xnu-123.5.tar.gz

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

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This 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,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_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.
 */
#ifdef MACH_BSD
/* remove after component merge */
extern int      vnode_pager_workaround;
#endif

#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/mach_host_server.h>
#include <mach/vm_param.h>
#include <mach/vm_statistics.h>
#include <kern/host_statistics.h>
#include <kern/counters.h>
#include <kern/thread.h>
#include <kern/thread_swap.h>
#include <kern/xpr.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <machine/vm_tuning.h>
#include <kern/misc_protos.h>

extern ipc_port_t       memory_manager_default;

#ifndef VM_PAGE_LAUNDRY_MAX
#define VM_PAGE_LAUNDRY_MAX     10      /* outstanding DMM page cleans */
#endif  /* VM_PAGEOUT_LAUNDRY_MAX */

#ifndef VM_PAGEOUT_BURST_MAX
#define VM_PAGEOUT_BURST_MAX    32      /* simultaneous EMM page cleans */
#endif  /* VM_PAGEOUT_BURST_MAX */

#ifndef VM_PAGEOUT_DISCARD_MAX
#define VM_PAGEOUT_DISCARD_MAX  68      /* simultaneous EMM page cleans */
#endif  /* VM_PAGEOUT_DISCARD_MAX */

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

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

/*
 *      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
#define VM_PAGE_FREE_TARGET(free)       (15 + (free) / 80)
#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
#define VM_PAGE_FREE_MIN(free)  (10 + (free) / 100)
#endif  /* VM_PAGE_FREE_MIN */

/*
 *      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   \
        ((8 * VM_PAGE_LAUNDRY_MAX) + NCPUS)
#endif  /* VM_PAGE_FREE_RESERVED */


/*
 * Forward declarations for internal routines.
 */
extern void vm_pageout_continue(void);
extern void vm_pageout_scan(void);
extern void vm_pageout_throttle(vm_page_t m);
extern vm_page_t vm_pageout_cluster_page(
                        vm_object_t             object,
                        vm_object_offset_t      offset,
                        boolean_t               precious_clean);

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

unsigned int vm_page_laundry_max = 0;           /* # of clusters outstanding */
unsigned int vm_page_laundry_min = 0;
unsigned int vm_pageout_burst_max = 0;
unsigned int vm_pageout_burst_wait = 0;         /* milliseconds per page */
unsigned int vm_pageout_empty_wait = 0;         /* milliseconds */
unsigned int vm_pageout_burst_min = 0;
unsigned int vm_pageout_pause_count = 0;
unsigned int vm_pageout_pause_max = 0;
unsigned int vm_free_page_pause = 100;          /* milliseconds */

/*
 *      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_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_absent = 0;    /* debugging */
unsigned int vm_pageout_inactive_used = 0;      /* debugging */
unsigned int vm_pageout_inactive_clean = 0;     /* debugging */
unsigned int vm_pageout_inactive_dirty = 0;     /* debugging */
unsigned int vm_pageout_dirty_no_pager = 0;     /* debugging */
unsigned int vm_pageout_inactive_pinned = 0;    /* debugging */
unsigned int vm_pageout_inactive_limbo = 0;     /* debugging */
unsigned int vm_pageout_setup_limbo = 0;        /* debugging */
unsigned int vm_pageout_setup_unprepped = 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_scan_active_emm_throttle = 0;           /* debugging */
unsigned int vm_pageout_scan_active_emm_throttle_success = 0;   /* debugging */
unsigned int vm_pageout_scan_active_emm_throttle_failure = 0;   /* debugging */
unsigned int vm_pageout_scan_inactive_emm_throttle = 0;         /* debugging */
unsigned int vm_pageout_scan_inactive_emm_throttle_success = 0; /* debugging */
unsigned int vm_pageout_scan_inactive_emm_throttle_failure = 0; /* debugging */


unsigned int vm_pageout_out_of_line  = 0;
unsigned int vm_pageout_in_place  = 0;
/*
 *      Routine:        vm_pageout_object_allocate
 *      Purpose:
 *              Allocate an object for use as out-of-line memory in a
 *              data_return/data_initialize message.
 *              The page must be in an unlocked object.
 *
 *              If the page belongs to a trusted pager, cleaning in place
 *              will be used, which utilizes a special "pageout object"
 *              containing private alias pages for the real page frames.
 *              Untrusted pagers use normal out-of-line memory.
 */
vm_object_t
vm_pageout_object_allocate(
        vm_page_t               m,
        vm_size_t               size,
        vm_object_offset_t      offset)
{
        vm_object_t     object = m->object;
        vm_object_t     new_object;

        assert(object->pager_ready);

        if (object->pager_trusted || object->internal)
                vm_pageout_throttle(m);

        new_object = vm_object_allocate(size);

        if (object->pager_trusted) {
                assert (offset < object->size);

                vm_object_lock(new_object);
                new_object->pageout = TRUE;
                new_object->shadow = object;
                new_object->can_persist = FALSE;
                new_object->copy_strategy = MEMORY_OBJECT_COPY_NONE;
                new_object->shadow_offset = offset;
                vm_object_unlock(new_object);

                /*
                 * Take a paging reference on the object. This will be dropped
                 * in vm_pageout_object_terminate()
                 */
                vm_object_lock(object);
                vm_object_paging_begin(object);
                vm_object_unlock(object);

                vm_pageout_in_place++;
        } else
                vm_pageout_out_of_line++;
        return(new_object);
}

#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;
unsigned long vm_pageout_target_page_pinned = 0;
unsigned long vm_pageout_target_page_limbo = 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 allocated by
 *              vm_pageout_object_allocate(), 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->shadow_offset);

                if(m == VM_PAGE_NULL)
                        continue;
                assert(m->cleaning);

                /*
                 * Account for the paging reference taken when
                 * m->cleaning was set on this page.
                 */
                vm_object_paging_end(shadow_object);
                assert((m->dirty) || (m->precious) ||
                                (m->busy && m->cleaning));

                /*
                 * Handle the trusted pager throttle.
                 */
                vm_page_lock_queues();
                if (m->laundry) {
                    vm_page_laundry_count--;
                    m->laundry = FALSE;
                    if (vm_page_laundry_count < vm_page_laundry_min) {
                        vm_page_laundry_min = 0;
                        thread_wakeup((event_t) &vm_page_laundry_count);
                    }
                }

                /*
                 * 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->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_is_modified() call
                         * returns.
                         */
                        pmap_page_protect(m->phys_addr, VM_PROT_NONE);

                        /*
                         * Since the page is left "dirty" but "not modifed", we
                         * can detect whether the page was redirtied during
                         * pageout by checking the modify state.
                         */
                        m->dirty = pmap_is_modified(m->phys_addr);

                        if (m->dirty) {
                                CLUSTER_STAT(vm_pageout_target_page_dirtied++;)
                                vm_page_unwire(m);/* reactivates */
                                VM_STAT(reactivations++);
                                PAGE_WAKEUP_DONE(m);
                        } else if (m->prep_pin_count != 0) {
                                vm_page_pin_lock();
                                if (m->pin_count != 0) {
                                        /* page is pinned; reactivate */
                                        CLUSTER_STAT(
                                            vm_pageout_target_page_pinned++;)
                                        vm_page_unwire(m);/* reactivates */
                                        VM_STAT(reactivations++);
                                        PAGE_WAKEUP_DONE(m);
                                } else {
                                        /*
                                         * page is prepped but not pinned; send
                                         * it into limbo.  Note that
                                         * vm_page_free (which will be called
                                         * after releasing the pin lock) knows
                                         * how to handle a page with limbo set.
                                         */
                                        m->limbo = TRUE;
                                        CLUSTER_STAT(
                                            vm_pageout_target_page_limbo++;)
                                }
                                vm_page_pin_unlock();
                                if (m->limbo)
                                        vm_page_free(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) {
                        if (m->reference || m->prep_pin_count != 0)
                                vm_page_activate(m);
                        else
                                vm_page_deactivate(m);
                }
                if((m->busy) && (m->cleaning)) {

                        /* the request_page_list case, (COPY_OUT_FROM FALSE) */
                        m->busy = FALSE;

                        /* We do not re-set m->dirty ! */
                        /* The page was busy so no extraneous activity     */
                        /* could have occured. 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_addr);
                        if(m->absent) {
                                m->absent = FALSE;
                                if(shadow_object->absent_count == 1)
                                        vm_object_absent_release(shadow_object);
                                else
                                        shadow_object->absent_count--;
                        }
                        m->overwriting = FALSE;
                } else if (m->overwriting) {
                        /* alternate request page list, write to page_list */
                        /* case.  Occurs when the original page was wired  */
                        /* at the time of the list request */
                        assert(m->wire_count != 0);
                        vm_page_unwire(m);/* 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_addr);

                        if (m->dirty)   vm_pageout_cluster_dirtied++;
                        else            vm_pageout_cluster_cleaned++;
                        if (m->wanted)  vm_pageout_cluster_collisions++;
#else
                        m->dirty = 0;
#endif
                }
                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_paging_end(shadow_object);
        vm_object_unlock(shadow_object);

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

/*
 *      Routine:        vm_pageout_setup
 *      Purpose:
 *              Set up a page for pageout (clean & flush).
 *
 *              Move the page to a new object, as part of which it will be
 *              sent to its memory manager in a memory_object_data_write or
 *              memory_object_initialize message.
 *
 *              The "new_object" and "new_offset" arguments
 *              indicate where the page should be moved.
 *
 *      In/Out conditions:
 *              The page in question must not be on any pageout queues,
 *              and must be busy.  The object to which it belongs
 *              must be unlocked, and the caller must hold a paging
 *              reference to it.  The new_object must not be locked.
 *
 *              This routine returns a pointer to a place-holder page,
 *              inserted at the same offset, to block out-of-order
 *              requests for the page.  The place-holder page must
 *              be freed after the data_write or initialize message
 *              has been sent.
 *
 *              The original page is put on a paging queue and marked
 *              not busy on exit.
 */
vm_page_t
vm_pageout_setup(
        register vm_page_t      m,
        register vm_object_t    new_object,
        vm_object_offset_t      new_offset)
{
        register vm_object_t    old_object = m->object;
        vm_object_offset_t      paging_offset;
        vm_object_offset_t      offset;
        register vm_page_t      holding_page;
        register vm_page_t      new_m;
        register vm_page_t      new_page;
        boolean_t               need_to_wire = FALSE;


        XPR(XPR_VM_PAGEOUT,
     "vm_pageout_setup, obj 0x%X off 0x%X page 0x%X new obj 0x%X offset 0x%X\n",
                (integer_t)m->object, (integer_t)m->offset, 
                (integer_t)m, (integer_t)new_object, 
                (integer_t)new_offset);
        assert(m && m->busy && !m->absent && !m->fictitious && !m->error &&
                !m->restart);

        assert(m->dirty || m->precious);

        /*
         *      Create a place-holder page where the old one was, to prevent
         *      attempted pageins of this page while we're unlocked.
         *      If the pageout daemon put this page in limbo and we're not
         *      going to clean in place, get another fictitious page to
         *      exchange for it now.
         */
        VM_PAGE_GRAB_FICTITIOUS(holding_page);

        if (m->limbo)
                VM_PAGE_GRAB_FICTITIOUS(new_page);

        vm_object_lock(old_object);

        offset = m->offset;
        paging_offset = offset + old_object->paging_offset;

        if (old_object->pager_trusted) {
                /*
                 * This pager is trusted, so we can clean this page
                 * in place. Leave it in the old object, and mark it
                 * cleaning & pageout.
                 */
                new_m = holding_page;
                holding_page = VM_PAGE_NULL;

                /*
                 * If the pageout daemon put this page in limbo, exchange the
                 * identities of the limbo page and the new fictitious page,
                 * and continue with the new page, unless the prep count has
                 * gone to zero in the meantime (which means no one is
                 * interested in the page any more).  In that case, just clear
                 * the limbo bit and free the extra fictitious page.
                 */
                if (m->limbo) {
                        if (m->prep_pin_count == 0) {
                                /* page doesn't have to be in limbo any more */
                                m->limbo = FALSE;
                                vm_page_lock_queues();
                                vm_page_free(new_page);
                                vm_page_unlock_queues();
                                vm_pageout_setup_unprepped++;
                        } else {
                                vm_page_lock_queues();
                                VM_PAGE_QUEUES_REMOVE(m);
                                vm_page_remove(m);
                                vm_page_limbo_exchange(m, new_page);
                                vm_pageout_setup_limbo++;
                                vm_page_release_limbo(m);
                                m = new_page;
                                vm_page_insert(m, old_object, offset);
                                vm_page_unlock_queues();
                        }
                }

                /*
                 * Set up new page to be private shadow of real page.
                 */
                new_m->phys_addr = m->phys_addr;
                new_m->fictitious = FALSE;
                new_m->private = TRUE;
                new_m->pageout = TRUE;

                /*
                 * Mark real page as cleaning (indicating that we hold a
                 * paging reference to be released via m_o_d_r_c) and
                 * pageout (indicating that the page should be freed
                 * when the pageout completes).
                 */
                pmap_clear_modify(m->phys_addr);
                vm_page_lock_queues();
                vm_page_wire(new_m);
                m->cleaning = TRUE;
                m->pageout = TRUE;

                vm_page_wire(m);
                assert(m->wire_count == 1);
                vm_page_unlock_queues();

                m->dirty = TRUE;
                m->precious = FALSE;
                m->page_lock = VM_PROT_NONE;
                m->unusual = FALSE;
                m->unlock_request = VM_PROT_NONE;
        } else {
                /*
                 * Cannot clean in place, so rip the old page out of the
                 * object, and stick the holding page in. Set new_m to the
                 * page in the new object.
                 */
                vm_page_lock_queues();
                VM_PAGE_QUEUES_REMOVE(m);
                vm_page_remove(m);

                /*
                 * If the pageout daemon put this page in limbo, exchange the
                 * identities of the limbo page and the new fictitious page,
                 * and continue with the new page, unless the prep count has
                 * gone to zero in the meantime (which means no one is
                 * interested in the page any more).  In that case, just clear
                 * the limbo bit and free the extra fictitious page.
                 */
                if (m->limbo) {
                        if (m->prep_pin_count == 0) {
                                /* page doesn't have to be in limbo any more */
                                m->limbo = FALSE;
                                vm_page_free(new_page);
                                vm_pageout_setup_unprepped++;
                        } else {
                                vm_page_limbo_exchange(m, new_page);
                                vm_pageout_setup_limbo++;
                                vm_page_release_limbo(m);
                                m = new_page;
                        }
                }
                
                vm_page_insert(holding_page, old_object, offset);
                vm_page_unlock_queues();

                m->dirty = TRUE;
                m->precious = FALSE;
                new_m = m;
                new_m->page_lock = VM_PROT_NONE;
                new_m->unlock_request = VM_PROT_NONE;

                if (old_object->internal)
                        need_to_wire = TRUE;
        }
        /*
         *      Record that this page has been written out
         */
#if     MACH_PAGEMAP
        vm_external_state_set(old_object->existence_map, offset);
#endif  /* MACH_PAGEMAP */

        vm_object_unlock(old_object);

        vm_object_lock(new_object);

        /*
         *      Put the page into the new object. If it is a not wired
         *      (if it's the real page) it will be activated.
         */

        vm_page_lock_queues();
        vm_page_insert(new_m, new_object, new_offset);
        if (need_to_wire)
                vm_page_wire(new_m);
        else
                vm_page_activate(new_m);
        PAGE_WAKEUP_DONE(new_m);
        vm_page_unlock_queues();

        vm_object_unlock(new_object);

        /*
         *      Return the placeholder page to simplify cleanup.
         */
        return (holding_page);
}

/*
 * 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 the object and page
 *              queues 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)
{
        vm_object_t old_object = m->object;
        assert(!m->busy);
        assert(!m->cleaning);

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

        pmap_clear_modify(m->phys_addr);
        vm_object_paging_begin(old_object);

        /*
         *      Record that this page has been written out
         */
#if     MACH_PAGEMAP
        vm_external_state_set(old_object->existence_map, m->offset);
#endif  /*MACH_PAGEMAP*/

        /*
         * 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);
        new_m->fictitious = FALSE;
        new_m->private = TRUE;
        new_m->pageout = TRUE;
        new_m->phys_addr = m->phys_addr;
        vm_page_wire(new_m);

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

void
vm_pageclean_copy(
        vm_page_t               m,
        vm_page_t               new_m,
        vm_object_t             new_object,
        vm_object_offset_t      new_offset)
{
        XPR(XPR_VM_PAGEOUT,
        "vm_pageclean_copy, page 0x%X new_m 0x%X new_obj 0x%X offset 0x%X\n",
                m, new_m, new_object, new_offset, 0);

        assert((!m->busy) && (!m->cleaning));

        assert(!new_m->private && !new_m->fictitious);

        pmap_clear_modify(m->phys_addr);

        m->busy = TRUE;
        vm_object_paging_begin(m->object);
        vm_page_unlock_queues();
        vm_object_unlock(m->object);

        /*
         * Copy the original page to the new page.
         */
        vm_page_copy(m, new_m);

        /*
         * Mark the old page as clean. A request to pmap_is_modified
         * will get the right answer.
         */
        vm_object_lock(m->object);
        m->dirty = FALSE;

        vm_object_paging_end(m->object);

        vm_page_lock_queues();
        if (!m->active && !m->inactive)
                vm_page_activate(m);
        PAGE_WAKEUP_DONE(m);

        vm_page_insert(new_m, new_object, new_offset);
        vm_page_activate(new_m);
        new_m->busy = FALSE;    /* No other thread can be waiting */
}


/*
 *      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_map_copy_t           copy;
        vm_object_t             new_object;
        vm_object_t             object;
        vm_object_offset_t      paging_offset;
        vm_page_t               holding_page;


        XPR(XPR_VM_PAGEOUT,
                "vm_pageout_initialize_page, page 0x%X\n",
                (integer_t)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;
        vm_object_paging_begin(object);
        vm_object_unlock(object);
        if (m->absent || m->error || m->restart ||
            (!m->dirty && !m->precious)) {
                VM_PAGE_FREE(m);
                panic("reservation without pageout?"); /* alan */
                return;
        }

        /* set the page for future call to vm_fault_list_request */
        holding_page = NULL;
        vm_object_lock(m->object);
        vm_page_lock_queues();
        pmap_clear_modify(m->phys_addr);
        m->dirty = TRUE;
        m->busy = TRUE;
        m->list_req_pending = TRUE;
        m->cleaning = TRUE;
        m->pageout = TRUE;
        vm_page_wire(m);
        vm_page_unlock_queues();
        vm_object_unlock(m->object);
        vm_pageout_throttle(m);
        copy = NULL;

        VM_STAT(pageouts++);
        /* VM_STAT(pages_pagedout++); */

        /*
         *      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(object->pager,
                                        object->pager_request,
                                        paging_offset,
                                        POINTER_T(copy),
                                        PAGE_SIZE);

        vm_object_lock(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 */

boolean_t allow_clustered_pageouts = FALSE;

/*
 * vm_pageout_cluster:
 *
 * Given a page, page it out, and attempt to clean adjacent pages
 * in the same operation.
 *
 * The page must be busy, and the object unlocked w/ paging reference
 * to prevent deallocation or collapse. The page must not be on any
 * pageout queue.
 */
void
vm_pageout_cluster(
        vm_page_t m)
{
        vm_object_t     object = m->object;
        vm_object_offset_t offset = m->offset;  /* from vm_object start */
        vm_object_offset_t paging_offset = m->offset + object->paging_offset;
        vm_object_t     new_object;
        vm_object_offset_t new_offset;
        vm_size_t       cluster_size;
        vm_object_offset_t cluster_offset;      /* from memory_object start */
        vm_object_offset_t cluster_lower_bound; /* from vm_object_start */
        vm_object_offset_t cluster_upper_bound; /* from vm_object_start */
        vm_object_offset_t cluster_start, cluster_end;/* from vm_object start */
        vm_object_offset_t offset_within_cluster;
        vm_size_t       length_of_data;
        vm_page_t       friend, holding_page;
        vm_map_copy_t   copy;
        kern_return_t   rc;
        boolean_t       precious_clean = TRUE;
        int             pages_in_cluster;

        CLUSTER_STAT(int pages_at_higher_offsets = 0;)
        CLUSTER_STAT(int pages_at_lower_offsets = 0;)

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

        CLUSTER_STAT(vm_pageout_cluster_clusters++;)
        /*
         * Only a certain kind of page is appreciated here.
         */
        assert(m->busy && (m->dirty || m->precious) && (m->wire_count == 0));
        assert(!m->cleaning && !m->pageout && !m->inactive && !m->active);

        vm_object_lock(object);
        cluster_size = object->cluster_size;

        assert(cluster_size >= PAGE_SIZE);
        if (cluster_size < PAGE_SIZE) cluster_size = PAGE_SIZE;
        assert(object->pager_created && object->pager_initialized);
        assert(object->internal || object->pager_ready);

        if (m->precious && !m->dirty)
                precious_clean = TRUE;

        if (!object->pager_trusted || !allow_clustered_pageouts)
                cluster_size = PAGE_SIZE;
        vm_object_unlock(object);

        cluster_offset = paging_offset & (vm_object_offset_t)(cluster_size - 1);
                        /* bytes from beginning of cluster */
        /* 
         * Due to unaligned mappings, we have to be careful
         * of negative offsets into the VM object. Clip the cluster 
         * boundary to the VM object, not the memory object.
         */
        if (offset > cluster_offset) {
                cluster_lower_bound = offset - cluster_offset;
                                                /* from vm_object */
        } else {
                cluster_lower_bound = 0;
        }
        cluster_upper_bound = (offset - cluster_offset) + 
                                (vm_object_offset_t)cluster_size;

        /* set the page for future call to vm_fault_list_request */
        holding_page = NULL;
        vm_object_lock(m->object);
        vm_page_lock_queues();
        m->busy = TRUE;
        m->list_req_pending = TRUE;
        m->cleaning = TRUE;
        m->pageout = TRUE;
        vm_page_wire(m);
        vm_page_unlock_queues();
        vm_object_unlock(m->object);
        vm_pageout_throttle(m);

        /*
         * Search backward for adjacent eligible pages to clean in 
         * this operation.
         */

        cluster_start = offset;
        if (offset) {   /* avoid wrap-around at zero */
            for (cluster_start = offset - PAGE_SIZE_64;
                cluster_start >= cluster_lower_bound;
                cluster_start -= PAGE_SIZE_64) {
                assert(cluster_size > PAGE_SIZE);

                vm_object_lock(object);
                vm_page_lock_queues();

                if ((friend = vm_pageout_cluster_page(object, cluster_start,
                                precious_clean)) == VM_PAGE_NULL) {
                        vm_page_unlock_queues();
                        vm_object_unlock(object);
                        break;
                }
                new_offset = (cluster_start + object->paging_offset)
                                & (cluster_size - 1);

                assert(new_offset < cluster_offset);
                m->list_req_pending = TRUE;
                m->cleaning = TRUE;
/* do nothing except advance the write request, all we really need to */
/* do is push the target page and let the code at the other end decide */
/* what is really the right size */
                if (vm_page_free_count <= vm_page_free_reserved) {
                        m->busy = TRUE;
                        m->pageout = TRUE;
                        vm_page_wire(m);
                }

                vm_page_unlock_queues();
                vm_object_unlock(object);
                if(m->dirty || m->object->internal) {
                        CLUSTER_STAT(pages_at_lower_offsets++;)
                }

            }
            cluster_start += PAGE_SIZE_64;
        }
        assert(cluster_start >= cluster_lower_bound);
        assert(cluster_start <= offset);
        /*
         * Search forward for adjacent eligible pages to clean in 
         * this operation.
         */
        for (cluster_end = offset + PAGE_SIZE_64;
                cluster_end < cluster_upper_bound;
                cluster_end += PAGE_SIZE_64) {
                assert(cluster_size > PAGE_SIZE);

                vm_object_lock(object);
                vm_page_lock_queues();

                if ((friend = vm_pageout_cluster_page(object, cluster_end,
                                precious_clean)) == VM_PAGE_NULL) {
                        vm_page_unlock_queues();
                        vm_object_unlock(object);
                        break;
                }
                new_offset = (cluster_end + object->paging_offset)
                                & (cluster_size - 1);

                assert(new_offset < cluster_size);
                m->list_req_pending = TRUE;
                m->cleaning = TRUE;
/* do nothing except advance the write request, all we really need to */
/* do is push the target page and let the code at the other end decide */
/* what is really the right size */
                if (vm_page_free_count <= vm_page_free_reserved) {
                        m->busy = TRUE;
                        m->pageout = TRUE;
                        vm_page_wire(m);
                }

                vm_page_unlock_queues();
                vm_object_unlock(object);
                
                if(m->dirty || m->object->internal) {
                        CLUSTER_STAT(pages_at_higher_offsets++;)
                }
        }
        assert(cluster_end <= cluster_upper_bound);
        assert(cluster_end >= offset + PAGE_SIZE);

        /*
         * (offset - cluster_offset) is beginning of cluster_object
         * relative to vm_object start.
         */
        offset_within_cluster = cluster_start - (offset - cluster_offset);
        length_of_data = cluster_end - cluster_start;

        assert(offset_within_cluster < cluster_size);
        assert((offset_within_cluster + length_of_data) <= cluster_size);

        rc = KERN_SUCCESS;
        assert(rc == KERN_SUCCESS);

        pages_in_cluster = length_of_data/PAGE_SIZE;
        if(m->dirty || m->object->internal) {
                VM_STAT(pageouts++);
        }
        /* VM_STAT(pages_pagedout += pages_in_cluster); */

#if     MACH_CLUSTER_STATS
        (cluster_stats[pages_at_lower_offsets].pages_at_lower_offsets)++;
        (cluster_stats[pages_at_higher_offsets].pages_at_higher_offsets)++;
        (cluster_stats[pages_in_cluster].pages_in_cluster)++;
#endif  /* MACH_CLUSTER_STATS */

        /*
         * Send the data to the pager.
         */
        paging_offset = cluster_start + object->paging_offset;
#ifdef MACH_BSD
        if(((rpc_subsystem_t)pager_mux_hash_lookup(object->pager)) ==
        ((rpc_subsystem_t) &vnode_pager_workaround)) {
        rc = vnode_pager_data_return(object->pager,
                                       object->pager_request,
                                       paging_offset,
                                       POINTER_T(copy),
                                       length_of_data,
                                       !precious_clean,
                                       FALSE);
        } else {
                        rc = memory_object_data_return(object->pager,
                                       object->pager_request,
                                       paging_offset,
                                       POINTER_T(copy),
                                       length_of_data,
                                       !precious_clean,
                                       FALSE);
        }
#else
        rc = memory_object_data_return(object->pager,
                                       object->pager_request,
                                       paging_offset,
                                       POINTER_T(copy),
                                       length_of_data,
                                       !precious_clean,
                                       FALSE);
#endif
        vm_object_lock(object);
        vm_object_paging_end(object);

        if (holding_page) {
                assert(!object->pager_trusted);
                VM_PAGE_FREE(holding_page);
                vm_object_paging_end(object);
        }

        vm_object_unlock(object);
}

/*
 *      vm_pageout_return_write_pages
 *      Recover pages from an aborted write attempt
 *
 */

vm_pageout_return_write_pages(
        ipc_port_t              control_port,  
        vm_object_offset_t      object_offset, 
        vm_map_copy_t           copy)
{
        vm_object_t     object;
        int             offset;
        int             size;
        int             shadow_offset;
        int             copy_offset;
        int             j;
        vm_page_t       m;


        object = copy->cpy_object;
        copy_offset = copy->offset;
        size = copy->size;

        if((copy->type != VM_MAP_COPY_OBJECT) || (object->shadow == 0)) {
                object = (vm_object_t)control_port->ip_kobject;
                shadow_offset = (object_offset - object->paging_offset)
                                                                 - copy->offset;
        } else {
                /* get the offset from the copy object */
                shadow_offset = object->shadow_offset;
                /* find the backing object */
                object = object->shadow;
        }
        vm_object_lock(object);

        for(offset = 0, j=0; offset < size; offset+=page_size, j++) {
                m = vm_page_lookup(object, 
                                offset + shadow_offset + copy_offset);
                if((m == VM_PAGE_NULL) || m->fictitious) {

                        vm_page_t       p;
                        int             i;
                        vm_object_t     copy_object;

                        /* m might be fictitious if the original page */
                        /* was found to be in limbo at the time of    */
                        /* vm_pageout_setup                           */

                        if((m != VM_PAGE_NULL) && m->fictitious) {
                                m->cleaning = FALSE;
                                vm_page_remove(m);
                                /* if object is not pager trusted then       */
                                /* this fictitious page will be removed      */
                                /* as the holding page in vm_pageout_cluster */
                                if (object->pager_trusted)
                                        vm_page_free(m);
                                if(vm_page_laundry_count)
                                        vm_page_laundry_count--;
                                if (vm_page_laundry_count 
                                        < vm_page_laundry_min) {
                                        vm_page_laundry_min = 0;
                                        thread_wakeup((event_t) 
                                                &vm_page_laundry_count);
                                }
                        }
                        else if ((object->pager_trusted) &&
                                        (copy->type == VM_MAP_COPY_OBJECT)) {
                                vm_object_paging_end(object);
                        }

                        copy_object = copy->cpy_object;

                        if(copy->type == VM_MAP_COPY_OBJECT) {
                                p = (vm_page_t) queue_first(&copy_object->memq);

                                for(i = 0; 
                                        i < copy_object->resident_page_count; 
                                        i++) {
                                        if(p->offset == (offset + copy_offset))
                                                break;
                                        p = (vm_page_t) queue_next(&p->listq);
                                }

                                vm_page_remove(p);
                        } else {
                                p = copy->cpy_page_list[j];
                                copy->cpy_page_list[j] = 0;
                                p->gobbled = FALSE;
                        }

                        vm_page_insert(p, object, 
                                offset + shadow_offset + copy_offset);
                        p->busy = TRUE;
                        p->dirty = TRUE;
                        p->laundry = FALSE;
                        if (p->pageout) {
                                p->pageout = FALSE;  /*dont throw away target*/
                                vm_page_unwire(p);/* reactivates */
                        }
                } else if(m->pageout) {
                        m->pageout = FALSE;  /* dont throw away target pages */
                        vm_page_unwire(m);/* reactivates */
                }
        }

        vm_object_unlock(object);
        vm_map_copy_discard(copy);
        vm_object_lock(object);

        for(offset = 0; offset < size; offset+=page_size) { 
                m = vm_page_lookup(object,
                                offset + shadow_offset + copy_offset);
                m->dirty = TRUE;  /* we'll send the pages home later */
                m->busy = FALSE;  /* allow system access again */
        }

        vm_object_unlock(object);
}

/*
 *      Trusted pager throttle.
 *      Object must be unlocked, page queues must be unlocked.
 */
void
vm_pageout_throttle(
        register vm_page_t m)
{
        vm_page_lock_queues();
        assert(!m->laundry);
        m->laundry = TRUE;
        while (vm_page_laundry_count >= vm_page_laundry_max) {
                /*
                 * Set the threshold for when vm_page_free()
                 * should wake us up.
                 */
                vm_page_laundry_min = vm_page_laundry_max/2;
                assert_wait((event_t) &vm_page_laundry_count, THREAD_UNINT);
                vm_page_unlock_queues();

                /*
                 * Pause to let the default pager catch up.
                 */
                thread_block((void (*)(void)) 0);
                vm_page_lock_queues();
        }
        vm_page_laundry_count++;
        vm_page_unlock_queues();
}

/*
 * The global variable vm_pageout_clean_active_pages controls whether
 * active pages are considered valid to be cleaned in place during a
 * clustered pageout. Performance measurements are necessary to determine
 * the best policy.
 */
int vm_pageout_clean_active_pages = 1;
/*
 * vm_pageout_cluster_page: [Internal]
 *
 * return a vm_page_t to the page at (object,offset) if it is appropriate
 * to clean in place. Pages that are non-existent, busy, absent, already
 * cleaning, or not dirty are not eligible to be cleaned as an adjacent
 * page in a cluster.
 *
 * The object must be locked on entry, and remains locked throughout
 * this call.
 */

vm_page_t
vm_pageout_cluster_page(
        vm_object_t             object,
        vm_object_offset_t      offset,
        boolean_t               precious_clean)
{
        vm_page_t m;

        XPR(XPR_VM_PAGEOUT,
                "vm_pageout_cluster_page, object 0x%X offset 0x%X\n",
                (integer_t)object, offset, 0, 0, 0);

        if ((m = vm_page_lookup(object, offset)) == VM_PAGE_NULL)
                return(VM_PAGE_NULL);

        if (m->busy || m->absent || m->cleaning || 
            m->prep_pin_count != 0 ||
            (m->wire_count != 0) || m->error)
                return(VM_PAGE_NULL);

        if (vm_pageout_clean_active_pages) {
                if (!m->active && !m->inactive) return(VM_PAGE_NULL);
        } else {
                if (!m->inactive) return(VM_PAGE_NULL);
        }

        assert(!m->private);
        assert(!m->fictitious);

        if (!m->dirty) m->dirty = pmap_is_modified(m->phys_addr);

        if (precious_clean) {
                if (!m->precious || !m->dirty)
                        return(VM_PAGE_NULL);
        } else {
                if (!m->dirty)
                        return(VM_PAGE_NULL);
        }
        return(m);
}

/*
 *      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.
 */
extern void vm_pageout_scan_continue(void);     /* forward; */

void
vm_pageout_scan(void)
{
        unsigned int burst_count;
        boolean_t now = FALSE;
        unsigned int laundry_pages;
        boolean_t need_more_inactive_pages;
        unsigned int    loop_detect;

        XPR(XPR_VM_PAGEOUT, "vm_pageout_scan\n", 0, 0, 0, 0, 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.
         *      data_write messages consume memory, for message buffers and
         *      for map-copy objects.  If we get too far ahead of the pagers,
         *      we can potentially run out of memory.
         *
         *      We can use the laundry count to limit directly the number
         *      of pages outstanding to the default pager.  A similar
         *      strategy for external pagers doesn't work, because
         *      external pagers don't have to deallocate the pages sent them,
         *      and because we might have to send pages to external pagers
         *      even if they aren't processing writes.  So we also
         *      use a burst count to limit writes to external pagers.
         *
         *      When memory is very tight, we can't rely on external pagers to
         *      clean pages.  They probably aren't running, because they
         *      aren't vm-privileged.  If we kept sending dirty pages to them,
         *      we could exhaust the free list.  However, we can't just ignore
         *      pages belonging to external objects, because there might be no
         *      pages belonging to internal objects.  Hence, we get the page
         *      into an internal object and then immediately double-page it,
         *      sending it to the default pager.
         *
         *      consider_zone_gc should be last, because the other operations
         *      might return memory to zones.
         */

    Restart:

        mutex_lock(&vm_page_queue_free_lock);
        now = (vm_page_free_count < vm_page_free_min);
        mutex_unlock(&vm_page_queue_free_lock);
#if     THREAD_SWAPPER
        swapout_threads(now);
#endif  /* THREAD_SWAPPER */

        stack_collect();
        consider_task_collect();
        consider_thread_collect();
        cleanup_limbo_queue();
        consider_zone_gc();
        consider_machine_collect();

        loop_detect = vm_page_active_count + vm_page_inactive_count;
#if 0
        if (vm_page_free_count <= vm_page_free_reserved) {
                need_more_inactive_pages = TRUE;
        } else {
                need_more_inactive_pages = FALSE;
        }
#else
        need_more_inactive_pages = FALSE;
#endif

        for (burst_count = 0;;) {
                register vm_page_t m;
                register vm_object_t object;
                unsigned int free_count;

                /*
                 *      Recalculate vm_page_inactivate_target.
                 */

                vm_page_lock_queues();
                vm_page_inactive_target =
                        VM_PAGE_INACTIVE_TARGET(vm_page_active_count +
                                                vm_page_inactive_count);

                /*
                 *      Move pages from active to inactive.
                 */

                while ((vm_page_inactive_count < vm_page_inactive_target ||
                        need_more_inactive_pages) &&
                       !queue_empty(&vm_page_queue_active)) {
                        register vm_object_t object;

                        vm_pageout_active++;
                        m = (vm_page_t) queue_first(&vm_page_queue_active);

                        /*
                         * If we're getting really low on memory,
                         * try selecting a page that will go 
                         * directly to the default_pager.
                         * If there are no such pages, we have to
                         * page out a page backed by an EMM,
                         * so that the default_pager can recover
                         * it eventually.
                         */
                        if (need_more_inactive_pages && 
                                (IP_VALID(memory_manager_default))) {
                                vm_pageout_scan_active_emm_throttle++;
                                do {
                                        assert(m->active && !m->inactive);
                                        object = m->object;

                                        if (vm_object_lock_try(object)) {
#if 0
                                                if (object->pager_trusted ||
                                                    object->internal) {
                                                        /* found one ! */
                                                        vm_pageout_scan_active_emm_throttle_success++;
                                                        goto object_locked_active;
                                                }
#else
                                        vm_pageout_scan_active_emm_throttle_success++;
                                                        goto object_locked_active;
#endif
                                                vm_object_unlock(object);
                                        }
                                        m = (vm_page_t) queue_next(&m->pageq);
                                } while (!queue_end(&vm_page_queue_active,
                                                    (queue_entry_t) m));
                                if (queue_end(&vm_page_queue_active,
                                              (queue_entry_t) m)) {
                                        vm_pageout_scan_active_emm_throttle_failure++;
                                        m = (vm_page_t)
                                                queue_first(&vm_page_queue_active);
                                }
                        }

                        assert(m->active && !m->inactive);

                        object = m->object;
                        if (!vm_object_lock_try(object)) {
                                /*
                                 *      Move page to end and continue.
                                 */

                                queue_remove(&vm_page_queue_active, m,
                                             vm_page_t, pageq);
                                queue_enter(&vm_page_queue_active, m,
                                            vm_page_t, pageq);
                                vm_page_unlock_queues();
                                mutex_pause();
                                vm_page_lock_queues();
                                continue;
                        }

                    object_locked_active:
                        /*
                         *      If the page is busy, then we pull it
                         *      off the active queue and leave it alone.
                         */

                        if (m->busy) {
                                vm_object_unlock(object);
                                queue_remove(&vm_page_queue_active, m,
                                             vm_page_t, pageq);
                                m->active = FALSE;
                                if (!m->fictitious)
                                        vm_page_active_count--;
                                continue;
                        }

                        /*
                         *      Deactivate the page while holding the object
                         *      locked, so we know the page is still not busy.
                         *      This should prevent races between pmap_enter
                         *      and pmap_clear_reference.  The page might be
                         *      absent or fictitious, but vm_page_deactivate
                         *      can handle that.
                         */

                        vm_page_deactivate(m);
                        vm_object_unlock(object);
                }

                /*
                 *      We are done if we have met our target *and*
                 *      nobody is still waiting for a page.
                 */

                mutex_lock(&vm_page_queue_free_lock);
                free_count = vm_page_free_count;
                if ((free_count >= vm_page_free_target) &&
                    (vm_page_free_wanted == 0)) {
                        vm_page_unlock_queues();
                        break;
                }
                mutex_unlock(&vm_page_queue_free_lock);

                /*
                 * Sometimes we have to pause:
                 *      1) No inactive pages - nothing to do.
                 *      2) Flow control - wait for untrusted pagers to catch up.
                 */

                if (queue_empty(&vm_page_queue_inactive) ||
                    ((--loop_detect) == 0)      ||
                    (burst_count >= vm_pageout_burst_max)) {
                        unsigned int pages, msecs;
                        int wait_result;

                        consider_machine_adjust();
                        /*
                         *      vm_pageout_burst_wait is msecs/page.
                         *      If there is nothing for us to do, we wait
                         *      at least vm_pageout_empty_wait msecs.
                         */
                        pages = burst_count;
        
                        if (loop_detect == 0) {
                                printf("Warning: No physical memory suitable for pageout or reclaim, pageout thread temporarily going to sleep\n");
                                msecs = vm_free_page_pause;
                        }
                        else {
                                msecs = burst_count * vm_pageout_burst_wait;
                        }

                        if (queue_empty(&vm_page_queue_inactive) &&
                            (msecs < vm_pageout_empty_wait))
                                msecs = vm_pageout_empty_wait;
                        vm_page_unlock_queues();
                        assert_wait_timeout(msecs, THREAD_INTERRUPTIBLE);
                        counter(c_vm_pageout_scan_block++);

                        /*
                         *      Unfortunately, we don't have call_continuation
                         *      so we can't rely on tail-recursion.
                         */
                        wait_result = thread_block((void (*)(void)) 0);
                        if (wait_result != THREAD_TIMED_OUT)
                                thread_cancel_timer();
                        vm_pageout_scan_continue();
                        goto Restart;
                        /*NOTREACHED*/
                }

                vm_pageout_inactive++;
                m = (vm_page_t) queue_first(&vm_page_queue_inactive);

                if ((vm_page_free_count <= vm_page_free_reserved) && 
                                (IP_VALID(memory_manager_default))) {
                        /*
                         * We're really low on memory. Try to select a page that
                         * would go directly to the default_pager.
                         * If there are no such pages, we have to page out a 
                         * page backed by an EMM, so that the default_pager
                         * can recover it eventually.
                         */
                        vm_pageout_scan_inactive_emm_throttle++;
                        do {
                                assert(!m->active && m->inactive);
                                object = m->object;

                                if (vm_object_lock_try(object)) {
#if 0
                                        if (object->pager_trusted ||
                                            object->internal) {
                                                /* found one ! */
                                                vm_pageout_scan_inactive_emm_throttle_success++;
                                                goto object_locked_inactive;
                                        }
#else
                                vm_pageout_scan_inactive_emm_throttle_success++;
                                                goto object_locked_inactive;
#endif /* 0 */
                                        vm_object_unlock(object);
                                }
                                m = (vm_page_t) queue_next(&m->pageq);
                        } while (!queue_end(&vm_page_queue_inactive,
                                            (queue_entry_t) m));
                        if (queue_end(&vm_page_queue_inactive,
                                      (queue_entry_t) m)) {
                                vm_pageout_scan_inactive_emm_throttle_failure++;
                                /*
                                 * We should check the "active" queue
                                 * for good candidates to page out.
                                 */
                                need_more_inactive_pages = TRUE;

                                m = (vm_page_t)
                                        queue_first(&vm_page_queue_inactive);
                        }
                }

                assert(!m->active && m->inactive);
                object = m->object;

                /*
                 *      Try to lock object; since we've got the
                 *      page queues lock, we can only try for this one.
                 */

                if (!vm_object_lock_try(object)) {
                        /*
                         *      Move page to end and continue.
                         */
                        queue_remove(&vm_page_queue_inactive, m,
                                     vm_page_t, pageq);
                        queue_enter(&vm_page_queue_inactive, m,
                                    vm_page_t, pageq);
                        vm_page_unlock_queues();
                        mutex_pause();
                        vm_pageout_inactive_nolock++;
                        continue;
                }

            object_locked_inactive:
                /*
                 *      Paging out pages of objects which pager is being
                 *      created by another thread must be avoided, because
                 *      this thread may claim for memory, thus leading to a
                 *      possible dead lock between it and the pageout thread
                 *      which will wait for pager creation, if such pages are
                 *      finally chosen. The remaining assumption is that there
                 *      will finally be enough available pages in the inactive
                 *      pool to page out in order to satisfy all memory claimed
                 *      by the thread which concurrently creates the pager.
                 */

                if (!object->pager_initialized && object->pager_created) {
                        /*
                         *      Move page to end and continue, hoping that
                         *      there will be enough other inactive pages to
                         *      page out so that the thread which currently
                         *      initializes the pager will succeed.
                         */
                        queue_remove(&vm_page_queue_inactive, m,
                                     vm_page_t, pageq);
                        queue_enter(&vm_page_queue_inactive, m,
                                    vm_page_t, pageq);
                        vm_page_unlock_queues();
                        vm_object_unlock(object);
                        vm_pageout_inactive_avoid++;
                        continue;
                }

                /*
                 *      Remove the page from the inactive list.
                 */

                queue_remove(&vm_page_queue_inactive, m, vm_page_t, pageq);
                m->inactive = FALSE;
                if (!m->fictitious)
                        vm_page_inactive_count--;

                if (m->busy || !object->alive) {
                        /*
                         *      Somebody is already playing with this page.
                         *      Leave it off the pageout queues.
                         */

                        vm_page_unlock_queues();
                        vm_object_unlock(object);
                        vm_pageout_inactive_busy++;
                        continue;
                }

                /*
                 *      If it's absent or in error, we can reclaim the page.
                 */

                if (m->absent || m->error) {
                        vm_pageout_inactive_absent++;
                    reclaim_page:
                        vm_page_free(m);
                        vm_page_unlock_queues();
                        vm_object_unlock(object);
                        continue;
                }

                assert(!m->private);
                assert(!m->fictitious);

                /*
                 *      If already cleaning this page in place, convert from
                 *      "adjacent" to "target". We can leave the page mapped,
                 *      and vm_pageout_object_terminate will determine whether
                 *      to free or reactivate.
                 */

                if (m->cleaning) {
#if     MACH_CLUSTER_STATS
                        vm_pageout_cluster_conversions++;
#endif
                        if (m->prep_pin_count == 0) {
                                m->busy = TRUE;
                                m->pageout = TRUE;
                                vm_page_wire(m);
                        }
                        vm_object_unlock(object);
                        vm_page_unlock_queues();
                        continue;
                }

                /*
                 *      If it's being used, reactivate.
                 *      (Fictitious pages are either busy or absent.)
                 */

                if (m->reference || pmap_is_referenced(m->phys_addr)) {
                        vm_pageout_inactive_used++;
                    reactivate_page:
#if     ADVISORY_PAGEOUT
                        if (m->discard_request) {
                                m->discard_request = FALSE;
                        }
#endif  /* ADVISORY_PAGEOUT */
                        vm_object_unlock(object);
                        vm_page_activate(m);
                        VM_STAT(reactivations++);
                        vm_page_unlock_queues();
                        continue;
                }

                if (m->prep_pin_count != 0) {
                        boolean_t pinned = FALSE;

                        vm_page_pin_lock();
                        if (m->pin_count != 0) {
                                /* skip and reactivate pinned page */
                                pinned = TRUE;
                                vm_pageout_inactive_pinned++;
                        } else {
                                /* page is prepped; send it into limbo */
                                m->limbo = TRUE;
                                vm_pageout_inactive_limbo++;
                        }
                        vm_page_pin_unlock();
                        if (pinned)
                                goto reactivate_page;
                }

#if     ADVISORY_PAGEOUT
                if (object->advisory_pageout) {
                        boolean_t               do_throttle;
                        ipc_port_t              port;
                        vm_object_offset_t      discard_offset;

                        if (m->discard_request) {
                                vm_stat_discard_failure++;
                                goto mandatory_pageout;
                        }

                        assert(object->pager_initialized);
                        m->discard_request = TRUE;
                        port = object->pager;

                        /* system-wide throttle */
                        do_throttle = (vm_page_free_count <=
                                       vm_page_free_reserved);
                        if (!do_throttle) {
                                /* throttle on this pager */
                                /* XXX lock ordering ? */
                                ip_lock(port);
                                do_throttle= imq_full(&port->ip_messages);
                                ip_unlock(port);
                        }
                        if (do_throttle) {
                                vm_stat_discard_throttle++;
#if 0
                                /* ignore this page and skip to next */
                                vm_page_unlock_queues();
                                vm_object_unlock(object);
                                continue;
#else
                                /* force mandatory pageout */
                                goto mandatory_pageout;
#endif
                        }

                        /* proceed with discard_request */
                        vm_page_activate(m);
                        vm_stat_discard++;
                        VM_STAT(reactivations++);
                        discard_offset = m->offset + object->paging_offset;
                        vm_stat_discard_sent++;
                        vm_page_unlock_queues();
                        vm_object_unlock(object);
/*
                        memory_object_discard_request(object->pager,
                                                      object->pager_request,
                                                      discard_offset,
                                                      PAGE_SIZE);
*/
                        continue;
                }
        mandatory_pageout:
#endif  /* ADVISORY_PAGEOUT */
                        
                XPR(XPR_VM_PAGEOUT,
                "vm_pageout_scan, replace object 0x%X offset 0x%X page 0x%X\n",
                (integer_t)object, (integer_t)m->offset, (integer_t)m, 0,0);

                /*
                 *      Eliminate all mappings.
                 */

                m->busy = TRUE;
                pmap_page_protect(m->phys_addr, VM_PROT_NONE);
                if (!m->dirty)
                        m->dirty = pmap_is_modified(m->phys_addr);

                /*
                 *      If it's clean and not precious, we can free the page.
                 */

                if (!m->dirty && !m->precious) {
                        vm_pageout_inactive_clean++;
                        goto reclaim_page;
                }
                vm_page_unlock_queues();

                /*
                 *      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);
                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_lock_queues();
                        vm_page_activate(m);
                        vm_page_unlock_queues();

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

                        /*
                         * break here to get back to the preemption
                         * point in the outer loop so that we don't
                         * spin forever if there is no default pager.
                         */
                        vm_pageout_dirty_no_pager++;
                        /*
                         * Well there's no pager, but we can still reclaim
                         * free pages out of the inactive list.  Go back
                         * to top of loop and look for suitable pages.
                         */
                        continue;
                }

                if (object->pager_initialized && object->pager == IP_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.
                         * Just free the page.
                         */
                        VM_PAGE_FREE(m);
                        vm_object_unlock(object);
                        continue;
                }

                vm_pageout_inactive_dirty++;
/*
                if (!object->internal)
                        burst_count++;
*/
                vm_object_paging_begin(object);
                vm_object_unlock(object);
                vm_pageout_cluster(m);  /* flush it */
        }
        consider_machine_adjust();
}

counter(unsigned int    c_vm_pageout_scan_continue = 0;)

void
vm_pageout_scan_continue(void)
{
        /*
         *      We just paused to let the pagers catch up.
         *      If vm_page_laundry_count is still high,
         *      then we aren't waiting long enough.
         *      If we have paused some vm_pageout_pause_max times without
         *      adjusting vm_pageout_burst_wait, it might be too big,
         *      so we decrease it.
         */

        vm_page_lock_queues();
        counter(++c_vm_pageout_scan_continue);
        if (vm_page_laundry_count > vm_pageout_burst_min) {
                vm_pageout_burst_wait++;
                vm_pageout_pause_count = 0;
        } else if (++vm_pageout_pause_count > vm_pageout_pause_max) {
                vm_pageout_burst_wait = (vm_pageout_burst_wait * 3) / 4;
                if (vm_pageout_burst_wait < 1)
                        vm_pageout_burst_wait = 1;
                vm_pageout_pause_count = 0;
        }
        vm_page_unlock_queues();
}

void vm_page_free_reserve(int pages);
int vm_page_free_count_init;

void
vm_page_free_reserve(
        int pages)
{
        int             free_after_reserve;

        vm_page_free_reserved += pages;

        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);

        vm_page_free_target = vm_page_free_reserved +
                VM_PAGE_FREE_TARGET(free_after_reserve);

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

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


void
vm_pageout(void)
{
        thread_t        self = current_thread();

        /*
         * Set thread privileges.
         */
        self->vm_privilege = TRUE;
        stack_privilege(self);
        thread_swappable(current_act(), FALSE);

        /*
         *      Initialize some paging parameters.
         */

        if (vm_page_laundry_max == 0)
                vm_page_laundry_max = VM_PAGE_LAUNDRY_MAX;

        if (vm_pageout_burst_max == 0)
                vm_pageout_burst_max = VM_PAGEOUT_BURST_MAX;

        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;

        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)
                vm_page_free_reserve(VM_PAGE_FREE_RESERVED - vm_page_free_reserved);
        else
                vm_page_free_reserve(0);

        /*
         *      vm_pageout_scan will set vm_page_inactive_target.
         *
         *      The pageout daemon is never done, so loop forever.
         *      We should call vm_pageout_scan at least once each
         *      time we are woken, even if vm_page_free_wanted is
         *      zero, to check vm_page_free_target and
         *      vm_page_inactive_target.
         */
        for (;;) {
                vm_pageout_scan();
                /* we hold vm_page_queue_free_lock now */
                assert(vm_page_free_wanted == 0);
                assert_wait((event_t) &vm_page_free_wanted, THREAD_UNINT);
                mutex_unlock(&vm_page_queue_free_lock);
                counter(c_vm_pageout_block++);
                thread_block((void (*)(void)) 0);
        }
        /*NOTREACHED*/
}


void
upl_dealloc(
        upl_t   upl)
{
        upl->ref_count -= 1;
        if(upl->ref_count == 0) {
                upl_destroy(upl);
        }
}


/*  
 *      Routine:        vm_fault_list_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.
 *
 */
kern_return_t
vm_fault_list_request(
        vm_object_t             object,
        vm_object_offset_t      offset,
        vm_size_t               size,
        upl_t                   *upl_ptr,
        upl_page_info_t         **user_page_list_ptr,
        int                     page_list_count,
        int                     cntrl_flags)
{
        vm_page_t               dst_page;
        vm_object_offset_t      dst_offset = offset;
        upl_page_info_t         *user_page_list;
        vm_size_t               xfer_size = size;
        boolean_t               do_m_lock = FALSE;
        boolean_t               dirty;
        upl_t                   upl = NULL;
        int                     entry;
        boolean_t               encountered_lrp = FALSE;

        vm_page_t               alias_page = NULL;

        if(cntrl_flags & UPL_SET_INTERNAL)
                page_list_count = MAX_UPL_TRANSFER;
        if(((user_page_list_ptr || (cntrl_flags & UPL_SET_INTERNAL)) && 
                !(object->private)) && (page_list_count < (size/page_size)))
                return KERN_INVALID_ARGUMENT;

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

        if((cntrl_flags & UPL_COPYOUT_FROM) && (upl_ptr == NULL)) {
                return KERN_SUCCESS;
        }
        if(upl_ptr) {
                if((cntrl_flags & UPL_SET_INTERNAL) && !(object->private)) {
                        upl = upl_create(TRUE);
                        user_page_list = (upl_page_info_t *)
                                (((vm_offset_t)upl) + sizeof(struct upl));
                        if(user_page_list_ptr)
                                *user_page_list_ptr = user_page_list;
                        upl->flags |= UPL_INTERNAL;
                } else {
                        upl = upl_create(FALSE);
                        if(user_page_list_ptr)
                                user_page_list = *user_page_list_ptr;
                        else
                                user_page_list = NULL;
                        if(object->private) {
                                upl->size = size;
                                upl->offset = offset;
                                *upl_ptr = upl;
                                if(user_page_list) {
                                        user_page_list[0].phys_addr = offset;
                                        user_page_list[0].device = TRUE;
                                }
                                upl->flags = UPL_DEVICE_MEMORY;
                                return KERN_SUCCESS;
                        }
                
                        
                }
                upl->map_object = vm_object_allocate(size);
                vm_object_lock(upl->map_object);
                upl->map_object->shadow = object;
                upl->size = size;
                upl->offset = offset + object->paging_offset;
                upl->map_object->pageout = TRUE;
                upl->map_object->can_persist = FALSE;
                upl->map_object->copy_strategy = MEMORY_OBJECT_COPY_NONE;
                upl->map_object->shadow_offset = offset;
                vm_object_unlock(upl->map_object);
                *upl_ptr = upl;
        }
        VM_PAGE_GRAB_FICTITIOUS(alias_page);
        vm_object_lock(object);
#ifdef UBC_DEBUG
        if(upl_ptr)
                queue_enter(&object->uplq, upl, upl_t, uplq);
#endif /* UBC_DEBUG */
        vm_object_paging_begin(object);
        entry = 0;
        if(cntrl_flags & UPL_COPYOUT_FROM) {
                upl->flags |= UPL_PAGE_SYNC_DONE;
                while (xfer_size) {
                        if(alias_page == NULL) {
                                vm_object_unlock(object);
                                VM_PAGE_GRAB_FICTITIOUS(alias_page);
                                vm_object_lock(object);
                        }
                        if(((dst_page = vm_page_lookup(object, 
                                dst_offset)) == VM_PAGE_NULL) ||
                                dst_page->fictitious ||
                                dst_page->absent ||
                                dst_page->error ||
                                (dst_page->wire_count != 0 && 
                                                        !dst_page->pageout) ||
                                ((!(dst_page->dirty || dst_page->precious ||
                                      pmap_is_modified(dst_page->phys_addr)))
                                      && (cntrl_flags & UPL_RET_ONLY_DIRTY))) {
                                if(user_page_list)
                                        user_page_list[entry].phys_addr = 0;
                        } else {
                                
                                if(dst_page->busy && 
                                        (!(dst_page->list_req_pending && 
                                                dst_page->pageout))) {
                                        if(cntrl_flags & UPL_NOBLOCK) {
                                                if(user_page_list)
                                                        user_page_list[entry]
                                                                .phys_addr = 0;
                                                entry++;
                                                dst_offset += PAGE_SIZE_64;
                                                xfer_size -= PAGE_SIZE;
                                                continue;
                                        }
                                        /*someone else is playing with the */
                                        /* page.  We will have to wait.    */
                                        PAGE_ASSERT_WAIT(
                                                dst_page, THREAD_UNINT);
                                        vm_object_unlock(object);
                                        thread_block((void(*)(void))0);
                                        vm_object_lock(object);
                                        continue;
                                }
                                /* Someone else already cleaning the page? */
                                if((dst_page->cleaning || dst_page->absent ||
                                        dst_page->prep_pin_count != 0 ||
                                        dst_page->wire_count != 0) && 
                                        !dst_page->list_req_pending) {
                                   if(user_page_list)
                                           user_page_list[entry].phys_addr = 0;
                                   entry++;
                                   dst_offset += PAGE_SIZE_64;
                                   xfer_size -= PAGE_SIZE;
                                   continue;
                                }
                                /* eliminate all mappings from the */
                                /* original object and its prodigy */
                                
                                vm_page_lock_queues();
                                pmap_page_protect(dst_page->phys_addr, 
                                                                VM_PROT_NONE);

                                /* 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 
                                        == FALSE)) {
                                        if(encountered_lrp) {
                                                CLUSTER_STAT
                                                (pages_at_higher_offsets++;)
                                        } else {
                                                CLUSTER_STAT
                                                (pages_at_lower_offsets++;)
                                        }
                                }

                                /* 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;
                                dst_page->cleaning = FALSE;

                                dirty = pmap_is_modified(dst_page->phys_addr);
                                dirty = dirty ? TRUE : dst_page->dirty;

                                /* use pageclean setup, it is more convenient */
                                /* even for the pageout cases here */
                                vm_pageclean_setup(dst_page, alias_page,
                                        upl->map_object, size - xfer_size);
                                                
                                if(!dirty) {
                                        dst_page->dirty = FALSE;
                                        dst_page->precious = TRUE;
                                }

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

                                alias_page->absent = FALSE;
                                alias_page = NULL;
                                if(!(cntrl_flags & UPL_CLEAN_IN_PLACE)) {
                                        /* deny access to the target page */
                                        /* while it is being worked on    */
                                        if((!dst_page->pageout) &&
                                                (dst_page->wire_count == 0)) {
                                                dst_page->busy = TRUE;
                                                dst_page->pageout = TRUE;
                                                vm_page_wire(dst_page);
                                        }
                                }
                                if(user_page_list) {
                                        user_page_list[entry].phys_addr
                                                = dst_page->phys_addr;
                                        user_page_list[entry].dirty =   
                                                        dst_page->dirty;
                                        user_page_list[entry].pageout =
                                                        dst_page->pageout;
                                        user_page_list[entry].absent =
                                                        dst_page->absent;
                                        user_page_list[entry].precious =
                                                        dst_page->precious;
                                }

                                vm_page_unlock_queues();
                        }
                        entry++;
                        dst_offset += PAGE_SIZE_64;
                        xfer_size -= PAGE_SIZE;
                }
        } else {
                while (xfer_size) {
                        if(alias_page == NULL) {
                                vm_object_unlock(object);
                                VM_PAGE_GRAB_FICTITIOUS(alias_page);
                                vm_object_lock(object);
                        }
                        dst_page = vm_page_lookup(object, dst_offset);
                        if(dst_page != VM_PAGE_NULL) {
                           if((dst_page->cleaning) && 
                                        !(dst_page->list_req_pending)) {
                                   /*someone else is writing to the */
                                   /* page.  We will have to wait.  */
                                   PAGE_ASSERT_WAIT(dst_page, THREAD_UNINT);
                                   vm_object_unlock(object);
                                   thread_block((void(*)(void))0);
                                   vm_object_lock(object);
                                   continue;
                           }
                           if ((dst_page->fictitious && 
                                        dst_page->list_req_pending)) {
                                /* dump the fictitious page */
                                dst_page->list_req_pending = FALSE;
                                dst_page->clustered = FALSE;
                                vm_page_lock_queues();
                                vm_page_free(dst_page);
                                vm_page_unlock_queues();
                           } else if ((dst_page->absent && 
                                        dst_page->list_req_pending)) {
                                /* the default_pager case */
                                dst_page->list_req_pending = FALSE;
                                dst_page->busy = FALSE;
                                dst_page->clustered = FALSE;
                           }
                        }
                        if((dst_page = vm_page_lookup(
                                object, dst_offset)) == VM_PAGE_NULL) {
                                /* need to allocate a page */
                                dst_page = vm_page_alloc(object, dst_offset);
                                if (dst_page == VM_PAGE_NULL) {
                                   vm_object_unlock(object);
                                   VM_PAGE_WAIT();
                                   vm_object_lock(object);
                                   continue;
                                }
                                dst_page->busy = FALSE;
#if 0
                                if(cntrl_flags & UPL_NO_SYNC) {
                                        dst_page->page_lock = 0;
                                        dst_page->unlock_request = 0;
                                }
#endif
                                dst_page->absent = TRUE;
                                object->absent_count++;
                        }
#if 1
                        if(cntrl_flags & UPL_NO_SYNC) {
                                dst_page->page_lock = 0;
                                dst_page->unlock_request = 0;
                        }
#endif /* 1 */
                        dst_page->overwriting = TRUE;
                        if(dst_page->fictitious) {
                                panic("need corner case for fictitious page");
                        }
                        if(dst_page->page_lock) {
                                do_m_lock = TRUE;
                        }
                        if(upl_ptr) {

                                /* eliminate all mappings from the */
                                /* original object and its prodigy */
                                
                                if(dst_page->busy) {
                                        /*someone else is playing with the */
                                        /* page.  We will have to wait.    */
                                        PAGE_ASSERT_WAIT(
                                                dst_page, THREAD_UNINT);
                                        vm_object_unlock(object);
                                        thread_block((void(*)(void))0);
                                        vm_object_lock(object);
                                        continue;
                                }
                                
                                vm_page_lock_queues();
                                pmap_page_protect(dst_page->phys_addr, 
                                                                VM_PROT_NONE);
                                dirty = pmap_is_modified(dst_page->phys_addr);
                                dirty = dirty ? TRUE : dst_page->dirty;

                                vm_pageclean_setup(dst_page, alias_page,
                                        upl->map_object, size - xfer_size);

                                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;
                                }

                                if(!dirty) {
                                        dst_page->dirty = FALSE;
                                        dst_page->precious = TRUE;
                                }
                                                
                                if (dst_page->wire_count == 0) {
                                   /* deny access to the target page while */
                                   /* it is being worked on */
                                        dst_page->busy = TRUE;
                                } else {
                                        vm_page_wire(dst_page);
                                }
                                /* expect the page to be used */
                                dst_page->reference = TRUE;
                                dst_page->precious = 
                                        (cntrl_flags & UPL_PRECIOUS) 
                                                        ? TRUE : FALSE;
                                alias_page->absent = FALSE;
                                alias_page = NULL;
                                if(user_page_list) {
                                        user_page_list[entry].phys_addr
                                                = dst_page->phys_addr;
                                        user_page_list[entry].dirty =
                                                        dst_page->dirty;
                                        user_page_list[entry].pageout =
                                                        dst_page->pageout;
                                        user_page_list[entry].absent =
                                                        dst_page->absent;
                                        user_page_list[entry].precious =
                                                        dst_page->precious;
                                }
                                vm_page_unlock_queues();
                        }
                        entry++;
                        dst_offset += PAGE_SIZE_64;
                        xfer_size -= PAGE_SIZE;
                }
        }
        if(alias_page != NULL) {
                vm_page_lock_queues();
                vm_page_free(alias_page);
                vm_page_unlock_queues();
        }
        if(do_m_lock) {
           vm_prot_t    access_required;
           /* call back all associated pages from other users of the pager */
           /* all future updates will be on data which is based on the     */
           /* changes we are going to make here. Note: it is assumed that  */
           /* we already hold copies of the data so we will not be seeing  */
           /* an avalanche of incoming data from the pager */
           access_required = (cntrl_flags & UPL_COPYOUT_FROM) 
                                        ? VM_PROT_READ : VM_PROT_WRITE;
           while (TRUE) {
                kern_return_t   rc;
                thread_t        thread;

                if(!object->pager_ready) {
                   thread = current_thread();
                   vm_object_assert_wait(object, 
                                VM_OBJECT_EVENT_PAGER_READY, THREAD_UNINT);
                   vm_object_unlock(object);
                   thread_block((void (*)(void))0);
                   if (thread->wait_result !=  THREAD_AWAKENED) {
                      return(KERN_FAILURE);
                   }
                   vm_object_lock(object);
                   continue;
                }

                vm_object_unlock(object);

                if (rc = memory_object_data_unlock(
                        object->pager,
                        object->pager_request,
                        dst_offset + object->paging_offset,
                        size,
                        access_required)) {
                        if (rc == MACH_SEND_INTERRUPTED) 
                                continue;
                        else
                                return KERN_FAILURE;
                }
                break;
                
           }
           /* lets wait on the last page requested */
           /* NOTE: we will have to update lock completed routine to signal */
           if(dst_page != VM_PAGE_NULL && 
                (access_required & dst_page->page_lock) != access_required) {
                PAGE_ASSERT_WAIT(dst_page, THREAD_UNINT);
                thread_block((void (*)(void))0);
                vm_object_lock(object);
           }
        }
        vm_object_unlock(object);
        return KERN_SUCCESS;
}


kern_return_t
upl_system_list_request(
        vm_object_t             object,
        vm_object_offset_t      offset,
        vm_size_t               size,
        vm_size_t               super_cluster,
        upl_t                   *upl,
        upl_page_info_t         **user_page_list_ptr,
        int                     page_list_count,
        int                     cntrl_flags)
{
        if(object->paging_offset > offset)
                return KERN_FAILURE;
        offset = offset - object->paging_offset;

/* turns off super cluster exercised by the default_pager */
/*
super_cluster = size;
*/
        if ((super_cluster > size) && 
                        (vm_page_free_count > vm_page_free_reserved)) {

                vm_object_offset_t      base_offset;
                vm_size_t               super_size;

                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 = ((base_offset + super_size) > object->size) ? 
                                (object->size - base_offset) : super_size;
                if(offset > (base_offset + super_size))
                   panic("upl_system_list_request: Missed target pageout 0x%x,0x%x, 0x%x, 0x%x, 0x%x, 0x%x\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 = (offset + size) - base_offset;

                offset = base_offset;
                size = super_size;
        }
        vm_fault_list_request(object, offset, size, upl, user_page_list_ptr,
                                                page_list_count, cntrl_flags);
}


kern_return_t
uc_upl_map(
        vm_map_t        map, 
        upl_t           upl, 
        vm_offset_t     *dst_addr)
{
        vm_size_t               size;
        vm_object_offset_t      offset;
        vm_offset_t             addr;
        vm_page_t               m;
        kern_return_t           kr;

        /* check to see if already mapped */
        if(UPL_PAGE_LIST_MAPPED & upl->flags)
                return KERN_FAILURE;

        offset = 0;  /* Always map the entire object */
        size = upl->size;
        
        vm_object_lock(upl->map_object);
        upl->map_object->ref_count++;
        vm_object_res_reference(upl->map_object);
        vm_object_unlock(upl->map_object);

        *dst_addr = 0;


        /* NEED A UPL_MAP ALIAS */
        kr = vm_map_enter(map, dst_addr, size, (vm_offset_t) 0, TRUE,
                upl->map_object, offset, FALSE,
                VM_PROT_DEFAULT, VM_PROT_ALL, VM_INHERIT_DEFAULT);

        if (kr != KERN_SUCCESS)
                return(kr);

        for(addr=*dst_addr; size > 0; size-=PAGE_SIZE,addr+=PAGE_SIZE) {
                m = vm_page_lookup(upl->map_object, offset);
                if(m) {
                        PMAP_ENTER(map->pmap, addr, m, VM_PROT_ALL, TRUE);
                }
                offset+=PAGE_SIZE_64;
        }

        upl->flags |= UPL_PAGE_LIST_MAPPED;
        upl->kaddr = *dst_addr;
        return KERN_SUCCESS;
}
        

kern_return_t
uc_upl_un_map(
        vm_map_t        map, 
        upl_t           upl)
{
        vm_size_t       size;

        if(upl->flags & UPL_PAGE_LIST_MAPPED) {
                size = upl->size;
                vm_deallocate(map, upl->kaddr, size);
                upl->flags &= ~UPL_PAGE_LIST_MAPPED;
                upl->kaddr = (vm_offset_t) 0;
                return KERN_SUCCESS;
        } else {
                return KERN_FAILURE;
        }
}

kern_return_t
uc_upl_commit_range(
        upl_t                   upl, 
        vm_offset_t             offset, 
        vm_size_t               size,
        int                     flags,
        upl_page_info_t          *page_list) 
{
        vm_size_t               xfer_size = size;
        vm_object_t             shadow_object = upl->map_object->shadow;
        vm_object_t             object = upl->map_object;
        vm_object_offset_t      target_offset;
        vm_object_offset_t      page_offset;
        int                     entry;

        if(upl->flags & UPL_DEVICE_MEMORY) {
                xfer_size = 0;
        } else if ((offset + size) > upl->size) {
                return KERN_FAILURE;
        }

        vm_object_lock(shadow_object);

        entry = offset/PAGE_SIZE;
        target_offset = (vm_object_offset_t)offset;
        while(xfer_size) {
                vm_page_t       t,m;
                upl_page_info_t *p;

                if((t = vm_page_lookup(object, target_offset)) != NULL) {

                        t->pageout = FALSE;
                        page_offset = t->offset;
                        VM_PAGE_FREE(t);
                        t = VM_PAGE_NULL;
                        m = vm_page_lookup(shadow_object, 
                                        page_offset + object->shadow_offset);
                        if(m != VM_PAGE_NULL) {
                           vm_object_paging_end(shadow_object);
                           vm_page_lock_queues();
                           if ((upl->flags & UPL_CLEAR_DIRTY) ||
                                        (flags & UPL_COMMIT_CLEAR_DIRTY)) {
                                pmap_clear_modify(m->phys_addr);
                                m->dirty = FALSE;
                           }
                           if(page_list) {
                                p = &(page_list[entry]);
                                if(p->phys_addr && p->pageout && !m->pageout) {
                                        m->busy = TRUE;
                                        m->pageout = TRUE;
                                        vm_page_wire(m);
                                } else if (page_list[entry].phys_addr &&
                                                !p->pageout && m->pageout) {
                                        m->pageout = FALSE;
                                        m->absent = FALSE;
                                        m->overwriting = FALSE;
                                        vm_page_unwire(m);
                                        PAGE_WAKEUP_DONE(m);
                                }
                                page_list[entry].phys_addr = 0;
                           }
                           if(m->laundry) {
                              vm_page_laundry_count--;
                              m->laundry = FALSE;
                              if (vm_page_laundry_count < vm_page_laundry_min) {
                                 vm_page_laundry_min = 0;
                                 thread_wakeup((event_t) 
                                             &vm_page_laundry_count);
                              }
                           }
                           if(m->pageout) {
                              m->cleaning = FALSE;
                              m->pageout = FALSE;
#if MACH_CLUSTER_STATS
                              if (m->wanted) vm_pageout_target_collisions++;
#endif
                              pmap_page_protect(m->phys_addr, VM_PROT_NONE);
                              m->dirty = pmap_is_modified(m->phys_addr);
                              if(m->dirty) {
                                 CLUSTER_STAT(
                                      vm_pageout_target_page_dirtied++;)
                                 vm_page_unwire(m);/* reactivates */
                                 VM_STAT(reactivations++);
                                 PAGE_WAKEUP_DONE(m);
                              } else if (m->prep_pin_count != 0) {
                                 vm_page_pin_lock();
                                 if (m->pin_count != 0) {
                                    /* page is pinned; reactivate */
                                    CLUSTER_STAT(
                                               vm_pageout_target_page_pinned++;)
                                    vm_page_unwire(m);/* reactivates */
                                    VM_STAT(reactivations++);
                                    PAGE_WAKEUP_DONE(m);
                                 } else {
                                   /*
                                    * page is prepped but not pinned; 
                                    * send it into limbo.  Note that
                                    * vm_page_free (which will be 
                                    * called after releasing the pin 
                                    * lock) knows how to handle a page 
                                    * with limbo set.
                                    */
                                    m->limbo = TRUE;
                                    CLUSTER_STAT(
                                                vm_pageout_target_page_limbo++;)
                                 }
                                 vm_page_pin_unlock();
                                 if (m->limbo)
                                    vm_page_free(m);
                                 } else {
                                    CLUSTER_STAT(
                                               vm_pageout_target_page_freed++;)
                                    vm_page_free(m);/* clears busy, etc. */
                                 }
                                 vm_page_unlock_queues();
                                 target_offset += PAGE_SIZE_64;
                                 xfer_size -= PAGE_SIZE;
                                 entry++;
                                 continue;
                              }
                              if (flags & UPL_COMMIT_INACTIVATE) {
                                      vm_page_deactivate(m);
                                      m->reference = FALSE;
                                      pmap_clear_reference(m->phys_addr);
                              } else if (!m->active && !m->inactive) {
                                   if (m->reference || m->prep_pin_count != 0)
                                      vm_page_activate(m);
                                   else
                                      vm_page_deactivate(m);
                              }
#if MACH_CLUSTER_STATS
                              m->dirty = pmap_is_modified(m->phys_addr);

                              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->busy) && (m->cleaning)) {
                                 /* the request_page_list case */
                                if(m->absent) {
                                   m->absent = FALSE;
                                   if(shadow_object->absent_count == 1)
                                      vm_object_absent_release(shadow_object);
                                   else
                                      shadow_object->absent_count--;
                                }
                                 m->overwriting = FALSE;
                                 m->busy = FALSE;
                                 m->dirty = FALSE;
                              }
                              else if (m->overwriting) {
                                 /* alternate request page list, write to 
                                 /* page_list case.  Occurs when the original
                                 /* page was wired at the time of the list
                                 /* request */
                                 assert(m->wire_count != 0);
                                 vm_page_unwire(m);/* reactivates */
                                 m->overwriting = FALSE;
                              }
                              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)
                                 m->precious = FALSE;

                              if (flags & UPL_COMMIT_SET_DIRTY) {
                                 m->dirty = TRUE;
                              }
                              /*
                               * Wakeup any thread waiting for the page to be un-cleaning.
                               */
                              PAGE_WAKEUP(m);
                              vm_page_unlock_queues();

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

        vm_object_unlock(shadow_object);
        if(flags & UPL_COMMIT_FREE_ON_EMPTY) {
                if((upl->flags & UPL_DEVICE_MEMORY) 
                                || (queue_empty(&upl->map_object->memq))) {
                        upl_dealloc(upl);
                }
        }
        return KERN_SUCCESS;
}

uc_upl_abort_range(
        upl_t                   upl, 
        vm_offset_t             offset, 
        vm_size_t               size,
        int                     error) 
{
        vm_size_t               xfer_size = size;
        vm_object_t             shadow_object = upl->map_object->shadow;
        vm_object_t             object = upl->map_object;
        vm_object_offset_t      target_offset;
        vm_object_offset_t      page_offset;
        int                     entry;

        if(upl->flags & UPL_DEVICE_MEMORY) {
                xfer_size = 0;
        } else if ((offset + size) > upl->size) {
                return KERN_FAILURE;
        }


        vm_object_lock(shadow_object);

        entry = offset/PAGE_SIZE;
        target_offset = (vm_object_offset_t)offset;
        while(xfer_size) {
                vm_page_t       t,m;
                upl_page_info_t *p;

                if((t = vm_page_lookup(object, target_offset)) != NULL) {

                        t->pageout = FALSE;
                        page_offset = t->offset;
                        VM_PAGE_FREE(t);
                        t = VM_PAGE_NULL;
                        m = vm_page_lookup(shadow_object, 
                                        page_offset + object->shadow_offset);
                   if(m != VM_PAGE_NULL) {
                        vm_object_paging_end(m->object);
                        vm_page_lock_queues();
                        if(m->absent) {
                                /* 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;
                                        vm_object_absent_release(m->object);
                                        m->page_error = KERN_MEMORY_ERROR;
                                        m->error = TRUE;
                                } else if(error & UPL_ABORT_UNAVAILABLE) {
                                        m->restart = FALSE;
                                        m->unusual = TRUE;
                                        m->clustered = FALSE;
                                } else if(error & UPL_ABORT_ERROR) {
                                        m->restart = FALSE;
                                        m->absent = FALSE;
                                        vm_object_absent_release(m->object);
                                        m->page_error = KERN_MEMORY_ERROR;
                                        m->error = TRUE;
                                } else if(error & UPL_ABORT_DUMP_PAGES) {
                                        m->clustered = TRUE;    
                                } else {
                                        m->clustered = TRUE;
                                }
                                

                                m->cleaning = FALSE;
                                m->overwriting = FALSE;
                                PAGE_WAKEUP_DONE(m);
                                if(m->clustered) {
                                        vm_page_free(m);
                                } else {
                                        vm_page_activate(m);
                                }

                                vm_page_unlock_queues();
                                target_offset += PAGE_SIZE_64;
                                xfer_size -= PAGE_SIZE;
                                entry++;
                                continue;
                        }
                        /*                          
                         * Handle the trusted pager throttle.
                         */                     
                        if (m->laundry) { 
                                vm_page_laundry_count--;
                                m->laundry = FALSE;  
                                if (vm_page_laundry_count 
                                                < vm_page_laundry_min) {
                                        vm_page_laundry_min = 0;
                                        thread_wakeup((event_t) 
                                                &vm_page_laundry_count); 
                                }                    
                        }         
                        if(m->pageout) {
                                assert(m->busy);
                                assert(m->wire_count == 1);
                                m->pageout = FALSE;
                                vm_page_unwire(m);
                        }
                        m->cleaning = FALSE;
                        m->busy = FALSE;
                        m->overwriting = FALSE;
#if     MACH_PAGEMAP
                        vm_external_state_clr(
                                m->object->existence_map, m->offset);
#endif  /* MACH_PAGEMAP */
                        if(error & UPL_ABORT_DUMP_PAGES) {
                                vm_page_free(m);
                                pmap_page_protect(m->phys_addr, VM_PROT_NONE);
                        } else {
                                PAGE_WAKEUP(m);
                        }
                        vm_page_unlock_queues();
                }
           }
           target_offset += PAGE_SIZE_64;
           xfer_size -= PAGE_SIZE;
           entry++;
        }
        vm_object_unlock(shadow_object);
        if(error & UPL_ABORT_FREE_ON_EMPTY) {
                if((upl->flags & UPL_DEVICE_MEMORY) 
                                || (queue_empty(&upl->map_object->memq))) {
                        upl_dealloc(upl);
                }
        }
        return KERN_SUCCESS;
}

kern_return_t
uc_upl_abort(
        upl_t   upl,
        int     error)
{
        vm_object_t             object = NULL;
        vm_object_t             shadow_object = NULL;
        vm_object_offset_t      offset;
        vm_object_offset_t      shadow_offset;
        vm_object_offset_t      target_offset;
        int                     i;
        vm_page_t               t,m;

        if(upl->flags & UPL_DEVICE_MEMORY) {
                upl_dealloc(upl);
                return KERN_SUCCESS;
        }
        object = upl->map_object;

        if(object == NULL) {
                panic("upl_abort: upl object is not backed by an object");
                return KERN_INVALID_ARGUMENT;
        }

        shadow_object = upl->map_object->shadow;
        shadow_offset = upl->map_object->shadow_offset;
        offset = 0;
        vm_object_lock(shadow_object);
        for(i = 0; i<(upl->size); i+=PAGE_SIZE, offset += PAGE_SIZE_64) {
            if((t = vm_page_lookup(object,offset)) != NULL) {
                target_offset = t->offset + shadow_offset;
                if((m = vm_page_lookup(shadow_object, target_offset)) != NULL) {
                        vm_object_paging_end(m->object);
                        vm_page_lock_queues();
                        if(m->absent) {
                                /* 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;
                                        vm_object_absent_release(m->object);
                                        m->page_error = KERN_MEMORY_ERROR;
                                        m->error = TRUE;
                                } else if(error & UPL_ABORT_UNAVAILABLE) {
                                        m->restart = FALSE;
                                        m->unusual = TRUE;
                                        m->clustered = FALSE;
                                } else if(error & UPL_ABORT_ERROR) {
                                        m->restart = FALSE;
                                        m->absent = FALSE;
                                        vm_object_absent_release(m->object);
                                        m->page_error = KERN_MEMORY_ERROR;
                                        m->error = TRUE;
                                } else if(error & UPL_ABORT_DUMP_PAGES) {
                                        m->clustered = TRUE;    
                                } else {
                                        m->clustered = TRUE;
                                }
                                
                                m->cleaning = FALSE;
                                m->overwriting = FALSE;
                                PAGE_WAKEUP_DONE(m);
                                if(m->clustered) {
                                        vm_page_free(m);
                                } else {
                                        vm_page_activate(m);
                                }
                                vm_page_unlock_queues();
                                continue;
                        }
                        /*                          
                         * Handle the trusted pager throttle.
                         */                     
                        if (m->laundry) { 
                                vm_page_laundry_count--;
                                m->laundry = FALSE;  
                                if (vm_page_laundry_count 
                                                < vm_page_laundry_min) {
                                        vm_page_laundry_min = 0;
                                        thread_wakeup((event_t) 
                                                &vm_page_laundry_count); 
                                }                    
                        }         
                        if(m->pageout) {
                                assert(m->busy);
                                assert(m->wire_count == 1);
                                m->pageout = FALSE;
                                vm_page_unwire(m);
                        }
                        m->cleaning = FALSE;
                        m->busy = FALSE;
                        m->overwriting = FALSE;
#if     MACH_PAGEMAP
                        vm_external_state_clr(
                                m->object->existence_map, m->offset);
#endif  /* MACH_PAGEMAP */
                        if(error & UPL_ABORT_DUMP_PAGES) {
                                vm_page_free(m);
                                pmap_page_protect(m->phys_addr, VM_PROT_NONE);
                        } else {
                                PAGE_WAKEUP(m);
                        }
                        vm_page_unlock_queues();
                }
           }
        }
        vm_object_unlock(shadow_object);
        /* Remove all the pages from the map object so */
        /* vm_pageout_object_terminate will work properly. */
        while (!queue_empty(&upl->map_object->memq)) {
                vm_page_t p;

                p = (vm_page_t) queue_first(&upl->map_object->memq);

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

                VM_PAGE_FREE(p);
        }
        upl_dealloc(upl);
        return KERN_SUCCESS;
}

/* an option on commit should be wire */
kern_return_t
uc_upl_commit(
        upl_t           upl,
        upl_page_info_t *page_list)
{
        if (upl->flags & UPL_DEVICE_MEMORY)
                page_list = NULL;
        if ((upl->flags & UPL_CLEAR_DIRTY) ||
                (upl->flags & UPL_PAGE_SYNC_DONE)) {
                vm_object_t     shadow_object = upl->map_object->shadow;
                vm_object_t     object = upl->map_object;
                vm_object_offset_t target_offset;
                vm_size_t       xfer_end;

                vm_page_t       t,m;

                vm_object_lock(shadow_object);

                target_offset = object->shadow_offset;
                xfer_end = upl->size + object->shadow_offset;

                while(target_offset < xfer_end) {
                        if ((t = vm_page_lookup(object, 
                                target_offset - object->shadow_offset))
                                != NULL) {
                                m = vm_page_lookup(
                                        shadow_object, target_offset);
                                if(m != VM_PAGE_NULL) {
                                        if (upl->flags & UPL_CLEAR_DIRTY) {
                                                pmap_clear_modify(m->phys_addr);
                                                m->dirty = 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)
                                                m->precious = FALSE;
                                }
                        }
                        target_offset += PAGE_SIZE_64;
                }
                vm_object_unlock(shadow_object);
        }
        if (page_list) {
                vm_object_t     shadow_object = upl->map_object->shadow;
                vm_object_t     object = upl->map_object;
                vm_object_offset_t target_offset;
                vm_size_t       xfer_end;
                int             entry;

                vm_page_t       t, m;
                upl_page_info_t *p;

                vm_object_lock(shadow_object);

                entry = 0;
                target_offset = object->shadow_offset;
                xfer_end = upl->size + object->shadow_offset;

                while(target_offset < xfer_end) {

                        if ((t = vm_page_lookup(object, 
                                target_offset - object->shadow_offset))
                                == NULL) {
                                target_offset += PAGE_SIZE_64;
                                entry++;
                                continue;
                        }

                        m = vm_page_lookup(shadow_object, target_offset);
                        if(m != VM_PAGE_NULL) {
                           p = &(page_list[entry]);
                           if(page_list[entry].phys_addr &&
                                                p->pageout && !m->pageout) {
                                        vm_page_lock_queues();
                                        m->busy = TRUE;
                                        m->pageout = TRUE;
                                        vm_page_wire(m);
                                        vm_page_unlock_queues();
                           } else if (page_list[entry].phys_addr &&
                                                !p->pageout && m->pageout) {
                                        vm_page_lock_queues();
                                        m->pageout = FALSE;
                                        m->absent = FALSE;
                                        m->overwriting = FALSE;
                                        vm_page_unwire(m);
                                        PAGE_WAKEUP_DONE(m);
                                        vm_page_unlock_queues();
                           }
                           page_list[entry].phys_addr = 0;
                        }
                        target_offset += PAGE_SIZE_64;
                        entry++;
                }

                vm_object_unlock(shadow_object);
        }
        upl_dealloc(upl);
        return KERN_SUCCESS;
}

upl_t
upl_create(
        boolean_t       internal)
{
        upl_t   upl;

        if(internal) {
                upl = (upl_t)kalloc(sizeof(struct upl)
                        + (sizeof(struct upl_page_info)*MAX_UPL_TRANSFER));
        } else {
                upl = (upl_t)kalloc(sizeof(struct upl));
        }
        upl->flags = 0;
        upl->src_object = NULL;
        upl->kaddr = (vm_offset_t)0;
        upl->size = 0;
        upl->map_object = NULL;
        upl->ref_count = 1;
        upl_lock_init(upl);
#ifdef UBC_DEBUG
        upl->ubc_alias1 = 0;
        upl->ubc_alias2 = 0;
#endif /* UBC_DEBUG */
        return(upl);
}

void
upl_destroy(
        upl_t   upl)
{

#ifdef UBC_DEBUG
        {
                upl_t   upl_ele;
                vm_object_lock(upl->map_object->shadow);
                queue_iterate(&upl->map_object->shadow->uplq, 
                                                upl_ele, upl_t, uplq) {
                        if(upl_ele == upl) {
                                queue_remove(&upl->map_object->shadow->uplq, 
                                        upl_ele, upl_t, uplq);
                                break;
                        }
                }
                vm_object_unlock(upl->map_object->shadow);
        }
#endif /* UBC_DEBUG */
        if(!(upl->flags & UPL_DEVICE_MEMORY))
                vm_object_deallocate(upl->map_object);
        if(upl->flags & UPL_INTERNAL) {
                kfree((vm_offset_t)upl,
                        sizeof(struct upl) + 
                        (sizeof(struct upl_page_info) * MAX_UPL_TRANSFER));
        } else {
                kfree((vm_offset_t)upl, sizeof(struct upl));
        }
}

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

void
upl_set_dirty(
        upl_t   upl)
{
        upl->flags |= UPL_CLEAR_DIRTY;
}

void
upl_clear_dirty(
        upl_t   upl)
{
        upl->flags &= ~UPL_CLEAR_DIRTY;
}


#ifdef MACH_BSD
boolean_t  upl_page_present(upl_page_info_t *upl, int index);
boolean_t  upl_dirty_page(upl_page_info_t *upl, int index);
boolean_t  upl_valid_page(upl_page_info_t *upl, int index);
vm_offset_t  upl_phys_page(upl_page_info_t *upl, int index);

boolean_t  upl_page_present(upl_page_info_t *upl, int index)
{
        return(UPL_PAGE_PRESENT(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));
}
vm_offset_t  upl_phys_page(upl_page_info_t *upl, int index)
{
        return((vm_offset_t)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++;

                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();

        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++;

                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 */

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



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

#define printf  kdbprintf
extern int      db_indent;
void            db_pageout(void);

void
db_vm(void)
{
        extern int vm_page_gobble_count;
        extern int vm_page_limbo_count, vm_page_limbo_real_count;
        extern int vm_page_pin_count;

        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);
        iprintf("laund %5d  limbo %5d  lim_r %5d   pin   %5d\n",
                vm_page_laundry_count, vm_page_limbo_count,
                vm_page_limbo_real_count, vm_page_pin_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("burst:\n");
        db_indent += 2;
        iprintf("max   %5d  min   %5d  wait  %5d   empty %5d\n",
                  vm_pageout_burst_max, vm_pageout_burst_min,
                  vm_pageout_burst_wait, vm_pageout_empty_wait);
        db_indent -= 2;
        iprintf("pause:\n");
        db_indent += 2;
        iprintf("count %5d  max   %5d\n",
                vm_pageout_pause_count, vm_pageout_pause_max);
#if     MACH_COUNTERS
        iprintf("scan_continue called %8d\n", c_vm_pageout_scan_continue);
#endif  /* MACH_COUNTERS */
        db_indent -= 2;
        db_pageout();
        db_indent -= 2;
}

void
db_pageout(void)
{
        extern int c_limbo_page_free;
        extern int c_limbo_convert;
#if     MACH_COUNTERS
        extern int c_laundry_pages_freed;
#endif  /* MACH_COUNTERS */

        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  %5d\n",
                vm_pageout_inactive_used, vm_pageout_inactive_clean,
                vm_pageout_inactive_dirty);
        iprintf("pinned %5d  limbo  %5d  setup_limbo %5d  setup_unprep %5d\n",
                vm_pageout_inactive_pinned, vm_pageout_inactive_limbo,
                vm_pageout_setup_limbo, vm_pageout_setup_unprepped);
        iprintf("limbo_page_free  %5d   limbo_convert  %5d\n",
                c_limbo_page_free, c_limbo_convert);
#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);
        iprintf("page_pinned  %5d   page_limbo    %5d\n",
                vm_pageout_target_page_pinned, vm_pageout_target_page_limbo);
        db_indent -= 2;
#endif  /* MACH_CLUSTER_STATS */
        db_indent -= 2;
}

#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;
unsigned long vm_pageout_target_page_pinned = 0;
unsigned long vm_pageout_target_page_limbo = 0;
#define CLUSTER_STAT(clause)    clause
#else   /* MACH_CLUSTER_STATS */
#define CLUSTER_STAT(clause)
#endif  /* MACH_CLUSTER_STATS */

#endif  /* MACH_KDB */