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freebsd-dev/sys/vm/vm_object.c
Matthew Dillon 1ce137be82 Fix a bug in the new madvise() code that would possibly (improperly) 
free swap space out from under a busy page.  This is not legal because
    the swap may be reallocated and I/O issued while I/O is still in
    progress on the same swap page from the madvise()'d object.  This bug
    could only occur under extreme paging conditions but might not cause
    an error until much later.  As a side-benefit, madvise() is now even
    smaller.
1999-02-15 02:03:40 +00:00

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/*
* 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 1.150 1999/02/12 20:42:19 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];
void
_vm_object_allocate(type, size, object)
objtype_t type;
vm_size_t size;
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 ((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;
/*
* 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;
{
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)
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)
vm_object_t object;
{
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;
{
vm_page_t p, np, tp;
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)
vm_object_t object;
{
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
/*
* 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)
vm_object_t object;
vm_pindex_t start;
vm_pindex_t end;
{
vm_pindex_t idx;
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)
vm_object_t object;
vm_pindex_t start;
vm_pindex_t end;
{
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;
/*
* 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) {
/*
* There may be swap even if there is no backing page
*/
if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
swap_pager_freespace(tobject, tpindex, 1);
/*
* next object
*/
tobject = tobject->backing_object;
if (tobject == NULL)
continue;
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) {
/*
* Mark the page clean. This will allow the page
* to be freed up by the system. However, such pages
* are often reused quickly by malloc()/free()
* so we do not do anything that would cause
* a page fault if we can help it.
*
* Specifically, we do not try to actually free
* the page now nor do we try to put it in the
* cache (which would cause a page fault on reuse).
*
* But we do make the page is freeable as we
* can without actually taking the step of unmapping
* it.
*/
pmap_clear_modify(VM_PAGE_TO_PHYS(m));
m->dirty = 0;
m->act_count = 0;
vm_page_deactivate(m);
if (tobject->type == OBJT_SWAP)
swap_pager_freespace(tobject, tpindex, 1);
}
}
}
/*
* 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;
{
vm_object_t source;
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.
*
* Try to optimize the result object's page color when shadowing
* in order to maintain page coloring consistancy in the combined
* shadowed object.
*/
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++;
result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) & PQ_L2_MASK;
}
/*
* 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;
}
#define OBSC_TEST_ALL_SHADOWED 0x0001
#define OBSC_COLLAPSE_NOWAIT 0x0002
#define OBSC_COLLAPSE_WAIT 0x0004
static __inline int
vm_object_backing_scan(vm_object_t object, int op)
{
int s;
int r = 1;
vm_page_t p;
vm_object_t backing_object;
vm_pindex_t backing_offset_index;
s = splvm();
backing_object = object->backing_object;
backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
/*
* Initial conditions
*/
if (op & OBSC_TEST_ALL_SHADOWED) {
/*
* We do not want to have to test for the existance of
* swap pages in the backing object. XXX but with the
* new swapper this would be pretty easy to do.
*
* XXX what about anonymous MAP_SHARED memory that hasn't
* been ZFOD faulted yet? If we do not test for this, the
* shadow test may succeed! XXX
*/
if (backing_object->type != OBJT_DEFAULT) {
splx(s);
return(0);
}
}
if (op & OBSC_COLLAPSE_WAIT) {
vm_object_set_flag(backing_object, OBJ_DEAD);
}
/*
* Our scan
*/
p = TAILQ_FIRST(&backing_object->memq);
while (p) {
vm_page_t next = TAILQ_NEXT(p, listq);
vm_pindex_t new_pindex = p->pindex - backing_offset_index;
if (op & OBSC_TEST_ALL_SHADOWED) {
vm_page_t pp;
/*
* Ignore pages outside the parent object's range
* and outside the parent object's mapping of the
* backing object.
*
* note that we do not busy the backing object's
* page.
*/
if (
p->pindex < backing_offset_index ||
new_pindex >= object->size
) {
p = next;
continue;
}
/*
* See if the parent has the page or if the parent's
* object pager has the page. If the parent has the
* page but the page is not valid, the parent's
* object pager must have the page.
*
* If this fails, the parent does not completely shadow
* the object and we might as well give up now.
*/
pp = vm_page_lookup(object, new_pindex);
if (
(pp == NULL || pp->valid == 0) &&
!vm_pager_has_page(object, new_pindex, NULL, NULL)
) {
r = 0;
break;
}
}
/*
* Check for busy page
*/
if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
vm_page_t pp;
if (op & OBSC_COLLAPSE_NOWAIT) {
if (
(p->flags & PG_BUSY) ||
!p->valid ||
p->hold_count ||
p->wire_count ||
p->busy
) {
p = next;
continue;
}
} else if (op & OBSC_COLLAPSE_WAIT) {
if (vm_page_sleep_busy(p, TRUE, "vmocol")) {
/*
* If we slept, anything could have
* happened. Since the object is
* marked dead, the backing offset
* should not have changed so we
* just restart our scan.
*/
p = TAILQ_FIRST(&backing_object->memq);
continue;
}
}
/*
* Busy the page
*/
vm_page_busy(p);
KASSERT(
p->object == backing_object,
("vm_object_qcollapse(): object mismatch")
);
/*
* Destroy any associated swap
*/
if (backing_object->type == OBJT_SWAP) {
swap_pager_freespace(
backing_object,
p->pindex,
1
);
}
if (
p->pindex < backing_offset_index ||
new_pindex >= object->size
) {
/*
* Page is out of the parent object's range, we
* can simply destroy it.
*/
vm_page_protect(p, VM_PROT_NONE);
vm_page_free(p);
p = next;
continue;
}
pp = vm_page_lookup(object, new_pindex);
if (
pp != NULL ||
vm_pager_has_page(object, new_pindex, NULL, NULL)
) {
/*
* page already exists in parent OR swap exists
* for this location in the parent. Destroy
* the original page from the backing object.
*
* Leave the parent's page alone
*/
vm_page_protect(p, VM_PROT_NONE);
vm_page_free(p);
p = next;
continue;
}
/*
* Page does not exist in parent, rename the
* page from the backing object to the main object.
*/
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;
}
splx(s);
return(r);
}
/*
* 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)
vm_object_t object;
{
vm_object_t backing_object = object->backing_object;
if (backing_object->ref_count != 1)
return;
backing_object->ref_count += 2;
vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT);
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;
{
while (TRUE) {
vm_object_t backing_object;
/*
* Verify that the conditions are right for collapse:
*
* The object exists and the backing object exists.
*/
if (object == NULL)
break;
if ((backing_object = object->backing_object) == NULL)
break;
/*
* 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)) {
break;
}
if (
object->paging_in_progress != 0 ||
backing_object->paging_in_progress != 0
) {
vm_object_qcollapse(object);
break;
}
/*
* We know that we can either collapse the backing object (if
* the parent is the only reference to it) or (perhaps) have
* the parent bypass the object if the parent happens to shadow
* all the resident pages in the entire backing object.
*
* This is ignoring pager-backed pages such as swap pages.
* vm_object_backing_scan fails the shadowing test in this
* case.
*/
if (backing_object->ref_count == 1) {
/*
* If there is exactly one reference to the backing
* object, we can collapse it into the parent.
*/
vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT);
/*
* 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 we do not entirely shadow the backing object,
* there is nothing we can do so we give up.
*/
if (vm_object_backing_scan(object, OBSC_TEST_ALL_SHADOWED) == 0) {
break;
}
/*
* 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)
vm_object_t object;
vm_pindex_t start;
vm_pindex_t end;
boolean_t clean_only;
{
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)
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 &&
prev_object->type != OBJT_SWAP) {
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_SUB_MAP) {
tmpm = entry->object.sub_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;
vm_page_t p;
/* XXX count is an (unused) arg. Avoid shadowing it. */
#define count was_count
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 */
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