics about UPL enforcement of copy-on-write obligations.
 */
unsigned long upl_cow = 0;
unsigned long upl_cow_again = 0;
unsigned long upl_cow_pages = 0;
unsigned long upl_cow_again_pages = 0;

unsigned long iopl_cow = 0;
unsigned long iopl_cow_pages = 0;
#endif

/*  
 *      Routine:        vm_object_upl_request 
 *      Purpose:        
 *              Cause the population of a portion of a vm_object.
 *              Depending on the nature of the request, the pages
 *              returned may be contain valid data or be uninitialized.
 *              A page list structure, listing the physical pages
 *              will be returned upon request.
 *              This function is called by the file system or any other
 *              supplier of backing store to a pager.
 *              IMPORTANT NOTE: The caller must still respect the relationship
 *              between the vm_object and its backing memory object.  The
 *              caller MUST NOT substitute changes in the backing file
 *              without first doing a memory_object_lock_request on the 
 *              target range unless it is know that the pages are not
 *              shared with another entity at the pager level.
 *              Copy_in_to:
 *                      if a page list structure is present
 *                      return the mapped physical pages, where a
 *                      page is not present, return a non-initialized
 *                      one.  If the no_sync bit is turned on, don't
 *                      call the pager unlock to synchronize with other
 *                      possible copies of the page. Leave pages busy
 *                      in the original object, if a page list structure
 *                      was specified.  When a commit of the page list
 *                      pages is done, the dirty bit will be set for each one.
 *              Copy_out_from:
 *                      If a page list structure is present, return
 *                      all mapped pages.  Where a page does not exist
 *                      map a zero filled one. Leave pages busy in
 *                      the original object.  If a page list structure
 *                      is not specified, this call is a no-op. 
 *
 *              Note:  access of default pager objects has a rather interesting
 *              twist.  The caller of this routine, presumably the file system
 *              page cache handling code, will never actually make a request
 *              against a default pager backed object.  Only the default
 *              pager will make requests on backing store related vm_objects
 *              In this way the default pager can maintain the relationship
 *              between backing store files (abstract memory objects) and 
 *              the vm_objects (cache objects), they support.
 *
 */

__private_extern__ kern_return_t
vm_object_upl_request(
        vm_object_t             object,
        vm_object_offset_t      offset,
        upl_size_t              size,
        upl_t                   *upl_ptr,
        upl_page_info_array_t   user_page_list,
        unsigned int            *page_list_count,
        int                     cntrl_flags)
{
        vm_page_t               dst_page = VM_PAGE_NULL;
        vm_object_offset_t      dst_offset;
        upl_size_t              xfer_size;
        unsigned int            size_in_pages;
        boolean_t               dirty;
        boolean_t               hw_dirty;
        upl_t                   upl = NULL;
        unsigned int            entry;
#if MACH_CLUSTER_STATS
        boolean_t               encountered_lrp = FALSE;
#endif
        vm_page_t               alias_page = NULL;
        int                     refmod_state = 0;
        wpl_array_t             lite_list = NULL;
        vm_object_t             last_copy_object;
        struct  vm_page_delayed_work    dw_array[DEFAULT_DELAYED_WORK_LIMIT];
        struct  vm_page_delayed_work    *dwp;
        int                     dw_count;
        int                     dw_limit;

        if (cntrl_flags & ~UPL_VALID_FLAGS) {
                /*
                 * For forward compatibility's sake,
                 * reject any unknown flag.
                 */
                return KERN_INVALID_VALUE;
        }
        if ( (!object->internal) && (object->paging_offset != 0) )
                panic("vm_object_upl_request: external object with non-zero paging offset\n");
        if (object->phys_contiguous)
                panic("vm_object_upl_request: contiguous object specified\n");


        if ((size / PAGE_SIZE) > MAX_UPL_SIZE)
                size = MAX_UPL_SIZE * PAGE_SIZE;

        if ( (cntrl_flags & UPL_SET_INTERNAL) && page_list_count != NULL)
                *page_list_count = MAX_UPL_SIZE;

        if (cntrl_flags & UPL_SET_INTERNAL) {
                if (cntrl_flags & UPL_SET_LITE) {

                        upl = upl_create(UPL_CREATE_INTERNAL | UPL_CREATE_LITE, 0, size);

                        user_page_list = (upl_page_info_t *) (((uintptr_t)upl) + sizeof(struct upl));
                        lite_list = (wpl_array_t)
                                        (((uintptr_t)user_page_list) + 
                                        ((size/PAGE_SIZE) * sizeof(upl_page_info_t)));
                        if (size == 0) {
                                user_page_list = NULL;
                                lite_list = NULL;
                        }
                } else {
                        upl = upl_create(UPL_CREATE_INTERNAL, 0, size);

                        user_page_list = (upl_page_info_t *) (((uintptr_t)upl) + sizeof(struct upl));
                        if (size == 0) {
                                user_page_list = NULL;
                        }
                }
        } else {
                if (cntrl_flags & UPL_SET_LITE) {

                        upl = upl_create(UPL_CREATE_EXTERNAL | UPL_CREATE_LITE, 0, size);

                        lite_list = (wpl_array_t) (((uintptr_t)upl) + sizeof(struct upl));
                        if (size == 0) {
                                lite_list = NULL;
                        }
                } else {
                        upl = upl_create(UPL_CREATE_EXTERNAL, 0, size);
                }
        }
        *upl_ptr = upl;
        
        if (user_page_list)
                user_page_list[0].device = FALSE;

        if (cntrl_flags & UPL_SET_LITE) {
                upl->map_object = object;
        } else {
                upl->map_object = vm_object_allocate(size);
                /*
                 * No neeed to lock the new object: nobody else knows
                 * about it yet, so it's all ours so far.
                 */
                upl->map_object->shadow = object;
                upl->map_object->pageout = TRUE;
                upl->map_object->can_persist = FALSE;
                upl->map_object->copy_strategy = MEMORY_OBJECT_COPY_NONE;
                upl->map_object->vo_shadow_offset = offset;
                upl->map_object->wimg_bits = object->wimg_bits;

                VM_PAGE_GRAB_FICTITIOUS(alias_page);

                upl->flags |= UPL_SHADOWED;
        }
        /*
         * ENCRYPTED SWAP:
         * Just mark the UPL as "encrypted" here.
         * We'll actually encrypt the pages later,
         * in upl_encrypt(), when the caller has
         * selected which pages need to go to swap.
         */
        if (cntrl_flags & UPL_ENCRYPT)
                upl->flags |= UPL_ENCRYPTED;

        if (cntrl_flags & UPL_FOR_PAGEOUT)
                upl->flags |= UPL_PAGEOUT;

        vm_object_lock(object);
        vm_object_activity_begin(object);

        /*
         * we can lock in the paging_offset once paging_in_progress is set
         */
        upl->size = size;
        upl->offset = offset + object->paging_offset;

#if UPL_DEBUG
        queue_enter(&object->uplq, upl, upl_t, uplq);
#endif /* UPL_DEBUG */

        if ((cntrl_flags & UPL_WILL_MODIFY) && object->copy != VM_OBJECT_NULL) {
                /*
                 * Honor copy-on-write obligations
                 *
                 * The caller is gathering these pages and
                 * might modify their contents.  We need to
                 * make sure that the copy object has its own
                 * private copies of these pages before we let
                 * the caller modify them.
                 */
                vm_object_update(object,
                                 offset,
                                 size,
                                 NULL,
                                 NULL,
                                 FALSE, /* should_return */
                                 MEMORY_OBJECT_COPY_SYNC,
                                 VM_PROT_NO_CHANGE);
#if DEVELOPMENT || DEBUG
                upl_cow++;
                upl_cow_pages += size >> PAGE_SHIFT;
#endif
        }
        /*
         * remember which copy object we synchronized with
         */
        last_copy_object = object->copy;
        entry = 0;

        xfer_size = size;
        dst_offset = offset;
        size_in_pages = size / PAGE_SIZE;

        dwp = &dw_array[0];
        dw_count = 0;
        dw_limit = DELAYED_WORK_LIMIT(DEFAULT_DELAYED_WORK_LIMIT);

        if (vm_page_free_count > (vm_page_free_target + size_in_pages) ||
            object->resident_page_count < (MAX_UPL_SIZE * 2))
                object->scan_collisions = 0;

        while (xfer_size) {

                dwp->dw_mask = 0;

                if ((alias_page == NULL) && !(cntrl_flags & UPL_SET_LITE)) {
                        vm_object_unlock(object);
                        VM_PAGE_GRAB_FICTITIOUS(alias_page);
                        vm_object_lock(object);
                }
                if (cntrl_flags & UPL_COPYOUT_FROM) {
                        upl->flags |= UPL_PAGE_SYNC_DONE;

                        if ( ((dst_page = vm_page_lookup(object, dst_offset)) == VM_PAGE_NULL) ||
                                dst_page->fictitious ||
                                dst_page->absent ||
                                dst_page->error ||
                               (VM_PAGE_WIRED(dst_page) && !dst_page->pageout && !dst_page->list_req_pending)) {

                                if (user_page_list)
                                        user_page_list[entry].phys_addr = 0;

                                goto try_next_page;
                        }
                        /*
                         * grab this up front...
                         * a high percentange of the time we're going to
                         * need the hardware modification state a bit later
                         * anyway... so we can eliminate an extra call into
                         * the pmap layer by grabbing it here and recording it
                         */
                        if (dst_page->pmapped)
                                refmod_state = pmap_get_refmod(dst_page->phys_page);
                        else
                                refmod_state = 0;

                        if ( (refmod_state & VM_MEM_REFERENCED) && dst_page->inactive ) {
                                /*
                                 * page is on inactive list and referenced...
                                 * reactivate it now... this gets it out of the
                                 * way of vm_pageout_scan which would have to
                                 * reactivate it upon tripping over it
                                 */
                                dwp->dw_mask |= DW_vm_page_activate;
                        }
                        if (cntrl_flags & UPL_RET_ONLY_DIRTY) {
                                /*
                                 * we're only asking for DIRTY pages to be returned
                                 */
                                if (dst_page->list_req_pending || !(cntrl_flags & UPL_FOR_PAGEOUT)) {
                                        /*
                                         * if we were the page stolen by vm_pageout_scan to be
                                         * cleaned (as opposed to a buddy being clustered in 
                                         * or this request is not being driven by a PAGEOUT cluster
                                         * then we only need to check for the page being dirty or
                                         * precious to decide whether to return it
                                         */
                                        if (dst_page->dirty || dst_page->precious || (refmod_state & VM_MEM_MODIFIED))
                                                goto check_busy;
                                        goto dont_return;
                                }
                                /*
                                 * this is a request for a PAGEOUT cluster and this page
                                 * is merely along for the ride as a 'buddy'... not only
                                 * does it have to be dirty to be returned, but it also
                                 * can't have been referenced recently... note that we've
                                 * already filtered above based on whether this page is
                                 * currently on the inactive queue or it meets the page
                                 * ticket (generation count) check
                                 */
                                if ( (cntrl_flags & UPL_CLEAN_IN_PLACE || !(refmod_state & VM_MEM_REFERENCED) || dst_page->throttled) && 
                                     ((refmod_state & VM_MEM_MODIFIED) || dst_page->dirty || dst_page->precious) ) {
                                        goto check_busy;
                                }
dont_return:
                                /*
                                 * if we reach here, we're not to return
                                 * the page... go on to the next one
                                 */
                                if (user_page_list)
                                        user_page_list[entry].phys_addr = 0;

                                goto try_next_page;
                        }
check_busy:                     
                        if (dst_page->busy && (!(dst_page->list_req_pending && (dst_page->pageout || dst_page->cleaning)))) {
                                if (cntrl_flags & UPL_NOBLOCK) {
                                        if (user_page_list)
                                                user_page_list[entry].phys_addr = 0;

                                        goto try_next_page;
                                }
                                /*
                                 * someone else is playing with the
                                 * page.  We will have to wait.
                                 */
                                PAGE_SLEEP(object, dst_page, THREAD_UNINT);

                                continue;
                        }
                        /*
                         * Someone else already cleaning the page?
                         */
                        if ((dst_page->cleaning || dst_page->absent || VM_PAGE_WIRED(dst_page)) && !dst_page->list_req_pending) {
                                if (user_page_list)
                                        user_page_list[entry].phys_addr = 0;

                                goto try_next_page;
                        }
                        /*
                         * ENCRYPTED SWAP:
                         * The caller is gathering this page and might
                         * access its contents later on.  Decrypt the
                         * page before adding it to the UPL, so that
                         * the caller never sees encrypted data.
                         */
                        if (! (cntrl_flags & UPL_ENCRYPT) && dst_page->encrypted) {
                                int  was_busy;

                                /*
                                 * save the current state of busy
                                 * mark page as busy while decrypt
                                 * is in progress since it will drop
                                 * the object lock...
                                 */
                                was_busy = dst_page->busy;
                                dst_page->busy = TRUE;

                                vm_page_decrypt(dst_page, 0);
                                vm_page_decrypt_for_upl_counter++;
                                /*
                                 * restore to original busy state
                                 */
                                dst_page->busy = was_busy;
                        }
                        if (dst_page->pageout_queue == TRUE) {

                                vm_page_lockspin_queues();

                                if (dst_page->pageout_queue == TRUE) {
                                        /*
                                         * we've buddied up a page for a clustered pageout
                                         * that has already been moved to the pageout
                                         * queue by pageout_scan... we need to remove
                                         * it from the queue and drop the laundry count
                                         * on that queue
                                         */
                                        vm_pageout_throttle_up(dst_page);
                                }
                                vm_page_unlock_queues();
                        }
#if MACH_CLUSTER_STATS
                        /*
                         * pageout statistics gathering.  count
                         * all the pages we will page out that
                         * were not counted in the initial
                         * vm_pageout_scan work
                         */
                        if (dst_page->list_req_pending)
                                encountered_lrp = TRUE;
                        if ((dst_page->dirty || (dst_page->object->internal && dst_page->precious)) && !dst_page->list_req_pending) {
                                if (encountered_lrp)
                                        CLUSTER_STAT(pages_at_higher_offsets++;)
                                else
                                        CLUSTER_STAT(pages_at_lower_offsets++;)
                        }
#endif
                        /*
                         * Turn off busy indication on pending
                         * pageout.  Note: we can only get here
                         * in the request pending case.
                         */
                        dst_page->list_req_pending = FALSE;
                        dst_page->busy = FALSE;

                        hw_dirty = refmod_state & VM_MEM_MODIFIED;
                        dirty = hw_dirty ? TRUE : dst_page->dirty;

                        if (dst_page->phys_page > upl->highest_page)
                                upl->highest_page = dst_page->phys_page;

                        if (cntrl_flags & UPL_SET_LITE) {
                                unsigned int    pg_num;

                                pg_num = (unsigned int) ((dst_offset-offset)/PAGE_SIZE);
                                assert(pg_num == (dst_offset-offset)/PAGE_SIZE);
                                lite_list[pg_num>>5] |= 1 << (pg_num & 31);

                                if (hw_dirty)
                                        pmap_clear_modify(dst_page->phys_page);

                                /*
                                 * Mark original page as cleaning 
                                 * in place.
                                 */
                                dst_page->cleaning = TRUE;
                                dst_page->precious = FALSE;
                        } else {
                                /*
                                 * use pageclean setup, it is more
                                 * convenient even for the pageout
                                 * cases here
                                 */
                                vm_object_lock(upl->map_object);
                                vm_pageclean_setup(dst_page, alias_page, upl->map_object, size - xfer_size);
                                vm_object_unlock(upl->map_object);

                                alias_page->absent = FALSE;
                                alias_page = NULL;
                        }
#if     MACH_PAGEMAP
                        /*
                         * Record that this page has been 
                         * written out
                         */
                        vm_external_state_set(object->existence_map, dst_page->offset);
#endif  /*MACH_PAGEMAP*/
                        dst_page->dirty = dirty;

                        if (!dirty)
                                dst_page->precious = TRUE;

                        if (dst_page->pageout)
                                dst_page->busy = TRUE;

                        if ( (cntrl_flags & UPL_ENCRYPT) ) {
                                /*
                                 * ENCRYPTED SWAP:
                                 * We want to deny access to the target page
                                 * because its contents are about to be
                                 * encrypted and the user would be very
                                 * confused to see encrypted data instead
                                 * of their data.
                                 * We also set "encrypted_cleaning" to allow
                                 * vm_pageout_scan() to demote that page
                                 * from "adjacent/clean-in-place" to
                                 * "target/clean-and-free" if it bumps into
                                 * this page during its scanning while we're
                                 * still processing this cluster.
                                 */
                                dst_page->busy = TRUE;
                                dst_page->encrypted_cleaning = TRUE;
                        }
                        if ( !(cntrl_flags & UPL_CLEAN_IN_PLACE) ) {
                                /*
                                 * deny access to the target page
                                 * while it is being worked on
                                 */
                                if ((!dst_page->pageout) && ( !VM_PAGE_WIRED(dst_page))) {
                                        dst_page->busy = TRUE;
                                        dst_page->pageout = TRUE;

                                        dwp->dw_mask |= DW_vm_page_wire;
                                }
                        }
                } else {
                        if ((cntrl_flags & UPL_WILL_MODIFY) && object->copy != last_copy_object) {
                                /*
                                 * Honor copy-on-write obligations
                                 *
                                 * The copy object has changed since we
                                 * last synchronized for copy-on-write.
                                 * Another copy object might have been
                                 * inserted while we released the object's
                                 * lock.  Since someone could have seen the
                                 * original contents of the remaining pages
                                 * through that new object, we have to
                                 * synchronize with it again for the remaining
                                 * pages only.  The previous pages are "busy"
                                 * so they can not be seen through the new
                                 * mapping.  The new mapping will see our
                                 * upcoming changes for those previous pages,
                                 * but that's OK since they couldn't see what
                                 * was there before.  It's just a race anyway
                                 * and there's no guarantee of consistency or
                                 * atomicity.  We just don't want new mappings
                                 * to see both the *before* and *after* pages.
                                 */
                                if (object->copy != VM_OBJECT_NULL) {
                                        vm_object_update(
                                                object,
                                                dst_offset,/* current offset */
                                                xfer_size, /* remaining size */
                                                NULL,
                                                NULL,
                                                FALSE,     /* should_return */
                                                MEMORY_OBJECT_COPY_SYNC,
                                                VM_PROT_NO_CHANGE);

#if DEVELOPMENT || DEBUG
                                        upl_cow_again++;
                                        upl_cow_again_pages += xfer_size >> PAGE_SHIFT;
#endif
                                }
                                /*
                                 * remember the copy object we synced with
                                 */
                                last_copy_object = object->copy;
                        }
                        dst_page = vm_page_lookup(object, dst_offset);
                        
                        if (dst_page != VM_PAGE_NULL) {

                                if ((cntrl_flags & UPL_RET_ONLY_ABSENT)) {

                                        if ( !(dst_page->absent && dst_page->list_req_pending) ) {
                                                /*
                                                 * skip over pages already present in the cache
                                                 */
                                                if (user_page_list)
                                                        user_page_list[entry].phys_addr = 0;

                                                goto try_next_page;
                                        }
                                }
                                if ( !(dst_page->list_req_pending) ) {

                                        if (dst_page->cleaning) {
                                                /*
                                                 * someone else is writing to the page... wait...
                                                 */
                                                PAGE_SLEEP(object, dst_page, THREAD_UNINT);

                                                continue;
                                        }
                                } else {
                                        if (dst_page->fictitious &&
                                            dst_page->phys_page == vm_page_fictitious_addr) {
                                                assert( !dst_page->speculative);
                                                /*
                                                 * dump the fictitious page
                                                 */
                                                dst_page->list_req_pending = FALSE;

                                                VM_PAGE_FREE(dst_page);

                                                dst_page = NULL;

                                        } else if (dst_page->absent) {
                                                /*
                                                 * the default_pager case
                                                 */
                                                dst_page->list_req_pending = FALSE;
                                                PAGE_WAKEUP_DONE(dst_page);

                                        } else if (dst_page->pageout || dst_page->cleaning) {
                                                /*
                                                 * page was earmarked by vm_pageout_scan
                                                 * to be cleaned and stolen... we're going
                                                 * to take it back since we are not attempting
                                                 * to read that page and we don't want to stall
                                                 * waiting for it to be cleaned for 2 reasons...
                                                 * 1 - no use paging it out and back in
                                                 * 2 - if we stall, we may casue a deadlock in 
                                                 *     the FS trying to acquire the its locks
                                                 *     on the VNOP_PAGEOUT path presuming that
                                                 *     those locks are already held on the read
                                                 *     path before trying to create this UPL
                                                 *
                                                 * so undo all of the state that vm_pageout_scan
                                                 * hung on this page
                                                 */
                                                vm_pageout_queue_steal(dst_page, FALSE);
                                                PAGE_WAKEUP_DONE(dst_page);
                                        }
                                }
                        }
                        if (dst_page == VM_PAGE_NULL) {
                                if (object->private) {
                                        /* 
                                         * This is a nasty wrinkle for users 
                                         * of upl who encounter device or 
                                         * private memory however, it is 
                                         * unavoidable, only a fault can
                                         * resolve the actual backing
                                         * physical page by asking the
                                         * backing device.
                                         */
                                        if (user_page_list)
                                                user_page_list[entry].phys_addr = 0;

                                        goto try_next_page;
                                }
                                if (object->scan_collisions) {
                                        /*
                                         * the pageout_scan thread is trying to steal
                                         * pages from this object, but has run into our
                                         * lock... grab 2 pages from the head of the object...
                                         * the first is freed on behalf of pageout_scan, the
                                         * 2nd is for our own use... we use vm_object_page_grab
                                         * in both cases to avoid taking pages from the free
                                         * list since we are under memory pressure and our
                                         * lock on this object is getting in the way of
                                         * relieving it
                                         */
                                        dst_page = vm_object_page_grab(object);

                                        if (dst_page != VM_PAGE_NULL)
                                                vm_page_release(dst_page);

                                        dst_page = vm_object_page_grab(object);
                                }
                                if (dst_page == VM_PAGE_NULL) {
                                        /*
                                         * need to allocate a page
                                         */
                                        dst_page = vm_page_grab();
                                }
                                if (dst_page == VM_PAGE_NULL) {
                                        if ( (cntrl_flags & (UPL_RET_ONLY_ABSENT | UPL_NOBLOCK)) == (UPL_RET_ONLY_ABSENT | UPL_NOBLOCK)) {
                                               /*
                                                * we don't want to stall waiting for pages to come onto the free list
                                                * while we're already holding absent pages in this UPL
                                                * the caller will deal with the empty slots
                                                */
                                                if (user_page_list)
                                                        user_page_list[entry].phys_addr = 0;

                                                goto try_next_page;
                                        }
                                        /*
                                         * no pages available... wait
                                         * then try again for the same
                                         * offset...
                                         */
                                        vm_object_unlock(object);
                                        
                                        OSAddAtomic(size_in_pages, &vm_upl_wait_for_pages);

                                        VM_DEBUG_EVENT(vm_upl_page_wait, VM_UPL_PAGE_WAIT, DBG_FUNC_START, vm_upl_wait_for_pages, 0, 0, 0);

                                        VM_PAGE_WAIT();
                                        OSAddAtomic(-size_in_pages, &vm_upl_wait_for_pages);

                                        VM_DEBUG_EVENT(vm_upl_page_wait, VM_UPL_PAGE_WAIT, DBG_FUNC_END, vm_upl_wait_for_pages, 0, 0, 0);

                                        vm_object_lock(object);

                                        continue;
                                }
                                vm_page_insert(dst_page, object, dst_offset);

                                dst_page->absent = TRUE;
                                dst_page->busy = FALSE;

                                if (cntrl_flags & UPL_RET_ONLY_ABSENT) {
                                        /*
                                         * if UPL_RET_ONLY_ABSENT was specified,
                                         * than we're definitely setting up a
                                         * upl for a clustered read/pagein 
                                         * operation... mark the pages as clustered
                                         * so upl_commit_range can put them on the
                                         * speculative list
                                         */
                                        dst_page->clustered = TRUE;
                                }
                        }
                        if (dst_page->fictitious) {
                                panic("need corner case for fictitious page");
                        }
                        if (dst_page->busy) {
                                /*
                                 * someone else is playing with the
                                 * page.  We will have to wait.
                                 */
                                PAGE_SLEEP(object, dst_page, THREAD_UNINT);

                                continue;
                        }
                        /*
                         * ENCRYPTED SWAP:
                         */
                        if (cntrl_flags & UPL_ENCRYPT) {
                                /*
                                 * The page is going to be encrypted when we
                                 * get it from the pager, so mark it so.
                                 */
                                dst_page->encrypted = TRUE;
                        } else {
                                /*
                                 * Otherwise, the page will not contain
                                 * encrypted data.
                                 */
                                dst_page->encrypted = FALSE;
                        }
                        dst_page->overwriting = TRUE;

                        if (dst_page->pmapped) {
                                if ( !(cntrl_flags & UPL_FILE_IO))
                                        /*
                                         * eliminate all mappings from the
                                         * original object and its prodigy
                                         */
                                        refmod_state = pmap_disconnect(dst_page->phys_page);
                                else
                                        refmod_state = pmap_get_refmod(dst_page->phys_page);
                        } else
                                refmod_state = 0;

                        hw_dirty = refmod_state & VM_MEM_MODIFIED;
                        dirty = hw_dirty ? TRUE : dst_page->dirty;

                        if (cntrl_flags & UPL_SET_LITE) {
                                unsigned int    pg_num;

                                pg_num = (unsigned int) ((dst_offset-offset)/PAGE_SIZE);
                                assert(pg_num == (dst_offset-offset)/PAGE_SIZE);
                                lite_list[pg_num>>5] |= 1 << (pg_num & 31);

                                if (hw_dirty)
                                        pmap_clear_modify(dst_page->phys_page);

                                /*
                                 * Mark original page as cleaning 
                                 * in place.
                                 */
                                dst_page->cleaning = TRUE;
                                dst_page->precious = FALSE;
                        } else {
                                /*
                                 * use pageclean setup, it is more
                                 * convenient even for the pageout
                                 * cases here
                                 */
                                vm_object_lock(upl->map_object);
                                vm_pageclean_setup(dst_page, alias_page, upl->map_object, size - xfer_size);
                                vm_object_unlock(upl->map_object);

                                alias_page->absent = FALSE;
                                alias_page = NULL;
                        }

                        if (cntrl_flags & UPL_REQUEST_SET_DIRTY) {
                                upl->flags &= ~UPL_CLEAR_DIRTY;
                                upl->flags |= UPL_SET_DIRTY;
                                dirty = TRUE;
                                upl->flags |= UPL_SET_DIRTY;
                        } else if (cntrl_flags & UPL_CLEAN_IN_PLACE) {
                                /*
                                 * clean in place for read implies
                                 * that a write will be done on all
                                 * the pages that are dirty before
                                 * a upl commit is done.  The caller
                                 * is obligated to preserve the
                                 * contents of all pages marked dirty
                                 */
                                upl->flags |= UPL_CLEAR_DIRTY;
                        }
                        dst_page->dirty = dirty;

                        if (!dirty)
                                dst_page->precious = TRUE;

                        if ( !VM_PAGE_WIRED(dst_page)) {
                                /*
                                 * deny access to the target page while
                                 * it is being worked on
                                 */
                                dst_page->busy = TRUE;
                        } else
                                dwp->dw_mask |= DW_vm_page_wire;

                        /*
                         * We might be about to satisfy a fault which has been
                         * requested. So no need for the "restart" bit.
                         */
                        dst_page->restart = FALSE;
                        if (!dst_page->absent && !(cntrl_flags & UPL_WILL_MODIFY)) {
                                /*
                                 * expect the page to be used
                                 */
                                dwp->dw_mask |= DW_set_reference;
                        }
                        if (cntrl_flags & UPL_PRECIOUS) {
                                if (dst_page->object->internal) {
                                        dst_page->dirty = TRUE;
                                        dst_page->precious = FALSE;
                                } else {
                                        dst_page->precious = TRUE;
                                }
                        } else {
                                dst_page->precious = FALSE;
                        }
                }
                if (dst_page->busy)
                        upl->flags |= UPL_HAS_BUSY;

                if (dst_page->phys_page > upl->highest_page)
                        upl->highest_page = dst_page->phys_page;
                if (user_page_list) {
                        user_page_list[entry].phys_addr = dst_page->phys_page;
                        user_page_list[entry].pageout   = dst_page->pageout;
                        user_page_list[entry].absent    = dst_page->absent;
                        user_page_list[entry].dirty     = dst_page->dirty;
                        user_page_list[entry].precious  = dst_page->precious;
                        user_page_list[entry].device    = FALSE;
                        if (dst_page->clustered == TRUE)
                                user_page_list[entry].speculative = dst_page->speculative;
                        else
                                user_page_list[entry].speculative = FALSE;
                        user_page_list[entry].cs_validated = dst_page->cs_validated;
                        user_page_list[entry].cs_tainted = dst_page->cs_tainted;
                }
                /*
                 * if UPL_RET_ONLY_ABSENT is set, then
                 * we are working with a fresh page and we've
                 * just set the clustered flag on it to
                 * indicate that it was drug in as part of a
                 * speculative cluster... so leave it alone
                 */
                if ( !(cntrl_flags & UPL_RET_ONLY_ABSENT)) {
                        /*
                         * someone is explicitly grabbing this page...
                         * update clustered and speculative state
                         * 
                         */
                        VM_PAGE_CONSUME_CLUSTERED(dst_page);
                }
try_next_page:
                if (dwp->dw_mask) {
                        if (dwp->dw_mask & DW_vm_page_activate)
                                VM_STAT_INCR(reactivations);

                        VM_PAGE_ADD_DELAYED_WORK(dwp, dst_page, dw_count);

                        if (dw_count >= dw_limit) {
                                vm_page_do_delayed_work(object, &dw_array[0], dw_count);

                                dwp = &dw_array[0];
                                dw_count = 0;
                        }
                }
                entry++;
                dst_offset += PAGE_SIZE_64;
                xfer_size -= PAGE_SIZE;
        }
        if (dw_count)
                vm_page_do_delayed_work(object, &dw_array[0], dw_count);

        if (alias_page != NULL) {
                VM_PAGE_FREE(alias_page);
        }

        if (page_list_count != NULL) {
                if (upl->flags & UPL_INTERNAL)
                        *page_list_count = 0;
                else if (*page_list_count > entry)
                        *page_list_count = entry;
        }
#if UPL_DEBUG
        upl->upl_state = 1;
#endif
        vm_object_unlock(object);

        return KERN_SUCCESS;
}

/* JMM - Backward compatability for now */
kern_return_t
vm_fault_list_request(                  /* forward */
        memory_object_control_t         control,
        vm_object_offset_t      offset,
        upl_size_t              size,
        upl_t                   *upl_ptr,
        upl_page_info_t         **user_page_list_ptr,
        unsigned int            page_list_count,
        int                     cntrl_flags);
kern_return_t
vm_fault_list_request(
        memory_object_control_t         control,
        vm_object_offset_t      offset,
        upl_size_t              size,
        upl_t                   *upl_ptr,
        upl_page_info_t         **user_page_list_ptr,
        unsigned int            page_list_count,
        int                     cntrl_flags)
{
        unsigned int            local_list_count;
        upl_page_info_t         *user_page_list;
        kern_return_t           kr;

        if((cntrl_flags & UPL_VECTOR)==UPL_VECTOR)
                 return KERN_INVALID_ARGUMENT;

        if (user_page_list_ptr != NULL) {
                local_list_count = page_list_count;
                user_page_list = *user_page_list_ptr;
        } else {
                local_list_count = 0;
                user_page_list = NULL;
        }
        kr =  memory_object_upl_request(control,
                                offset,
                                size,
                                upl_ptr,
                                user_page_list,
                                &local_list_count,
                                cntrl_flags);

        if(kr != KERN_SUCCESS)
                return kr;

        if ((user_page_list_ptr != NULL) && (cntrl_flags & UPL_INTERNAL)) {
                *user_page_list_ptr = UPL_GET_INTERNAL_PAGE_LIST(*upl_ptr);
        }

        return KERN_SUCCESS;
}

                

/*  
 *      Routine:        vm_object_super_upl_request
 *      Purpose:        
 *              Cause the population of a portion of a vm_object
 *              in much the same way as memory_object_upl_request.
 *              Depending on the nature of the request, the pages
 *              returned may be contain valid data or be uninitialized.
 *              However, the region may be expanded up to the super
 *              cluster size provided.
 */

__private_extern__ kern_return_t
vm_object_super_upl_request(
        vm_object_t object,
        vm_object_offset_t      offset,
        upl_size_t              size,
        upl_size_t              super_cluster,
        upl_t                   *upl,
        upl_page_info_t         *user_page_list,
        unsigned int            *page_list_count,
        int                     cntrl_flags)
{
        if (object->paging_offset > offset  || ((cntrl_flags & UPL_VECTOR)==UPL_VECTOR))
                return KERN_FAILURE;

        assert(object->paging_in_progress);
        offset = offset - object->paging_offset;

        if (super_cluster > size) {

                vm_object_offset_t      base_offset;
                upl_size_t              super_size;
                vm_object_size_t        super_size_64;

                base_offset = (offset & ~((vm_object_offset_t) super_cluster - 1));
                super_size = (offset + size) > (base_offset + super_cluster) ? super_cluster<<1 : super_cluster;
                super_size_64 = ((base_offset + super_size) > object->vo_size) ? (object->vo_size - base_offset) : super_size;
                super_size = (upl_size_t) super_size_64;
                assert(super_size == super_size_64);

                if (offset > (base_offset + super_size)) {
                        panic("vm_object_super_upl_request: Missed target pageout"
                              " %#llx,%#llx, %#x, %#x, %#x, %#llx\n",
                              offset, base_offset, super_size, super_cluster,
                              size, object->paging_offset);
                }
                /*
                 * apparently there is a case where the vm requests a
                 * page to be written out who's offset is beyond the
                 * object size
                 */
                if ((offset + size) > (base_offset + super_size)) {
                        super_size_64 = (offset + size) - base_offset;
                        super_size = (upl_size_t) super_size_64;
                        assert(super_size == super_size_64);
                }

                offset = base_offset;
                size = super_size;
        }
        return vm_object_upl_request(object, offset, size, upl, user_page_list, page_list_count, cntrl_flags);
}


kern_return_t
vm_map_create_upl(
        vm_map_t                map,
        vm_map_address_t        offset,
        upl_size_t              *upl_size,
        upl_t                   *upl,
        upl_page_info_array_t   page_list,
        unsigned int            *count,
        int                     *flags)
{
        vm_map_entry_t  entry;
        int             caller_flags;
        int             force_data_sync;
        int             sync_cow_data;
        vm_object_t     local_object;
        vm_map_offset_t local_offset;
        vm_map_offset_t local_start;
        kern_return_t   ret;

        caller_flags = *flags;

        if (caller_flags & ~UPL_VALID_FLAGS) {
                /*
                 * For forward compatibility's sake,
                 * reject any unknown flag.
                 */
                return KERN_INVALID_VALUE;
        }
        force_data_sync = (caller_flags & UPL_FORCE_DATA_SYNC);
        sync_cow_data = !(caller_flags & UPL_COPYOUT_FROM);

        if (upl == NULL)
                return KERN_INVALID_ARGUMENT;

REDISCOVER_ENTRY:
        vm_map_lock_read(map);

        if (vm_map_lookup_entry(map, offset, &entry)) {

                if ((entry->vme_end - offset) < *upl_size) {
                        *upl_size = (upl_size_t) (entry->vme_end - offset);
                        assert(*upl_size == entry->vme_end - offset);
                }

                if (caller_flags & UPL_QUERY_OBJECT_TYPE) {
                        *flags = 0;

                        if ( !entry->is_sub_map && entry->object.vm_object != VM_OBJECT_NULL) {
                                if (entry->object.vm_object->private)
                                        *flags = UPL_DEV_MEMORY;

                                if (entry->object.vm_object->phys_contiguous)
                                        *flags |= UPL_PHYS_CONTIG;
                        }
                        vm_map_unlock_read(map);

                        return KERN_SUCCESS;
                }

                if (entry->is_sub_map) {
                        vm_map_t        submap;

                        submap = entry->object.sub_map;
                        local_start = entry->vme_start;
                        local_offset = entry->offset;

                        vm_map_reference(submap);
                        vm_map_unlock_read(map);

                        ret = vm_map_create_upl(submap, 
                                                local_offset + (offset - local_start), 
                                                upl_size, upl, page_list, count, flags);
                        vm_map_deallocate(submap);

                        return ret;
                }

                if (entry->object.vm_object == VM_OBJECT_NULL || !entry->object.vm_object->phys_contiguous) {
                        if ((*upl_size/PAGE_SIZE) > MAX_UPL_SIZE)
                                *upl_size = MAX_UPL_SIZE * PAGE_SIZE;
                }

                /*
                 *      Create an object if necessary.
                 */
                if (entry->object.vm_object == VM_OBJECT_NULL) {

                        if (vm_map_lock_read_to_write(map))
                                goto REDISCOVER_ENTRY;

                        entry->object.vm_object = vm_object_allocate((vm_size_t)(entry->vme_end - entry->vme_start));
                        entry->offset = 0;

                        vm_map_lock_write_to_read(map);
                }
                if (!(caller_flags & UPL_COPYOUT_FROM)) {
                        if (!(entry->protection & VM_PROT_WRITE)) {
                                vm_map_unlock_read(map);
                                return KERN_PROTECTION_FAILURE;
                        }

#if !CONFIG_EMBEDDED
                        local_object = entry->object.vm_object;
                        if (vm_map_entry_should_cow_for_true_share(entry) &&
                            local_object->vo_size > *upl_size &&
                            *upl_size != 0) {
                                vm_prot_t       prot;

                                /*
                                 * Set up the targeted range for copy-on-write to avoid
                                 * applying true_share/copy_delay to the entire object.
                                 */

                                if (vm_map_lock_read_to_write(map)) {
                                        goto REDISCOVER_ENTRY;
                                }

                                vm_map_clip_start(map, entry, vm_map_trunc_page(offset));
                                vm_map_clip_end(map, entry, vm_map_round_page(offset + *upl_size));
                                prot = entry->protection & ~VM_PROT_WRITE;
                                if (override_nx(map, entry->alias) && prot)
                                        prot |= VM_PROT_EXECUTE;
                                vm_object_pmap_protect(local_object,
                                                       entry->offset,
                                                       entry->vme_end - entry->vme_start,
                                                       ((entry->is_shared || map->mapped)
                                                        ? PMAP_NULL
                                                        : map->pmap),
                                                       entry->vme_start,
                                                       prot);
                                entry->needs_copy = TRUE;

                                vm_map_lock_write_to_read(map);
                        }
#endif /* !CONFIG_EMBEDDED */

                        if (entry->needs_copy)  {
                                /*
                                 * Honor copy-on-write for COPY_SYMMETRIC
                                 * strategy.
                                 */
                                vm_map_t                local_map;
                                vm_object_t             object;
                                vm_object_offset_t      new_offset;
                                vm_prot_t               prot;
                                boolean_t               wired;
                                vm_map_version_t        version;
                                vm_map_t                real_map;

                                local_map = map;

                                if (vm_map_lookup_locked(&local_map,
                                                         offset, VM_PROT_WRITE,
                                                         OBJECT_LOCK_EXCLUSIVE,
                                                         &version, &object,
                                                         &new_offset, &prot, &wired,
                                                         NULL,
                                                         &real_map) != KERN_SUCCESS) {
                                        vm_map_unlock_read(local_map);
                                        return KERN_FAILURE;
                                }
                                if (real_map != map)
                                        vm_map_unlock(real_map);
                                vm_map_unlock_read(local_map);

                                vm_object_unlock(object);

                                goto REDISCOVER_ENTRY;
                        }
                }
                if (sync_cow_data) {
                        if (entry->object.vm_object->shadow || entry->object.vm_object->copy) {
                                local_object = entry->object.vm_object;
                                local_start = entry->vme_start;
                                local_offset = entry->offset;

                                vm_object_reference(local_object);
                                vm_map_unlock_read(map);

                                if (local_object->shadow && local_object->copy) {
                                        vm_object_lock_request(
                                                               local_object->shadow,
                                                               (vm_object_offset_t)
                                                               ((offset - local_start) +
                                                                local_offset) +
                                                               local_object->vo_shadow_offset,
                                                               *upl_size, FALSE, 
                                                               MEMORY_OBJECT_DATA_SYNC,
                                                               VM_PROT_NO_CHANGE);
                                }
                                sync_cow_data = FALSE;
                                vm_object_deallocate(local_object);

                                goto REDISCOVER_ENTRY;
                        }
                }
                if (force_data_sync) {
                        local_object = entry->object.vm_object;
                        local_start = entry->vme_start;
                        local_offset = entry->offset;

                        vm_object_reference(local_object);
                        vm_map_unlock_read(map);

                        vm_object_lock_request(
                                               local_object,
                                               (vm_object_offset_t)
                                               ((offset - local_start) + local_offset),
                                               (vm_object_size_t)*upl_size, FALSE, 
                                               MEMORY_OBJECT_DATA_SYNC,
                                               VM_PROT_NO_CHANGE);

                        force_data_sync = FALSE;
                        vm_object_deallocate(local_object);

                        goto REDISCOVER_ENTRY;
                }
                if (entry->object.vm_object->private)
                        *flags = UPL_DEV_MEMORY;
                else
                        *flags = 0;

                if (entry->object.vm_object->phys_contiguous)
                        *flags |= UPL_PHYS_CONTIG;

                local_object = entry->object.vm_object;
                local_offset = entry->offset;
                local_start = entry->vme_start;

                vm_object_reference(local_object);
                vm_map_unlock_read(map);

                ret = vm_object_iopl_request(local_object, 
                                              (vm_object_offset_t) ((offset - local_start) + local_offset),
                                              *upl_size,
                                              upl,
                                              page_list,
                                              count,
                                              caller_flags);
                vm_object_deallocate(local_object);

                return(ret);
        } 
        vm_map_unlock_read(map);

        return(KERN_FAILURE);
}

/*
 * Internal routine to enter a UPL into a VM map.
 * 
 * JMM - This should just be doable through the standard
 * vm_map_enter() API.
 */
kern_return_t
vm_map_enter_upl(
        vm_map_t                map, 
        upl_t                   upl, 
        vm_map_offset_t         *dst_addr)
{
        vm_map_size_t           size;
        vm_object_offset_t      offset;
        vm_map_offset_t         addr;
        vm_page_t               m;
        kern_return_t           kr;
        int                     isVectorUPL = 0, curr_upl=0;
        upl_t                   vector_upl = NULL;
        vm_offset_t             vector_upl_dst_addr = 0;
        vm_map_t                vector_upl_submap = NULL;
        upl_offset_t            subupl_offset = 0;
        upl_size_t              subupl_size = 0;

        if (upl == UPL_NULL)
                return KERN_INVALID_ARGUMENT;

        if((isVectorUPL = vector_upl_is_valid(upl))) {
                int mapped=0,valid_upls=0;
                vector_upl = upl;

                upl_lock(vector_upl);
                for(curr_upl=0; curr_upl < MAX_VECTOR_UPL_ELEMENTS; curr_upl++) {
                        upl =  vector_upl_subupl_byindex(vector_upl, curr_upl );
                        if(upl == NULL)
                                continue;
                        valid_upls++;
                        if (UPL_PAGE_LIST_MAPPED & upl->flags)
                                mapped++;
                }

                if(mapped) { 
                        if(mapped != valid_upls)
                                panic("Only %d of the %d sub-upls within the Vector UPL are alread mapped\n", mapped, valid_upls);
                        else {
                                upl_unlock(vector_upl);
                                return KERN_FAILURE;
                        }
                }

                kr = kmem_suballoc(map, &vector_upl_dst_addr, vector_upl->size, FALSE, VM_FLAGS_ANYWHERE, &vector_upl_submap);
                if( kr != KERN_SUCCESS )
                        panic("Vector UPL submap allocation failed\n");
                map = vector_upl_submap;
                vector_upl_set_submap(vector_upl, vector_upl_submap, vector_upl_dst_addr);
                curr_upl=0;
        }
        else
                upl_lock(upl);

process_upl_to_enter:
        if(isVectorUPL){
                if(curr_upl == MAX_VECTOR_UPL_ELEMENTS) {
                        *dst_addr = vector_upl_dst_addr;
                        upl_unlock(vector_upl);
                        return KERN_SUCCESS;
                }
                upl =  vector_upl_subupl_byindex(vector_upl, curr_upl++ );
                if(upl == NULL)
                        goto process_upl_to_enter;

                vector_upl_get_iostate(vector_upl, upl, &subupl_offset, &subupl_size);
                *dst_addr = (vm_map_offset_t)(vector_upl_dst_addr + (vm_map_offset_t)subupl_offset);
        } else {
                /*
                 * check to see if already mapped
                 */
                if (UPL_PAGE_LIST_MAPPED & upl->flags) {
                        upl_unlock(upl);
                        return KERN_FAILURE;
                }
        }
        if ((!(upl->flags & UPL_SHADOWED)) &&
            ((upl->flags & UPL_HAS_BUSY) ||
             !((upl->flags & (UPL_DEVICE_MEMORY | UPL_IO_WIRE)) || (upl->map_object->phys_contiguous)))) {

                vm_object_t             object;
                vm_page_t               alias_page;
                vm_object_offset_t      new_offset;
                unsigned int            pg_num;
                wpl_array_t             lite_list;

                if (upl->flags & UPL_INTERNAL) {
                        lite_list = (wpl_array_t) 
                                ((((uintptr_t)upl) + sizeof(struct upl))
                                 + ((upl->size/PAGE_SIZE) * sizeof(upl_page_info_t)));
                } else {
                        lite_list = (wpl_array_t)(((uintptr_t)upl) + sizeof(struct upl));
                }
                object = upl->map_object;
                upl->map_object = vm_object_allocate(upl->size);

                vm_object_lock(upl->map_object);

                upl->map_object->shadow = object;
                upl->map_object->pageout = TRUE;
                upl->map_object->can_persist = FALSE;
                upl->map_object->copy_strategy = MEMORY_OBJECT_COPY_NONE;
                upl->map_object->vo_shadow_offset = upl->offset - object->paging_offset;
                upl->map_object->wimg_bits = object->wimg_bits;
                offset = upl->map_object->vo_shadow_offset;
                new_offset = 0;
                size = upl->size;

                upl->flags |= UPL_SHADOWED;

                while (size) {
                        pg_num = (unsigned int) (new_offset / PAGE_SIZE);
                        assert(pg_num == new_offset / PAGE_SIZE);

                        if (lite_list[pg_num>>5] & (1 << (pg_num & 31))) {

                                VM_PAGE_GRAB_FICTITIOUS(alias_page);

                                vm_object_lock(object);

                                m = vm_page_lookup(object, offset);
                                if (m == VM_PAGE_NULL) {
                                        panic("vm_upl_map: page missing\n");
                                }

                                /*
                                 * Convert the fictitious page to a private 
                                 * shadow of the real page.
                                 */
                                assert(alias_page->fictitious);
                                alias_page->fictitious = FALSE;
                                alias_page->private = TRUE;
                                alias_page->pageout = TRUE;
                                /*
                                 * since m is a page in the upl it must
                                 * already be wired or BUSY, so it's
                                 * safe to assign the underlying physical
                                 * page to the alias
                                 */
                                alias_page->phys_page = m->phys_page;

                                vm_object_unlock(object);

                                vm_page_lockspin_queues();
                                vm_page_wire(alias_page);
                                vm_page_unlock_queues();
                                
                                /*
                                 * ENCRYPTED SWAP:
                                 * The virtual page ("m") has to be wired in some way
                                 * here or its physical page ("m->phys_page") could
                                 * be recycled at any time.
                                 * Assuming this is enforced by the caller, we can't
                                 * get an encrypted page here.  Since the encryption
                                 * key depends on the VM page's "pager" object and
                                 * the "paging_offset", we couldn't handle 2 pageable
                                 * VM pages (with different pagers and paging_offsets)
                                 * sharing the same physical page:  we could end up
                                 * encrypting with one key (via one VM page) and
                                 * decrypting with another key (via the alias VM page).
                                 */
                                ASSERT_PAGE_DECRYPTED(m);

                                vm_page_insert(alias_page, upl->map_object, new_offset);

                                assert(!alias_page->wanted);
                                alias_page->busy = FALSE;
                                alias_page->absent = FALSE;
                        }
                        size -= PAGE_SIZE;
                        offset += PAGE_SIZE_64;
                        new_offset += PAGE_SIZE_64;
                }
                vm_object_unlock(upl->map_object);
        }
        if (upl->flags & UPL_SHADOWED)
                offset = 0;
        else
                offset = upl->offset - upl->map_object->paging_offset;

        size = upl->size;
        
        vm_object_reference(upl->map_object);

        if(!isVectorUPL) {
                *dst_addr = 0;
                /*
                * NEED A UPL_MAP ALIAS
                */
                kr = vm_map_enter(map, dst_addr, (vm_map_size_t)size, (vm_map_offset_t) 0,
                                  VM_FLAGS_ANYWHERE, upl->map_object, offset, FALSE,
                                  VM_PROT_DEFAULT, VM_PROT_ALL, VM_INHERIT_DEFAULT);

                if (kr != KERN_SUCCESS) {
                        upl_unlock(upl);
                        return(kr);
                }
        }
        else {
                kr = vm_map_enter(map, dst_addr, (vm_map_size_t)size, (vm_map_offset_t) 0,
                                  VM_FLAGS_FIXED, upl->map_object, offset, FALSE,
                                  VM_PROT_DEFAULT, VM_PROT_ALL, VM_INHERIT_DEFAULT);
                if(kr)
                        panic("vm_map_enter failed for a Vector UPL\n");
        }
        vm_object_lock(upl->map_object);

        for (addr = *dst_addr; size > 0; size -= PAGE_SIZE, addr += PAGE_SIZE) {
                m = vm_page_lookup(upl->map_object, offset);

                if (m) {
                        m->pmapped = TRUE;

                        /* CODE SIGNING ENFORCEMENT: page has been wpmapped, 
                         * but only in kernel space. If this was on a user map,
                         * we'd have to set the wpmapped bit. */
                        /* m->wpmapped = TRUE; */
                        assert(map==kernel_map);
        
                        PMAP_ENTER(map->pmap, addr, m, VM_PROT_ALL, 0, TRUE);
                }
                offset += PAGE_SIZE_64;
        }
        vm_object_unlock(upl->map_object);

        /*
         * hold a reference for the mapping
         */
        upl->ref_count++;
        upl->flags |= UPL_PAGE_LIST_MAPPED;
        upl->kaddr = (vm_offset_t) *dst_addr;
        assert(upl->kaddr == *dst_addr);
        
        if(isVectorUPL)
                goto process_upl_to_enter;

        upl_unlock(upl);

        return KERN_SUCCESS;
}
        
/*
 * Internal routine to remove a UPL mapping from a VM map.
 *
 * XXX - This should just be doable through a standard
 * vm_map_remove() operation.  Otherwise, implicit clean-up
 * of the target map won't be able to correctly remove
 * these (and release the reference on the UPL).  Having
 * to do this means we can't map these into user-space
 * maps yet.
 */
kern_return_t
vm_map_remove_upl(
        vm_map_t        map, 
        upl_t           upl)
{
        vm_address_t    addr;
        upl_size_t      size;
        int             isVectorUPL = 0, curr_upl = 0;
        upl_t           vector_upl = NULL;

        if (upl == UPL_NULL)
                return KERN_INVALID_ARGUMENT;

        if((isVectorUPL = vector_upl_is_valid(upl))) {
                int     unmapped=0, valid_upls=0;
                vector_upl = upl;
                upl_lock(vector_upl);
                for(curr_upl=0; curr_upl < MAX_VECTOR_UPL_ELEMENTS; curr_upl++) {
                        upl =  vector_upl_subupl_byindex(vector_upl, curr_upl );
                        if(upl == NULL)
                                continue;
                        valid_upls++;
                        if (!(UPL_PAGE_LIST_MAPPED & upl->flags))
                                unmapped++;
                }

                if(unmapped) {
                        if(unmapped != valid_upls)
                                panic("%d of the %d sub-upls within the Vector UPL is/are not mapped\n", unmapped, valid_upls);
                        else {
                                upl_unlock(vector_upl);
                                return KERN_FAILURE;
                        }
                }
                curr_upl=0;
        }
        else
                upl_lock(upl);

process_upl_to_remove:
        if(isVectorUPL) {
                if(curr_upl == MAX_VECTOR_UPL_ELEMENTS) {
                        vm_map_t v_upl_submap;
                        vm_offset_t v_upl_submap_dst_addr;
                        vector_upl_get_submap(vector_upl, &v_upl_submap, &v_upl_submap_dst_addr);

                        vm_map_remove(map, v_upl_submap_dst_addr, v_upl_submap_dst_addr + vector_upl->size, VM_MAP_NO_FLAGS);
                        vm_map_deallocate(v_upl_submap);
                        upl_unlock(vector_upl);
                        return KERN_SUCCESS;
                }

                upl =  vector_upl_subupl_byindex(vector_upl, curr_upl++ );
                if(upl == NULL)
                        goto process_upl_to_remove;     
        }

        if (upl->flags & UPL_PAGE_LIST_MAPPED) {
                addr = upl->kaddr;
                size = upl->size;

                assert(upl->ref_count > 1);
                upl->ref_count--;               /* removing mapping ref */

                upl->flags &= ~UPL_PAGE_LIST_MAPPED;
                upl->kaddr = (vm_offset_t) 0;
                
                if(!isVectorUPL) {
                        upl_unlock(upl);
                
                        vm_map_remove(map,
                                vm_map_trunc_page(addr),
                                vm_map_round_page(addr + size),
                                VM_MAP_NO_FLAGS);
                
                        return KERN_SUCCESS;
                }
                else {
                        /*
                        * If it's a Vectored UPL, we'll be removing the entire
                        * submap anyways, so no need to remove individual UPL
                        * element mappings from within the submap
                        */      
                        goto process_upl_to_remove;
                }
        }
        upl_unlock(upl);

        return KERN_FAILURE;
}


kern_return_t
upl_commit_range(
        upl_t                   upl, 
        upl_offset_t            offset, 
        upl_size_t              size,
        int                     flags,
        upl_page_info_t         *page_list,
        mach_msg_type_number_t  count,
        boolean_t               *empty) 
{
        upl_size_t              xfer_size, subupl_size = size;
        vm_object_t             shadow_object;
        vm_object_t             object;
        vm_object_offset_t      target_offset;
        upl_offset_t            subupl_offset = offset;
        int                     entry;
        wpl_array_t             lite_list;
        int                     occupied;
        int                     clear_refmod = 0;
        int                     pgpgout_count = 0;
        struct  vm_page_delayed_work    dw_array[DEFAULT_DELAYED_WORK_LIMIT];
        struct  vm_page_delayed_work    *dwp;
        int                     dw_count;
        int                     dw_limit;
        int                     isVectorUPL = 0;
        upl_t                   vector_upl = NULL;
        boolean_t               should_be_throttled = FALSE;

        *empty = FALSE;

        if (upl == UPL_NULL)
                return KERN_INVALID_ARGUMENT;

        if (count == 0)
                page_list = NULL;

        if((isVectorUPL = vector_upl_is_valid(upl))) {
                vector_upl = upl;
                upl_lock(vector_upl);
        }
        else
                upl_lock(upl);

process_upl_to_commit:

        if(isVectorUPL) {
                size = subupl_size;
                offset = subupl_offset;
                if(size == 0) {
                        upl_unlock(vector_upl);
                        return KERN_SUCCESS;
                }
                upl =  vector_upl_subupl_byoffset(vector_upl, &offset, &size);
                if(upl == NULL) {
                        upl_unlock(vector_upl);
                        return KERN_FAILURE;
                }
                page_list = UPL_GET_INTERNAL_PAGE_LIST_SIMPLE(upl);
                subupl_size -= size;
                subupl_offset += size;
        }

#if UPL_DEBUG
        if (upl->upl_commit_index < UPL_DEBUG_COMMIT_RECORDS) {
                (void) OSBacktrace(&upl->upl_commit_records[upl->upl_commit_index].c_retaddr[0], UPL_DEBUG_STACK_FRAMES);
                
                upl->upl_commit_records[upl->upl_commit_index].c_beg = offset;
                upl->upl_commit_records[upl->upl_commit_index].c_end = (offset + size);

                upl->upl_commit_index++;
        }
#endif
        if (upl->flags & UPL_DEVICE_MEMORY)
                xfer_size = 0;
        else if ((offset + size) <= upl->size)
                xfer_size = size;
        else {
                if(!isVectorUPL)
                        upl_unlock(upl);
                else {
                        upl_unlock(vector_upl);
                }
                return KERN_FAILURE;
        }
        if (upl->flags & UPL_SET_DIRTY)
                flags |= UPL_COMMIT_SET_DIRTY;
        if (upl->flags & UPL_CLEAR_DIRTY)
                flags |= UPL_COMMIT_CLEAR_DIRTY;

        if (upl->flags & UPL_INTERNAL)
                lite_list = (wpl_array_t) ((((uintptr_t)upl) + sizeof(struct upl))
                                           + ((upl->size/PAGE_SIZE) * sizeof(upl_page_info_t)));
        else
                lite_list = (wpl_array_t) (((uintptr_t)upl) + sizeof(struct upl));

        object = upl->map_object;

        if (upl->flags & UPL_SHADOWED) {
                vm_object_lock(object);
                shadow_object = object->shadow;
        } else {
                shadow_object = object;
        }
        entry = offset/PAGE_SIZE;
        target_offset = (vm_object_offset_t)offset;

        if (upl->flags & UPL_KERNEL_OBJECT)
                vm_object_lock_shared(shadow_object);
        else
                vm_object_lock(shadow_object);

        if (upl->flags & UPL_ACCESS_BLOCKED) {
                assert(shadow_object->blocked_access);
                shadow_object->blocked_access = FALSE;
                vm_object_wakeup(object, VM_OBJECT_EVENT_UNBLOCKED);
        }

        if (shadow_object->code_signed) {
                /*
                 * CODE SIGNING:
                 * If the object is code-signed, do not let this UPL tell
                 * us if the pages are valid or not.  Let the pages be
                 * validated by VM the normal way (when they get mapped or
                 * copied).
                 */
                flags &= ~UPL_COMMIT_CS_VALIDATED;
        }
        if (! page_list) {
                /*
                 * No page list to get the code-signing info from !?
                 */
                flags &= ~UPL_COMMIT_CS_VALIDATED;
        }
        if (!VM_DYNAMIC_PAGING_ENABLED(memory_manager_default) && shadow_object->internal)
                should_be_throttled = TRUE;

        dwp = &dw_array[0];
        dw_count = 0;
        dw_limit = DELAYED_WORK_LIMIT(DEFAULT_DELAYED_WORK_LIMIT);

        while (xfer_size) {
                vm_page_t       t, m;

                dwp->dw_mask = 0;
                clear_refmod = 0;

                m = VM_PAGE_NULL;

                if (upl->flags & UPL_LITE) {
                        unsigned int    pg_num;

                        pg_num = (unsigned int) (target_offset/PAGE_SIZE);
                        assert(pg_num == target_offset/PAGE_SIZE);

                        if (lite_list[pg_num>>5] & (1 << (pg_num & 31))) {
                                lite_list[pg_num>>5] &= ~(1 << (pg_num & 31));

                                if (!(upl->flags & UPL_KERNEL_OBJECT))
                                        m = vm_page_lookup(shadow_object, target_offset + (upl->offset - shadow_object->paging_offset));
                        }
                }
                if (upl->flags & UPL_SHADOWED) {
                        if ((t = vm_page_lookup(object, target_offset)) != VM_PAGE_NULL) {

                                t->pageout = FALSE;

                                VM_PAGE_FREE(t);

                                if (m == VM_PAGE_NULL)
                                        m = vm_page_lookup(shadow_object, target_offset + object->vo_shadow_offset);
                        }
                }
                if ((upl->flags & UPL_KERNEL_OBJECT) || m == VM_PAGE_NULL)
                        goto commit_next_page;

                if (flags & UPL_COMMIT_CS_VALIDATED) {
                        /*
                         * CODE SIGNING:
                         * Set the code signing bits according to
                         * what the UPL says they should be.
                         */
                        m->cs_validated = page_list[entry].cs_validated;
                        m->cs_tainted = page_list[entry].cs_tainted;
                }
                if (upl->flags & UPL_IO_WIRE) {

                        if (page_list)
                                page_list[entry].phys_addr = 0;

                        if (flags & UPL_COMMIT_SET_DIRTY) {
                                m->dirty = TRUE;
                        } else if (flags & UPL_COMMIT_CLEAR_DIRTY) {
                                m->dirty = FALSE;

                                if (! (flags & UPL_COMMIT_CS_VALIDATED) &&
                                    m->cs_validated && !m->cs_tainted) {
                                        /*
                                         * CODE SIGNING:
                                         * This page is no longer dirty
                                         * but could have been modified,
                                         * so it will need to be
                                         * re-validated.
                                         */
                                        m->cs_validated = FALSE;
#if DEVELOPMENT || DEBUG
                                        vm_cs_validated_resets++;
#endif
                                        pmap_disconnect(m->phys_page);
                                }
                                clear_refmod |= VM_MEM_MODIFIED;
                        }
                        if (flags & UPL_COMMIT_INACTIVATE) {
                                dwp->dw_mask |= DW_vm_page_deactivate_internal;
                                clear_refmod |= VM_MEM_REFERENCED;
                        }
                        if (upl->flags & UPL_ACCESS_BLOCKED) {
                                /*
                                 * We blocked access to the pages in this UPL.
                                 * Clear the "busy" bit and wake up any waiter
                                 * for this page.
                                 */
                                dwp->dw_mask |= (DW_clear_busy | DW_PAGE_WAKEUP);
                        }
                        if (m->absent) {
                                if (flags & UPL_COMMIT_FREE_ABSENT)
                                        dwp->dw_mask |= DW_vm_page_free;
                                else {
                                        m->absent = FALSE;
                                        dwp->dw_mask |= (DW_clear_busy | DW_PAGE_WAKEUP);

                                        if ( !(dwp->dw_mask & DW_vm_page_deactivate_internal))
                                                dwp->dw_mask |= DW_vm_page_activate;
                                }
                        } else
                                dwp->dw_mask |= DW_vm_page_unwire;

                        goto commit_next_page;
                }
                /*
                 * make sure to clear the hardware
                 * modify or reference bits before
                 * releasing the BUSY bit on this page
                 * otherwise we risk losing a legitimate
                 * change of state
                 */
                if (flags & UPL_COMMIT_CLEAR_DIRTY) {
                        m->dirty = FALSE;

                        if (! (flags & UPL_COMMIT_CS_VALIDATED) &&
                            m->cs_validated && !m->cs_tainted) {
                                /*
                                 * CODE SIGNING:
                                 * This page is no longer dirty
                                 * but could have been modified,
                                 * so it will need to be
                                 * re-validated.
                                 */
                                m->cs_validated = FALSE;
#if DEVELOPMENT || DEBUG
                                vm_cs_validated_resets++;
#endif
                                pmap_disconnect(m->phys_page);
                        }
                        clear_refmod |= VM_MEM_MODIFIED;
                }
                if (page_list) {
                        upl_page_info_t *p;

                        p = &(page_list[entry]);

                        if (p->phys_addr && p->pageout && !m->pageout) {
                                m->busy = TRUE;
                                m->pageout = TRUE;

                                dwp->dw_mask |= DW_vm_page_wire;

                        } else if (p->phys_addr &&
                                   !p->pageout && m->pageout &&
                                   !m->dump_cleaning) {
                                m->pageout = FALSE;
                                m->absent = FALSE;
                                m->overwriting = FALSE;

                                dwp->dw_mask |= (DW_vm_page_unwire | DW_clear_busy | DW_PAGE_WAKEUP);
                        }
                        page_list[entry].phys_addr = 0;
                }
                m->dump_cleaning = FALSE;

                if (m->laundry)
                        dwp->dw_mask |= DW_vm_pageout_throttle_up;

                if (m->pageout) {
                        m->cleaning = FALSE;
                        m->encrypted_cleaning = FALSE;
                        m->pageout = FALSE;
#if MACH_CLUSTER_STATS
                        if (m->wanted) vm_pageout_target_collisions++;
#endif
                        m->dirty = FALSE;

                        if (! (flags & UPL_COMMIT_CS_VALIDATED) &&
                            m->cs_validated && !m->cs_tainted) {
                                /*
                                 * CODE SIGNING:
                                 * This page is no longer dirty
                                 * but could have been modified,
                                 * so it will need to be
                                 * re-validated.
                                 */
                                m->cs_validated = FALSE;
#if DEVELOPMENT || DEBUG
                                vm_cs_validated_resets++;
#endif
                                pmap_disconnect(m->phys_page);
                        }

                        if ((flags & UPL_COMMIT_SET_DIRTY) ||
                            (m->pmapped && (pmap_disconnect(m->phys_page) & VM_MEM_MODIFIED)))
                                m->dirty = TRUE;

                        if (m->dirty) {
                                /*
                                 * page was re-dirtied after we started
                                 * the pageout... reactivate it since 
                                 * we don't know whether the on-disk
                                 * copy matches what is now in memory
                                 */
                                dwp->dw_mask |= (DW_vm_page_unwire | DW_clear_busy | DW_PAGE_WAKEUP);

                                if (upl->flags & UPL_PAGEOUT) {
                                        CLUSTER_STAT(vm_pageout_target_page_dirtied++;)
                                        VM_STAT_INCR(reactivations);
                                        DTRACE_VM2(pgrec, int, 1, (uint64_t *), NULL);
                                }
                        } else {
                                /*
                                 * page has been successfully cleaned
                                 * go ahead and free it for other use
                                 */

                                if (m->object->internal) {
                                        DTRACE_VM2(anonpgout, int, 1, (uint64_t *), NULL);
                                } else {
                                        DTRACE_VM2(fspgout, int, 1, (uint64_t *), NULL);
                                }
                                dwp->dw_mask |= DW_vm_page_free;
 
                                if (upl->flags & UPL_PAGEOUT) {
                                        CLUSTER_STAT(vm_pageout_target_page_freed++;)

                                        if (page_list[entry].dirty) {
                                                VM_STAT_INCR(pageouts);
                                                DTRACE_VM2(pgout, int, 1, (uint64_t *), NULL);
                                                pgpgout_count++;
                                        }
                                }
                        }
                        goto commit_next_page;
                }
#if MACH_CLUSTER_STATS
                if (m->wpmapped)
                        m->dirty = pmap_is_modified(m->phys_page);

                if (m->dirty)   vm_pageout_cluster_dirtied++;
                else            vm_pageout_cluster_cleaned++;
                if (m->wanted)  vm_pageout_cluster_collisions++;
#endif
                m->dirty = FALSE;

                if (! (flags & UPL_COMMIT_CS_VALIDATED) &&
                    m->cs_validated && !m->cs_tainted) {
                        /*
                         * CODE SIGNING:
                         * This page is no longer dirty
                         * but could have been modified,
                         * so it will need to be
                         * re-validated.
                         */
                        m->cs_validated = FALSE;
#if DEVELOPMENT || DEBUG
                        vm_cs_validated_resets++;
#endif
                        pmap_disconnect(m->phys_page);
                }

                if (m->overwriting) {
                        /*
                         * the (COPY_OUT_FROM == FALSE) request_page_list case
                         */
                        if (m->busy) {
                                m->absent = FALSE;

                                dwp->dw_mask |= DW_clear_busy;
                        } else {
                                /*
                                 * alternate (COPY_OUT_FROM == FALSE) page_list case
                                 * Occurs when the original page was wired
                                 * at the time of the list request
                                 */
                                assert(VM_PAGE_WIRED(m));

                                dwp->dw_mask |= DW_vm_page_unwire; /* reactivates */
                        }
                        m->overwriting = FALSE;
                }
                if (m->encrypted_cleaning == TRUE) {
                        m->encrypted_cleaning = FALSE;

                        dwp->dw_mask |= DW_clear_busy;
                }
                m->cleaning = FALSE;

                /*
                 * It is a part of the semantic of COPYOUT_FROM
                 * UPLs that a commit implies cache sync
                 * between the vm page and the backing store
                 * this can be used to strip the precious bit
                 * as well as clean
                 */
                if ((upl->flags & UPL_PAGE_SYNC_DONE) || (flags & UPL_COMMIT_CLEAR_PRECIOUS))
                        m->precious = FALSE;

                if (flags & UPL_COMMIT_SET_DIRTY)
                        m->dirty = TRUE;

                if (should_be_throttled == TRUE && !m->active && !m->inactive && !m->speculative && !m->throttled) {
                        /*
                         * page coming back in from being 'frozen'...
                         * it was dirty before it was frozen, so keep it so
                         * the vm_page_activate will notice that it really belongs
                         * on the throttle queue and put it there
                         */
                        m->dirty = TRUE;
                        dwp->dw_mask |= DW_vm_page_activate;

                } else {
                        if ((flags & UPL_COMMIT_INACTIVATE) && !m->clustered && !m->speculative) {
                                dwp->dw_mask |= DW_vm_page_deactivate_internal;
                                clear_refmod |= VM_MEM_REFERENCED;
                        } else if (!m->active && !m->inactive && !m->speculative) {

                                if (m->clustered || (flags & UPL_COMMIT_SPECULATE))
                                        dwp->dw_mask |= DW_vm_page_speculate;
                                else if (m->reference)
                                        dwp->dw_mask |= DW_vm_page_activate;
                                else {
                                        dwp->dw_mask |= DW_vm_page_deactivate_internal;
                                        clear_refmod |= VM_MEM_REFERENCED;
                                }
                        }
                }
                if (upl->flags & UPL_ACCESS_BLOCKED) {
                        /*
                         * We blocked access to the pages in this URL.
                         * Clear the "busy" bit on this page before we
                         * wake up any waiter.
                         */
                        dwp->dw_mask |= DW_clear_busy;
                }
                /*
                 * Wakeup any thread waiting for the page to be un-cleaning.
                 */
                dwp->dw_mask |= DW_PAGE_WAKEUP;

commit_next_page:
                if (clear_refmod)
                        pmap_clear_refmod(m->phys_page, clear_refmod);

                target_offset += PAGE_SIZE_64;
                xfer_size -= PAGE_SIZE;
                entry++;

                if (dwp->dw_mask) {
                        if (dwp->dw_mask & ~(DW_clear_busy | DW_PAGE_WAKEUP)) {
                                VM_PAGE_ADD_DELAYED_WORK(dwp, m, dw_count);

                                if (dw_count >= dw_limit) {
                                        vm_page_do_delayed_work(shadow_object, &dw_array[0], dw_count);
                        
                                        dwp = &dw_array[0];
                                        dw_count = 0;
                                }
                        } else {
                                if (dwp->dw_mask & DW_clear_busy)
                                        m->busy = FALSE;

                                if (dwp->dw_mask & DW_PAGE_WAKEUP)
                                        PAGE_WAKEUP(m);
                        }
                }
        }
        if (dw_count)
                vm_page_do_delayed_work(shadow_object, &dw_array[0], dw_count);

        occupied = 1;

        if (upl->flags & UPL_DEVICE_MEMORY)  {
                occupied = 0;
        } else if (upl->flags & UPL_LITE) {
                int     pg_num;
                int     i;

                pg_num = upl->size/PAGE_SIZE;
                pg_num = (pg_num + 31) >> 5;
                occupied = 0;

                for (i = 0; i < pg_num; i++) {
                        if (lite_list[i] != 0) {
                                occupied = 1;
                                break;
                        }
                }
        } else {
                if (queue_empty(&upl->map_object->memq))
                        occupied = 0;
        }
        if (occupied == 0) {
                /*
                 * If this UPL element belongs to a Vector UPL and is
                 * empty, then this is the right function to deallocate
                 * it. So go ahead set the *empty variable. The flag
                 * UPL_COMMIT_NOTIFY_EMPTY, from the caller's point of view
                 * should be considered relevant for the Vector UPL and not
                 * the internal UPLs.
                 */
                if ((upl->flags & UPL_COMMIT_NOTIFY_EMPTY) || isVectorUPL)
                        *empty = TRUE;

                if (object == shadow_object && !(upl->flags & UPL_KERNEL_OBJECT)) {
                        /*
                         * this is not a paging object
                         * so we need to drop the paging reference
                         * that was taken when we created the UPL
                         * against this object
                         */
                        vm_object_activity_end(shadow_object);
                } else {
                         /*
                          * we dontated the paging reference to
                          * the map object... vm_pageout_object_terminate
                          * will drop this reference
                          */
                }
        }
        vm_object_unlock(shadow_object);
        if (object != shadow_object)
                vm_object_unlock(object);
        
        if(!isVectorUPL)
                upl_unlock(upl);
        else {
                /* 
                 * If we completed our operations on an UPL that is
                 * part of a Vectored UPL and if empty is TRUE, then
                 * we should go ahead and deallocate this UPL element. 
                 * Then we check if this was the last of the UPL elements
                 * within that Vectored UPL. If so, set empty to TRUE
                 * so that in ubc_upl_commit_range or ubc_upl_commit, we
                 * can go ahead and deallocate the Vector UPL too.
                 */
                if(*empty==TRUE) {
                        *empty = vector_upl_set_subupl(vector_upl, upl, 0);
                        upl_deallocate(upl);
                }
                goto process_upl_to_commit;
        }

        if (pgpgout_count) {
                DTRACE_VM2(pgpgout, int, pgpgout_count, (uint64_t *), NULL);
        }

        return KERN_SUCCESS;
}

kern_return_t
upl_abort_range(
        upl_t                   upl, 
        upl_offset_t            offset, 
        upl_size_t              size,
        int                     error,
        boolean_t               *empty) 
{
        upl_size_t              xfer_size, subupl_size = size;
        vm_object_t             shadow_object;
        vm_object_t             object;
        vm_object_offset_t      target_offset;
        upl_offset_t            subupl_offset = offset;
        int                     entry;
        wpl_array_t             lite_list;
        int                     occupied;
        struct  vm_page_delayed_work    dw_array[DEFAULT_DELAYED_WORK_LIMIT];
        struct  vm_page_delayed_work    *dwp;
        int                     dw_count;
        int                     dw_limit;
        int                     isVectorUPL = 0;
        upl_t                   vector_upl = NULL;

        *empty = FALSE;

        if (upl == UPL_NULL)
                return KERN_INVALID_ARGUMENT;

        if ( (upl->flags & UPL_IO_WIRE) && !(error & UPL_ABORT_DUMP_PAGES) )
                return upl_commit_range(upl, offset, size, UPL_COMMIT_FREE_ABSENT, NULL, 0, empty);

        if((isVectorUPL = vector_upl_is_valid(upl))) {
                vector_upl = upl;
                upl_lock(vector_upl);
        }
        else
                upl_lock(upl);

process_upl_to_abort:
        if(isVectorUPL) {
                size = subupl_size;
                offset = subupl_offset;
                if(size == 0) {
                        upl_unlock(vector_upl);
                        return KERN_SUCCESS;
                }
                upl =  vector_upl_subupl_byoffset(vector_upl, &offset, &size);
                if(upl == NULL) {
                        upl_unlock(vector_upl);
                        return KERN_FAILURE;
                }
                subupl_size -= size;
                subupl_offset += size;
        }

        *empty = FALSE;

#if UPL_DEBUG
        if (upl->upl_commit_index < UPL_DEBUG_COMMIT_RECORDS) {
                (void) OSBacktrace(&upl->upl_commit_records[upl->upl_commit_index].c_retaddr[0], UPL_DEBUG_STACK_FRAMES);
                
                upl->upl_commit_records[upl->upl_commit_index].c_beg = offset;
                upl->upl_commit_records[upl->upl_commit_index].c_end = (offset + size);
                upl->upl_commit_records[upl->upl_commit_index].c_aborted = 1;

                upl->upl_commit_index++;
        }
#endif
        if (upl->flags & UPL_DEVICE_MEMORY)
                xfer_size = 0;
        else if ((offset + size) <= upl->size)
                xfer_size = size;
        else {
                if(!isVectorUPL)
                        upl_unlock(upl);
                else {
                        upl_unlock(vector_upl);
                }

                return KERN_FAILURE;
        }
        if (upl->flags & UPL_INTERNAL) {
                lite_list = (wpl_array_t) 
                        ((((uintptr_t)upl) + sizeof(struct upl))
                        + ((upl->size/PAGE_SIZE) * sizeof(upl_page_info_t)));
        } else {
                lite_list = (wpl_array_t) 
                        (((uintptr_t)upl) + sizeof(struct upl));
        }
        object = upl->map_object;

        if (upl->flags & UPL_SHADOWED) {
                vm_object_lock(object);
                shadow_object = object->shadow;
        } else
                shadow_object = object;

        entry = offset/PAGE_SIZE;
        target_offset = (vm_object_offset_t)offset;

        if (upl->flags & UPL_KERNEL_OBJECT)
                vm_object_lock_shared(shadow_object);
        else
                vm_object_lock(shadow_object);

        if (upl->flags & UPL_ACCESS_BLOCKED) {
                assert(shadow_object->blocked_access);
                shadow_object->blocked_access = FALSE;
                vm_object_wakeup(object, VM_OBJECT_EVENT_UNBLOCKED);
        }

        dwp = &dw_array[0];
        dw_count = 0;
        dw_limit = DELAYED_WORK_LIMIT(DEFAULT_DELAYED_WORK_LIMIT);

        if ((error & UPL_ABORT_DUMP_PAGES) && (upl->flags & UPL_KERNEL_OBJECT))
                panic("upl_abort_range: kernel_object being DUMPED");

        while (xfer_size) {
                vm_page_t       t, m;

                dwp->dw_mask = 0;

                m = VM_PAGE_NULL;

                if (upl->flags & UPL_LITE) {
                        unsigned int    pg_num;

                        pg_num = (unsigned int) (target_offset/PAGE_SIZE);
                        assert(pg_num == target_offset/PAGE_SIZE);
                        

                        if (lite_list[pg_num>>5] & (1 << (pg_num & 31))) {
                                lite_list[pg_num>>5] &= ~(1 << (pg_num & 31));

                                if ( !(upl->flags & UPL_KERNEL_OBJECT))
                                        m = vm_page_lookup(shadow_object, target_offset +
                                                           (upl->offset - shadow_object->paging_offset));
                        }
                }
                if (upl->flags & UPL_SHADOWED) {
                        if ((t = vm_page_lookup(object, target_offset)) != VM_PAGE_NULL) {
                                t->pageout = FALSE;

                                VM_PAGE_FREE(t);

                                if (m == VM_PAGE_NULL)
                                        m = vm_page_lookup(shadow_object, target_offset + object->vo_shadow_offset);
                        }
                }
                if ((upl->flags & UPL_KERNEL_OBJECT))
                        goto abort_next_page;

                if (m != VM_PAGE_NULL) {

                        if (m->absent) {
                                boolean_t must_free = TRUE;

                                /*
                                 * COPYOUT = FALSE case
                                 * check for error conditions which must
                                 * be passed back to the pages customer
                                 */
                                if (error & UPL_ABORT_RESTART) {
                                        m->restart = TRUE;
                                        m->absent = FALSE;
                                        m->unusual = TRUE;
                                        must_free = FALSE;
                                } else if (error & UPL_ABORT_UNAVAILABLE) {
                                        m->restart = FALSE;
                                        m->unusual = TRUE;
                                        must_free = FALSE;
                                } else if (error & UPL_ABORT_ERROR) {
                                        m->restart = FALSE;
                                        m->absent = FALSE;
                                        m->error = TRUE;
                                        m->unusual = TRUE;
                                        must_free = FALSE;
                                }
                                if (m->clustered) {
                                        /*
                                         * This page was a part of a speculative
                                         * read-ahead initiated by the kernel
                                         * itself.  No one is expecting this
                                         * page and no one will clean up its
                                         * error state if it ever becomes valid
                                         * in the future.
                                         * We have to free it here.
                                         */
                                        must_free = TRUE;
                                }

                                /*
                                 * ENCRYPTED SWAP:
                                 * If the page was already encrypted,
                                 * we don't really need to decrypt it
                                 * now.  It will get decrypted later,
                                 * on demand, as soon as someone needs
                                 * to access its contents.
                                 */

                                m->cleaning = FALSE;
                                m->encrypted_cleaning = FALSE;

                                if (m->overwriting && !m->busy) {
                                        /*
                                         * this shouldn't happen since
                                         * this is an 'absent' page, but
                                         * it doesn't hurt to check for
                                         * the 'alternate' method of 
                                         * stabilizing the page...
                                         * we will mark 'busy' to be cleared
                                         * in the following code which will
                                         * take care of the primary stabilzation
                                         * method (i.e. setting 'busy' to TRUE)
                                         */
                                        dwp->dw_mask |= DW_vm_page_unwire;
                                }
                                m->overwriting = FALSE;

                                dwp->dw_mask |= (DW_clear_busy | DW_PAGE_WAKEUP);

                                if (must_free == TRUE)
                                        dwp->dw_mask |= DW_vm_page_free;
                                else
                                        dwp->dw_mask |= DW_vm_page_activate;
                        } else {
                                /*                          
                                 * Handle the trusted pager throttle.
                                 */                     
                                if (m->laundry)
                                        dwp->dw_mask |= DW_vm_pageout_throttle_up;

                                if (upl->flags & UPL_ACCESS_BLOCKED) {
                                        /*
                                         * We blocked access to the pages in this UPL.
                                         * Clear the "busy" bit and wake up any waiter
                                         * for this page.
                                         */
                                        dwp->dw_mask |= DW_clear_busy;
                                }
                                if (m->pageout) {
                                        assert(m->busy);
                                        assert(m->wire_count == 1);
                                        m->pageout = FALSE;

                                        dwp->dw_mask |= (DW_vm_page_unwire | DW_clear_busy);
                                }
                                if (m->overwriting) {
                                        if (m->busy)
                                                dwp->dw_mask |= DW_clear_busy;
                                        else {
                                                /*
                                                 * deal with the 'alternate' method
                                                 * of stabilizing the page...
                                                 * we will either free the page
                                                 * or mark 'busy' to be cleared
                                                 * in the following code which will
                                                 * take care of the primary stabilzation
                                                 * method (i.e. setting 'busy' to TRUE)
                                                 */
                                                dwp->dw_mask |= DW_vm_page_unwire;
                                        }
                                        m->overwriting = FALSE;
                                }
                                if (m->encrypted_cleaning == TRUE) {
                                        m->encrypted_cleaning = FALSE;

                                        dwp->dw_mask |= DW_clear_busy;
                                }
                                m->dump_cleaning = FALSE;
                                m->cleaning = FALSE;
#if     MACH_PAGEMAP
                                vm_external_state_clr(m->object->existence_map, m->offset);
#endif  /* MACH_PAGEMAP */
                                if (error & UPL_ABORT_DUMP_PAGES) {
                                        pmap_disconnect(m->phys_page);

                                        dwp->dw_mask |= DW_vm_page_free;
                                } else {
                                        if (error & UPL_ABORT_REFERENCE) {
                                                /*
                                                 * we've been told to explictly
                                                 * reference this page... for 
                                                 * file I/O, this is done by
                                                 * implementing an LRU on the inactive q
                                                 */
                                                dwp->dw_mask |= DW_vm_page_lru;
                                        }
                                        dwp->dw_mask |= DW_PAGE_WAKEUP;
                                }
                        }
                }
abort_next_page:
                target_offset += PAGE_SIZE_64;
                xfer_size -= PAGE_SIZE;
                entry++;

                if (dwp->dw_mask) {
                        if (dwp->dw_mask & ~(DW_clear_busy | DW_PAGE_WAKEUP)) {
                                VM_PAGE_ADD_DELAYED_WORK(dwp, m, dw_count);

                                if (dw_count >= dw_limit) {
                                        vm_page_do_delayed_work(shadow_object, &dw_array[0], dw_count);
                                
                                        dwp = &dw_array[0];
                                        dw_count = 0;
                                }
                        } else {
                                if (dwp->dw_mask & DW_clear_busy)
                                        m->busy = FALSE;

                                if (dwp->dw_mask & DW_PAGE_WAKEUP)
                                        PAGE_WAKEUP(m);
                        }
                }
        }
        if (dw_count)
                vm_page_do_delayed_work(shadow_object, &dw_array[0], dw_count);

        occupied = 1;

        if (upl->flags & UPL_DEVICE_MEMORY)  {
                occupied = 0;
        } else if (upl->flags & UPL_LITE) {
                int     pg_num;
                int     i;

                pg_num = upl->size/PAGE_SIZE;
                pg_num = (pg_num + 31) >> 5;
                occupied = 0;

                for (i = 0; i < pg_num; i++) {
                        if (lite_list[i] != 0) {
                                occupied = 1;
                                break;
                        }
                }
        } else {
                if (queue_empty(&upl->map_object->memq))
                        occupied = 0;
        }
        if (occupied == 0) {
                /*
                 * If this UPL element belongs to a Vector UPL and is
                 * empty, then this is the right function to deallocate
                 * it. So go ahead set the *empty variable. The flag
                 * UPL_COMMIT_NOTIFY_EMPTY, from the caller's point of view
                 * should be considered relevant for the Vector UPL and
                 * not the internal UPLs.
                 */
                if ((upl->flags & UPL_COMMIT_NOTIFY_EMPTY) || isVectorUPL)
                        *empty = TRUE;

                if (object == shadow_object && !(upl->flags & UPL_KERNEL_OBJECT)) {
                        /*
                         * this is not a paging object
                         * so we need to drop the paging reference
                         * that was taken when we created the UPL
                         * against this object
                         */
                        vm_object_activity_end(shadow_object);
                } else {
                         /*
                          * we dontated the paging reference to
                          * the map object... vm_pageout_object_terminate
                          * will drop this reference
                          */
                }
        }
        vm_object_unlock(shadow_object);
        if (object != shadow_object)
                vm_object_unlock(object);
        
        if(!isVectorUPL)
                upl_unlock(upl);
        else {
                /* 
                * If we completed our operations on an UPL that is
                * part of a Vectored UPL and if empty is TRUE, then
                * we should go ahead and deallocate this UPL element. 
                * Then we check if this was the last of the UPL elements
                * within that Vectored UPL. If so, set empty to TRUE
                * so that in ubc_upl_abort_range or ubc_upl_abort, we
                * can go ahead and deallocate the Vector UPL too.
                */
                if(*empty == TRUE) {
                        *empty = vector_upl_set_subupl(vector_upl, upl,0);
                        upl_deallocate(upl);
                }
                goto process_upl_to_abort;
        }

        return KERN_SUCCESS;
}


kern_return_t
upl_abort(
        upl_t   upl,
        int     error)
{
        boolean_t       empty;

        return upl_abort_range(upl, 0, upl->size, error, &empty);
}


/* an option on commit should be wire */
kern_return_t
upl_commit(
        upl_t                   upl,
        upl_page_info_t         *page_list,
        mach_msg_type_number_t  count)
{
        boolean_t       empty;

        return upl_commit_range(upl, 0, upl->size, 0, page_list, count, &empty);
}


unsigned int vm_object_iopl_request_sleep_for_cleaning = 0;

kern_return_t
vm_object_iopl_request(
        vm_object_t             object,
        vm_object_offset_t      offset,
        upl_size_t              size,
        upl_t                   *upl_ptr,
        upl_page_info_array_t   user_page_list,
        unsigned int            *page_list_count,
        int                     cntrl_flags)
{
        vm_page_t               dst_page;
        vm_object_offset_t      dst_offset;
        upl_size_t              xfer_size;
        upl_t                   upl = NULL;
        unsigned int            entry;
        wpl_array_t             lite_list = NULL;
        int                     no_zero_fill = FALSE;
        unsigned int            size_in_pages;
        u_int32_t               psize;
        kern_return_t           ret;
        vm_prot_t               prot;
        struct vm_object_fault_info fault_info;
        struct  vm_page_delayed_work    dw_array[DEFAULT_DELAYED_WORK_LIMIT];
        struct  vm_page_delayed_work    *dwp;
        int                     dw_count;
        int                     dw_limit;
        int                     dw_index;

        if (cntrl_flags & ~UPL_VALID_FLAGS) {
                /*
                 * For forward compatibility's sake,
                 * reject any unknown flag.
                 */
                return KERN_INVALID_VALUE;
        }
        if (vm_lopage_needed == FALSE)
                cntrl_flags &= ~UPL_NEED_32BIT_ADDR;

        if (cntrl_flags & UPL_NEED_32BIT_ADDR) {
                if ( (cntrl_flags & (UPL_SET_IO_WIRE | UPL_SET_LITE)) != (UPL_SET_IO_WIRE | UPL_SET_LITE))
                        return KERN_INVALID_VALUE;

                if (object->phys_contiguous) {
                        if ((offset + object->vo_shadow_offset) >= (vm_object_offset_t)max_valid_dma_address)
                                return KERN_INVALID_ADDRESS;
              
                        if (((offset + object->vo_shadow_offset) + size) >= (vm_object_offset_t)max_valid_dma_address)
                                return KERN_INVALID_ADDRESS;
                }
        }

        if (cntrl_flags & UPL_ENCRYPT) {
                /*
                 * ENCRYPTED SWAP:
                 * The paging path doesn't use this interface,
                 * so we don't support the UPL_ENCRYPT flag
                 * here.  We won't encrypt the pages.
                 */
                assert(! (cntrl_flags & UPL_ENCRYPT));
        }
        if (cntrl_flags & UPL_NOZEROFILL)
                no_zero_fill = TRUE;

        if (cntrl_flags & UPL_COPYOUT_FROM)
                prot = VM_PROT_READ;
        else
                prot = VM_PROT_READ | VM_PROT_WRITE;

        if (((size/PAGE_SIZE) > MAX_UPL_SIZE) && !object->phys_contiguous)
                size = MAX_UPL_SIZE * PAGE_SIZE;

        if (cntrl_flags & UPL_SET_INTERNAL) {
                if (page_list_count != NULL)
                        *page_list_count = MAX_UPL_SIZE;
        }
        if (((cntrl_flags & UPL_SET_INTERNAL) && !(object->phys_contiguous)) &&
            ((page_list_count != NULL) && (*page_list_count != 0) && *page_list_count < (size/page_size)))
                return KERN_INVALID_ARGUMENT;

        if ((!object->internal) && (object->paging_offset != 0))
                panic("vm_object_iopl_request: external object with non-zero paging offset\n");


        if (object->phys_contiguous)
                psize = PAGE_SIZE;
        else
                psize = size;

        if (cntrl_flags & UPL_SET_INTERNAL) {
                upl = upl_create(UPL_CREATE_INTERNAL | UPL_CREATE_LITE, UPL_IO_WIRE, psize);

                user_page_list = (upl_page_info_t *) (((uintptr_t)upl) + sizeof(struct upl));
                lite_list = (wpl_array_t) (((uintptr_t)user_page_list) +
                                           ((psize / PAGE_SIZE) * sizeof(upl_page_info_t)));
                if (size == 0) {
                        user_page_list = NULL;
                        lite_list = NULL;
                }
        } else {
                upl = upl_create(UPL_CREATE_LITE, UPL_IO_WIRE, psize);

                lite_list = (wpl_array_t) (((uintptr_t)upl) + sizeof(struct upl));
                if (size == 0) {
                        lite_list = NULL;
                }
        }
        if (user_page_list)
                user_page_list[0].device = FALSE;
        *upl_ptr = upl;

        upl->map_object = object;
        upl->size = size;

        size_in_pages = size / PAGE_SIZE;

        if (object == kernel_object &&
            !(cntrl_flags & (UPL_NEED_32BIT_ADDR | UPL_BLOCK_ACCESS))) {
                upl->flags |= UPL_KERNEL_OBJECT;
#if UPL_DEBUG
                vm_object_lock(object);
#else
                vm_object_lock_shared(object);
#endif
        } else {
                vm_object_lock(object);
                vm_object_activity_begin(object);
        }
        /*
         * paging in progress also protects the paging_offset
         */
        upl->offset = offset + object->paging_offset;

        if (cntrl_flags & UPL_BLOCK_ACCESS) {
                /*
                 * The user requested that access to the pages in this URL
                 * be blocked until the UPL is commited or aborted.
                 */
                upl->flags |= UPL_ACCESS_BLOCKED;
        }

        if (object->phys_contiguous) {
#if UPL_DEBUG
                queue_enter(&object->uplq, upl, upl_t, uplq);
#endif /* UPL_DEBUG */

                if (upl->flags & UPL_ACCESS_BLOCKED) {
                        assert(!object->blocked_access);
                        object->blocked_access = TRUE;
                }

                vm_object_unlock(object);

                /*
                 * don't need any shadow mappings for this one
                 * since it is already I/O memory
                 */
                upl->flags |= UPL_DEVICE_MEMORY;

                upl->highest_page = (ppnum_t) ((offset + object->vo_shadow_offset + size - 1)>>PAGE_SHIFT);

                if (user_page_list) {
                        user_page_list[0].phys_addr = (ppnum_t) ((offset + object->vo_shadow_offset)>>PAGE_SHIFT);
                        user_page_list[0].device = TRUE;
                }
                if (page_list_count != NULL) {
                        if (upl->flags & UPL_INTERNAL)
                                *page_list_count = 0;
                        else
                                *page_list_count = 1;
                }
                return KERN_SUCCESS;
        }
        if (object != kernel_object) {
                /*
                 * Protect user space from future COW operations
                 */
                object->true_share = TRUE;

                if (object->copy_strategy == MEMORY_OBJECT_COPY_SYMMETRIC)
                        object->copy_strategy = MEMORY_OBJECT_COPY_DELAY;
        }
 
#if UPL_DEBUG
        queue_enter(&object->uplq, upl, upl_t, uplq);
#endif /* UPL_DEBUG */

        if (!(cntrl_flags & UPL_COPYOUT_FROM) &&
            object->copy != VM_OBJECT_NULL) {
                /*
                 * Honor copy-on-write obligations
                 *
                 * The caller is gathering these pages and
                 * might modify their contents.  We need to
                 * make sure that the copy object has its own
                 * private copies of these pages before we let
                 * the caller modify them.
                 *
                 * NOTE: someone else could map the original object
                 * after we've done this copy-on-write here, and they
                 * could then see an inconsistent picture of the memory
                 * while it's being modified via the UPL.  To prevent this,
                 * we would have to block access to these pages until the
                 * UPL is released.  We could use the UPL_BLOCK_ACCESS
                 * code path for that...
                 */
                vm_object_update(object,
                                 offset,
                                 size,
                                 NULL,
                                 NULL,
                                 FALSE, /* should_return */
                                 MEMORY_OBJECT_COPY_SYNC,
                                 VM_PROT_NO_CHANGE);
#if DEVELOPMENT || DEBUG
                iopl_cow++;
                iopl_cow_pages += size >> PAGE_SHIFT;
#endif
        }


        entry = 0;

        xfer_size = size;
        dst_offset = offset;

        fault_info.behavior = VM_BEHAVIOR_SEQUENTIAL;
        fault_info.user_tag  = 0;
        fault_info.lo_offset = offset;
        fault_info.hi_offset = offset + xfer_size;
        fault_info.no_cache  = FALSE;
        fault_info.stealth = FALSE;
        fault_info.io_sync = FALSE;
        fault_info.cs_bypass = FALSE;
        fault_info.mark_zf_absent = TRUE;

        dwp = &dw_array[0];
        dw_count = 0;
        dw_limit = DELAYED_WORK_LIMIT(DEFAULT_DELAYED_WORK_LIMIT);

        while (xfer_size) {
                vm_fault_return_t       result;
                unsigned int            pg_num;

                dwp->dw_mask = 0;

                dst_page = vm_page_lookup(object, dst_offset);

                /*
                 * ENCRYPTED SWAP:
                 * If the page is encrypted, we need to decrypt it,
                 * so force a soft page fault.
                 */
                if (dst_page == VM_PAGE_NULL ||
                    dst_page->busy ||
                    dst_page->encrypted ||
                    dst_page->error || 
                    dst_page->restart ||
                    dst_page->absent ||
                    dst_page->fictitious) {

                   if (object == kernel_object)
                           panic("vm_object_iopl_request: missing/bad page in kernel object\n");

                   do {
                        vm_page_t       top_page;
                        kern_return_t   error_code;
                        int             interruptible;

                        if (cntrl_flags & UPL_SET_INTERRUPTIBLE)
                                interruptible = THREAD_ABORTSAFE;
                        else
                                interruptible = THREAD_UNINT;

                        fault_info.interruptible = interruptible;
                        fault_info.cluster_size = xfer_size;

                        vm_object_paging_begin(object);

                        result = vm_fault_page(object, dst_offset,
                                               prot | VM_PROT_WRITE, FALSE, 
                                               &prot, &dst_page, &top_page,
                                               (int *)0,
                                               &error_code, no_zero_fill,
                                               FALSE, &fault_info);

                        switch (result) {

                        case VM_FAULT_SUCCESS:

                                if ( !dst_page->absent) {
                                        PAGE_WAKEUP_DONE(dst_page);
                                } else {
                                        /*
                                         * we only get back an absent page if we
                                         * requested that it not be zero-filled
                                         * because we are about to fill it via I/O
                                         * 
                                         * absent pages should be left BUSY
                                         * to prevent them from being faulted
                                         * into an address space before we've
                                         * had a chance to complete the I/O on
                                         * them since they may contain info that
                                         * shouldn't be seen by the faulting task
                                         */
                                }
                                /*
                                 *      Release paging references and
                                 *      top-level placeholder page, if any.
                                 */
                                if (top_page != VM_PAGE_NULL) {
                                        vm_object_t local_object;

                                        local_object = top_page->object;

                                        if (top_page->object != dst_page->object) {
                                                vm_object_lock(local_object);
                                                VM_PAGE_FREE(top_page);
                                                vm_object_paging_end(local_object);
                                                vm_object_unlock(local_object);
                                        } else {
                                                VM_PAGE_FREE(top_page);
                                                vm_object_paging_end(local_object);
                                        }
                                }
                                vm_object_paging_end(object);
                                break;
                        
                        case VM_FAULT_RETRY:
                                vm_object_lock(object);
                                break;

                        case VM_FAULT_MEMORY_SHORTAGE:
                                OSAddAtomic(size_in_pages, &vm_upl_wait_for_pages);

                                VM_DEBUG_EVENT(vm_iopl_page_wait, VM_IOPL_PAGE_WAIT, DBG_FUNC_START, vm_upl_wait_for_pages, 0, 0, 0);

                                if (vm_page_wait(interruptible)) {
                                        OSAddAtomic(-size_in_pages, &vm_upl_wait_for_pages);

                                        VM_DEBUG_EVENT(vm_iopl_page_wait, VM_IOPL_PAGE_WAIT, DBG_FUNC_END, vm_upl_wait_for_pages, 0, 0, 0);
                                        vm_object_lock(object);

                                        break;
                                }
                                OSAddAtomic(-size_in_pages, &vm_upl_wait_for_pages);

                                VM_DEBUG_EVENT(vm_iopl_page_wait, VM_IOPL_PAGE_WAIT, DBG_FUNC_END, vm_upl_wait_for_pages, 0, 0, -1);

                                /* fall thru */

                        case VM_FAULT_INTERRUPTED:
                                error_code = MACH_SEND_INTERRUPTED;
                        case VM_FAULT_MEMORY_ERROR:
                        memory_error:
                                ret = (error_code ? error_code: KERN_MEMORY_ERROR);

                                vm_object_lock(object);
                                goto return_err;

                        case VM_FAULT_SUCCESS_NO_VM_PAGE:
                                /* success but no page: fail */
                                vm_object_paging_end(object);
                                vm_object_unlock(object);
                                goto memory_error;

                        default:
                                panic("vm_object_iopl_request: unexpected error"
                                      " 0x%x from vm_fault_page()\n", result);
                        }
                   } while (result != VM_FAULT_SUCCESS);

                }
                if (upl->flags & UPL_KERNEL_OBJECT)
                        goto record_phys_addr;

                if (dst_page->cleaning) {
                        /*
                         * Someone else is cleaning this page in place.as
                         * In theory, we should be able to  proceed and use this
                         * page but they'll probably end up clearing the "busy"
                         * bit on it in upl_commit_range() but they didn't set
                         * it, so they would clear our "busy" bit and open
                         * us to race conditions.
                         * We'd better wait for the cleaning to complete and
                         * then try again.
                         */
                        vm_object_iopl_request_sleep_for_cleaning++;
                        PAGE_SLEEP(object, dst_page, THREAD_UNINT);
                        continue;
                }
                if ( (cntrl_flags & UPL_NEED_32BIT_ADDR) &&
                     dst_page->phys_page >= (max_valid_dma_address >> PAGE_SHIFT) ) {
                        vm_page_t       low_page;
                        int             refmod;

                        /*
                         * support devices that can't DMA above 32 bits
                         * by substituting pages from a pool of low address
                         * memory for any pages we find above the 4G mark
                         * can't substitute if the page is already wired because
                         * we don't know whether that physical address has been
                         * handed out to some other 64 bit capable DMA device to use
                         */
                        if (VM_PAGE_WIRED(dst_page)) {
                                ret = KERN_PROTECTION_FAILURE;
                                goto return_err;
                        }
                        low_page = vm_page_grablo();

                        if (low_page == VM_PAGE_NULL) {
                                ret = KERN_RESOURCE_SHORTAGE;
                                goto return_err;
                        }
                        /*
                         * from here until the vm_page_replace completes
                         * we musn't drop the object lock... we don't
                         * want anyone refaulting this page in and using
                         * it after we disconnect it... we want the fault
                         * to find the new page being substituted.
                         */
                        if (dst_page->pmapped)
                                refmod = pmap_disconnect(dst_page->phys_page);
                        else
                                refmod = 0;

                        if (!dst_page->absent)
                                vm_page_copy(dst_page, low_page);
                  
                        low_page->reference = dst_page->reference;
                        low_page->dirty     = dst_page->dirty;
                        low_page->absent    = dst_page->absent;

                        if (refmod & VM_MEM_REFERENCED)
                                low_page->reference = TRUE;
                        if (refmod & VM_MEM_MODIFIED)
                                low_page->dirty = TRUE;

                        vm_page_replace(low_page, object, dst_offset);

                        dst_page = low_page;
                        /*
                         * vm_page_grablo returned the page marked
                         * BUSY... we don't need a PAGE_WAKEUP_DONE
                         * here, because we've never dropped the object lock
                         */
                        if ( !dst_page->absent)
                                dst_page->busy = FALSE;
                }
                if ( !dst_page->busy)
                        dwp->dw_mask |= DW_vm_page_wire;

                if (cntrl_flags & UPL_BLOCK_ACCESS) {
                        /*
                         * Mark the page "busy" to block any future page fault
                         * on this page in addition to wiring it.
                         * We'll also remove the mapping
                         * of all these pages before leaving this routine.
                         */
                        assert(!dst_page->fictitious);
                        dst_page->busy = TRUE;
                }
                /*
                 * expect the page to be used
                 * page queues lock must be held to set 'reference'
                 */
                dwp->dw_mask |= DW_set_reference;

                if (!(cntrl_flags & UPL_COPYOUT_FROM))
                        dst_page->dirty = TRUE;
record_phys_addr:
                if (dst_page->busy)
                        upl->flags |= UPL_HAS_BUSY;

                pg_num = (unsigned int) ((dst_offset-offset)/PAGE_SIZE);
                assert(pg_num == (dst_offset-offset)/PAGE_SIZE);
                lite_list[pg_num>>5] |= 1 << (pg_num & 31);

                if (dst_page->phys_page > upl->highest_page)
                        upl->highest_page = dst_page->phys_page;

                if (user_page_list) {
                        user_page_list[entry].phys_addr = dst_page->phys_page;
                        user_page_list[entry].pageout   = dst_page->pageout;
                        user_page_list[entry].absent    = dst_page->absent;
                        user_page_list[entry].dirty     = dst_page->dirty;
                        user_page_list[entry].precious  = dst_page->precious;
                        user_page_list[entry].device    = FALSE;
                        if (dst_page->clustered == TRUE)
                                user_page_list[entry].speculative = dst_page->speculative;
                        else
                                user_page_list[entry].speculative = FALSE;
                        user_page_list[entry].cs_validated = dst_page->cs_validated;
                        user_page_list[entry].cs_tainted = dst_page->cs_tainted;
                }
                if (object != kernel_object) {
                        /*
                         * someone is explicitly grabbing this page...
                         * update clustered and speculative state
                         * 
                         */
                        VM_PAGE_CONSUME_CLUSTERED(dst_page);
                }
                entry++;
                dst_offset += PAGE_SIZE_64;
                xfer_size -= PAGE_SIZE;

                if (dwp->dw_mask) {
                        VM_PAGE_ADD_DELAYED_WORK(dwp, dst_page, dw_count);

                        if (dw_count >= dw_limit) {
                                vm_page_do_delayed_work(object, &dw_array[0], dw_count);
                                
                                dwp = &dw_array[0];
                                dw_count = 0;
                        }
                }
        }
        if (dw_count)
                vm_page_do_delayed_work(object, &dw_array[0], dw_count);

        if (page_list_count != NULL) {
                if (upl->flags & UPL_INTERNAL)
                        *page_list_count = 0;
                else if (*page_list_count > entry)
                        *page_list_count = entry;
        }
        vm_object_unlock(object);

        if (cntrl_flags & UPL_BLOCK_ACCESS) {
                /*
                 * We've marked all the pages "busy" so that future
                 * page faults will block.
                 * Now remove the mapping for these pages, so that they
                 * can't be accessed without causing a page fault.
                 */
                vm_object_pmap_protect(object, offset, (vm_object_size_t)size,
                                       PMAP_NULL, 0, VM_PROT_NONE);
                assert(!object->blocked_access);
                object->blocked_access = TRUE;
        }
        return KERN_SUCCESS;

return_err:
        dw_index = 0;

        for (; offset < dst_offset; offset += PAGE_SIZE) {
                boolean_t need_unwire;

                dst_page = vm_page_lookup(object, offset);

                if (dst_page == VM_PAGE_NULL)
                        panic("vm_object_iopl_request: Wired page missing. \n");

                /*
                 * if we've already processed this page in an earlier 
                 * dw_do_work, we need to undo the wiring... we will
                 * leave the dirty and reference bits on if they
                 * were set, since we don't have a good way of knowing
                 * what the previous state was and we won't get here
                 * under any normal circumstances...  we will always
                 * clear BUSY and wakeup any waiters via vm_page_free
                 * or PAGE_WAKEUP_DONE
                 */
                need_unwire = TRUE;

                if (dw_count) {
                        if (dw_array[dw_index].dw_m == dst_page) {
                                /*
                                 * still in the deferred work list
                                 * which means we haven't yet called
                                 * vm_page_wire on this page
                                 */
                                need_unwire = FALSE;

                                dw_index++;
                                dw_count--;
                        }
                }
                vm_page_lock_queues();

                if (dst_page->absent) {
                        vm_page_free(dst_page);

                        need_unwire = FALSE;
                } else {
                        if (need_unwire == TRUE)
                                vm_page_unwire(dst_page, TRUE);

                        PAGE_WAKEUP_DONE(dst_page);
                }
                vm_page_unlock_queues();

                if (need_unwire == TRUE)
                        VM_STAT_INCR(reactivations);
        }
#if UPL_DEBUG
        upl->upl_state = 2;
#endif
        if (! (upl->flags & UPL_KERNEL_OBJECT)) {
                vm_object_activity_end(object);
        }
        vm_object_unlock(object);
        upl_destroy(upl);

        return ret;
}

kern_return_t
upl_transpose(
        upl_t           upl1,
        upl_t           upl2)
{
        kern_return_t           retval;
        boolean_t               upls_locked;
        vm_object_t             object1, object2;

        if (upl1 == UPL_NULL || upl2 == UPL_NULL || upl1 == upl2  || ((upl1->flags & UPL_VECTOR)==UPL_VECTOR)  || ((upl2->flags & UPL_VECTOR)==UPL_VECTOR)) {
                return KERN_INVALID_ARGUMENT;
        }
        
        upls_locked = FALSE;

        /*
         * Since we need to lock both UPLs at the same time,
         * avoid deadlocks by always taking locks in the same order.
         */
        if (upl1 < upl2) {
                upl_lock(upl1);
                upl_lock(upl2);
        } else {
                upl_lock(upl2);
                upl_lock(upl1);
        }
        upls_locked = TRUE;     /* the UPLs will need to be unlocked */

        object1 = upl1->map_object;
        object2 = upl2->map_object;

        if (upl1->offset != 0 || upl2->offset != 0 ||
            upl1->size != upl2->size) {
                /*
                 * We deal only with full objects, not subsets.
                 * That's because we exchange the entire backing store info
                 * for the objects: pager, resident pages, etc...  We can't do
                 * only part of it.
                 */
                retval = KERN_INVALID_VALUE;
                goto done;
        }

        /*
         * Tranpose the VM objects' backing store.
         */
        retval = vm_object_transpose(object1, object2,
                                     (vm_object_size_t) upl1->size);

        if (retval == KERN_SUCCESS) {
                /*
                 * Make each UPL point to the correct VM object, i.e. the
                 * object holding the pages that the UPL refers to...
                 */
#if UPL_DEBUG
                queue_remove(&object1->uplq, upl1, upl_t, uplq);
                queue_remove(&object2->uplq, upl2, upl_t, uplq);
#endif
                upl1->map_object = object2;
                upl2->map_object = object1;
#if UPL_DEBUG
                queue_enter(&object1->uplq, upl2, upl_t, uplq);
                queue_enter(&object2->uplq, upl1, upl_t, uplq);
#endif
        }

done:
        /*
         * Cleanup.
         */
        if (upls_locked) {
                upl_unlock(upl1);
                upl_unlock(upl2);
                upls_locked = FALSE;
        }

        return retval;
}

/*
 * ENCRYPTED SWAP:
 *
 * Rationale:  the user might have some encrypted data on disk (via
 * FileVault or any other mechanism).  That data is then decrypted in
 * memory, which is safe as long as the machine is secure.  But that
 * decrypted data in memory could be paged out to disk by the default
 * pager.  The data would then be stored on disk in clear (not encrypted)
 * and it could be accessed by anyone who gets physical access to the
 * disk (if the laptop or the disk gets stolen for example).  This weakens
 * the security offered by FileVault.
 *
 * Solution:  the default pager will optionally request that all the
 * pages it gathers for pageout be encrypted, via the UPL interfaces,
 * before it sends this UPL to disk via the vnode_pageout() path.
 * 
 * Notes:
 * 
 * To avoid disrupting the VM LRU algorithms, we want to keep the
 * clean-in-place mechanisms, which allow us to send some extra pages to 
 * swap (clustering) without actually removing them from the user's
 * address space.  We don't want the user to unknowingly access encrypted
 * data, so we have to actually remove the encrypted pages from the page
 * table.  When the user accesses the data, the hardware will fail to
 * locate the virtual page in its page table and will trigger a page
 * fault.  We can then decrypt the page and enter it in the page table
 * again.  Whenever we allow the user to access the contents of a page,
 * we have to make sure it's not encrypted.
 *
 * 
 */
/*
 * ENCRYPTED SWAP:
 * Reserve of virtual addresses in the kernel address space.
 * We need to map the physical pages in the kernel, so that we
 * can call the encryption/decryption routines with a kernel
 * virtual address.  We keep this pool of pre-allocated kernel
 * virtual addresses so that we don't have to scan the kernel's
 * virtual address space each time we need to encrypt or decrypt
 * a physical page.
 * It would be nice to be able to encrypt and decrypt in physical
 * mode but that might not always be more efficient...
 */
decl_simple_lock_data(,vm_paging_lock)
#define VM_PAGING_NUM_PAGES     64
vm_map_offset_t vm_paging_base_address = 0;
boolean_t       vm_paging_page_inuse[VM_PAGING_NUM_PAGES] = { FALSE, };
int             vm_paging_max_index = 0;
int             vm_paging_page_waiter = 0;
int             vm_paging_page_waiter_total = 0;
unsigned long   vm_paging_no_kernel_page = 0;
unsigned long   vm_paging_objects_mapped = 0;
unsigned long   vm_paging_pages_mapped = 0;
unsigned long   vm_paging_objects_mapped_slow = 0;
unsigned long   vm_paging_pages_mapped_slow = 0;

void
vm_paging_map_init(void)
{
        kern_return_t   kr;
        vm_map_offset_t page_map_offset;
        vm_map_entry_t  map_entry;

        assert(vm_paging_base_address == 0);

        /*
         * Initialize our pool of pre-allocated kernel
         * virtual addresses.
         */
        page_map_offset = 0;
        kr = vm_map_find_space(kernel_map,
                               &page_map_offset,
                               VM_PAGING_NUM_PAGES * PAGE_SIZE,
                               0,
                               0,
                               &map_entry);
        if (kr != KERN_SUCCESS) {
                panic("vm_paging_map_init: kernel_map full\n");
        }
        map_entry->object.vm_object = kernel_object;
        map_entry->offset = page_map_offset;
        map_entry->protection = VM_PROT_NONE;
        map_entry->max_protection = VM_PROT_NONE;
        map_entry->permanent = TRUE;
        vm_object_reference(kernel_object);
        vm_map_unlock(kernel_map);

        assert(vm_paging_base_address == 0);
        vm_paging_base_address = page_map_offset;
}

/*
 * ENCRYPTED SWAP:
 * vm_paging_map_object:
 *      Maps part of a VM object's pages in the kernel
 *      virtual address space, using the pre-allocated
 *      kernel virtual addresses, if possible.
 * Context:
 *      The VM object is locked.  This lock will get
 *      dropped and re-acquired though, so the caller
 *      must make sure the VM object is kept alive
 *      (by holding a VM map that has a reference
 *      on it, for example, or taking an extra reference).
 *      The page should also be kept busy to prevent
 *      it from being reclaimed.
 */
kern_return_t
vm_paging_map_object(
        vm_map_offset_t         *address,
        vm_page_t               page,
        vm_object_t             object,
        vm_object_offset_t      offset,
        vm_map_size_t           *size,
        vm_prot_t               protection,
        boolean_t               can_unlock_object)
{
        kern_return_t           kr;
        vm_map_offset_t         page_map_offset;
        vm_map_size_t           map_size;
        vm_object_offset_t      object_offset;
        int                     i;

        
        if (page != VM_PAGE_NULL && *size == PAGE_SIZE) {
                assert(page->busy);
                /*
                 * Use one of the pre-allocated kernel virtual addresses
                 * and just enter the VM page in the kernel address space
                 * at that virtual address.
                 */
                simple_lock(&vm_paging_lock);

                /*
                 * Try and find an available kernel virtual address
                 * from our pre-allocated pool.
                 */
                page_map_offset = 0;
                for (;;) {
                        for (i = 0; i < VM_PAGING_NUM_PAGES; i++) {
                                if (vm_paging_page_inuse[i] == FALSE) {
                                        page_map_offset =
                                                vm_paging_base_address +
                                                (i * PAGE_SIZE);
                                        break;
                                }
                        }
                        if (page_map_offset != 0) {
                                /* found a space to map our page ! */
                                break;
                        }

                        if (can_unlock_object) {
                                /*
                                 * If we can afford to unlock the VM object,
                                 * let's take the slow path now...
                                 */
                                break;
                        }
                        /*
                         * We can't afford to unlock the VM object, so
                         * let's wait for a space to become available...
                         */
                        vm_paging_page_waiter_total++;
                        vm_paging_page_waiter++;
                        thread_sleep_fast_usimple_lock(&vm_paging_page_waiter,
                                                       &vm_paging_lock,
                                                       THREAD_UNINT);
                        vm_paging_page_waiter--;
                        /* ... and try again */
                }

                if (page_map_offset != 0) {
                        /*
                         * We found a kernel virtual address;
                         * map the physical page to that virtual address.
                         */
                        if (i > vm_paging_max_index) {
                                vm_paging_max_index = i;
                        }
                        vm_paging_page_inuse[i] = TRUE;
                        simple_unlock(&vm_paging_lock);

                        page->pmapped = TRUE;

                        /*
                         * Keep the VM object locked over the PMAP_ENTER
                         * and the actual use of the page by the kernel,
                         * or this pmap mapping might get undone by a 
                         * vm_object_pmap_protect() call...
                         */
                        PMAP_ENTER(kernel_pmap,
                                   page_map_offset,
                                   page,
                                   protection,
                                   0,
                                   TRUE);
                        vm_paging_objects_mapped++;
                        vm_paging_pages_mapped++; 
                        *address = page_map_offset;

                        /* all done and mapped, ready to use ! */
                        return KERN_SUCCESS;
                }

                /*
                 * We ran out of pre-allocated kernel virtual
                 * addresses.  Just map the page in the kernel
                 * the slow and regular way.
                 */
                vm_paging_no_kernel_page++;
                simple_unlock(&vm_paging_lock);
        }

        if (! can_unlock_object) {
                return KERN_NOT_SUPPORTED;
        }

        object_offset = vm_object_trunc_page(offset);
        map_size = vm_map_round_page(*size);

        /*
         * Try and map the required range of the object
         * in the kernel_map
         */

        vm_object_reference_locked(object);     /* for the map entry */
        vm_object_unlock(object);

        kr = vm_map_enter(kernel_map,
                          address,
                          map_size,
                          0,
                          VM_FLAGS_ANYWHERE,
                          object,
                          object_offset,
                          FALSE,
                          protection,
                          VM_PROT_ALL,
                          VM_INHERIT_NONE);
        if (kr != KERN_SUCCESS) {
                *address = 0;
                *size = 0;
                vm_object_deallocate(object);   /* for the map entry */
                vm_object_lock(object);
                return kr;
        }

        *size = map_size;

        /*
         * Enter the mapped pages in the page table now.
         */
        vm_object_lock(object);
        /*
         * VM object must be kept locked from before PMAP_ENTER()
         * until after the kernel is done accessing the page(s).
         * Otherwise, the pmap mappings in the kernel could be
         * undone by a call to vm_object_pmap_protect().
         */

        for (page_map_offset = 0;
             map_size != 0;
             map_size -= PAGE_SIZE_64, page_map_offset += PAGE_SIZE_64) {

                page = vm_page_lookup(object, offset + page_map_offset);
                if (page == VM_PAGE_NULL) {
                        printf("vm_paging_map_object: no page !?");
                        vm_object_unlock(object);
                        kr = vm_map_remove(kernel_map, *address, *size,
                                           VM_MAP_NO_FLAGS);
                        assert(kr == KERN_SUCCESS);
                        *address = 0;
                        *size = 0;
                        vm_object_lock(object);
                        return KERN_MEMORY_ERROR;
                }
                page->pmapped = TRUE;

                //assert(pmap_verify_free(page->phys_page));
                PMAP_ENTER(kernel_pmap,
                           *address + page_map_offset,
                           page,
                           protection,
                           0,
                           TRUE);
        }
                           
        vm_paging_objects_mapped_slow++;
        vm_paging_pages_mapped_slow += (unsigned long) (map_size / PAGE_SIZE_64);

        return KERN_SUCCESS;
}

/*
 * ENCRYPTED SWAP:
 * vm_paging_unmap_object:
 *      Unmaps part of a VM object's pages from the kernel
 *      virtual address space.
 * Context:
 *      The VM object is locked.  This lock will get
 *      dropped and re-acquired though.
 */
void
vm_paging_unmap_object(
        vm_object_t     object,
        vm_map_offset_t start,
        vm_map_offset_t end)
{
        kern_return_t   kr;
        int             i;

        if ((vm_paging_base_address == 0) ||
            (start < vm_paging_base_address) ||
            (end > (vm_paging_base_address
                     + (VM_PAGING_NUM_PAGES * PAGE_SIZE)))) {
                /*
                 * We didn't use our pre-allocated pool of
                 * kernel virtual address.  Deallocate the
                 * virtual memory.
                 */
                if (object != VM_OBJECT_NULL) {
                        vm_object_unlock(object);
                }
                kr = vm_map_remove(kernel_map, start, end, VM_MAP_NO_FLAGS);
                if (object != VM_OBJECT_NULL) {
                        vm_object_lock(object);
                }
                assert(kr == KERN_SUCCESS);
        } else {
                /*
                 * We used a kernel virtual address from our
                 * pre-allocated pool.  Put it back in the pool
                 * for next time.
                 */
                assert(end - start == PAGE_SIZE);
                i = (int) ((start - vm_paging_base_address) >> PAGE_SHIFT);
                assert(i >= 0 && i < VM_PAGING_NUM_PAGES);

                /* undo the pmap mapping */
                pmap_remove(kernel_pmap, start, end);

                simple_lock(&vm_paging_lock);
                vm_paging_page_inuse[i] = FALSE;
                if (vm_paging_page_waiter) {
                        thread_wakeup(&vm_paging_page_waiter);
                }
                simple_unlock(&vm_paging_lock);
        }
}

#if CRYPTO
/*
 * Encryption data.
 * "iv" is the "initial vector".  Ideally, we want to
 * have a different one for each page we encrypt, so that
 * crackers can't find encryption patterns too easily.
 */
#define SWAP_CRYPT_AES_KEY_SIZE 128     /* XXX 192 and 256 don't work ! */
boolean_t               swap_crypt_ctx_initialized = FALSE;
aes_32t                 swap_crypt_key[8]; /* big enough for a 256 key */
aes_ctx                 swap_crypt_ctx;
const unsigned char     swap_crypt_null_iv[AES_BLOCK_SIZE] = {0xa, };

#if DEBUG
boolean_t               swap_crypt_ctx_tested = FALSE;
unsigned char swap_crypt_test_page_ref[4096] __attribute__((aligned(4096)));
unsigned char swap_crypt_test_page_encrypt[4096] __attribute__((aligned(4096)));
unsigned char swap_crypt_test_page_decrypt[4096] __attribute__((aligned(4096)));
#endif /* DEBUG */

/*
 * Initialize the encryption context: key and key size.
 */
void swap_crypt_ctx_initialize(void); /* forward */
void
swap_crypt_ctx_initialize(void)
{
        unsigned int    i;

        /*
         * No need for locking to protect swap_crypt_ctx_initialized
         * because the first use of encryption will come from the
         * pageout thread (we won't pagein before there's been a pageout)
         * and there's only one pageout thread.
         */
        if (swap_crypt_ctx_initialized == FALSE) {
                for (i = 0;
                     i < (sizeof (swap_crypt_key) /
                          sizeof (swap_crypt_key[0]));
                     i++) {
                        swap_crypt_key[i] = random();
                }
                aes_encrypt_key((const unsigned char *) swap_crypt_key,
                                SWAP_CRYPT_AES_KEY_SIZE,
                                &swap_crypt_ctx.encrypt);
                aes_decrypt_key((const unsigned char *) swap_crypt_key,
                                SWAP_CRYPT_AES_KEY_SIZE,
                                &swap_crypt_ctx.decrypt);
                swap_crypt_ctx_initialized = TRUE;
        }

#if DEBUG
        /*
         * Validate the encryption algorithms.
         */
        if (swap_crypt_ctx_tested == FALSE) {
                /* initialize */
                for (i = 0; i < 4096; i++) {
                        swap_crypt_test_page_ref[i] = (char) i;
                }
                /* encrypt */
                aes_encrypt_cbc(swap_crypt_test_page_ref,
                                swap_crypt_null_iv,
                                PAGE_SIZE / AES_BLOCK_SIZE,
                                swap_crypt_test_page_encrypt,
                                &swap_crypt_ctx.encrypt);
                /* decrypt */
                aes_decrypt_cbc(swap_crypt_test_page_encrypt,
                                swap_crypt_null_iv,
                                PAGE_SIZE / AES_BLOCK_SIZE,
                                swap_crypt_test_page_decrypt,
                                &swap_crypt_ctx.decrypt);
                /* compare result with original */
                for (i = 0; i < 4096; i ++) {
                        if (swap_crypt_test_page_decrypt[i] !=
                            swap_crypt_test_page_ref[i]) {
                                panic("encryption test failed");
                        }
                }

                /* encrypt again */
                aes_encrypt_cbc(swap_crypt_test_page_decrypt,
                                swap_crypt_null_iv,
                                PAGE_SIZE / AES_BLOCK_SIZE,
                                swap_crypt_test_page_decrypt,
                                &swap_crypt_ctx.encrypt);
                /* decrypt in place */
                aes_decrypt_cbc(swap_crypt_test_page_decrypt,
                                swap_crypt_null_iv,
                                PAGE_SIZE / AES_BLOCK_SIZE,
                                swap_crypt_test_page_decrypt,
                                &swap_crypt_ctx.decrypt);
                for (i = 0; i < 4096; i ++) {
                        if (swap_crypt_test_page_decrypt[i] !=
                            swap_crypt_test_page_ref[i]) {
                                panic("in place encryption test failed");
                        }
                }

                swap_crypt_ctx_tested = TRUE;
        }
#endif /* DEBUG */
}

/*
 * ENCRYPTED SWAP:
 * vm_page_encrypt:
 *      Encrypt the given page, for secure paging.
 *      The page might already be mapped at kernel virtual
 *      address "kernel_mapping_offset".  Otherwise, we need
 *      to map it.
 * 
 * Context:
 *      The page's object is locked, but this lock will be released
 *      and re-acquired.
 *      The page is busy and not accessible by users (not entered in any pmap).
 */
void
vm_page_encrypt(
        vm_page_t       page,
        vm_map_offset_t kernel_mapping_offset)
{
        kern_return_t           kr;
        vm_map_size_t           kernel_mapping_size;
        vm_offset_t             kernel_vaddr;
        union {
                unsigned char   aes_iv[AES_BLOCK_SIZE];
                struct {
                        memory_object_t         pager_object;
                        vm_object_offset_t      paging_offset;
                } vm;
        } encrypt_iv;

        if (! vm_pages_encrypted) {
                vm_pages_encrypted = TRUE;
        }

        assert(page->busy);
        assert(page->dirty || page->precious);
        
        if (page->encrypted) {
                /*
                 * Already encrypted: no need to do it again.
                 */
                vm_page_encrypt_already_encrypted_counter++;
                return;
        }
        ASSERT_PAGE_DECRYPTED(page);

        /*
         * Take a paging-in-progress reference to keep the object
         * alive even if we have to unlock it (in vm_paging_map_object()
         * for example)...
         */
        vm_object_paging_begin(page->object);

        if (kernel_mapping_offset == 0) {
                /*
                 * The page hasn't already been mapped in kernel space
                 * by the caller.  Map it now, so that we can access
                 * its contents and encrypt them.
                 */
                kernel_mapping_size = PAGE_SIZE;
                kr = vm_paging_map_object(&kernel_mapping_offset,
                                          page,
                                          page->object,
                                          page->offset,
                                          &kernel_mapping_size,
                                          VM_PROT_READ | VM_PROT_WRITE,
                                          FALSE);
                if (kr != KERN_SUCCESS) {
                        panic("vm_page_encrypt: "
                              "could not map page in kernel: 0x%x\n",
                              kr);
                }
        } else {
                kernel_mapping_size = 0;
        }
        kernel_vaddr = CAST_DOWN(vm_offset_t, kernel_mapping_offset);

        if (swap_crypt_ctx_initialized == FALSE) {
                swap_crypt_ctx_initialize();
        }
        assert(swap_crypt_ctx_initialized);

        /*
         * Prepare an "initial vector" for the encryption.
         * We use the "pager" and the "paging_offset" for that
         * page to obfuscate the encrypted data a bit more and
         * prevent crackers from finding patterns that they could
         * use to break the key.
         */
        bzero(&encrypt_iv.aes_iv[0], sizeof (encrypt_iv.aes_iv));
        encrypt_iv.vm.pager_object = page->object->pager;
        encrypt_iv.vm.paging_offset =
                page->object->paging_offset + page->offset;

        /* encrypt the "initial vector" */
        aes_encrypt_cbc((const unsigned char *) &encrypt_iv.aes_iv[0],
                        swap_crypt_null_iv,
                        1,
                        &encrypt_iv.aes_iv[0],
                        &swap_crypt_ctx.encrypt);
                  
        /*
         * Encrypt the page.
         */
        aes_encrypt_cbc((const unsigned char *) kernel_vaddr,
                        &encrypt_iv.aes_iv[0],
                        PAGE_SIZE / AES_BLOCK_SIZE,
                        (unsigned char *) kernel_vaddr,
                        &swap_crypt_ctx.encrypt);

        vm_page_encrypt_counter++;

        /*
         * Unmap the page from the kernel's address space,
         * if we had to map it ourselves.  Otherwise, let
         * the caller undo the mapping if needed.
         */
        if (kernel_mapping_size != 0) {
                vm_paging_unmap_object(page->object,
                                       kernel_mapping_offset,
                                       kernel_mapping_offset + kernel_mapping_size);
        }

        /*
         * Clear the "reference" and "modified" bits.
         * This should clean up any impact the encryption had
         * on them.
         * The page was kept busy and disconnected from all pmaps,
         * so it can't have been referenced or modified from user
         * space.
         * The software bits will be reset later after the I/O
         * has completed (in upl_commit_range()).
         */
        pmap_clear_refmod(page->phys_page, VM_MEM_REFERENCED | VM_MEM_MODIFIED);

        page->encrypted = TRUE;

        vm_object_paging_end(page->object);
}

/*
 * ENCRYPTED SWAP:
 * vm_page_decrypt:
 *      Decrypt the given page.
 *      The page might already be mapped at kernel virtual
 *      address "kernel_mapping_offset".  Otherwise, we need
 *      to map it.
 *
 * Context:
 *      The page's VM object is locked but will be unlocked and relocked.
 *      The page is busy and not accessible by users (not entered in any pmap).
 */
void
vm_page_decrypt(
        vm_page_t       page,
        vm_map_offset_t kernel_mapping_offset)
{
        kern_return_t           kr;
        vm_map_size_t           kernel_mapping_size;
        vm_offset_t             kernel_vaddr;
        union {
                unsigned char   aes_iv[AES_BLOCK_SIZE];
                struct {
                        memory_object_t         pager_object;
                        vm_object_offset_t      paging_offset;
                } vm;
        } decrypt_iv;
        boolean_t               was_dirty;

        assert(page->busy);
        assert(page->encrypted);

        was_dirty = page->dirty;

        /*
         * Take a paging-in-progress reference to keep the object
         * alive even if we have to unlock it (in vm_paging_map_object()
         * for example)...
         */
        vm_object_paging_begin(page->object);

        if (kernel_mapping_offset == 0) {
                /*
                 * The page hasn't already been mapped in kernel space
                 * by the caller.  Map it now, so that we can access
                 * its contents and decrypt them.
                 */
                kernel_mapping_size = PAGE_SIZE;
                kr = vm_paging_map_object(&kernel_mapping_offset,
                                          page,
                                          page->object,
                                          page->offset,
                                          &kernel_mapping_size,
                                          VM_PROT_READ | VM_PROT_WRITE,
                                          FALSE);
                if (kr != KERN_SUCCESS) {
                        panic("vm_page_decrypt: "
                              "could not map page in kernel: 0x%x\n",
                              kr);
                }
        } else {
                kernel_mapping_size = 0;
        }
        kernel_vaddr = CAST_DOWN(vm_offset_t, kernel_mapping_offset);

        assert(swap_crypt_ctx_initialized);

        /*
         * Prepare an "initial vector" for the decryption.
         * It has to be the same as the "initial vector" we
         * used to encrypt that page.
         */
        bzero(&decrypt_iv.aes_iv[0], sizeof (decrypt_iv.aes_iv));
        decrypt_iv.vm.pager_object = page->object->pager;
        decrypt_iv.vm.paging_offset =
                page->object->paging_offset + page->offset;

        /* encrypt the "initial vector" */
        aes_encrypt_cbc((const unsigned char *) &decrypt_iv.aes_iv[0],
                        swap_crypt_null_iv,
                        1,
                        &decrypt_iv.aes_iv[0],
                        &swap_crypt_ctx.encrypt);

        /*
         * Decrypt the page.
         */
        aes_decrypt_cbc((const unsigned char *) kernel_vaddr,
                        &decrypt_iv.aes_iv[0],
                        PAGE_SIZE / AES_BLOCK_SIZE,
                        (unsigned char *) kernel_vaddr,
                        &swap_crypt_ctx.decrypt);
        vm_page_decrypt_counter++;

        /*
         * Unmap the page from the kernel's address space,
         * if we had to map it ourselves.  Otherwise, let
         * the caller undo the mapping if needed.
         */
        if (kernel_mapping_size != 0) {
                vm_paging_unmap_object(page->object,
                                       kernel_vaddr,
                                       kernel_vaddr + PAGE_SIZE);
        }

        if (was_dirty) {
                /*
                 * The pager did not specify that the page would be
                 * clean when it got paged in, so let's not clean it here
                 * either.
                 */
        } else {
                /*
                 * After decryption, the page is actually still clean.
                 * It was encrypted as part of paging, which "cleans"
                 * the "dirty" pages.
                 * Noone could access it after it was encrypted
                 * and the decryption doesn't count.
                 */
                page->dirty = FALSE;
                assert (page->cs_validated == FALSE);
                pmap_clear_refmod(page->phys_page, VM_MEM_MODIFIED | VM_MEM_REFERENCED);
        }
        page->encrypted = FALSE;

        /*
         * We've just modified the page's contents via the data cache and part
         * of the new contents might still be in the cache and not yet in RAM.
         * Since the page is now available and might get gathered in a UPL to
         * be part of a DMA transfer from a driver that expects the memory to
         * be coherent at this point, we have to flush the data cache.
         */
        pmap_sync_page_attributes_phys(page->phys_page);
        /*
         * Since the page is not mapped yet, some code might assume that it
         * doesn't need to invalidate the instruction cache when writing to
         * that page.  That code relies on "pmapped" being FALSE, so that the
         * caches get synchronized when the page is first mapped.
         */
        assert(pmap_verify_free(page->phys_page));
        page->pmapped = FALSE;
        page->wpmapped = FALSE;

        vm_object_paging_end(page->object);
}

#if DEVELOPMENT || DEBUG
unsigned long upl_encrypt_upls = 0;
unsigned long upl_encrypt_pages = 0;
#endif

/*
 * ENCRYPTED SWAP:
 *
 * upl_encrypt:
 *      Encrypts all the pages in the UPL, within the specified range.
 *
 */
void
upl_encrypt(
        upl_t                   upl,
        upl_offset_t            crypt_offset,
        upl_size_t              crypt_size)
{
        upl_size_t              upl_size, subupl_size=crypt_size;
        upl_offset_t            offset_in_upl, subupl_offset=crypt_offset;
        vm_object_t             upl_object;
        vm_object_offset_t      upl_offset;
        vm_page_t               page;
        vm_object_t             shadow_object;
        vm_object_offset_t      shadow_offset;
        vm_object_offset_t      paging_offset;
        vm_object_offset_t      base_offset;
        int                     isVectorUPL = 0;
        upl_t                   vector_upl = NULL;

        if((isVectorUPL = vector_upl_is_valid(upl)))
                vector_upl = upl;

process_upl_to_encrypt:
        if(isVectorUPL) {
                crypt_size = subupl_size;
                crypt_offset = subupl_offset;
                upl =  vector_upl_subupl_byoffset(vector_upl, &crypt_offset, &crypt_size);
                if(upl == NULL)
                        panic("upl_encrypt: Accessing a sub-upl that doesn't exist\n");
                subupl_size -= crypt_size;
                subupl_offset += crypt_size;
        }

#if DEVELOPMENT || DEBUG
        upl_encrypt_upls++;
        upl_encrypt_pages += crypt_size / PAGE_SIZE;
#endif
        upl_object = upl->map_object;
        upl_offset = upl->offset;
        upl_size = upl->size;

        vm_object_lock(upl_object);

        /*
         * Find the VM object that contains the actual pages.
         */
        if (upl_object->pageout) {
                shadow_object = upl_object->shadow;
                /*
                 * The offset in the shadow object is actually also
                 * accounted for in upl->offset.  It possibly shouldn't be
                 * this way, but for now don't account for it twice.
                 */
                shadow_offset = 0;
                assert(upl_object->paging_offset == 0); /* XXX ? */
                vm_object_lock(shadow_object);
        } else {
                shadow_object = upl_object;
                shadow_offset = 0;
        }

        paging_offset = shadow_object->paging_offset;
        vm_object_paging_begin(shadow_object);

        if (shadow_object != upl_object)
                vm_object_unlock(upl_object);


        base_offset = shadow_offset;
        base_offset += upl_offset;
        base_offset += crypt_offset;
        base_offset -= paging_offset;

        assert(crypt_offset + crypt_size <= upl_size);

        for (offset_in_upl = 0;
             offset_in_upl < crypt_size;
             offset_in_upl += PAGE_SIZE) {
                page = vm_page_lookup(shadow_object,
                                      base_offset + offset_in_upl);
                if (page == VM_PAGE_NULL) {
                        panic("upl_encrypt: "
                              "no page for (obj=%p,off=0x%llx+0x%x)!\n",
                              shadow_object,
                              base_offset,
                              offset_in_upl);
                }
                /*
                 * Disconnect the page from all pmaps, so that nobody can
                 * access it while it's encrypted.  After that point, all
                 * accesses to this page will cause a page fault and block
                 * while the page is busy being encrypted.  After the
                 * encryption completes, any access will cause a
                 * page fault and the page gets decrypted at that time.
                 */
                pmap_disconnect(page->phys_page);
                vm_page_encrypt(page, 0);

                if (vm_object_lock_avoid(shadow_object)) {
                        /*
                         * Give vm_pageout_scan() a chance to convert more
                         * pages from "clean-in-place" to "clean-and-free",
                         * if it's interested in the same pages we selected
                         * in this cluster.
                         */
                        vm_object_unlock(shadow_object);
                        mutex_pause(2);
                        vm_object_lock(shadow_object);
                }
        }

        vm_object_paging_end(shadow_object);
        vm_object_unlock(shadow_object);
        
        if(isVectorUPL && subupl_size)
                goto process_upl_to_encrypt;
}

#else /* CRYPTO */
void
upl_encrypt(
        __unused upl_t                  upl,
        __unused upl_offset_t   crypt_offset,
        __unused upl_size_t     crypt_size)
{
}

void
vm_page_encrypt(
        __unused vm_page_t              page,
        __unused vm_map_offset_t        kernel_mapping_offset)
{
} 

void
vm_page_decrypt(
        __unused vm_page_t              page,
        __unused vm_map_offset_t        kernel_mapping_offset)
{
}

#endif /* CRYPTO */

void
vm_pageout_queue_steal(vm_page_t page, boolean_t queues_locked)
{
        boolean_t       pageout;

        pageout = page->pageout;

        page->list_req_pending = FALSE;
        page->cleaning = FALSE;
        page->pageout = FALSE;

        if (!queues_locked) {
                vm_page_lockspin_queues();
        }

        /*
         * need to drop the laundry count...
         * we may also need to remove it
         * from the I/O paging queue...
         * vm_pageout_throttle_up handles both cases
         *
         * the laundry and pageout_queue flags are cleared...
         */
        vm_pageout_throttle_up(page);

        if (pageout == TRUE) {
                /*
                 * toss the wire count we picked up
                 * when we intially set this page up
                 * to be cleaned...
                 */
                vm_page_unwire(page, TRUE);
        }
        vm_page_steal_pageout_page++;

        if (!queues_locked) {
                vm_page_unlock_queues();
        }
}

upl_t
vector_upl_create(vm_offset_t upl_offset)
{
        int     vector_upl_size  = sizeof(struct _vector_upl);
        int i=0;
        upl_t   upl;
        vector_upl_t vector_upl = (vector_upl_t)kalloc(vector_upl_size);

        upl = upl_create(0,UPL_VECTOR,0);
        upl->vector_upl = vector_upl;
        upl->offset = upl_offset;
        vector_upl->size = 0;
        vector_upl->offset = upl_offset;
        vector_upl->invalid_upls=0;
        vector_upl->num_upls=0;
        vector_upl->pagelist = NULL;
        
        for(i=0; i < MAX_VECTOR_UPL_ELEMENTS ; i++) {
                vector_upl->upl_iostates[i].size = 0;
                vector_upl->upl_iostates[i].offset = 0;
                
        }
        return upl;
}

void
vector_upl_deallocate(upl_t upl)
{
        if(upl) {
                vector_upl_t vector_upl = upl->vector_upl;
                if(vector_upl) {
                        if(vector_upl->invalid_upls != vector_upl->num_upls)
                                panic("Deallocating non-empty Vectored UPL\n");
                        kfree(vector_upl->pagelist,(sizeof(struct upl_page_info)*(vector_upl->size/PAGE_SIZE)));
                        vector_upl->invalid_upls=0;
                        vector_upl->num_upls = 0;
                        vector_upl->pagelist = NULL;
                        vector_upl->size = 0;
                        vector_upl->offset = 0;
                        kfree(vector_upl, sizeof(struct _vector_upl));
                        vector_upl = (vector_upl_t)0xdeadbeef;
                }
                else
                        panic("vector_upl_deallocate was passed a non-vectored upl\n");
        }
        else
                panic("vector_upl_deallocate was passed a NULL upl\n");
}

boolean_t
vector_upl_is_valid(upl_t upl)
{
        if(upl &&  ((upl->flags & UPL_VECTOR)==UPL_VECTOR)) {
                vector_upl_t vector_upl = upl->vector_upl;
                if(vector_upl == NULL || vector_upl == (vector_upl_t)0xdeadbeef || vector_upl == (vector_upl_t)0xfeedbeef)
                        return FALSE;
                else
                        return TRUE;
        }
        return FALSE;
}

boolean_t
vector_upl_set_subupl(upl_t upl,upl_t subupl, uint32_t io_size)
{
        if(vector_upl_is_valid(upl)) {          
                vector_upl_t vector_upl = upl->vector_upl;
                
                if(vector_upl) {
                        if(subupl) {
                                if(io_size) {
                                        if(io_size < PAGE_SIZE)
                                                io_size = PAGE_SIZE;
                                        subupl->vector_upl = (void*)vector_upl;
                                        vector_upl->upl_elems[vector_upl->num_upls++] = subupl;
                                        vector_upl->size += io_size;
                                        upl->size += io_size;
                                }
                                else {
                                        uint32_t i=0,invalid_upls=0;
                                        for(i = 0; i < vector_upl->num_upls; i++) {
                                                if(vector_upl->upl_elems[i] == subupl)
                                                        break;
                                        }
                                        if(i == vector_upl->num_upls)
                                                panic("Trying to remove sub-upl when none exists");
                                        
                                        vector_upl->upl_elems[i] = NULL;
                                        invalid_upls = hw_atomic_add(&(vector_upl)->invalid_upls, 1); 
                                        if(invalid_upls == vector_upl->num_upls)
                                                return TRUE;
                                        else 
                                                return FALSE;
                                }
                        }
                        else
                                panic("vector_upl_set_subupl was passed a NULL upl element\n");
                }
                else
                        panic("vector_upl_set_subupl was passed a non-vectored upl\n");
        }
        else
                panic("vector_upl_set_subupl was passed a NULL upl\n");

        return FALSE;
}       

void
vector_upl_set_pagelist(upl_t upl)
{
        if(vector_upl_is_valid(upl)) {          
                uint32_t i=0;
                vector_upl_t vector_upl = upl->vector_upl;

                if(vector_upl) {
                        vm_offset_t pagelist_size=0, cur_upl_pagelist_size=0;

                        vector_upl->pagelist = (upl_page_info_array_t)kalloc(sizeof(struct upl_page_info)*(vector_upl->size/PAGE_SIZE));
                        
                        for(i=0; i < vector_upl->num_upls; i++) {
                                cur_upl_pagelist_size = sizeof(struct upl_page_info) * vector_upl->upl_elems[i]->size/PAGE_SIZE;
                                bcopy(UPL_GET_INTERNAL_PAGE_LIST_SIMPLE(vector_upl->upl_elems[i]), (char*)vector_upl->pagelist + pagelist_size, cur_upl_pagelist_size);
                                pagelist_size += cur_upl_pagelist_size;
                                if(vector_upl->upl_elems[i]->highest_page > upl->highest_page)
                                        upl->highest_page = vector_upl->upl_elems[i]->highest_page;
                        }
                        assert( pagelist_size == (sizeof(struct upl_page_info)*(vector_upl->size/PAGE_SIZE)) );
                }
                else
                        panic("vector_upl_set_pagelist was passed a non-vectored upl\n");
        }
        else
                panic("vector_upl_set_pagelist was passed a NULL upl\n");

}

upl_t
vector_upl_subupl_byindex(upl_t upl, uint32_t index)
{
        if(vector_upl_is_valid(upl)) {          
                vector_upl_t vector_upl = upl->vector_upl;
                if(vector_upl) {
                        if(index < vector_upl->num_upls)
                                return vector_upl->upl_elems[index];
                }
                else
                        panic("vector_upl_subupl_byindex was passed a non-vectored upl\n");
        }
        return NULL;
}

upl_t
vector_upl_subupl_byoffset(upl_t upl, upl_offset_t *upl_offset, upl_size_t *upl_size)
{
        if(vector_upl_is_valid(upl)) {          
                uint32_t i=0;
                vector_upl_t vector_upl = upl->vector_upl;

                if(vector_upl) {
                        upl_t subupl = NULL;
                        vector_upl_iostates_t subupl_state;

                        for(i=0; i < vector_upl->num_upls; i++) {
                                subupl = vector_upl->upl_elems[i];
                                subupl_state = vector_upl->upl_iostates[i];
                                if( *upl_offset <= (subupl_state.offset + subupl_state.size - 1)) {
                                        /* We could have been passed an offset/size pair that belongs
                                         * to an UPL element that has already been committed/aborted.
                                         * If so, return NULL.
                                         */
                                        if(subupl == NULL)
                                                return NULL;
                                        if((subupl_state.offset + subupl_state.size) < (*upl_offset + *upl_size)) {
                                                *upl_size = (subupl_state.offset + subupl_state.size) - *upl_offset;
                                                if(*upl_size > subupl_state.size)
                                                        *upl_size = subupl_state.size;
                                        }
                                        if(*upl_offset >= subupl_state.offset)
                                                *upl_offset -= subupl_state.offset;
                                        else if(i)
                                                panic("Vector UPL offset miscalculation\n");
                                        return subupl;
                                }       
                        }
                }
                else
                        panic("vector_upl_subupl_byoffset was passed a non-vectored UPL\n");
        }
        return NULL;
}

void
vector_upl_get_submap(upl_t upl, vm_map_t *v_upl_submap, vm_offset_t *submap_dst_addr)
{
        *v_upl_submap = NULL;

        if(vector_upl_is_valid(upl)) {          
                vector_upl_t vector_upl = upl->vector_upl;
                if(vector_upl) {
                        *v_upl_submap = vector_upl->submap;
                        *submap_dst_addr = vector_upl->submap_dst_addr;
                }
                else
                        panic("vector_upl_get_submap was passed a non-vectored UPL\n");
        }
        else
                panic("vector_upl_get_submap was passed a null UPL\n");
}

void
vector_upl_set_submap(upl_t upl, vm_map_t submap, vm_offset_t submap_dst_addr)
{
        if(vector_upl_is_valid(upl)) {          
                vector_upl_t vector_upl = upl->vector_upl;
                if(vector_upl) {
                        vector_upl->submap = submap;
                        vector_upl->submap_dst_addr = submap_dst_addr;
                }
                else
                        panic("vector_upl_get_submap was passed a non-vectored UPL\n");
        }
        else
                panic("vector_upl_get_submap was passed a NULL UPL\n");
}

void
vector_upl_set_iostate(upl_t upl, upl_t subupl, upl_offset_t offset, upl_size_t size)
{
        if(vector_upl_is_valid(upl)) {          
                uint32_t i = 0;
                vector_upl_t vector_upl = upl->vector_upl;

                if(vector_upl) {
                        for(i = 0; i < vector_upl->num_upls; i++) {
                                if(vector_upl->upl_elems[i] == subupl)
                                        break;
                        }
                        
                        if(i == vector_upl->num_upls)
                                panic("setting sub-upl iostate when none exists");

                        vector_upl->upl_iostates[i].offset = offset;
                        if(size < PAGE_SIZE)
                                size = PAGE_SIZE;
                        vector_upl->upl_iostates[i].size = size;
                }
                else
                        panic("vector_upl_set_iostate was passed a non-vectored UPL\n");
        }
        else
                panic("vector_upl_set_iostate was passed a NULL UPL\n");
}

void
vector_upl_get_iostate(upl_t upl, upl_t subupl, upl_offset_t *offset, upl_size_t *size)
{
        if(vector_upl_is_valid(upl)) {          
                uint32_t i = 0;
                vector_upl_t vector_upl = upl->vector_upl;

                if(vector_upl) {
                        for(i = 0; i < vector_upl->num_upls; i++) {
                                if(vector_upl->upl_elems[i] == subupl)
                                        break;
                        }
                        
                        if(i == vector_upl->num_upls)
                                panic("getting sub-upl iostate when none exists");

                        *offset = vector_upl->upl_iostates[i].offset;
                        *size = vector_upl->upl_iostates[i].size;
                }
                else
                        panic("vector_upl_get_iostate was passed a non-vectored UPL\n");
        }
        else
                panic("vector_upl_get_iostate was passed a NULL UPL\n");
}

void
vector_upl_get_iostate_byindex(upl_t upl, uint32_t index, upl_offset_t *offset, upl_size_t *size)
{
        if(vector_upl_is_valid(upl)) {          
                vector_upl_t vector_upl = upl->vector_upl;
                if(vector_upl) {
                        if(index < vector_upl->num_upls) {
                                *offset = vector_upl->upl_iostates[index].offset;
                                *size = vector_upl->upl_iostates[index].size;
                        }
                        else
                                *offset = *size = 0;
                }
                else
                        panic("vector_upl_get_iostate_byindex was passed a non-vectored UPL\n");
        }
        else
                panic("vector_upl_get_iostate_byindex was passed a NULL UPL\n");
}

upl_page_info_t *
upl_get_internal_vectorupl_pagelist(upl_t upl)
{
        return ((vector_upl_t)(upl->vector_upl))->pagelist;
}

void *
upl_get_internal_vectorupl(upl_t upl)
{
        return upl->vector_upl;
}

vm_size_t
upl_get_internal_pagelist_offset(void)
{
        return sizeof(struct upl);
}

void
upl_clear_dirty(
        upl_t           upl,
        boolean_t       value)
{
        if (value) {
                upl->flags |= UPL_CLEAR_DIRTY;
        } else {
                upl->flags &= ~UPL_CLEAR_DIRTY;
        }
}

void
upl_set_referenced(
        upl_t           upl,
        boolean_t       value)
{
        upl_lock(upl);
        if (value) {
                upl->ext_ref_count++;
        } else {
                if (!upl->ext_ref_count) {
                        panic("upl_set_referenced not %p\n", upl);
                }
                upl->ext_ref_count--;
        }
        upl_unlock(upl);
}

boolean_t
vm_page_is_slideable(vm_page_t m)
{
        boolean_t result = FALSE;
        vm_object_t slide_object = slide_info.slide_object;
        mach_vm_offset_t start = slide_info.start;
        mach_vm_offset_t end = slide_info.end;

        /* make sure our page belongs to the one object allowed to do this */
        if (slide_object == VM_OBJECT_NULL) {
                return result;
        }

        /*Should we traverse down the chain?*/
        if (m->object != slide_object) {
                return result;
        }

        if(!m->slid && (start <= m->offset && end > m->offset)) {
                result = TRUE;
        }
        return result;
}

int vm_page_slide_counter = 0;
int vm_page_slide_errors = 0;
kern_return_t
vm_page_slide(
        vm_page_t       page,
        vm_map_offset_t kernel_mapping_offset)
{
        kern_return_t           kr;
        vm_map_size_t           kernel_mapping_size;
        vm_offset_t             kernel_vaddr;
        uint32_t                pageIndex = 0;

        assert(!page->slid);
        
        /*
         * Take a paging-in-progress reference to keep the object
         * alive even if we have to unlock it (in vm_paging_map_object()
         * for example)...
         */
        vm_object_paging_begin(page->object);

        if (kernel_mapping_offset == 0) {
                /*
                 * The page hasn't already been mapped in kernel space
                 * by the caller.  Map it now, so that we can access
                 * its contents and decrypt them.
                 */
                kernel_mapping_size = PAGE_SIZE;
                kr = vm_paging_map_object(&kernel_mapping_offset,
                                          page,
                                          page->object,
                                          page->offset,
                                          &kernel_mapping_size,
                                          VM_PROT_READ | VM_PROT_WRITE,
                                          FALSE);
                if (kr != KERN_SUCCESS) {
                        panic("vm_page_slide: "
                              "could not map page in kernel: 0x%x\n",
                              kr);
                }
        } else {
                kernel_mapping_size = 0;
        }
        kernel_vaddr = CAST_DOWN(vm_offset_t, kernel_mapping_offset);

        /*
         * Slide the pointers on the page.
         */

        /*assert that slide_file_info.start/end are page-aligned?*/

        pageIndex = (uint32_t)((page->offset - slide_info.start)/PAGE_SIZE);
        kr = vm_shared_region_slide(kernel_vaddr, pageIndex);
        vm_page_slide_counter++;

        /*
         * Unmap the page from the kernel's address space,
         */
        if (kernel_mapping_size != 0) {
                vm_paging_unmap_object(page->object,
                                       kernel_vaddr,
                                       kernel_vaddr + PAGE_SIZE);
        }
        
        page->dirty = FALSE;
        pmap_clear_refmod(page->phys_page, VM_MEM_MODIFIED | VM_MEM_REFERENCED);

        if (kr == KERN_SUCCESS) {
                page->slid = TRUE;
        } else {
                page->error = TRUE;
                vm_page_slide_errors++;
        }

        vm_object_paging_end(page->object);

        return kr;
}


#ifdef MACH_BSD

boolean_t  upl_device_page(upl_page_info_t *upl)
{
        return(UPL_DEVICE_PAGE(upl));
}
boolean_t  upl_page_present(upl_page_info_t *upl, int index)
{
        return(UPL_PAGE_PRESENT(upl, index));
}
boolean_t  upl_speculative_page(upl_page_info_t *upl, int index)
{
        return(UPL_SPECULATIVE_PAGE(upl, index));
}
boolean_t  upl_dirty_page(upl_page_info_t *upl, int index)
{
        return(UPL_DIRTY_PAGE(upl, index));
}
boolean_t  upl_valid_page(upl_page_info_t *upl, int index)
{
        return(UPL_VALID_PAGE(upl, index));
}
ppnum_t  upl_phys_page(upl_page_info_t *upl, int index)
{
        return(UPL_PHYS_PAGE(upl, index));
}


void
vm_countdirtypages(void)
{
        vm_page_t m;
        int dpages;
        int pgopages;
        int precpages;


        dpages=0;
        pgopages=0;
        precpages=0;

        vm_page_lock_queues();
        m = (vm_page_t) queue_first(&vm_page_queue_inactive);
        do {
                if (m ==(vm_page_t )0) break;

                if(m->dirty) dpages++;
                if(m->pageout) pgopages++;
                if(m->precious) precpages++;

                assert(m->object != kernel_object);
                m = (vm_page_t) queue_next(&m->pageq);
                if (m ==(vm_page_t )0) break;

        } while (!queue_end(&vm_page_queue_inactive,(queue_entry_t) m));
        vm_page_unlock_queues();

        vm_page_lock_queues();
        m = (vm_page_t) queue_first(&vm_page_queue_throttled);
        do {
                if (m ==(vm_page_t )0) break;

                dpages++;
                assert(m->dirty);
                assert(!m->pageout);
                assert(m->object != kernel_object);
                m = (vm_page_t) queue_next(&m->pageq);
                if (m ==(vm_page_t )0) break;

        } while (!queue_end(&vm_page_queue_throttled,(queue_entry_t) m));
        vm_page_unlock_queues();

        vm_page_lock_queues();
        m = (vm_page_t) queue_first(&vm_page_queue_zf);
        do {
                if (m ==(vm_page_t )0) break;

                if(m->dirty) dpages++;
                if(m->pageout) pgopages++;
                if(m->precious) precpages++;

                assert(m->object != kernel_object);
                m = (vm_page_t) queue_next(&m->pageq);
                if (m ==(vm_page_t )0) break;

        } while (!queue_end(&vm_page_queue_zf,(queue_entry_t) m));
        vm_page_unlock_queues();

        printf("IN Q: %d : %d : %d\n", dpages, pgopages, precpages);

        dpages=0;
        pgopages=0;
        precpages=0;

        vm_page_lock_queues();
        m = (vm_page_t) queue_first(&vm_page_queue_active);

        do {
                if(m == (vm_page_t )0) break;
                if(m->dirty) dpages++;
                if(m->pageout) pgopages++;
                if(m->precious) precpages++;

                assert(m->object != kernel_object);
                m = (vm_page_t) queue_next(&m->pageq);
                if(m == (vm_page_t )0) break;

        } while (!queue_end(&vm_page_queue_active,(queue_entry_t) m));
        vm_page_unlock_queues();

        printf("AC Q: %d : %d : %d\n", dpages, pgopages, precpages);

}
#endif /* MACH_BSD */

ppnum_t upl_get_highest_page(
                             upl_t                      upl)
{
        return upl->highest_page;
}

upl_size_t upl_get_size(
                             upl_t                      upl)
{
        return upl->size;
}

#if UPL_DEBUG
kern_return_t  upl_ubc_alias_set(upl_t upl, uintptr_t alias1, uintptr_t alias2)
{
        upl->ubc_alias1 = alias1;
        upl->ubc_alias2 = alias2;
        return KERN_SUCCESS;
}
int  upl_ubc_alias_get(upl_t upl, uintptr_t * al, uintptr_t * al2)
{
        if(al)
                *al = upl->ubc_alias1;
        if(al2)
                *al2 = upl->ubc_alias2;
        return KERN_SUCCESS;
}
#endif /* UPL_DEBUG */



#if     MACH_KDB
#include <ddb/db_output.h>
#include <ddb/db_print.h>
#include <vm/vm_print.h>

#define printf  kdbprintf
void            db_pageout(void);

void
db_vm(void)
{

        iprintf("VM Statistics:\n");
        db_indent += 2;
        iprintf("pages:\n");
        db_indent += 2;
        iprintf("activ %5d  inact %5d  free  %5d",
                vm_page_active_count, vm_page_inactive_count,
                vm_page_free_count);
        printf("   wire  %5d  gobbl %5d\n",
               vm_page_wire_count, vm_page_gobble_count);
        db_indent -= 2;
        iprintf("target:\n");
        db_indent += 2;
        iprintf("min   %5d  inact %5d  free  %5d",
                vm_page_free_min, vm_page_inactive_target,
                vm_page_free_target);
        printf("   resrv %5d\n", vm_page_free_reserved);
        db_indent -= 2;
        iprintf("pause:\n");
        db_pageout();
        db_indent -= 2;
}

#if     MACH_COUNTERS
extern int c_laundry_pages_freed;
#endif  /* MACH_COUNTERS */

void
db_pageout(void)
{
        iprintf("Pageout Statistics:\n");
        db_indent += 2;
        iprintf("active %5d  inactv %5d\n",
                vm_pageout_active, vm_pageout_inactive);
        iprintf("nolock %5d  avoid  %5d  busy   %5d  absent %5d\n",
                vm_pageout_inactive_nolock, vm_pageout_inactive_avoid,
                vm_pageout_inactive_busy, vm_pageout_inactive_absent);
        iprintf("used   %5d  clean  %5d  dirty(internal)  %5d  dirty(external)  %5d\n",
                vm_pageout_inactive_used, vm_pageout_inactive_clean,
                vm_pageout_inactive_dirty_internal, vm_pageout_inactive_dirty_external);
#if     MACH_COUNTERS
        iprintf("laundry_pages_freed %d\n", c_laundry_pages_freed);
#endif  /* MACH_COUNTERS */
#if     MACH_CLUSTER_STATS
        iprintf("Cluster Statistics:\n");
        db_indent += 2;
        iprintf("dirtied   %5d   cleaned  %5d   collisions  %5d\n",
                vm_pageout_cluster_dirtied, vm_pageout_cluster_cleaned,
                vm_pageout_cluster_collisions);
        iprintf("clusters  %5d   conversions  %5d\n",
                vm_pageout_cluster_clusters, vm_pageout_cluster_conversions);
        db_indent -= 2;
        iprintf("Target Statistics:\n");
        db_indent += 2;
        iprintf("collisions   %5d   page_dirtied  %5d   page_freed  %5d\n",
                vm_pageout_target_collisions, vm_pageout_target_page_dirtied,
                vm_pageout_target_page_freed);
        db_indent -= 2;
#endif  /* MACH_CLUSTER_STATS */
        db_indent -= 2;
}

#endif  /* MACH_KDB */