Fix warnings in preparation for adding -Wall -Wcast-qual to the

[FreeBSD/FreeBSD.git] / sys / vm / vm_object.c

/*
 * Copyright (c) 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * The Mach Operating System project at Carnegie-Mellon University.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      from: @(#)vm_object.c   8.5 (Berkeley) 3/22/94
 *
 *
 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
 *
 * 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 the
 * rights to redistribute these changes.
 *
 * $Id: vm_object.c,v 1.141 1999/01/24 01:01:38 dillon Exp $
 */

/*
 *      Virtual memory object module.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>           /* for curproc, pageproc */
#include <sys/vnode.h>
#include <sys/vmmeter.h>
#include <sys/mman.h>
#include <sys/mount.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_prot.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 <vm/vm_pager.h>
#include <vm/swap_pager.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/vm_zone.h>

static void     vm_object_qcollapse __P((vm_object_t object));

/*
 *      Virtual memory objects maintain the actual data
 *      associated with allocated virtual memory.  A given
 *      page of memory exists within exactly one object.
 *
 *      An object is only deallocated when all "references"
 *      are given up.  Only one "reference" to a given
 *      region of an object should be writeable.
 *
 *      Associated with each object is a list of all resident
 *      memory pages belonging to that object; this list is
 *      maintained by the "vm_page" module, and locked by the object's
 *      lock.
 *
 *      Each object also records a "pager" routine which is
 *      used to retrieve (and store) pages to the proper backing
 *      storage.  In addition, objects may be backed by other
 *      objects from which they were virtual-copied.
 *
 *      The only items within the object structure which are
 *      modified after time of creation are:
 *              reference count         locked by object's lock
 *              pager routine           locked by object's lock
 *
 */

struct object_q vm_object_list;
#ifndef NULL_SIMPLELOCKS
static struct simplelock vm_object_list_lock;
#endif
static long vm_object_count;            /* count of all objects */
vm_object_t kernel_object;
vm_object_t kmem_object;
static struct vm_object kernel_object_store;
static struct vm_object kmem_object_store;
extern int vm_pageout_page_count;

static long object_collapses;
static long object_bypasses;
static int next_index;
static vm_zone_t obj_zone;
static struct vm_zone obj_zone_store;
static int object_hash_rand;
#define VM_OBJECTS_INIT 256
static struct vm_object vm_objects_init[VM_OBJECTS_INIT];
#if 0
static int objidnumber;
#endif

void
_vm_object_allocate(type, size, object)
        objtype_t type;
        vm_size_t size;
        register vm_object_t object;
{
        int incr;
        TAILQ_INIT(&object->memq);
        TAILQ_INIT(&object->shadow_head);

        object->type = type;
        object->size = size;
        object->ref_count = 1;
        object->flags = 0;
#if 0
        object->id = ++objidnumber;
#endif
        if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP))
                vm_object_set_flag(object, OBJ_ONEMAPPING);
        object->behavior = OBJ_NORMAL;
        object->paging_in_progress = 0;
        object->resident_page_count = 0;
        object->cache_count = 0;
        object->wire_count = 0;
        object->shadow_count = 0;
        object->pg_color = next_index;
        if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1))
                incr = PQ_L2_SIZE / 3 + PQ_PRIME1;
        else
                incr = size;
        next_index = (next_index + incr) & PQ_L2_MASK;
        object->handle = NULL;
        object->backing_object = NULL;
        object->backing_object_offset = (vm_ooffset_t) 0;
#if 0
        object->page_hint = NULL;
#endif
        /*
         * Try to generate a number that will spread objects out in the
         * hash table.  We 'wipe' new objects across the hash in 128 page
         * increments plus 1 more to offset it a little more by the time
         * it wraps around.
         */
        object->hash_rand = object_hash_rand - 129;

        object->last_read = 0;
        object->generation++;

        TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
        vm_object_count++;
        object_hash_rand = object->hash_rand;
}

/*
 *      vm_object_init:
 *
 *      Initialize the VM objects module.
 */
void
vm_object_init()
{
        TAILQ_INIT(&vm_object_list);
        simple_lock_init(&vm_object_list_lock);
        vm_object_count = 0;
        
        kernel_object = &kernel_object_store;
        _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
            kernel_object);

        kmem_object = &kmem_object_store;
        _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
            kmem_object);

        obj_zone = &obj_zone_store;
        zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object),
                vm_objects_init, VM_OBJECTS_INIT);
}

void
vm_object_init2() {
        zinitna(obj_zone, NULL, NULL, 0, 0, 0, 1);
}

/*
 *      vm_object_allocate:
 *
 *      Returns a new object with the given size.
 */

vm_object_t
vm_object_allocate(type, size)
        objtype_t type;
        vm_size_t size;
{
        register vm_object_t result;
        result = (vm_object_t) zalloc(obj_zone);

        _vm_object_allocate(type, size, result);

        return (result);
}


/*
 *      vm_object_reference:
 *
 *      Gets another reference to the given object.
 */
void
vm_object_reference(object)
        register vm_object_t object;
{
        if (object == NULL)
                return;

        KASSERT(!(object->flags & OBJ_DEAD),
            ("vm_object_reference: attempting to reference dead obj"));

        object->ref_count++;
        if (object->type == OBJT_VNODE) {
                while (vget((struct vnode *) object->handle, LK_RETRY|LK_NOOBJ, curproc)) {
#if !defined(MAX_PERF)
                        printf("vm_object_reference: delay in getting object\n");
#endif
                }
        }
}

void
vm_object_vndeallocate(object)
        vm_object_t object;
{
        struct vnode *vp = (struct vnode *) object->handle;

        KASSERT(object->type == OBJT_VNODE,
            ("vm_object_vndeallocate: not a vnode object"));
        KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
#ifdef INVARIANTS
        if (object->ref_count == 0) {
                vprint("vm_object_vndeallocate", vp);
                panic("vm_object_vndeallocate: bad object reference count");
        }
#endif

        object->ref_count--;
        if (object->ref_count == 0) {
                vp->v_flag &= ~VTEXT;
                vm_object_clear_flag(object, OBJ_OPT);
        }
        vrele(vp);
}

/*
 *      vm_object_deallocate:
 *
 *      Release a reference to the specified object,
 *      gained either through a vm_object_allocate
 *      or a vm_object_reference call.  When all references
 *      are gone, storage associated with this object
 *      may be relinquished.
 *
 *      No object may be locked.
 */
void
vm_object_deallocate(object)
        vm_object_t object;
{
        vm_object_t temp;

        while (object != NULL) {

                if (object->type == OBJT_VNODE) {
                        vm_object_vndeallocate(object);
                        return;
                }

                if (object->ref_count == 0) {
                        panic("vm_object_deallocate: object deallocated too many times: %d", object->type);
                } else if (object->ref_count > 2) {
                        object->ref_count--;
                        return;
                }

                /*
                 * Here on ref_count of one or two, which are special cases for
                 * objects.
                 */
                if ((object->ref_count == 2) && (object->shadow_count == 0)) {
                        vm_object_set_flag(object, OBJ_ONEMAPPING);
                        object->ref_count--;
                        return;
                } else if ((object->ref_count == 2) && (object->shadow_count == 1)) {
                        object->ref_count--;
                        if ((object->handle == NULL) &&
                            (object->type == OBJT_DEFAULT ||
                             object->type == OBJT_SWAP)) {
                                vm_object_t robject;

                                robject = TAILQ_FIRST(&object->shadow_head);
                                KASSERT(robject != NULL,
                                    ("vm_object_deallocate: ref_count: %d, shadow_count: %d",
                                         object->ref_count,
                                         object->shadow_count));
                                if ((robject->handle == NULL) &&
                                    (robject->type == OBJT_DEFAULT ||
                                     robject->type == OBJT_SWAP)) {

                                        robject->ref_count++;

                                        while (
                                                robject->paging_in_progress ||
                                                object->paging_in_progress
                                        ) {
                                                vm_object_pip_sleep(robject, "objde1");
                                                vm_object_pip_sleep(object, "objde2");
                                        }

                                        if (robject->ref_count == 1) {
                                                robject->ref_count--;
                                                object = robject;
                                                goto doterm;
                                        }

                                        object = robject;
                                        vm_object_collapse(object);
                                        continue;
                                }
                        }

                        return;

                } else {
                        object->ref_count--;
                        if (object->ref_count != 0)
                                return;
                }

doterm:

                temp = object->backing_object;
                if (temp) {
                        TAILQ_REMOVE(&temp->shadow_head, object, shadow_list);
                        temp->shadow_count--;
                        if (temp->ref_count == 0)
                                vm_object_clear_flag(temp, OBJ_OPT);
                        temp->generation++;
                        object->backing_object = NULL;
                }
                vm_object_terminate(object);
                /* unlocks and deallocates object */
                object = temp;
        }
}

/*
 *      vm_object_terminate actually destroys the specified object, freeing
 *      up all previously used resources.
 *
 *      The object must be locked.
 *      This routine may block.
 */
void
vm_object_terminate(object)
        register vm_object_t object;
{
        register vm_page_t p;
        int s;

        /*
         * Make sure no one uses us.
         */
        vm_object_set_flag(object, OBJ_DEAD);

        /*
         * wait for the pageout daemon to be done with the object
         */
        vm_object_pip_wait(object, "objtrm");

        KASSERT(!object->paging_in_progress,
                ("vm_object_terminate: pageout in progress"));

        /*
         * Clean and free the pages, as appropriate. All references to the
         * object are gone, so we don't need to lock it.
         */
        if (object->type == OBJT_VNODE) {
                struct vnode *vp;

                /*
                 * Freeze optimized copies.
                 */
                vm_freeze_copyopts(object, 0, object->size);

                /*
                 * Clean pages and flush buffers.
                 */
                vm_object_page_clean(object, 0, 0, OBJPC_SYNC);

                vp = (struct vnode *) object->handle;
                vinvalbuf(vp, V_SAVE, NOCRED, NULL, 0, 0);
        }

        if (object->ref_count != 0)
                panic("vm_object_terminate: object with references, ref_count=%d", object->ref_count);

        /*
         * Now free any remaining pages. For internal objects, this also
         * removes them from paging queues. Don't free wired pages, just
         * remove them from the object. 
         */
        s = splvm();
        while ((p = TAILQ_FIRST(&object->memq)) != NULL) {
#if !defined(MAX_PERF)
                if (p->busy || (p->flags & PG_BUSY))
                        panic("vm_object_terminate: freeing busy page %p\n", p);
#endif
                if (p->wire_count == 0) {
                        vm_page_busy(p);
                        vm_page_free(p);
                        cnt.v_pfree++;
                } else {
                        vm_page_busy(p);
                        vm_page_remove(p);
                }
        }
        splx(s);

        /*
         * Let the pager know object is dead.
         */
        vm_pager_deallocate(object);

        /*
         * Remove the object from the global object list.
         */
        simple_lock(&vm_object_list_lock);
        TAILQ_REMOVE(&vm_object_list, object, object_list);
        simple_unlock(&vm_object_list_lock);

        wakeup(object);

        /*
         * Free the space for the object.
         */
        zfree(obj_zone, object);
}

/*
 *      vm_object_page_clean
 *
 *      Clean all dirty pages in the specified range of object.
 *      Leaves page on whatever queue it is currently on.
 *
 *      Odd semantics: if start == end, we clean everything.
 *
 *      The object must be locked.
 */

void
vm_object_page_clean(object, start, end, flags)
        vm_object_t object;
        vm_pindex_t start;
        vm_pindex_t end;
        int flags;
{
        register vm_page_t p, np, tp;
        register vm_offset_t tstart, tend;
        vm_pindex_t pi;
        int s;
        struct vnode *vp;
        int runlen;
        int maxf;
        int chkb;
        int maxb;
        int i;
        int pagerflags;
        vm_page_t maf[vm_pageout_page_count];
        vm_page_t mab[vm_pageout_page_count];
        vm_page_t ma[vm_pageout_page_count];
        int curgeneration;

        if (object->type != OBJT_VNODE ||
                (object->flags & OBJ_MIGHTBEDIRTY) == 0)
                return;

        pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? VM_PAGER_PUT_SYNC : 0;
        pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0;

        vp = object->handle;

        vm_object_set_flag(object, OBJ_CLEANING);

        tstart = start;
        if (end == 0) {
                tend = object->size;
        } else {
                tend = end;
        }

        for(p = TAILQ_FIRST(&object->memq); p; p = TAILQ_NEXT(p, listq)) {
                vm_page_flag_set(p, PG_CLEANCHK);
                vm_page_protect(p, VM_PROT_READ);
        }

        if ((tstart == 0) && (tend == object->size)) {
                vm_object_clear_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
        }

rescan:
        curgeneration = object->generation;

        for(p = TAILQ_FIRST(&object->memq); p; p = np) {
                np = TAILQ_NEXT(p, listq);

                pi = p->pindex;
                if (((p->flags & PG_CLEANCHK) == 0) ||
                        (pi < tstart) || (pi >= tend) ||
                        (p->valid == 0) ||
                        ((p->queue - p->pc) == PQ_CACHE)) {
                        vm_page_flag_clear(p, PG_CLEANCHK);
                        continue;
                }

                vm_page_test_dirty(p);
                if ((p->dirty & p->valid) == 0) {
                        vm_page_flag_clear(p, PG_CLEANCHK);
                        continue;
                }

                s = splvm();
                while (vm_page_sleep_busy(p, TRUE, "vpcwai")) {
                        if (object->generation != curgeneration) {
                                splx(s);
                                goto rescan;
                        }
                }

                maxf = 0;
                for(i=1;i<vm_pageout_page_count;i++) {
                        if ((tp = vm_page_lookup(object, pi + i)) != NULL) {
                                if ((tp->flags & PG_BUSY) ||
                                        (tp->flags & PG_CLEANCHK) == 0 ||
                                        (tp->busy != 0))
                                        break;
                                if((tp->queue - tp->pc) == PQ_CACHE) {
                                        vm_page_flag_clear(tp, PG_CLEANCHK);
                                        break;
                                }
                                vm_page_test_dirty(tp);
                                if ((tp->dirty & tp->valid) == 0) {
                                        vm_page_flag_clear(tp, PG_CLEANCHK);
                                        break;
                                }
                                maf[ i - 1 ] = tp;
                                maxf++;
                                continue;
                        }
                        break;
                }

                maxb = 0;
                chkb = vm_pageout_page_count -  maxf;
                if (chkb) {
                        for(i = 1; i < chkb;i++) {
                                if ((tp = vm_page_lookup(object, pi - i)) != NULL) {
                                        if ((tp->flags & PG_BUSY) ||
                                                (tp->flags & PG_CLEANCHK) == 0 ||
                                                (tp->busy != 0))
                                                break;
                                        if((tp->queue - tp->pc) == PQ_CACHE) {
                                                vm_page_flag_clear(tp, PG_CLEANCHK);
                                                break;
                                        }
                                        vm_page_test_dirty(tp);
                                        if ((tp->dirty & tp->valid) == 0) {
                                                vm_page_flag_clear(tp, PG_CLEANCHK);
                                                break;
                                        }
                                        mab[ i - 1 ] = tp;
                                        maxb++;
                                        continue;
                                }
                                break;
                        }
                }

                for(i=0;i<maxb;i++) {
                        int index = (maxb - i) - 1;
                        ma[index] = mab[i];
                        vm_page_flag_clear(ma[index], PG_CLEANCHK);
                }
                vm_page_flag_clear(p, PG_CLEANCHK);
                ma[maxb] = p;
                for(i=0;i<maxf;i++) {
                        int index = (maxb + i) + 1;
                        ma[index] = maf[i];
                        vm_page_flag_clear(ma[index], PG_CLEANCHK);
                }
                runlen = maxb + maxf + 1;

                splx(s);
                vm_pageout_flush(ma, runlen, pagerflags);
                for (i = 0; i<runlen; i++) {
                        if (ma[i]->valid & ma[i]->dirty) {
                                vm_page_protect(ma[i], VM_PROT_READ);
                                vm_page_flag_set(ma[i], PG_CLEANCHK);
                        }
                }
                if (object->generation != curgeneration)
                        goto rescan;
        }

        VOP_FSYNC(vp, NULL, (pagerflags & VM_PAGER_PUT_SYNC)?MNT_WAIT:0, curproc);

        vm_object_clear_flag(object, OBJ_CLEANING);
        return;
}

#ifdef not_used
/* XXX I cannot tell if this should be an exported symbol */
/*
 *      vm_object_deactivate_pages
 *
 *      Deactivate all pages in the specified object.  (Keep its pages
 *      in memory even though it is no longer referenced.)
 *
 *      The object must be locked.
 */
static void
vm_object_deactivate_pages(object)
        register vm_object_t object;
{
        register vm_page_t p, next;

        for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) {
                next = TAILQ_NEXT(p, listq);
                vm_page_deactivate(p);
        }
}
#endif

#if 0

/*
 *      vm_object_pmap_copy:
 *
 *      Makes all physical pages in the specified
 *      object range copy-on-write.  No writeable
 *      references to these pages should remain.
 *
 *      The object must *not* be locked.
 */
void
vm_object_pmap_copy(object, start, end)
        register vm_object_t object;
        register vm_pindex_t start;
        register vm_pindex_t end;
{
        register vm_page_t p;

        if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
                return;

        for (p = TAILQ_FIRST(&object->memq);
                p != NULL;
                p = TAILQ_NEXT(p, listq)) {
                vm_page_protect(p, VM_PROT_READ);
        }

        vm_object_clear_flag(object, OBJ_WRITEABLE);
}

#endif

/*
 * Same as vm_object_pmap_copy, except range checking really
 * works, and is meant for small sections of an object.
 *
 * This code protects resident pages by making them read-only
 * and is typically called on a fork or split when a page
 * is converted to copy-on-write.  
 *
 * NOTE: If the page is already at VM_PROT_NONE, calling
 * vm_page_protect will have no effect.
 */

void
vm_object_pmap_copy_1(object, start, end)
        register vm_object_t object;
        register vm_pindex_t start;
        register vm_pindex_t end;
{
        vm_pindex_t idx;
        register vm_page_t p;

        if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
                return;

        for (idx = start; idx < end; idx++) {
                p = vm_page_lookup(object, idx);
                if (p == NULL)
                        continue;
                vm_page_protect(p, VM_PROT_READ);
        }
}

/*
 *      vm_object_pmap_remove:
 *
 *      Removes all physical pages in the specified
 *      object range from all physical maps.
 *
 *      The object must *not* be locked.
 */
void
vm_object_pmap_remove(object, start, end)
        register vm_object_t object;
        register vm_pindex_t start;
        register vm_pindex_t end;
{
        register vm_page_t p;
        if (object == NULL)
                return;
        for (p = TAILQ_FIRST(&object->memq);
                p != NULL;
                p = TAILQ_NEXT(p, listq)) {
                if (p->pindex >= start && p->pindex < end)
                        vm_page_protect(p, VM_PROT_NONE);
        }
        if ((start == 0) && (object->size == end))
                vm_object_clear_flag(object, OBJ_WRITEABLE);
}

/*
 *      vm_object_madvise:
 *
 *      Implements the madvise function at the object/page level.
 *
 *      Currently, madvise() functions are limited to the default and
 *      swap object types only, and also limited to only the unshared portions 
 *      of a process's address space.  MADV_FREE, certainly, could never be
 *      run on anything else.  The others are more flexible and the code could
 *      be adjusted in the future to handle expanded cases for them.
 */
void
vm_object_madvise(object, pindex, count, advise)
        vm_object_t object;
        vm_pindex_t pindex;
        int count;
        int advise;
{
        vm_pindex_t end, tpindex;
        vm_object_t tobject;
        vm_page_t m;

        if (object == NULL)
                return;

        end = pindex + count;

        /*
         * MADV_FREE special case - free any swap backing store (as well
         * as resident pages later on).
         */

        if (advise == MADV_FREE) {
                tobject = object;
                tpindex = pindex;

                while (
                    (tobject->type == OBJT_DEFAULT || 
                     tobject->type == OBJT_SWAP) &&
                    (tobject->flags & OBJ_ONEMAPPING)
                ) {
                        if (tobject->type == OBJT_SWAP) {
                                swap_pager_freespace(tobject, tpindex, count);
                        }
                        if ((tobject = tobject->backing_object) == NULL)
                                break;
                        tpindex += OFF_TO_IDX(tobject->backing_object_offset);
                }
        }

        /*
         * Locate and adjust resident pages
         */

        for (; pindex < end; pindex += 1) {
relookup:
                tobject = object;
                tpindex = pindex;
shadowlookup:

                if (tobject->type != OBJT_DEFAULT &&
                    tobject->type != OBJT_SWAP
                ) {
                        continue;
                }

                if ((tobject->flags & OBJ_ONEMAPPING) == 0)
                        continue;

                m = vm_page_lookup(tobject, tpindex);

                if (m == NULL) {
                        tobject = tobject->backing_object;
                        if (tobject == NULL)
                                continue;
#if 0
                        if ((tobject == NULL) || (tobject->ref_count != 1)) {
                                continue;
                        }
#endif
                        tpindex += OFF_TO_IDX(tobject->backing_object_offset);
                        goto shadowlookup;
                }

                /*
                 * If the page is busy or not in a normal active state,
                 * we skip it.  Things can break if we mess with pages
                 * in any of the below states.
                 */
                if (
                    m->hold_count ||
                    m->wire_count ||
                    m->valid != VM_PAGE_BITS_ALL
                ) {
                        continue;
                }

                if (vm_page_sleep_busy(m, TRUE, "madvpo"))
                        goto relookup;

                if (advise == MADV_WILLNEED) {
                        vm_page_activate(m);
                } else if (advise == MADV_DONTNEED) {
                        vm_page_deactivate(m);
                } else if (advise == MADV_FREE) {
                        /*
                         * If MADV_FREE_FORCE_FREE is defined, we attempt to
                         * immediately free the page.  Otherwise we just 
                         * destroy any swap backing store, mark it clean,
                         * and stuff it into the cache.
                         */
                        pmap_clear_modify(VM_PAGE_TO_PHYS(m));
                        m->dirty = 0;

#ifdef MADV_FREE_FORCE_FREE
                        if (tobject->resident_page_count > 1) {
                                vm_page_busy(m);
                                vm_page_protect(m, VM_PROT_NONE);
                                vm_page_free(m);
                        } else
#endif
                        {
                                vm_page_cache(m);
                        }
                }
        }       
}

/*
 *      vm_object_shadow:
 *
 *      Create a new object which is backed by the
 *      specified existing object range.  The source
 *      object reference is deallocated.
 *
 *      The new object and offset into that object
 *      are returned in the source parameters.
 */

void
vm_object_shadow(object, offset, length)
        vm_object_t *object;    /* IN/OUT */
        vm_ooffset_t *offset;   /* IN/OUT */
        vm_size_t length;
{
        register vm_object_t source;
        register vm_object_t result;

        source = *object;

        /*
         * Allocate a new object with the given length
         */

        if ((result = vm_object_allocate(OBJT_DEFAULT, length)) == NULL)
                panic("vm_object_shadow: no object for shadowing");

        /*
         * The new object shadows the source object, adding a reference to it.
         * Our caller changes his reference to point to the new object,
         * removing a reference to the source object.  Net result: no change
         * of reference count.
         */
        result->backing_object = source;
        if (source) {
                TAILQ_INSERT_TAIL(&source->shadow_head, result, shadow_list);
                vm_object_clear_flag(source, OBJ_ONEMAPPING);
                source->shadow_count++;
                source->generation++;
        }

        /*
         * Store the offset into the source object, and fix up the offset into
         * the new object.
         */

        result->backing_object_offset = *offset;

        /*
         * Return the new things
         */

        *offset = 0;
        *object = result;
}


/*
 * this version of collapse allows the operation to occur earlier and
 * when paging_in_progress is true for an object...  This is not a complete
 * operation, but should plug 99.9% of the rest of the leaks.
 */
static void
vm_object_qcollapse(object)
        register vm_object_t object;
{
        register vm_object_t backing_object;
        register vm_pindex_t backing_offset_index;
        vm_pindex_t new_pindex;
        register vm_page_t p, pp;
        register vm_size_t size;

        backing_object = object->backing_object;
        if (backing_object->ref_count != 1)
                return;

        backing_object->ref_count += 2;

        backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
        size = object->size;

        p = TAILQ_FIRST(&backing_object->memq);
        while (p) {
                vm_page_t next;

                /*
                 * setup for loop.
                 * loop if the page isn't trivial.
                 */

                next = TAILQ_NEXT(p, listq);
                if ((p->flags & (PG_BUSY | PG_FICTITIOUS)) ||
                    !p->valid || p->hold_count || p->wire_count || p->busy) {
                        p = next;
                        continue;
                }

                /*
                 * busy the page and move it from the backing store to the
                 * parent object.
                 */

                vm_page_busy(p);

                KASSERT(p->object == object, ("vm_object_qcollapse(): object mismatch"));

                new_pindex = p->pindex - backing_offset_index;
                if (p->pindex < backing_offset_index ||
                    new_pindex >= size) {
                        if (backing_object->type == OBJT_SWAP)
                                swap_pager_freespace(backing_object,
                                    p->pindex,
                                    1);
                        vm_page_protect(p, VM_PROT_NONE);
                        vm_page_free(p);
                } else {
                        pp = vm_page_lookup(object, new_pindex);
                        if (pp != NULL ||
                                (object->type == OBJT_SWAP && vm_pager_has_page(object,
                                    new_pindex, NULL, NULL))) {
                                if (backing_object->type == OBJT_SWAP)
                                        swap_pager_freespace(backing_object,
                                            p->pindex, 1);
                                vm_page_protect(p, VM_PROT_NONE);
                                vm_page_free(p);
                        } else {
                                if (backing_object->type == OBJT_SWAP)
                                        swap_pager_freespace(backing_object,
                                            p->pindex, 1);

                                if ((p->queue - p->pc) == PQ_CACHE)
                                        vm_page_deactivate(p);
                                else
                                        vm_page_protect(p, VM_PROT_NONE);

                                vm_page_rename(p, object, new_pindex);
                                /* page automatically made dirty by rename */
                        }
                }
                p = next;
        }
        backing_object->ref_count -= 2;
}

/*
 *      vm_object_collapse:
 *
 *      Collapse an object with the object backing it.
 *      Pages in the backing object are moved into the
 *      parent, and the backing object is deallocated.
 */
void
vm_object_collapse(object)
        vm_object_t object;

{
        vm_object_t backing_object;
        vm_ooffset_t backing_offset;
        vm_size_t size;
        vm_pindex_t new_pindex, backing_offset_index;
        vm_page_t p, pp;

        while (TRUE) {
                /*
                 * Verify that the conditions are right for collapse:
                 *
                 * The object exists and no pages in it are currently being paged
                 * out.
                 */
                if (object == NULL)
                        return;

                /*
                 * Make sure there is a backing object.
                 */
                if ((backing_object = object->backing_object) == NULL)
                        return;

                /*
                 * we check the backing object first, because it is most likely
                 * not collapsable.
                 */
                if (backing_object->handle != NULL ||
                    (backing_object->type != OBJT_DEFAULT &&
                     backing_object->type != OBJT_SWAP) ||
                    (backing_object->flags & OBJ_DEAD) ||
                    object->handle != NULL ||
                    (object->type != OBJT_DEFAULT &&
                     object->type != OBJT_SWAP) ||
                    (object->flags & OBJ_DEAD)) {
                        return;
                }

                if (object->paging_in_progress != 0 ||
                    backing_object->paging_in_progress != 0) {
                        vm_object_qcollapse(object);
                        return;
                }

                /*
                 * We know that we can either collapse the backing object (if
                 * the parent is the only reference to it) or (perhaps) remove
                 * the parent's reference to it.
                 */

                backing_offset = object->backing_object_offset;
                backing_offset_index = OFF_TO_IDX(backing_offset);
                size = object->size;

                /*
                 * If there is exactly one reference to the backing object, we
                 * can collapse it into the parent.
                 */

                if (backing_object->ref_count == 1) {

                        vm_object_set_flag(backing_object, OBJ_DEAD);
                        /*
                         * We can collapse the backing object.
                         *
                         * Move all in-memory pages from backing_object to the
                         * parent.  Pages that have been paged out will be
                         * overwritten by any of the parent's pages that
                         * shadow them.
                         */

                        while ((p = TAILQ_FIRST(&backing_object->memq)) != 0) {
                                if (vm_page_sleep_busy(p, TRUE, "vmocol"))
                                        continue;
                                vm_page_busy(p);
                                new_pindex = p->pindex - backing_offset_index;

                                /*
                                 * If the parent has a page here, or if this
                                 * page falls outside the parent, dispose of
                                 * it.
                                 *
                                 * Otherwise, move it as planned.
                                 */

                                if (p->pindex < backing_offset_index ||
                                    new_pindex >= size) {
                                        vm_page_protect(p, VM_PROT_NONE);
                                        vm_page_free(p);
                                } else {
                                        pp = vm_page_lookup(object, new_pindex);
                                        if (pp != NULL || (object->type == OBJT_SWAP && vm_pager_has_page(object,
                                            new_pindex, NULL, NULL))) {
                                                vm_page_protect(p, VM_PROT_NONE);
                                                vm_page_free(p);
                                        } else {
                                                if ((p->queue - p->pc) == PQ_CACHE)
                                                        vm_page_deactivate(p);
                                                else
                                                        vm_page_protect(p, VM_PROT_NONE);
                                                vm_page_rename(p, object, new_pindex);
                                                /* page automatically made dirty by rename */
                                        }
                                }
                        }

                        /*
                         * Move the pager from backing_object to object.
                         */

                        if (backing_object->type == OBJT_SWAP) {
                                vm_object_pip_add(backing_object, 1);

                                /*
                                 * scrap the paging_offset junk and do a 
                                 * discrete copy.  This also removes major 
                                 * assumptions about how the swap-pager 
                                 * works from where it doesn't belong.  The
                                 * new swapper is able to optimize the
                                 * destroy-source case.
                                 */

                                vm_object_pip_add(object, 1);
                                swap_pager_copy(
                                    backing_object,
                                    object,
                                    OFF_TO_IDX(object->backing_object_offset), TRUE);
                                vm_object_pip_wakeup(object);

                                vm_object_pip_wakeup(backing_object);
                        }
                        /*
                         * Object now shadows whatever backing_object did.
                         * Note that the reference to backing_object->backing_object
                         * moves from within backing_object to within object.
                         */

                        TAILQ_REMOVE(&object->backing_object->shadow_head, object,
                            shadow_list);
                        object->backing_object->shadow_count--;
                        object->backing_object->generation++;
                        if (backing_object->backing_object) {
                                TAILQ_REMOVE(&backing_object->backing_object->shadow_head,
                                    backing_object, shadow_list);
                                backing_object->backing_object->shadow_count--;
                                backing_object->backing_object->generation++;
                        }
                        object->backing_object = backing_object->backing_object;
                        if (object->backing_object) {
                                TAILQ_INSERT_TAIL(&object->backing_object->shadow_head,
                                    object, shadow_list);
                                object->backing_object->shadow_count++;
                                object->backing_object->generation++;
                        }

                        object->backing_object_offset += backing_object->backing_object_offset;
                        /*
                         * Discard backing_object.
                         *
                         * Since the backing object has no pages, no pager left,
                         * and no object references within it, all that is
                         * necessary is to dispose of it.
                         */

                        TAILQ_REMOVE(&vm_object_list, backing_object,
                            object_list);
                        vm_object_count--;

                        zfree(obj_zone, backing_object);

                        object_collapses++;
                } else {
                        vm_object_t new_backing_object;
                        /*
                         * If all of the pages in the backing object are
                         * shadowed by the parent object, the parent object no
                         * longer has to shadow the backing object; it can
                         * shadow the next one in the chain.
                         *
                         * The backing object must not be paged out - we'd have
                         * to check all of the paged-out pages, as well.
                         */

                        if (backing_object->type != OBJT_DEFAULT) {
                                return;
                        }
                        /*
                         * Should have a check for a 'small' number of pages
                         * here.
                         */

                        for (p = TAILQ_FIRST(&backing_object->memq); p;
                                        p = TAILQ_NEXT(p, listq)) {

                                new_pindex = p->pindex - backing_offset_index;
                                vm_page_busy(p);

                                /*
                                 * If the parent has a page here, or if this
                                 * page falls outside the parent, keep going.
                                 *
                                 * Otherwise, the backing_object must be left in
                                 * the chain.
                                 */

                                if (p->pindex >= backing_offset_index &&
                                        new_pindex <= size) {

                                        pp = vm_page_lookup(object, new_pindex);

                                        if ((pp == NULL) || (pp->flags & PG_BUSY) || pp->busy) {
                                                vm_page_wakeup(p);
                                                return;
                                        }

                                        vm_page_busy(pp);
                                        if ((pp->valid == 0) &&
                                            !vm_pager_has_page(object, new_pindex, NULL, NULL)) {
                                                /*
                                                 * Page still needed. Can't go any
                                                 * further.
                                                 */
                                                vm_page_wakeup(pp);
                                                vm_page_wakeup(p);
                                                return;
                                        }
                                        vm_page_wakeup(pp);
                                }
                                vm_page_wakeup(p);
                        }

                        /*
                         * Make the parent shadow the next object in the
                         * chain.  Deallocating backing_object will not remove
                         * it, since its reference count is at least 2.
                         */

                        TAILQ_REMOVE(&backing_object->shadow_head,
                            object, shadow_list);
                        backing_object->shadow_count--;
                        backing_object->generation++;

                        new_backing_object = backing_object->backing_object;
                        if ((object->backing_object = new_backing_object) != NULL) {
                                vm_object_reference(new_backing_object);
                                TAILQ_INSERT_TAIL(&new_backing_object->shadow_head,
                                    object, shadow_list);
                                new_backing_object->shadow_count++;
                                new_backing_object->generation++;
                                object->backing_object_offset +=
                                        backing_object->backing_object_offset;
                        }

                        /*
                         * Drop the reference count on backing_object. Since
                         * its ref_count was at least 2, it will not vanish;
                         * so we don't need to call vm_object_deallocate, but
                         * we do anyway.
                         */
                        vm_object_deallocate(backing_object);
                        object_bypasses++;
                }

                /*
                 * Try again with this object's new backing object.
                 */
        }
}

/*
 *      vm_object_page_remove: [internal]
 *
 *      Removes all physical pages in the specified
 *      object range from the object's list of pages.
 *
 *      The object must be locked.
 */
void
vm_object_page_remove(object, start, end, clean_only)
        register vm_object_t object;
        register vm_pindex_t start;
        register vm_pindex_t end;
        boolean_t clean_only;
{
        register vm_page_t p, next;
        unsigned int size;
        int all;

        if (object == NULL)
                return;

        all = ((end == 0) && (start == 0));

        vm_object_pip_add(object, 1);
again:
        size = end - start;
        if (all || size > 4 || size >= object->size / 4) {
                for (p = TAILQ_FIRST(&object->memq); p != NULL; p = next) {
                        next = TAILQ_NEXT(p, listq);
                        if (all || ((start <= p->pindex) && (p->pindex < end))) {
                                if (p->wire_count != 0) {
                                        vm_page_protect(p, VM_PROT_NONE);
                                        if (!clean_only)
                                                p->valid = 0;
                                        continue;
                                }

                                /*
                                 * The busy flags are only cleared at
                                 * interrupt -- minimize the spl transitions
                                 */

                                if (vm_page_sleep_busy(p, TRUE, "vmopar"))
                                        goto again;

                                if (clean_only && p->valid) {
                                        vm_page_test_dirty(p);
                                        if (p->valid & p->dirty)
                                                continue;
                                }

                                vm_page_busy(p);
                                vm_page_protect(p, VM_PROT_NONE);
                                vm_page_free(p);
                        }
                }
        } else {
                while (size > 0) {
                        if ((p = vm_page_lookup(object, start)) != 0) {

                                if (p->wire_count != 0) {
                                        vm_page_protect(p, VM_PROT_NONE);
                                        if (!clean_only)
                                                p->valid = 0;
                                        start += 1;
                                        size -= 1;
                                        continue;
                                }

                                /*
                                 * The busy flags are only cleared at
                                 * interrupt -- minimize the spl transitions
                                 */
                                if (vm_page_sleep_busy(p, TRUE, "vmopar"))
                                        goto again;

                                if (clean_only && p->valid) {
                                        vm_page_test_dirty(p);
                                        if (p->valid & p->dirty) {
                                                start += 1;
                                                size -= 1;
                                                continue;
                                        }
                                }

                                vm_page_busy(p);
                                vm_page_protect(p, VM_PROT_NONE);
                                vm_page_free(p);
                        }
                        start += 1;
                        size -= 1;
                }
        }
        vm_object_pip_wakeup(object);
}

/*
 *      Routine:        vm_object_coalesce
 *      Function:       Coalesces two objects backing up adjoining
 *                      regions of memory into a single object.
 *
 *      returns TRUE if objects were combined.
 *
 *      NOTE:   Only works at the moment if the second object is NULL -
 *              if it's not, which object do we lock first?
 *
 *      Parameters:
 *              prev_object     First object to coalesce
 *              prev_offset     Offset into prev_object
 *              next_object     Second object into coalesce
 *              next_offset     Offset into next_object
 *
 *              prev_size       Size of reference to prev_object
 *              next_size       Size of reference to next_object
 *
 *      Conditions:
 *      The object must *not* be locked.
 */
boolean_t
vm_object_coalesce(prev_object, prev_pindex, prev_size, next_size)
        register vm_object_t prev_object;
        vm_pindex_t prev_pindex;
        vm_size_t prev_size, next_size;
{
        vm_size_t newsize;

        if (prev_object == NULL) {
                return (TRUE);
        }

        if (prev_object->type != OBJT_DEFAULT) {
                return (FALSE);
        }

        /*
         * Try to collapse the object first
         */
        vm_object_collapse(prev_object);

        /*
         * Can't coalesce if: . more than one reference . paged out . shadows
         * another object . has a copy elsewhere (any of which mean that the
         * pages not mapped to prev_entry may be in use anyway)
         */

        if (prev_object->backing_object != NULL) {
                return (FALSE);
        }

        prev_size >>= PAGE_SHIFT;
        next_size >>= PAGE_SHIFT;

        if ((prev_object->ref_count > 1) &&
            (prev_object->size != prev_pindex + prev_size)) {
                return (FALSE);
        }

        /*
         * Remove any pages that may still be in the object from a previous
         * deallocation.
         */

        vm_object_page_remove(prev_object,
            prev_pindex + prev_size,
            prev_pindex + prev_size + next_size, FALSE);

        /*
         * Extend the object if necessary.
         */
        newsize = prev_pindex + prev_size + next_size;
        if (newsize > prev_object->size)
                prev_object->size = newsize;

        return (TRUE);
}

#include "opt_ddb.h"
#ifdef DDB
#include <sys/kernel.h>

#include <machine/cons.h>

#include <ddb/ddb.h>

static int      _vm_object_in_map __P((vm_map_t map, vm_object_t object,
                                       vm_map_entry_t entry));
static int      vm_object_in_map __P((vm_object_t object));

static int
_vm_object_in_map(map, object, entry)
        vm_map_t map;
        vm_object_t object;
        vm_map_entry_t entry;
{
        vm_map_t tmpm;
        vm_map_entry_t tmpe;
        vm_object_t obj;
        int entcount;

        if (map == 0)
                return 0;

        if (entry == 0) {
                tmpe = map->header.next;
                entcount = map->nentries;
                while (entcount-- && (tmpe != &map->header)) {
                        if( _vm_object_in_map(map, object, tmpe)) {
                                return 1;
                        }
                        tmpe = tmpe->next;
                }
        } else if (entry->eflags & (MAP_ENTRY_IS_A_MAP|MAP_ENTRY_IS_SUB_MAP)) {
                tmpm = entry->object.share_map;
                tmpe = tmpm->header.next;
                entcount = tmpm->nentries;
                while (entcount-- && tmpe != &tmpm->header) {
                        if( _vm_object_in_map(tmpm, object, tmpe)) {
                                return 1;
                        }
                        tmpe = tmpe->next;
                }
        } else if ((obj = entry->object.vm_object) != NULL) {
                for(; obj; obj=obj->backing_object)
                        if( obj == object) {
                                return 1;
                        }
        }
        return 0;
}

static int
vm_object_in_map( object)
        vm_object_t object;
{
        struct proc *p;
        for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
                if( !p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */)
                        continue;
                if( _vm_object_in_map(&p->p_vmspace->vm_map, object, 0))
                        return 1;
        }
        if( _vm_object_in_map( kernel_map, object, 0))
                return 1;
        if( _vm_object_in_map( kmem_map, object, 0))
                return 1;
        if( _vm_object_in_map( pager_map, object, 0))
                return 1;
        if( _vm_object_in_map( buffer_map, object, 0))
                return 1;
        if( _vm_object_in_map( io_map, object, 0))
                return 1;
        if( _vm_object_in_map( phys_map, object, 0))
                return 1;
        if( _vm_object_in_map( mb_map, object, 0))
                return 1;
        if( _vm_object_in_map( u_map, object, 0))
                return 1;
        return 0;
}

DB_SHOW_COMMAND(vmochk, vm_object_check)
{
        vm_object_t object;

        /*
         * make sure that internal objs are in a map somewhere
         * and none have zero ref counts.
         */
        for (object = TAILQ_FIRST(&vm_object_list);
                        object != NULL;
                        object = TAILQ_NEXT(object, object_list)) {
                if (object->handle == NULL &&
                    (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) {
                        if (object->ref_count == 0) {
                                db_printf("vmochk: internal obj has zero ref count: %d\n",
                                        object->size);
                        }
                        if (!vm_object_in_map(object)) {
                                db_printf(
                        "vmochk: internal obj is not in a map: "
                        "ref: %d, size: %lu: 0x%lx, backing_object: %p\n",
                                    object->ref_count, (u_long)object->size, 
                                    (u_long)object->size,
                                    (void *)object->backing_object);
                        }
                }
        }
}

/*
 *      vm_object_print:        [ debug ]
 */
DB_SHOW_COMMAND(object, vm_object_print_static)
{
        /* XXX convert args. */
        vm_object_t object = (vm_object_t)addr;
        boolean_t full = have_addr;

        register vm_page_t p;

        /* XXX count is an (unused) arg.  Avoid shadowing it. */
#define count   was_count

        register int count;

        if (object == NULL)
                return;

        db_iprintf(
            "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n",
            object, (int)object->type, (u_long)object->size,
            object->resident_page_count, object->ref_count, object->flags);
        /*
         * XXX no %qd in kernel.  Truncate object->backing_object_offset.
         */
        db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n",
            object->shadow_count, 
            object->backing_object ? object->backing_object->ref_count : 0,
            object->backing_object, (long)object->backing_object_offset);

        if (!full)
                return;

        db_indent += 2;
        count = 0;
        for (p = TAILQ_FIRST(&object->memq); p != NULL; p = TAILQ_NEXT(p, listq)) {
                if (count == 0)
                        db_iprintf("memory:=");
                else if (count == 6) {
                        db_printf("\n");
                        db_iprintf(" ...");
                        count = 0;
                } else
                        db_printf(",");
                count++;

                db_printf("(off=0x%lx,page=0x%lx)",
                    (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p));
        }
        if (count != 0)
                db_printf("\n");
        db_indent -= 2;
}

/* XXX. */
#undef count

/* XXX need this non-static entry for calling from vm_map_print. */
void
vm_object_print(addr, have_addr, count, modif)
        /* db_expr_t */ long addr;
        boolean_t have_addr;
        /* db_expr_t */ long count;
        char *modif;
{
        vm_object_print_static(addr, have_addr, count, modif);
}

DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
{
        vm_object_t object;
        int nl = 0;
        int c;
        for (object = TAILQ_FIRST(&vm_object_list);
                        object != NULL;
                        object = TAILQ_NEXT(object, object_list)) {
                vm_pindex_t idx, fidx;
                vm_pindex_t osize;
                vm_offset_t pa = -1, padiff;
                int rcount;
                vm_page_t m;

                db_printf("new object: %p\n", (void *)object);
                if ( nl > 18) {
                        c = cngetc();
                        if (c != ' ')
                                return;
                        nl = 0;
                }
                nl++;
                rcount = 0;
                fidx = 0;
                osize = object->size;
                if (osize > 128)
                        osize = 128;
                for(idx=0;idx<osize;idx++) {
                        m = vm_page_lookup(object, idx);
                        if (m == NULL) {
                                if (rcount) {
                                        db_printf(" index(%d)run(%d)pa(0x%x)\n",
                                                fidx, rcount, pa);
                                        if ( nl > 18) {
                                                c = cngetc();
                                                if (c != ' ')
                                                        return;
                                                nl = 0;
                                        }
                                        nl++;
                                        rcount = 0;
                                }
                                continue;
                        }

                                
                        if (rcount &&
                                (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
                                ++rcount;
                                continue;
                        }
                        if (rcount) {
                                padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m);
                                padiff >>= PAGE_SHIFT;
                                padiff &= PQ_L2_MASK;
                                if (padiff == 0) {
                                        pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE;
                                        ++rcount;
                                        continue;
                                }
                                db_printf(" index(%d)run(%d)pa(0x%x)", fidx, rcount, pa);
                                db_printf("pd(%d)\n", padiff);
                                if ( nl > 18) {
                                        c = cngetc();
                                        if (c != ' ')
                                                return;
                                        nl = 0;
                                }
                                nl++;
                        }
                        fidx = idx;
                        pa = VM_PAGE_TO_PHYS(m);
                        rcount = 1;
                }
                if (rcount) {
                        db_printf(" index(%d)run(%d)pa(0x%x)\n", fidx, rcount, pa);
                        if ( nl > 18) {
                                c = cngetc();
                                if (c != ' ')
                                        return;
                                nl = 0;
                        }
                        nl++;
                }
        }
}
#endif /* DDB */