2 * Copyright (c) 1991, 1993, 2013
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * The Mach Operating System project at Carnegie-Mellon University.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * from: @(#)vm_object.c 8.5 (Berkeley) 3/22/94
35 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
36 * All rights reserved.
38 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
40 * Permission to use, copy, modify and distribute this software and
41 * its documentation is hereby granted, provided that both the copyright
42 * notice and this permission notice appear in all copies of the
43 * software, derivative works or modified versions, and any portions
44 * thereof, and that both notices appear in supporting documentation.
46 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
47 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
48 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
50 * Carnegie Mellon requests users of this software to return to
52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
53 * School of Computer Science
54 * Carnegie Mellon University
55 * Pittsburgh PA 15213-3890
57 * any improvements or extensions that they make and grant Carnegie the
58 * rights to redistribute these changes.
60 * $FreeBSD: src/sys/vm/vm_object.c,v 1.171.2.8 2003/05/26 19:17:56 alc Exp $
64 * Virtual memory object module.
67 #include <sys/param.h>
68 #include <sys/systm.h>
69 #include <sys/proc.h> /* for curproc, pageproc */
70 #include <sys/thread.h>
71 #include <sys/vnode.h>
72 #include <sys/vmmeter.h>
74 #include <sys/mount.h>
75 #include <sys/kernel.h>
76 #include <sys/sysctl.h>
77 #include <sys/refcount.h>
80 #include <vm/vm_param.h>
82 #include <vm/vm_map.h>
83 #include <vm/vm_object.h>
84 #include <vm/vm_page.h>
85 #include <vm/vm_pageout.h>
86 #include <vm/vm_pager.h>
87 #include <vm/swap_pager.h>
88 #include <vm/vm_kern.h>
89 #include <vm/vm_extern.h>
90 #include <vm/vm_zone.h>
92 #include <vm/vm_page2.h>
94 #include <machine/specialreg.h>
96 #define EASY_SCAN_FACTOR 8
98 static void vm_object_qcollapse(vm_object_t object,
99 vm_object_t backing_object);
100 static void vm_object_page_collect_flush(vm_object_t object, vm_page_t p,
102 static void vm_object_lock_init(vm_object_t);
106 * Virtual memory objects maintain the actual data
107 * associated with allocated virtual memory. A given
108 * page of memory exists within exactly one object.
110 * An object is only deallocated when all "references"
111 * are given up. Only one "reference" to a given
112 * region of an object should be writeable.
114 * Associated with each object is a list of all resident
115 * memory pages belonging to that object; this list is
116 * maintained by the "vm_page" module, and locked by the object's
119 * Each object also records a "pager" routine which is
120 * used to retrieve (and store) pages to the proper backing
121 * storage. In addition, objects may be backed by other
122 * objects from which they were virtual-copied.
124 * The only items within the object structure which are
125 * modified after time of creation are:
126 * reference count locked by object's lock
127 * pager routine locked by object's lock
131 struct vm_object kernel_object;
133 static long vm_object_count;
135 static long object_collapses;
136 static long object_bypasses;
137 static int next_index;
138 static vm_zone_t obj_zone;
139 static struct vm_zone obj_zone_store;
140 #define VM_OBJECTS_INIT 256
141 static struct vm_object vm_objects_init[VM_OBJECTS_INIT];
143 struct object_q vm_object_lists[VMOBJ_HSIZE];
144 struct lwkt_token vmobj_tokens[VMOBJ_HSIZE];
146 #if defined(DEBUG_LOCKS)
148 #define vm_object_vndeallocate(obj, vpp) \
149 debugvm_object_vndeallocate(obj, vpp, __FILE__, __LINE__)
152 * Debug helper to track hold/drop/ref/deallocate calls.
155 debugvm_object_add(vm_object_t obj, char *file, int line, int addrem)
159 i = atomic_fetchadd_int(&obj->debug_index, 1);
160 i = i & (VMOBJ_DEBUG_ARRAY_SIZE - 1);
161 ksnprintf(obj->debug_hold_thrs[i],
162 sizeof(obj->debug_hold_thrs[i]),
164 (addrem == -1 ? '-' : (addrem == 1 ? '+' : '=')),
165 (curthread->td_proc ? curthread->td_proc->p_pid : -1),
168 obj->debug_hold_file[i] = file;
169 obj->debug_hold_line[i] = line;
171 /* Uncomment for debugging obj refs/derefs in reproducable cases */
172 if (strcmp(curthread->td_comm, "sshd") == 0) {
173 kprintf("%d %p refs=%d ar=%d file: %s/%d\n",
174 (curthread->td_proc ? curthread->td_proc->p_pid : -1),
175 obj, obj->ref_count, addrem, file, line);
183 * Misc low level routines
186 vm_object_lock_init(vm_object_t obj)
188 #if defined(DEBUG_LOCKS)
191 obj->debug_index = 0;
192 for (i = 0; i < VMOBJ_DEBUG_ARRAY_SIZE; i++) {
193 obj->debug_hold_thrs[i][0] = 0;
194 obj->debug_hold_file[i] = NULL;
195 obj->debug_hold_line[i] = 0;
201 vm_object_lock_swap(void)
207 vm_object_lock(vm_object_t obj)
209 lwkt_gettoken(&obj->token);
213 * Returns TRUE on sucesss
216 vm_object_lock_try(vm_object_t obj)
218 return(lwkt_trytoken(&obj->token));
222 vm_object_lock_shared(vm_object_t obj)
224 lwkt_gettoken_shared(&obj->token);
228 vm_object_unlock(vm_object_t obj)
230 lwkt_reltoken(&obj->token);
234 vm_object_upgrade(vm_object_t obj)
236 lwkt_reltoken(&obj->token);
237 lwkt_gettoken(&obj->token);
241 vm_object_downgrade(vm_object_t obj)
243 lwkt_reltoken(&obj->token);
244 lwkt_gettoken_shared(&obj->token);
248 vm_object_assert_held(vm_object_t obj)
250 ASSERT_LWKT_TOKEN_HELD(&obj->token);
254 VMOBJDEBUG(vm_object_hold)(vm_object_t obj VMOBJDBARGS)
256 KKASSERT(obj != NULL);
259 * Object must be held (object allocation is stable due to callers
260 * context, typically already holding the token on a parent object)
261 * prior to potentially blocking on the lock, otherwise the object
262 * can get ripped away from us.
264 refcount_acquire(&obj->hold_count);
267 #if defined(DEBUG_LOCKS)
268 debugvm_object_add(obj, file, line, 1);
273 VMOBJDEBUG(vm_object_hold_try)(vm_object_t obj VMOBJDBARGS)
275 KKASSERT(obj != NULL);
278 * Object must be held (object allocation is stable due to callers
279 * context, typically already holding the token on a parent object)
280 * prior to potentially blocking on the lock, otherwise the object
281 * can get ripped away from us.
283 refcount_acquire(&obj->hold_count);
284 if (vm_object_lock_try(obj) == 0) {
285 if (refcount_release(&obj->hold_count)) {
286 if (obj->ref_count == 0 && (obj->flags & OBJ_DEAD))
287 zfree(obj_zone, obj);
292 #if defined(DEBUG_LOCKS)
293 debugvm_object_add(obj, file, line, 1);
299 VMOBJDEBUG(vm_object_hold_shared)(vm_object_t obj VMOBJDBARGS)
301 KKASSERT(obj != NULL);
304 * Object must be held (object allocation is stable due to callers
305 * context, typically already holding the token on a parent object)
306 * prior to potentially blocking on the lock, otherwise the object
307 * can get ripped away from us.
309 refcount_acquire(&obj->hold_count);
310 vm_object_lock_shared(obj);
312 #if defined(DEBUG_LOCKS)
313 debugvm_object_add(obj, file, line, 1);
318 * Drop the token and hold_count on the object.
320 * WARNING! Token might be shared.
323 VMOBJDEBUG(vm_object_drop)(vm_object_t obj VMOBJDBARGS)
329 * No new holders should be possible once we drop hold_count 1->0 as
330 * there is no longer any way to reference the object.
332 KKASSERT(obj->hold_count > 0);
333 if (refcount_release(&obj->hold_count)) {
334 #if defined(DEBUG_LOCKS)
335 debugvm_object_add(obj, file, line, -1);
338 if (obj->ref_count == 0 && (obj->flags & OBJ_DEAD)) {
339 vm_object_unlock(obj);
340 zfree(obj_zone, obj);
342 vm_object_unlock(obj);
345 #if defined(DEBUG_LOCKS)
346 debugvm_object_add(obj, file, line, -1);
348 vm_object_unlock(obj);
353 * Initialize a freshly allocated object, returning a held object.
355 * Used only by vm_object_allocate() and zinitna().
360 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object)
365 RB_INIT(&object->rb_memq);
366 LIST_INIT(&object->shadow_head);
367 lwkt_token_init(&object->token, "vmobj");
371 object->ref_count = 1;
372 object->memattr = VM_MEMATTR_DEFAULT;
373 object->hold_count = 0;
375 if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP))
376 vm_object_set_flag(object, OBJ_ONEMAPPING);
377 object->paging_in_progress = 0;
378 object->resident_page_count = 0;
379 object->agg_pv_list_count = 0;
380 object->shadow_count = 0;
381 /* cpu localization twist */
382 object->pg_color = (int)(intptr_t)curthread;
383 if ( size > (PQ_L2_SIZE / 3 + PQ_PRIME1))
384 incr = PQ_L2_SIZE / 3 + PQ_PRIME1;
387 next_index = (next_index + incr) & PQ_L2_MASK;
388 object->handle = NULL;
389 object->backing_object = NULL;
390 object->backing_object_offset = (vm_ooffset_t)0;
392 object->generation++;
393 object->swblock_count = 0;
394 RB_INIT(&object->swblock_root);
395 vm_object_lock_init(object);
396 pmap_object_init(object);
398 vm_object_hold(object);
400 n = VMOBJ_HASH(object);
401 atomic_add_long(&vm_object_count, 1);
402 lwkt_gettoken(&vmobj_tokens[n]);
403 TAILQ_INSERT_TAIL(&vm_object_lists[n], object, object_list);
404 lwkt_reltoken(&vmobj_tokens[n]);
408 * Initialize the VM objects module.
410 * Called from the low level boot code only.
417 for (i = 0; i < VMOBJ_HSIZE; ++i) {
418 TAILQ_INIT(&vm_object_lists[i]);
419 lwkt_token_init(&vmobj_tokens[i], "vmobjlst");
422 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(KvaEnd),
424 vm_object_drop(&kernel_object);
426 obj_zone = &obj_zone_store;
427 zbootinit(obj_zone, "VM OBJECT", sizeof (struct vm_object),
428 vm_objects_init, VM_OBJECTS_INIT);
432 vm_object_init2(void)
434 zinitna(obj_zone, NULL, NULL, 0, 0, ZONE_PANICFAIL, 1);
438 * Allocate and return a new object of the specified type and size.
443 vm_object_allocate(objtype_t type, vm_pindex_t size)
447 result = (vm_object_t) zalloc(obj_zone);
449 _vm_object_allocate(type, size, result);
450 vm_object_drop(result);
456 * This version returns a held object, allowing further atomic initialization
460 vm_object_allocate_hold(objtype_t type, vm_pindex_t size)
464 result = (vm_object_t) zalloc(obj_zone);
466 _vm_object_allocate(type, size, result);
472 * Add an additional reference to a vm_object. The object must already be
473 * held. The original non-lock version is no longer supported. The object
474 * must NOT be chain locked by anyone at the time the reference is added.
476 * Referencing a chain-locked object can blow up the fairly sensitive
477 * ref_count and shadow_count tests in the deallocator. Most callers
478 * will call vm_object_chain_wait() prior to calling
479 * vm_object_reference_locked() to avoid the case.
481 * The object must be held, but may be held shared if desired (hence why
482 * we use an atomic op).
485 VMOBJDEBUG(vm_object_reference_locked)(vm_object_t object VMOBJDBARGS)
487 KKASSERT(object != NULL);
488 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
489 KKASSERT((object->chainlk & (CHAINLK_EXCL | CHAINLK_MASK)) == 0);
490 atomic_add_int(&object->ref_count, 1);
491 if (object->type == OBJT_VNODE) {
492 vref(object->handle);
493 /* XXX what if the vnode is being destroyed? */
495 #if defined(DEBUG_LOCKS)
496 debugvm_object_add(object, file, line, 1);
501 * This version is only allowed for vnode objects.
504 VMOBJDEBUG(vm_object_reference_quick)(vm_object_t object VMOBJDBARGS)
506 KKASSERT(object->type == OBJT_VNODE);
507 atomic_add_int(&object->ref_count, 1);
508 vref(object->handle);
509 #if defined(DEBUG_LOCKS)
510 debugvm_object_add(object, file, line, 1);
515 * Object OBJ_CHAINLOCK lock handling.
517 * The caller can chain-lock backing objects recursively and then
518 * use vm_object_chain_release_all() to undo the whole chain.
520 * Chain locks are used to prevent collapses and are only applicable
521 * to OBJT_DEFAULT and OBJT_SWAP objects. Chain locking operations
522 * on other object types are ignored. This is also important because
523 * it allows e.g. the vnode underlying a memory mapping to take concurrent
526 * The object must usually be held on entry, though intermediate
527 * objects need not be held on release. The object must be held exclusively,
528 * NOT shared. Note that the prefault path checks the shared state and
529 * avoids using the chain functions.
532 vm_object_chain_wait(vm_object_t object, int shared)
534 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
536 uint32_t chainlk = object->chainlk;
540 if (chainlk & (CHAINLK_EXCL | CHAINLK_EXCLREQ)) {
541 tsleep_interlock(object, 0);
542 if (atomic_cmpset_int(&object->chainlk,
544 chainlk | CHAINLK_WAIT)) {
545 tsleep(object, PINTERLOCKED,
554 if (chainlk & (CHAINLK_MASK | CHAINLK_EXCL)) {
555 tsleep_interlock(object, 0);
556 if (atomic_cmpset_int(&object->chainlk,
558 chainlk | CHAINLK_WAIT))
560 tsleep(object, PINTERLOCKED,
565 if (atomic_cmpset_int(&object->chainlk,
567 chainlk & ~CHAINLK_WAIT))
569 if (chainlk & CHAINLK_WAIT)
581 vm_object_chain_acquire(vm_object_t object, int shared)
583 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP)
585 if (vm_shared_fault == 0)
589 uint32_t chainlk = object->chainlk;
593 if (chainlk & (CHAINLK_EXCL | CHAINLK_EXCLREQ)) {
594 tsleep_interlock(object, 0);
595 if (atomic_cmpset_int(&object->chainlk,
597 chainlk | CHAINLK_WAIT)) {
598 tsleep(object, PINTERLOCKED,
602 } else if (atomic_cmpset_int(&object->chainlk,
603 chainlk, chainlk + 1)) {
608 if (chainlk & (CHAINLK_MASK | CHAINLK_EXCL)) {
609 tsleep_interlock(object, 0);
610 if (atomic_cmpset_int(&object->chainlk,
615 tsleep(object, PINTERLOCKED,
620 if (atomic_cmpset_int(&object->chainlk,
622 (chainlk | CHAINLK_EXCL) &
625 if (chainlk & CHAINLK_WAIT)
637 vm_object_chain_release(vm_object_t object)
639 /*ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));*/
640 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP)
642 KKASSERT(object->chainlk & (CHAINLK_MASK | CHAINLK_EXCL));
644 uint32_t chainlk = object->chainlk;
647 if (chainlk & CHAINLK_MASK) {
648 if ((chainlk & CHAINLK_MASK) == 1 &&
649 atomic_cmpset_int(&object->chainlk,
651 (chainlk - 1) & ~CHAINLK_WAIT)) {
652 if (chainlk & CHAINLK_WAIT)
656 if ((chainlk & CHAINLK_MASK) > 1 &&
657 atomic_cmpset_int(&object->chainlk,
658 chainlk, chainlk - 1)) {
663 KKASSERT(chainlk & CHAINLK_EXCL);
664 if (atomic_cmpset_int(&object->chainlk,
666 chainlk & ~(CHAINLK_EXCL |
668 if (chainlk & CHAINLK_WAIT)
677 * Release the chain from first_object through and including stopobj.
678 * The caller is typically holding the first and last object locked
679 * (shared or exclusive) to prevent destruction races.
681 * We release stopobj first as an optimization as this object is most
682 * likely to be shared across multiple processes.
685 vm_object_chain_release_all(vm_object_t first_object, vm_object_t stopobj)
687 vm_object_t backing_object;
690 vm_object_chain_release(stopobj);
691 object = first_object;
693 while (object != stopobj) {
695 backing_object = object->backing_object;
696 vm_object_chain_release(object);
697 object = backing_object;
702 * Dereference an object and its underlying vnode. The object may be
703 * held shared. On return the object will remain held.
705 * This function may return a vnode in *vpp which the caller must release
706 * after the caller drops its own lock. If vpp is NULL, we assume that
707 * the caller was holding an exclusive lock on the object and we vrele()
711 VMOBJDEBUG(vm_object_vndeallocate)(vm_object_t object, struct vnode **vpp
714 struct vnode *vp = (struct vnode *) object->handle;
716 KASSERT(object->type == OBJT_VNODE,
717 ("vm_object_vndeallocate: not a vnode object"));
718 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
719 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
721 if (object->ref_count == 0) {
722 vprint("vm_object_vndeallocate", vp);
723 panic("vm_object_vndeallocate: bad object reference count");
727 int count = object->ref_count;
730 vm_object_upgrade(object);
731 if (atomic_cmpset_int(&object->ref_count, count, 0)) {
732 vclrflags(vp, VTEXT);
736 if (atomic_cmpset_int(&object->ref_count,
743 #if defined(DEBUG_LOCKS)
744 debugvm_object_add(object, file, line, -1);
748 * vrele or return the vp to vrele. We can only safely vrele(vp)
749 * if the object was locked exclusively. But there are two races
752 * We had to upgrade the object above to safely clear VTEXT
753 * but the alternative path where the shared lock is retained
754 * can STILL race to 0 in other paths and cause our own vrele()
755 * to terminate the vnode. We can't allow that if the VM object
756 * is still locked shared.
765 * Release a reference to the specified object, gained either through a
766 * vm_object_allocate or a vm_object_reference call. When all references
767 * are gone, storage associated with this object may be relinquished.
769 * The caller does not have to hold the object locked but must have control
770 * over the reference in question in order to guarantee that the object
771 * does not get ripped out from under us.
773 * XXX Currently all deallocations require an exclusive lock.
776 VMOBJDEBUG(vm_object_deallocate)(vm_object_t object VMOBJDBARGS)
785 count = object->ref_count;
789 * If decrementing the count enters into special handling
790 * territory (0, 1, or 2) we have to do it the hard way.
791 * Fortunate though, objects with only a few refs like this
792 * are not likely to be heavily contended anyway.
794 * For vnode objects we only care about 1->0 transitions.
796 if (count <= 3 || (object->type == OBJT_VNODE && count <= 1)) {
797 #if defined(DEBUG_LOCKS)
798 debugvm_object_add(object, file, line, 0);
800 vm_object_hold(object);
801 vm_object_deallocate_locked(object);
802 vm_object_drop(object);
807 * Try to decrement ref_count without acquiring a hold on
808 * the object. This is particularly important for the exec*()
809 * and exit*() code paths because the program binary may
810 * have a great deal of sharing and an exclusive lock will
811 * crowbar performance in those circumstances.
813 if (object->type == OBJT_VNODE) {
814 vp = (struct vnode *)object->handle;
815 if (atomic_cmpset_int(&object->ref_count,
817 #if defined(DEBUG_LOCKS)
818 debugvm_object_add(object, file, line, -1);
826 if (atomic_cmpset_int(&object->ref_count,
828 #if defined(DEBUG_LOCKS)
829 debugvm_object_add(object, file, line, -1);
840 VMOBJDEBUG(vm_object_deallocate_locked)(vm_object_t object VMOBJDBARGS)
842 struct vm_object_dealloc_list *dlist = NULL;
843 struct vm_object_dealloc_list *dtmp;
848 * We may chain deallocate object, but additional objects may
849 * collect on the dlist which also have to be deallocated. We
850 * must avoid a recursion, vm_object chains can get deep.
854 while (object != NULL) {
856 * vnode case, caller either locked the object exclusively
857 * or this is a recursion with must_drop != 0 and the vnode
858 * object will be locked shared.
860 * If locked shared we have to drop the object before we can
861 * call vrele() or risk a shared/exclusive livelock.
863 if (object->type == OBJT_VNODE) {
864 ASSERT_LWKT_TOKEN_HELD(&object->token);
866 struct vnode *tmp_vp;
868 vm_object_vndeallocate(object, &tmp_vp);
869 vm_object_drop(object);
874 vm_object_vndeallocate(object, NULL);
878 ASSERT_LWKT_TOKEN_HELD_EXCL(&object->token);
881 * Normal case (object is locked exclusively)
883 if (object->ref_count == 0) {
884 panic("vm_object_deallocate: object deallocated "
885 "too many times: %d", object->type);
887 if (object->ref_count > 2) {
888 atomic_add_int(&object->ref_count, -1);
889 #if defined(DEBUG_LOCKS)
890 debugvm_object_add(object, file, line, -1);
896 * Here on ref_count of one or two, which are special cases for
899 * Nominal ref_count > 1 case if the second ref is not from
902 * (ONEMAPPING only applies to DEFAULT AND SWAP objects)
904 if (object->ref_count == 2 && object->shadow_count == 0) {
905 if (object->type == OBJT_DEFAULT ||
906 object->type == OBJT_SWAP) {
907 vm_object_set_flag(object, OBJ_ONEMAPPING);
909 atomic_add_int(&object->ref_count, -1);
910 #if defined(DEBUG_LOCKS)
911 debugvm_object_add(object, file, line, -1);
917 * If the second ref is from a shadow we chain along it
918 * upwards if object's handle is exhausted.
920 * We have to decrement object->ref_count before potentially
921 * collapsing the first shadow object or the collapse code
922 * will not be able to handle the degenerate case to remove
923 * object. However, if we do it too early the object can
924 * get ripped out from under us.
926 if (object->ref_count == 2 && object->shadow_count == 1 &&
927 object->handle == NULL && (object->type == OBJT_DEFAULT ||
928 object->type == OBJT_SWAP)) {
929 temp = LIST_FIRST(&object->shadow_head);
930 KKASSERT(temp != NULL);
931 vm_object_hold(temp);
934 * Wait for any paging to complete so the collapse
935 * doesn't (or isn't likely to) qcollapse. pip
936 * waiting must occur before we acquire the
940 temp->paging_in_progress ||
941 object->paging_in_progress
943 vm_object_pip_wait(temp, "objde1");
944 vm_object_pip_wait(object, "objde2");
948 * If the parent is locked we have to give up, as
949 * otherwise we would be acquiring locks in the
950 * wrong order and potentially deadlock.
952 if (temp->chainlk & (CHAINLK_EXCL | CHAINLK_MASK)) {
953 vm_object_drop(temp);
956 vm_object_chain_acquire(temp, 0);
959 * Recheck/retry after the hold and the paging
960 * wait, both of which can block us.
962 if (object->ref_count != 2 ||
963 object->shadow_count != 1 ||
965 LIST_FIRST(&object->shadow_head) != temp ||
966 (object->type != OBJT_DEFAULT &&
967 object->type != OBJT_SWAP)) {
968 vm_object_chain_release(temp);
969 vm_object_drop(temp);
974 * We can safely drop object's ref_count now.
976 KKASSERT(object->ref_count == 2);
977 atomic_add_int(&object->ref_count, -1);
978 #if defined(DEBUG_LOCKS)
979 debugvm_object_add(object, file, line, -1);
983 * If our single parent is not collapseable just
984 * decrement ref_count (2->1) and stop.
986 if (temp->handle || (temp->type != OBJT_DEFAULT &&
987 temp->type != OBJT_SWAP)) {
988 vm_object_chain_release(temp);
989 vm_object_drop(temp);
994 * At this point we have already dropped object's
995 * ref_count so it is possible for a race to
996 * deallocate obj out from under us. Any collapse
997 * will re-check the situation. We must not block
998 * until we are able to collapse.
1000 * Bump temp's ref_count to avoid an unwanted
1001 * degenerate recursion (can't call
1002 * vm_object_reference_locked() because it asserts
1003 * that CHAINLOCK is not set).
1005 atomic_add_int(&temp->ref_count, 1);
1006 KKASSERT(temp->ref_count > 1);
1009 * Collapse temp, then deallocate the extra ref
1012 vm_object_collapse(temp, &dlist);
1013 vm_object_chain_release(temp);
1015 vm_object_lock_swap();
1016 vm_object_drop(object);
1024 * Drop the ref and handle termination on the 1->0 transition.
1025 * We may have blocked above so we have to recheck.
1028 KKASSERT(object->ref_count != 0);
1029 if (object->ref_count >= 2) {
1030 atomic_add_int(&object->ref_count, -1);
1031 #if defined(DEBUG_LOCKS)
1032 debugvm_object_add(object, file, line, -1);
1036 KKASSERT(object->ref_count == 1);
1039 * 1->0 transition. Chain through the backing_object.
1040 * Maintain the ref until we've located the backing object,
1043 while ((temp = object->backing_object) != NULL) {
1044 if (temp->type == OBJT_VNODE)
1045 vm_object_hold_shared(temp);
1047 vm_object_hold(temp);
1048 if (temp == object->backing_object)
1050 vm_object_drop(temp);
1054 * 1->0 transition verified, retry if ref_count is no longer
1055 * 1. Otherwise disconnect the backing_object (temp) and
1058 if (object->ref_count != 1) {
1059 vm_object_drop(temp);
1064 * It shouldn't be possible for the object to be chain locked
1065 * if we're removing the last ref on it.
1067 * Removing object from temp's shadow list requires dropping
1068 * temp, which we will do on loop.
1070 * NOTE! vnodes do not use the shadow list, but still have
1071 * the backing_object reference.
1073 KKASSERT((object->chainlk & (CHAINLK_EXCL|CHAINLK_MASK)) == 0);
1076 if (object->flags & OBJ_ONSHADOW) {
1077 LIST_REMOVE(object, shadow_list);
1078 temp->shadow_count--;
1080 vm_object_clear_flag(object, OBJ_ONSHADOW);
1082 object->backing_object = NULL;
1085 atomic_add_int(&object->ref_count, -1);
1086 if ((object->flags & OBJ_DEAD) == 0)
1087 vm_object_terminate(object);
1088 if (must_drop && temp)
1089 vm_object_lock_swap();
1091 vm_object_drop(object);
1096 if (must_drop && object)
1097 vm_object_drop(object);
1100 * Additional tail recursion on dlist. Avoid a recursion. Objects
1101 * on the dlist have a hold count but are not locked.
1103 if ((dtmp = dlist) != NULL) {
1105 object = dtmp->object;
1106 kfree(dtmp, M_TEMP);
1108 vm_object_lock(object); /* already held, add lock */
1109 must_drop = 1; /* and we're responsible for it */
1115 * Destroy the specified object, freeing up related resources.
1117 * The object must have zero references.
1119 * The object must held. The caller is responsible for dropping the object
1120 * after terminate returns. Terminate does NOT drop the object.
1122 static int vm_object_terminate_callback(vm_page_t p, void *data);
1125 vm_object_terminate(vm_object_t object)
1127 struct rb_vm_page_scan_info info;
1131 * Make sure no one uses us. Once we set OBJ_DEAD we should be
1132 * able to safely block.
1134 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
1135 KKASSERT((object->flags & OBJ_DEAD) == 0);
1136 vm_object_set_flag(object, OBJ_DEAD);
1139 * Wait for the pageout daemon to be done with the object
1141 vm_object_pip_wait(object, "objtrm1");
1143 KASSERT(!object->paging_in_progress,
1144 ("vm_object_terminate: pageout in progress"));
1147 * Clean and free the pages, as appropriate. All references to the
1148 * object are gone, so we don't need to lock it.
1150 if (object->type == OBJT_VNODE) {
1154 * Clean pages and flush buffers.
1156 * NOTE! TMPFS buffer flushes do not typically flush the
1157 * actual page to swap as this would be highly
1158 * inefficient, and normal filesystems usually wrap
1159 * page flushes with buffer cache buffers.
1161 * To deal with this we have to call vinvalbuf() both
1162 * before and after the vm_object_page_clean().
1164 vp = (struct vnode *) object->handle;
1165 vinvalbuf(vp, V_SAVE, 0, 0);
1166 vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
1167 vinvalbuf(vp, V_SAVE, 0, 0);
1171 * Wait for any I/O to complete, after which there had better not
1172 * be any references left on the object.
1174 vm_object_pip_wait(object, "objtrm2");
1176 if (object->ref_count != 0) {
1177 panic("vm_object_terminate: object with references, "
1178 "ref_count=%d", object->ref_count);
1182 * Cleanup any shared pmaps associated with this object.
1184 pmap_object_free(object);
1187 * Now free any remaining pages. For internal objects, this also
1188 * removes them from paging queues. Don't free wired pages, just
1189 * remove them from the object.
1192 info.object = object;
1193 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL,
1194 vm_object_terminate_callback, &info);
1197 * Let the pager know object is dead.
1199 vm_pager_deallocate(object);
1202 * Wait for the object hold count to hit 1, clean out pages as
1203 * we go. vmobj_token interlocks any race conditions that might
1204 * pick the object up from the vm_object_list after we have cleared
1208 if (RB_ROOT(&object->rb_memq) == NULL)
1210 kprintf("vm_object_terminate: Warning, object %p "
1211 "still has %d pages\n",
1212 object, object->resident_page_count);
1213 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL,
1214 vm_object_terminate_callback, &info);
1218 * There had better not be any pages left
1220 KKASSERT(object->resident_page_count == 0);
1223 * Remove the object from the global object list.
1225 n = VMOBJ_HASH(object);
1226 lwkt_gettoken(&vmobj_tokens[n]);
1227 TAILQ_REMOVE(&vm_object_lists[n], object, object_list);
1228 lwkt_reltoken(&vmobj_tokens[n]);
1229 atomic_add_long(&vm_object_count, -1);
1231 if (object->ref_count != 0) {
1232 panic("vm_object_terminate2: object with references, "
1233 "ref_count=%d", object->ref_count);
1237 * NOTE: The object hold_count is at least 1, so we cannot zfree()
1238 * the object here. See vm_object_drop().
1243 * The caller must hold the object.
1246 vm_object_terminate_callback(vm_page_t p, void *data)
1248 struct rb_vm_page_scan_info *info = data;
1251 if ((++info->count & 63) == 0)
1254 if (object != info->object) {
1255 kprintf("vm_object_terminate_callback: obj/pg race %p/%p\n",
1259 vm_page_busy_wait(p, TRUE, "vmpgtrm");
1260 if (object != p->object) {
1261 kprintf("vm_object_terminate: Warning: Encountered "
1262 "busied page %p on queue %d\n", p, p->queue);
1264 } else if (p->wire_count == 0) {
1266 * NOTE: p->dirty and PG_NEED_COMMIT are ignored.
1269 mycpu->gd_cnt.v_pfree++;
1271 if (p->queue != PQ_NONE)
1272 kprintf("vm_object_terminate: Warning: Encountered "
1273 "wired page %p on queue %d\n", p, p->queue);
1281 * Clean all dirty pages in the specified range of object. Leaves page
1282 * on whatever queue it is currently on. If NOSYNC is set then do not
1283 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC),
1284 * leaving the object dirty.
1286 * When stuffing pages asynchronously, allow clustering. XXX we need a
1287 * synchronous clustering mode implementation.
1289 * Odd semantics: if start == end, we clean everything.
1291 * The object must be locked? XXX
1293 static int vm_object_page_clean_pass1(struct vm_page *p, void *data);
1294 static int vm_object_page_clean_pass2(struct vm_page *p, void *data);
1297 vm_object_page_clean(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
1300 struct rb_vm_page_scan_info info;
1306 vm_object_hold(object);
1307 if (object->type != OBJT_VNODE ||
1308 (object->flags & OBJ_MIGHTBEDIRTY) == 0) {
1309 vm_object_drop(object);
1313 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ?
1314 VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK;
1315 pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0;
1317 vp = object->handle;
1320 * Interlock other major object operations. This allows us to
1321 * temporarily clear OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY.
1323 vm_object_set_flag(object, OBJ_CLEANING);
1326 * Handle 'entire object' case
1328 info.start_pindex = start;
1330 info.end_pindex = object->size - 1;
1332 info.end_pindex = end - 1;
1334 wholescan = (start == 0 && info.end_pindex == object->size - 1);
1336 info.pagerflags = pagerflags;
1337 info.object = object;
1341 * If cleaning the entire object do a pass to mark the pages read-only.
1342 * If everything worked out ok, clear OBJ_WRITEABLE and
1347 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
1348 vm_object_page_clean_pass1, &info);
1349 if (info.error == 0) {
1350 vm_object_clear_flag(object,
1351 OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
1352 if (object->type == OBJT_VNODE &&
1353 (vp = (struct vnode *)object->handle) != NULL) {
1355 * Use new-style interface to clear VISDIRTY
1356 * because the vnode is not necessarily removed
1357 * from the syncer list(s) as often as it was
1358 * under the old interface, which can leave
1359 * the vnode on the syncer list after reclaim.
1367 * Do a pass to clean all the dirty pages we find.
1371 generation = object->generation;
1372 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
1373 vm_object_page_clean_pass2, &info);
1374 } while (info.error || generation != object->generation);
1376 vm_object_clear_flag(object, OBJ_CLEANING);
1377 vm_object_drop(object);
1381 * The caller must hold the object.
1385 vm_object_page_clean_pass1(struct vm_page *p, void *data)
1387 struct rb_vm_page_scan_info *info = data;
1389 if ((++info->count & 63) == 0)
1391 if (p->object != info->object ||
1392 p->pindex < info->start_pindex ||
1393 p->pindex > info->end_pindex) {
1394 kprintf("vm_object_page_clean_pass1: obj/pg race %p/%p\n",
1398 vm_page_flag_set(p, PG_CLEANCHK);
1399 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) {
1401 } else if (vm_page_busy_try(p, FALSE) == 0) {
1402 if (p->object == info->object)
1403 vm_page_protect(p, VM_PROT_READ);
1412 * The caller must hold the object
1416 vm_object_page_clean_pass2(struct vm_page *p, void *data)
1418 struct rb_vm_page_scan_info *info = data;
1421 if (p->object != info->object ||
1422 p->pindex < info->start_pindex ||
1423 p->pindex > info->end_pindex) {
1424 kprintf("vm_object_page_clean_pass2: obj/pg race %p/%p\n",
1430 * Do not mess with pages that were inserted after we started
1431 * the cleaning pass.
1433 if ((p->flags & PG_CLEANCHK) == 0)
1436 generation = info->object->generation;
1437 vm_page_busy_wait(p, TRUE, "vpcwai");
1439 if (p->object != info->object ||
1440 p->pindex < info->start_pindex ||
1441 p->pindex > info->end_pindex ||
1442 info->object->generation != generation) {
1449 * Before wasting time traversing the pmaps, check for trivial
1450 * cases where the page cannot be dirty.
1452 if (p->valid == 0 || (p->queue - p->pc) == PQ_CACHE) {
1453 KKASSERT((p->dirty & p->valid) == 0 &&
1454 (p->flags & PG_NEED_COMMIT) == 0);
1460 * Check whether the page is dirty or not. The page has been set
1461 * to be read-only so the check will not race a user dirtying the
1464 vm_page_test_dirty(p);
1465 if ((p->dirty & p->valid) == 0 && (p->flags & PG_NEED_COMMIT) == 0) {
1466 vm_page_flag_clear(p, PG_CLEANCHK);
1472 * If we have been asked to skip nosync pages and this is a
1473 * nosync page, skip it. Note that the object flags were
1474 * not cleared in this case (because pass1 will have returned an
1475 * error), so we do not have to set them.
1477 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) {
1478 vm_page_flag_clear(p, PG_CLEANCHK);
1484 * Flush as many pages as we can. PG_CLEANCHK will be cleared on
1485 * the pages that get successfully flushed. Set info->error if
1486 * we raced an object modification.
1488 vm_object_page_collect_flush(info->object, p, info->pagerflags);
1489 /* vm_wait_nominal(); this can deadlock the system in syncer/pageout */
1491 if ((++info->count & 63) == 0)
1498 * Collect the specified page and nearby pages and flush them out.
1499 * The number of pages flushed is returned. The passed page is busied
1500 * by the caller and we are responsible for its disposition.
1502 * The caller must hold the object.
1505 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags)
1513 vm_page_t ma[BLIST_MAX_ALLOC];
1515 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
1518 page_base = pi % BLIST_MAX_ALLOC;
1526 tp = vm_page_lookup_busy_try(object, pi - page_base + ib,
1532 if ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 &&
1533 (tp->flags & PG_CLEANCHK) == 0) {
1537 if ((tp->queue - tp->pc) == PQ_CACHE) {
1538 vm_page_flag_clear(tp, PG_CLEANCHK);
1542 vm_page_test_dirty(tp);
1543 if ((tp->dirty & tp->valid) == 0 &&
1544 (tp->flags & PG_NEED_COMMIT) == 0) {
1545 vm_page_flag_clear(tp, PG_CLEANCHK);
1554 while (is < BLIST_MAX_ALLOC &&
1555 pi - page_base + is < object->size) {
1558 tp = vm_page_lookup_busy_try(object, pi - page_base + is,
1564 if ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 &&
1565 (tp->flags & PG_CLEANCHK) == 0) {
1569 if ((tp->queue - tp->pc) == PQ_CACHE) {
1570 vm_page_flag_clear(tp, PG_CLEANCHK);
1574 vm_page_test_dirty(tp);
1575 if ((tp->dirty & tp->valid) == 0 &&
1576 (tp->flags & PG_NEED_COMMIT) == 0) {
1577 vm_page_flag_clear(tp, PG_CLEANCHK);
1586 * All pages in the ma[] array are busied now
1588 for (i = ib; i < is; ++i) {
1589 vm_page_flag_clear(ma[i], PG_CLEANCHK);
1590 vm_page_hold(ma[i]); /* XXX need this any more? */
1592 vm_pageout_flush(&ma[ib], is - ib, pagerflags);
1593 for (i = ib; i < is; ++i) /* XXX need this any more? */
1594 vm_page_unhold(ma[i]);
1598 * Same as vm_object_pmap_copy, except range checking really
1599 * works, and is meant for small sections of an object.
1601 * This code protects resident pages by making them read-only
1602 * and is typically called on a fork or split when a page
1603 * is converted to copy-on-write.
1605 * NOTE: If the page is already at VM_PROT_NONE, calling
1606 * vm_page_protect will have no effect.
1609 vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
1614 if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
1617 vm_object_hold(object);
1618 for (idx = start; idx < end; idx++) {
1619 p = vm_page_lookup(object, idx);
1622 vm_page_protect(p, VM_PROT_READ);
1624 vm_object_drop(object);
1628 * Removes all physical pages in the specified object range from all
1631 * The object must *not* be locked.
1634 static int vm_object_pmap_remove_callback(vm_page_t p, void *data);
1637 vm_object_pmap_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
1639 struct rb_vm_page_scan_info info;
1643 info.start_pindex = start;
1644 info.end_pindex = end - 1;
1646 info.object = object;
1648 vm_object_hold(object);
1649 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
1650 vm_object_pmap_remove_callback, &info);
1651 if (start == 0 && end == object->size)
1652 vm_object_clear_flag(object, OBJ_WRITEABLE);
1653 vm_object_drop(object);
1657 * The caller must hold the object
1660 vm_object_pmap_remove_callback(vm_page_t p, void *data)
1662 struct rb_vm_page_scan_info *info = data;
1664 if ((++info->count & 63) == 0)
1667 if (info->object != p->object ||
1668 p->pindex < info->start_pindex ||
1669 p->pindex > info->end_pindex) {
1670 kprintf("vm_object_pmap_remove_callback: obj/pg race %p/%p\n",
1675 vm_page_protect(p, VM_PROT_NONE);
1681 * Implements the madvise function at the object/page level.
1683 * MADV_WILLNEED (any object)
1685 * Activate the specified pages if they are resident.
1687 * MADV_DONTNEED (any object)
1689 * Deactivate the specified pages if they are resident.
1691 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, OBJ_ONEMAPPING only)
1693 * Deactivate and clean the specified pages if they are
1694 * resident. This permits the process to reuse the pages
1695 * without faulting or the kernel to reclaim the pages
1701 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, int count, int advise)
1703 vm_pindex_t end, tpindex;
1704 vm_object_t tobject;
1712 end = pindex + count;
1714 vm_object_hold(object);
1718 * Locate and adjust resident pages
1720 for (; pindex < end; pindex += 1) {
1722 if (tobject != object)
1723 vm_object_drop(tobject);
1728 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
1729 * and those pages must be OBJ_ONEMAPPING.
1731 if (advise == MADV_FREE) {
1732 if ((tobject->type != OBJT_DEFAULT &&
1733 tobject->type != OBJT_SWAP) ||
1734 (tobject->flags & OBJ_ONEMAPPING) == 0) {
1739 m = vm_page_lookup_busy_try(tobject, tpindex, TRUE, &error);
1742 vm_page_sleep_busy(m, TRUE, "madvpo");
1747 * There may be swap even if there is no backing page
1749 if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
1750 swap_pager_freespace(tobject, tpindex, 1);
1755 while ((xobj = tobject->backing_object) != NULL) {
1756 KKASSERT(xobj != object);
1757 vm_object_hold(xobj);
1758 if (xobj == tobject->backing_object)
1760 vm_object_drop(xobj);
1764 tpindex += OFF_TO_IDX(tobject->backing_object_offset);
1765 if (tobject != object) {
1766 vm_object_lock_swap();
1767 vm_object_drop(tobject);
1774 * If the page is not in a normal active state, we skip it.
1775 * If the page is not managed there are no page queues to
1776 * mess with. Things can break if we mess with pages in
1777 * any of the below states.
1779 if (m->wire_count ||
1780 (m->flags & (PG_UNMANAGED | PG_NEED_COMMIT)) ||
1781 m->valid != VM_PAGE_BITS_ALL
1788 * Theoretically once a page is known not to be busy, an
1789 * interrupt cannot come along and rip it out from under us.
1792 if (advise == MADV_WILLNEED) {
1793 vm_page_activate(m);
1794 } else if (advise == MADV_DONTNEED) {
1795 vm_page_dontneed(m);
1796 } else if (advise == MADV_FREE) {
1798 * Mark the page clean. This will allow the page
1799 * to be freed up by the system. However, such pages
1800 * are often reused quickly by malloc()/free()
1801 * so we do not do anything that would cause
1802 * a page fault if we can help it.
1804 * Specifically, we do not try to actually free
1805 * the page now nor do we try to put it in the
1806 * cache (which would cause a page fault on reuse).
1808 * But we do make the page is freeable as we
1809 * can without actually taking the step of unmapping
1812 pmap_clear_modify(m);
1815 vm_page_dontneed(m);
1816 if (tobject->type == OBJT_SWAP)
1817 swap_pager_freespace(tobject, tpindex, 1);
1821 if (tobject != object)
1822 vm_object_drop(tobject);
1823 vm_object_drop(object);
1827 * Create a new object which is backed by the specified existing object
1828 * range. Replace the pointer and offset that was pointing at the existing
1829 * object with the pointer/offset for the new object.
1831 * If addref is non-zero the returned object is given an additional reference.
1832 * This mechanic exists to avoid the situation where refs might be 1 and
1833 * race against a collapse when the caller intends to bump it. So the
1834 * caller cannot add the ref after the fact. Used when the caller is
1835 * duplicating a vm_map_entry.
1837 * No other requirements.
1840 vm_object_shadow(vm_object_t *objectp, vm_ooffset_t *offset, vm_size_t length,
1850 * Don't create the new object if the old object isn't shared.
1851 * We have to chain wait before adding the reference to avoid
1852 * racing a collapse or deallocation.
1854 * Clear OBJ_ONEMAPPING flag when shadowing.
1856 * The caller owns a ref on source via *objectp which we are going
1857 * to replace. This ref is inherited by the backing_object assignment.
1858 * from nobject and does not need to be incremented here.
1860 * However, we add a temporary extra reference to the original source
1861 * prior to holding nobject in case we block, to avoid races where
1862 * someone else might believe that the source can be collapsed.
1866 if (source->type != OBJT_VNODE) {
1868 vm_object_hold(source);
1869 vm_object_chain_wait(source, 0);
1870 if (source->ref_count == 1 &&
1871 source->handle == NULL &&
1872 (source->type == OBJT_DEFAULT ||
1873 source->type == OBJT_SWAP)) {
1875 vm_object_reference_locked(source);
1876 vm_object_clear_flag(source,
1879 vm_object_drop(source);
1882 vm_object_reference_locked(source);
1883 vm_object_clear_flag(source, OBJ_ONEMAPPING);
1885 vm_object_reference_quick(source);
1886 vm_object_clear_flag(source, OBJ_ONEMAPPING);
1891 * Allocate a new object with the given length. The new object
1892 * is returned referenced but we may have to add another one.
1893 * If we are adding a second reference we must clear OBJ_ONEMAPPING.
1894 * (typically because the caller is about to clone a vm_map_entry).
1896 * The source object currently has an extra reference to prevent
1897 * collapses into it while we mess with its shadow list, which
1898 * we will remove later in this routine.
1900 * The target object may require a second reference if asked for one
1903 result = vm_object_allocate(OBJT_DEFAULT, length);
1905 panic("vm_object_shadow: no object for shadowing");
1906 vm_object_hold(result);
1908 vm_object_reference_locked(result);
1909 vm_object_clear_flag(result, OBJ_ONEMAPPING);
1913 * The new object shadows the source object. Chain wait before
1914 * adjusting shadow_count or the shadow list to avoid races.
1916 * Try to optimize the result object's page color when shadowing
1917 * in order to maintain page coloring consistency in the combined
1920 * The backing_object reference to source requires adding a ref to
1921 * source. We simply inherit the ref from the original *objectp
1922 * (which we are replacing) so no additional refs need to be added.
1923 * (we must still clean up the extra ref we had to prevent collapse
1926 * SHADOWING IS NOT APPLICABLE TO OBJT_VNODE OBJECTS
1928 KKASSERT(result->backing_object == NULL);
1929 result->backing_object = source;
1931 if (useshadowlist) {
1932 vm_object_chain_wait(source, 0);
1933 LIST_INSERT_HEAD(&source->shadow_head,
1934 result, shadow_list);
1935 source->shadow_count++;
1936 source->generation++;
1937 vm_object_set_flag(result, OBJ_ONSHADOW);
1939 /* cpu localization twist */
1940 result->pg_color = (int)(intptr_t)curthread;
1944 * Adjust the return storage. Drop the ref on source before
1947 result->backing_object_offset = *offset;
1948 vm_object_drop(result);
1951 if (useshadowlist) {
1952 vm_object_deallocate_locked(source);
1953 vm_object_drop(source);
1955 vm_object_deallocate(source);
1960 * Return the new things
1965 #define OBSC_TEST_ALL_SHADOWED 0x0001
1966 #define OBSC_COLLAPSE_NOWAIT 0x0002
1967 #define OBSC_COLLAPSE_WAIT 0x0004
1969 static int vm_object_backing_scan_callback(vm_page_t p, void *data);
1972 * The caller must hold the object.
1975 vm_object_backing_scan(vm_object_t object, vm_object_t backing_object, int op)
1977 struct rb_vm_page_scan_info info;
1980 vm_object_assert_held(object);
1981 vm_object_assert_held(backing_object);
1983 KKASSERT(backing_object == object->backing_object);
1984 info.backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
1987 * Initial conditions
1989 if (op & OBSC_TEST_ALL_SHADOWED) {
1991 * We do not want to have to test for the existence of
1992 * swap pages in the backing object. XXX but with the
1993 * new swapper this would be pretty easy to do.
1995 * XXX what about anonymous MAP_SHARED memory that hasn't
1996 * been ZFOD faulted yet? If we do not test for this, the
1997 * shadow test may succeed! XXX
1999 if (backing_object->type != OBJT_DEFAULT)
2002 if (op & OBSC_COLLAPSE_WAIT) {
2003 KKASSERT((backing_object->flags & OBJ_DEAD) == 0);
2004 vm_object_set_flag(backing_object, OBJ_DEAD);
2006 n = VMOBJ_HASH(backing_object);
2007 lwkt_gettoken(&vmobj_tokens[n]);
2008 TAILQ_REMOVE(&vm_object_lists[n], backing_object, object_list);
2009 lwkt_reltoken(&vmobj_tokens[n]);
2010 atomic_add_long(&vm_object_count, -1);
2014 * Our scan. We have to retry if a negative error code is returned,
2015 * otherwise 0 or 1 will be returned in info.error. 0 Indicates that
2016 * the scan had to be stopped because the parent does not completely
2019 info.object = object;
2020 info.backing_object = backing_object;
2024 vm_page_rb_tree_RB_SCAN(&backing_object->rb_memq, NULL,
2025 vm_object_backing_scan_callback,
2027 } while (info.error < 0);
2033 * The caller must hold the object.
2036 vm_object_backing_scan_callback(vm_page_t p, void *data)
2038 struct rb_vm_page_scan_info *info = data;
2039 vm_object_t backing_object;
2042 vm_pindex_t new_pindex;
2043 vm_pindex_t backing_offset_index;
2047 new_pindex = pindex - info->backing_offset_index;
2049 object = info->object;
2050 backing_object = info->backing_object;
2051 backing_offset_index = info->backing_offset_index;
2053 if (op & OBSC_TEST_ALL_SHADOWED) {
2057 * Ignore pages outside the parent object's range
2058 * and outside the parent object's mapping of the
2061 * note that we do not busy the backing object's
2064 if (pindex < backing_offset_index ||
2065 new_pindex >= object->size
2071 * See if the parent has the page or if the parent's
2072 * object pager has the page. If the parent has the
2073 * page but the page is not valid, the parent's
2074 * object pager must have the page.
2076 * If this fails, the parent does not completely shadow
2077 * the object and we might as well give up now.
2079 pp = vm_page_lookup(object, new_pindex);
2080 if ((pp == NULL || pp->valid == 0) &&
2081 !vm_pager_has_page(object, new_pindex)
2083 info->error = 0; /* problemo */
2084 return(-1); /* stop the scan */
2089 * Check for busy page. Note that we may have lost (p) when we
2090 * possibly blocked above.
2092 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
2095 if (vm_page_busy_try(p, TRUE)) {
2096 if (op & OBSC_COLLAPSE_NOWAIT) {
2100 * If we slept, anything could have
2101 * happened. Ask that the scan be restarted.
2103 * Since the object is marked dead, the
2104 * backing offset should not have changed.
2106 vm_page_sleep_busy(p, TRUE, "vmocol");
2113 * If (p) is no longer valid restart the scan.
2115 if (p->object != backing_object || p->pindex != pindex) {
2116 kprintf("vm_object_backing_scan: Warning: page "
2117 "%p ripped out from under us\n", p);
2123 if (op & OBSC_COLLAPSE_NOWAIT) {
2124 if (p->valid == 0 ||
2126 (p->flags & PG_NEED_COMMIT)) {
2131 /* XXX what if p->valid == 0 , hold_count, etc? */
2135 p->object == backing_object,
2136 ("vm_object_qcollapse(): object mismatch")
2140 * Destroy any associated swap
2142 if (backing_object->type == OBJT_SWAP)
2143 swap_pager_freespace(backing_object, p->pindex, 1);
2146 p->pindex < backing_offset_index ||
2147 new_pindex >= object->size
2150 * Page is out of the parent object's range, we
2151 * can simply destroy it.
2153 vm_page_protect(p, VM_PROT_NONE);
2158 pp = vm_page_lookup(object, new_pindex);
2159 if (pp != NULL || vm_pager_has_page(object, new_pindex)) {
2161 * page already exists in parent OR swap exists
2162 * for this location in the parent. Destroy
2163 * the original page from the backing object.
2165 * Leave the parent's page alone
2167 vm_page_protect(p, VM_PROT_NONE);
2173 * Page does not exist in parent, rename the
2174 * page from the backing object to the main object.
2176 * If the page was mapped to a process, it can remain
2177 * mapped through the rename.
2179 if ((p->queue - p->pc) == PQ_CACHE)
2180 vm_page_deactivate(p);
2182 vm_page_rename(p, object, new_pindex);
2184 /* page automatically made dirty by rename */
2190 * This version of collapse allows the operation to occur earlier and
2191 * when paging_in_progress is true for an object... This is not a complete
2192 * operation, but should plug 99.9% of the rest of the leaks.
2194 * The caller must hold the object and backing_object and both must be
2197 * (only called from vm_object_collapse)
2200 vm_object_qcollapse(vm_object_t object, vm_object_t backing_object)
2202 if (backing_object->ref_count == 1) {
2203 atomic_add_int(&backing_object->ref_count, 2);
2204 #if defined(DEBUG_LOCKS)
2205 debugvm_object_add(backing_object, "qcollapse", 1, 2);
2207 vm_object_backing_scan(object, backing_object,
2208 OBSC_COLLAPSE_NOWAIT);
2209 atomic_add_int(&backing_object->ref_count, -2);
2210 #if defined(DEBUG_LOCKS)
2211 debugvm_object_add(backing_object, "qcollapse", 2, -2);
2217 * Collapse an object with the object backing it. Pages in the backing
2218 * object are moved into the parent, and the backing object is deallocated.
2219 * Any conflict is resolved in favor of the parent's existing pages.
2221 * object must be held and chain-locked on call.
2223 * The caller must have an extra ref on object to prevent a race from
2224 * destroying it during the collapse.
2227 vm_object_collapse(vm_object_t object, struct vm_object_dealloc_list **dlistp)
2229 struct vm_object_dealloc_list *dlist = NULL;
2230 vm_object_t backing_object;
2233 * Only one thread is attempting a collapse at any given moment.
2234 * There are few restrictions for (object) that callers of this
2235 * function check so reentrancy is likely.
2237 KKASSERT(object != NULL);
2238 vm_object_assert_held(object);
2239 KKASSERT(object->chainlk & (CHAINLK_MASK | CHAINLK_EXCL));
2246 * We can only collapse a DEFAULT/SWAP object with a
2247 * DEFAULT/SWAP object.
2249 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP) {
2250 backing_object = NULL;
2254 backing_object = object->backing_object;
2255 if (backing_object == NULL)
2257 if (backing_object->type != OBJT_DEFAULT &&
2258 backing_object->type != OBJT_SWAP) {
2259 backing_object = NULL;
2264 * Hold the backing_object and check for races
2266 vm_object_hold(backing_object);
2267 if (backing_object != object->backing_object ||
2268 (backing_object->type != OBJT_DEFAULT &&
2269 backing_object->type != OBJT_SWAP)) {
2270 vm_object_drop(backing_object);
2275 * Chain-lock the backing object too because if we
2276 * successfully merge its pages into the top object we
2277 * will collapse backing_object->backing_object as the
2278 * new backing_object. Re-check that it is still our
2281 vm_object_chain_acquire(backing_object, 0);
2282 if (backing_object != object->backing_object) {
2283 vm_object_chain_release(backing_object);
2284 vm_object_drop(backing_object);
2289 * we check the backing object first, because it is most likely
2292 if (backing_object->handle != NULL ||
2293 (backing_object->type != OBJT_DEFAULT &&
2294 backing_object->type != OBJT_SWAP) ||
2295 (backing_object->flags & OBJ_DEAD) ||
2296 object->handle != NULL ||
2297 (object->type != OBJT_DEFAULT &&
2298 object->type != OBJT_SWAP) ||
2299 (object->flags & OBJ_DEAD)) {
2304 * If paging is in progress we can't do a normal collapse.
2307 object->paging_in_progress != 0 ||
2308 backing_object->paging_in_progress != 0
2310 vm_object_qcollapse(object, backing_object);
2315 * We know that we can either collapse the backing object (if
2316 * the parent is the only reference to it) or (perhaps) have
2317 * the parent bypass the object if the parent happens to shadow
2318 * all the resident pages in the entire backing object.
2320 * This is ignoring pager-backed pages such as swap pages.
2321 * vm_object_backing_scan fails the shadowing test in this
2324 if (backing_object->ref_count == 1) {
2326 * If there is exactly one reference to the backing
2327 * object, we can collapse it into the parent.
2329 KKASSERT(object->backing_object == backing_object);
2330 vm_object_backing_scan(object, backing_object,
2331 OBSC_COLLAPSE_WAIT);
2334 * Move the pager from backing_object to object.
2336 if (backing_object->type == OBJT_SWAP) {
2337 vm_object_pip_add(backing_object, 1);
2340 * scrap the paging_offset junk and do a
2341 * discrete copy. This also removes major
2342 * assumptions about how the swap-pager
2343 * works from where it doesn't belong. The
2344 * new swapper is able to optimize the
2345 * destroy-source case.
2347 vm_object_pip_add(object, 1);
2348 swap_pager_copy(backing_object, object,
2349 OFF_TO_IDX(object->backing_object_offset),
2351 vm_object_pip_wakeup(object);
2352 vm_object_pip_wakeup(backing_object);
2356 * Object now shadows whatever backing_object did.
2357 * Remove object from backing_object's shadow_list.
2359 * Removing object from backing_objects shadow list
2360 * requires releasing object, which we will do below.
2362 KKASSERT(object->backing_object == backing_object);
2363 if (object->flags & OBJ_ONSHADOW) {
2364 LIST_REMOVE(object, shadow_list);
2365 backing_object->shadow_count--;
2366 backing_object->generation++;
2367 vm_object_clear_flag(object, OBJ_ONSHADOW);
2371 * backing_object->backing_object moves from within
2372 * backing_object to within object.
2374 * OBJT_VNODE bbobj's should have empty shadow lists.
2376 while ((bbobj = backing_object->backing_object) != NULL) {
2377 if (bbobj->type == OBJT_VNODE)
2378 vm_object_hold_shared(bbobj);
2380 vm_object_hold(bbobj);
2381 if (bbobj == backing_object->backing_object)
2383 vm_object_drop(bbobj);
2387 * We are removing backing_object from bbobj's
2388 * shadow list and adding object to bbobj's shadow
2389 * list, so the ref_count on bbobj is unchanged.
2392 if (backing_object->flags & OBJ_ONSHADOW) {
2393 /* not locked exclusively if vnode */
2394 KKASSERT(bbobj->type != OBJT_VNODE);
2395 LIST_REMOVE(backing_object,
2397 bbobj->shadow_count--;
2398 bbobj->generation++;
2399 vm_object_clear_flag(backing_object,
2402 backing_object->backing_object = NULL;
2404 object->backing_object = bbobj;
2406 if (bbobj->type != OBJT_VNODE) {
2407 LIST_INSERT_HEAD(&bbobj->shadow_head,
2408 object, shadow_list);
2409 bbobj->shadow_count++;
2410 bbobj->generation++;
2411 vm_object_set_flag(object,
2416 object->backing_object_offset +=
2417 backing_object->backing_object_offset;
2419 vm_object_drop(bbobj);
2422 * Discard the old backing_object. Nothing should be
2423 * able to ref it, other than a vm_map_split(),
2424 * and vm_map_split() will stall on our chain lock.
2425 * And we control the parent so it shouldn't be
2426 * possible for it to go away either.
2428 * Since the backing object has no pages, no pager
2429 * left, and no object references within it, all
2430 * that is necessary is to dispose of it.
2432 KASSERT(backing_object->ref_count == 1,
2433 ("backing_object %p was somehow "
2434 "re-referenced during collapse!",
2436 KASSERT(RB_EMPTY(&backing_object->rb_memq),
2437 ("backing_object %p somehow has left "
2438 "over pages during collapse!",
2442 * The object can be destroyed.
2444 * XXX just fall through and dodealloc instead
2445 * of forcing destruction?
2447 atomic_add_int(&backing_object->ref_count, -1);
2448 #if defined(DEBUG_LOCKS)
2449 debugvm_object_add(backing_object, "collapse", 1, -1);
2451 if ((backing_object->flags & OBJ_DEAD) == 0)
2452 vm_object_terminate(backing_object);
2457 * If we do not entirely shadow the backing object,
2458 * there is nothing we can do so we give up.
2460 if (vm_object_backing_scan(object, backing_object,
2461 OBSC_TEST_ALL_SHADOWED) == 0) {
2466 * bbobj is backing_object->backing_object. Since
2467 * object completely shadows backing_object we can
2468 * bypass it and become backed by bbobj instead.
2470 * The shadow list for vnode backing objects is not
2471 * used and a shared hold is allowed.
2473 while ((bbobj = backing_object->backing_object) != NULL) {
2474 if (bbobj->type == OBJT_VNODE)
2475 vm_object_hold_shared(bbobj);
2477 vm_object_hold(bbobj);
2478 if (bbobj == backing_object->backing_object)
2480 vm_object_drop(bbobj);
2484 * Make object shadow bbobj instead of backing_object.
2485 * Remove object from backing_object's shadow list.
2487 * Deallocating backing_object will not remove
2488 * it, since its reference count is at least 2.
2490 * Removing object from backing_object's shadow
2491 * list requires releasing a ref, which we do
2492 * below by setting dodealloc to 1.
2494 KKASSERT(object->backing_object == backing_object);
2495 if (object->flags & OBJ_ONSHADOW) {
2496 LIST_REMOVE(object, shadow_list);
2497 backing_object->shadow_count--;
2498 backing_object->generation++;
2499 vm_object_clear_flag(object, OBJ_ONSHADOW);
2503 * Add a ref to bbobj, bbobj now shadows object.
2505 * NOTE: backing_object->backing_object still points
2506 * to bbobj. That relationship remains intact
2507 * because backing_object has > 1 ref, so
2508 * someone else is pointing to it (hence why
2509 * we can't collapse it into object and can
2510 * only handle the all-shadowed bypass case).
2513 if (bbobj->type != OBJT_VNODE) {
2514 vm_object_chain_wait(bbobj, 0);
2515 vm_object_reference_locked(bbobj);
2516 LIST_INSERT_HEAD(&bbobj->shadow_head,
2517 object, shadow_list);
2518 bbobj->shadow_count++;
2519 bbobj->generation++;
2520 vm_object_set_flag(object,
2523 vm_object_reference_quick(bbobj);
2525 object->backing_object_offset +=
2526 backing_object->backing_object_offset;
2527 object->backing_object = bbobj;
2528 vm_object_drop(bbobj);
2530 object->backing_object = NULL;
2534 * Drop the reference count on backing_object. To
2535 * handle ref_count races properly we can't assume
2536 * that the ref_count is still at least 2 so we
2537 * have to actually call vm_object_deallocate()
2538 * (after clearing the chainlock).
2545 * Ok, we want to loop on the new object->bbobj association,
2546 * possibly collapsing it further. However if dodealloc is
2547 * non-zero we have to deallocate the backing_object which
2548 * itself can potentially undergo a collapse, creating a
2549 * recursion depth issue with the LWKT token subsystem.
2551 * In the case where we must deallocate the backing_object
2552 * it is possible now that the backing_object has a single
2553 * shadow count on some other object (not represented here
2554 * as yet), since it no longer shadows us. Thus when we
2555 * call vm_object_deallocate() it may attempt to collapse
2556 * itself into its remaining parent.
2559 struct vm_object_dealloc_list *dtmp;
2561 vm_object_chain_release(backing_object);
2562 vm_object_unlock(backing_object);
2563 /* backing_object remains held */
2566 * Auto-deallocation list for caller convenience.
2571 dtmp = kmalloc(sizeof(*dtmp), M_TEMP, M_WAITOK);
2572 dtmp->object = backing_object;
2573 dtmp->next = *dlistp;
2576 vm_object_chain_release(backing_object);
2577 vm_object_drop(backing_object);
2579 /* backing_object = NULL; not needed */
2584 * Clean up any left over backing_object
2586 if (backing_object) {
2587 vm_object_chain_release(backing_object);
2588 vm_object_drop(backing_object);
2592 * Clean up any auto-deallocation list. This is a convenience
2593 * for top-level callers so they don't have to pass &dlist.
2594 * Do not clean up any caller-passed dlistp, the caller will
2598 vm_object_deallocate_list(&dlist);
2603 * vm_object_collapse() may collect additional objects in need of
2604 * deallocation. This routine deallocates these objects. The
2605 * deallocation itself can trigger additional collapses (which the
2606 * deallocate function takes care of). This procedure is used to
2607 * reduce procedural recursion since these vm_object shadow chains
2608 * can become quite long.
2611 vm_object_deallocate_list(struct vm_object_dealloc_list **dlistp)
2613 struct vm_object_dealloc_list *dlist;
2615 while ((dlist = *dlistp) != NULL) {
2616 *dlistp = dlist->next;
2617 vm_object_lock(dlist->object);
2618 vm_object_deallocate_locked(dlist->object);
2619 vm_object_drop(dlist->object);
2620 kfree(dlist, M_TEMP);
2625 * Removes all physical pages in the specified object range from the
2626 * object's list of pages.
2630 static int vm_object_page_remove_callback(vm_page_t p, void *data);
2633 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
2634 boolean_t clean_only)
2636 struct rb_vm_page_scan_info info;
2640 * Degenerate cases and assertions
2642 vm_object_hold(object);
2643 if (object == NULL ||
2644 (object->resident_page_count == 0 && object->swblock_count == 0)) {
2645 vm_object_drop(object);
2648 KASSERT(object->type != OBJT_PHYS,
2649 ("attempt to remove pages from a physical object"));
2652 * Indicate that paging is occuring on the object
2654 vm_object_pip_add(object, 1);
2657 * Figure out the actual removal range and whether we are removing
2658 * the entire contents of the object or not. If removing the entire
2659 * contents, be sure to get all pages, even those that might be
2660 * beyond the end of the object.
2662 info.object = object;
2663 info.start_pindex = start;
2665 info.end_pindex = (vm_pindex_t)-1;
2667 info.end_pindex = end - 1;
2668 info.limit = clean_only;
2669 all = (start == 0 && info.end_pindex >= object->size - 1);
2672 * Loop until we are sure we have gotten them all.
2676 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
2677 vm_object_page_remove_callback, &info);
2678 } while (info.error);
2681 * Remove any related swap if throwing away pages, or for
2682 * non-swap objects (the swap is a clean copy in that case).
2684 if (object->type != OBJT_SWAP || clean_only == FALSE) {
2686 swap_pager_freespace_all(object);
2688 swap_pager_freespace(object, info.start_pindex,
2689 info.end_pindex - info.start_pindex + 1);
2695 vm_object_pip_wakeup(object);
2696 vm_object_drop(object);
2700 * The caller must hold the object
2703 vm_object_page_remove_callback(vm_page_t p, void *data)
2705 struct rb_vm_page_scan_info *info = data;
2707 if ((++info->count & 63) == 0)
2710 if (info->object != p->object ||
2711 p->pindex < info->start_pindex ||
2712 p->pindex > info->end_pindex) {
2713 kprintf("vm_object_page_remove_callbackA: obj/pg race %p/%p\n",
2717 if (vm_page_busy_try(p, TRUE)) {
2718 vm_page_sleep_busy(p, TRUE, "vmopar");
2722 if (info->object != p->object) {
2723 /* this should never happen */
2724 kprintf("vm_object_page_remove_callbackB: obj/pg race %p/%p\n",
2731 * Wired pages cannot be destroyed, but they can be invalidated
2732 * and we do so if clean_only (limit) is not set.
2734 * WARNING! The page may be wired due to being part of a buffer
2735 * cache buffer, and the buffer might be marked B_CACHE.
2736 * This is fine as part of a truncation but VFSs must be
2737 * sure to fix the buffer up when re-extending the file.
2739 * NOTE! PG_NEED_COMMIT is ignored.
2741 if (p->wire_count != 0) {
2742 vm_page_protect(p, VM_PROT_NONE);
2743 if (info->limit == 0)
2750 * limit is our clean_only flag. If set and the page is dirty or
2751 * requires a commit, do not free it. If set and the page is being
2752 * held by someone, do not free it.
2754 if (info->limit && p->valid) {
2755 vm_page_test_dirty(p);
2756 if ((p->valid & p->dirty) || (p->flags & PG_NEED_COMMIT)) {
2765 vm_page_protect(p, VM_PROT_NONE);
2772 * Coalesces two objects backing up adjoining regions of memory into a
2775 * returns TRUE if objects were combined.
2777 * NOTE: Only works at the moment if the second object is NULL -
2778 * if it's not, which object do we lock first?
2781 * prev_object First object to coalesce
2782 * prev_offset Offset into prev_object
2783 * next_object Second object into coalesce
2784 * next_offset Offset into next_object
2786 * prev_size Size of reference to prev_object
2787 * next_size Size of reference to next_object
2789 * The caller does not need to hold (prev_object) but must have a stable
2790 * pointer to it (typically by holding the vm_map locked).
2793 vm_object_coalesce(vm_object_t prev_object, vm_pindex_t prev_pindex,
2794 vm_size_t prev_size, vm_size_t next_size)
2796 vm_pindex_t next_pindex;
2798 if (prev_object == NULL)
2801 vm_object_hold(prev_object);
2803 if (prev_object->type != OBJT_DEFAULT &&
2804 prev_object->type != OBJT_SWAP) {
2805 vm_object_drop(prev_object);
2810 * Try to collapse the object first
2812 vm_object_chain_acquire(prev_object, 0);
2813 vm_object_collapse(prev_object, NULL);
2816 * Can't coalesce if: . more than one reference . paged out . shadows
2817 * another object . has a copy elsewhere (any of which mean that the
2818 * pages not mapped to prev_entry may be in use anyway)
2821 if (prev_object->backing_object != NULL) {
2822 vm_object_chain_release(prev_object);
2823 vm_object_drop(prev_object);
2827 prev_size >>= PAGE_SHIFT;
2828 next_size >>= PAGE_SHIFT;
2829 next_pindex = prev_pindex + prev_size;
2831 if ((prev_object->ref_count > 1) &&
2832 (prev_object->size != next_pindex)) {
2833 vm_object_chain_release(prev_object);
2834 vm_object_drop(prev_object);
2839 * Remove any pages that may still be in the object from a previous
2842 if (next_pindex < prev_object->size) {
2843 vm_object_page_remove(prev_object,
2845 next_pindex + next_size, FALSE);
2846 if (prev_object->type == OBJT_SWAP)
2847 swap_pager_freespace(prev_object,
2848 next_pindex, next_size);
2852 * Extend the object if necessary.
2854 if (next_pindex + next_size > prev_object->size)
2855 prev_object->size = next_pindex + next_size;
2857 vm_object_chain_release(prev_object);
2858 vm_object_drop(prev_object);
2863 * Make the object writable and flag is being possibly dirty.
2865 * The object might not be held (or might be held but held shared),
2866 * the related vnode is probably not held either. Object and vnode are
2867 * stable by virtue of the vm_page busied by the caller preventing
2870 * If the related mount is flagged MNTK_THR_SYNC we need to call
2871 * vsetobjdirty(). Filesystems using this option usually shortcut
2872 * synchronization by only scanning the syncer list.
2875 vm_object_set_writeable_dirty(vm_object_t object)
2879 /*vm_object_assert_held(object);*/
2881 * Avoid contention in vm fault path by checking the state before
2882 * issuing an atomic op on it.
2884 if ((object->flags & (OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY)) !=
2885 (OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY)) {
2886 vm_object_set_flag(object, OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
2888 if (object->type == OBJT_VNODE &&
2889 (vp = (struct vnode *)object->handle) != NULL) {
2890 if ((vp->v_flag & VOBJDIRTY) == 0) {
2892 (vp->v_mount->mnt_kern_flag & MNTK_THR_SYNC)) {
2894 * New style THR_SYNC places vnodes on the
2895 * syncer list more deterministically.
2900 * Old style scan would not necessarily place
2901 * a vnode on the syncer list when possibly
2902 * modified via mmap.
2904 vsetflags(vp, VOBJDIRTY);
2910 #include "opt_ddb.h"
2912 #include <sys/kernel.h>
2914 #include <sys/cons.h>
2916 #include <ddb/ddb.h>
2918 static int _vm_object_in_map (vm_map_t map, vm_object_t object,
2919 vm_map_entry_t entry);
2920 static int vm_object_in_map (vm_object_t object);
2923 * The caller must hold the object.
2926 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry)
2929 vm_map_entry_t tmpe;
2930 vm_object_t obj, nobj;
2936 tmpe = map->header.next;
2937 entcount = map->nentries;
2938 while (entcount-- && (tmpe != &map->header)) {
2939 if( _vm_object_in_map(map, object, tmpe)) {
2946 switch(entry->maptype) {
2947 case VM_MAPTYPE_SUBMAP:
2948 tmpm = entry->object.sub_map;
2949 tmpe = tmpm->header.next;
2950 entcount = tmpm->nentries;
2951 while (entcount-- && tmpe != &tmpm->header) {
2952 if( _vm_object_in_map(tmpm, object, tmpe)) {
2958 case VM_MAPTYPE_NORMAL:
2959 case VM_MAPTYPE_VPAGETABLE:
2960 obj = entry->object.vm_object;
2962 if (obj == object) {
2963 if (obj != entry->object.vm_object)
2964 vm_object_drop(obj);
2967 while ((nobj = obj->backing_object) != NULL) {
2968 vm_object_hold(nobj);
2969 if (nobj == obj->backing_object)
2971 vm_object_drop(nobj);
2973 if (obj != entry->object.vm_object) {
2975 vm_object_lock_swap();
2976 vm_object_drop(obj);
2987 static int vm_object_in_map_callback(struct proc *p, void *data);
2989 struct vm_object_in_map_info {
2998 vm_object_in_map(vm_object_t object)
3000 struct vm_object_in_map_info info;
3003 info.object = object;
3005 allproc_scan(vm_object_in_map_callback, &info);
3008 if( _vm_object_in_map(&kernel_map, object, 0))
3010 if( _vm_object_in_map(&pager_map, object, 0))
3012 if( _vm_object_in_map(&buffer_map, object, 0))
3021 vm_object_in_map_callback(struct proc *p, void *data)
3023 struct vm_object_in_map_info *info = data;
3026 if (_vm_object_in_map(&p->p_vmspace->vm_map, info->object, 0)) {
3034 DB_SHOW_COMMAND(vmochk, vm_object_check)
3040 * make sure that internal objs are in a map somewhere
3041 * and none have zero ref counts.
3043 for (n = 0; n < VMOBJ_HSIZE; ++n) {
3044 for (object = TAILQ_FIRST(&vm_object_lists[n]);
3046 object = TAILQ_NEXT(object, object_list)) {
3047 if (object->type == OBJT_MARKER)
3049 if (object->handle != NULL ||
3050 (object->type != OBJT_DEFAULT &&
3051 object->type != OBJT_SWAP)) {
3054 if (object->ref_count == 0) {
3055 db_printf("vmochk: internal obj has "
3056 "zero ref count: %ld\n",
3057 (long)object->size);
3059 if (vm_object_in_map(object))
3061 db_printf("vmochk: internal obj is not in a map: "
3062 "ref: %d, size: %lu: 0x%lx, "
3063 "backing_object: %p\n",
3064 object->ref_count, (u_long)object->size,
3065 (u_long)object->size,
3066 (void *)object->backing_object);
3074 DB_SHOW_COMMAND(object, vm_object_print_static)
3076 /* XXX convert args. */
3077 vm_object_t object = (vm_object_t)addr;
3078 boolean_t full = have_addr;
3082 /* XXX count is an (unused) arg. Avoid shadowing it. */
3083 #define count was_count
3091 "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n",
3092 object, (int)object->type, (u_long)object->size,
3093 object->resident_page_count, object->ref_count, object->flags);
3095 * XXX no %qd in kernel. Truncate object->backing_object_offset.
3097 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n",
3098 object->shadow_count,
3099 object->backing_object ? object->backing_object->ref_count : 0,
3100 object->backing_object, (long)object->backing_object_offset);
3107 RB_FOREACH(p, vm_page_rb_tree, &object->rb_memq) {
3109 db_iprintf("memory:=");
3110 else if (count == 6) {
3118 db_printf("(off=0x%lx,page=0x%lx)",
3119 (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p));
3130 * XXX need this non-static entry for calling from vm_map_print.
3135 vm_object_print(/* db_expr_t */ long addr,
3136 boolean_t have_addr,
3137 /* db_expr_t */ long count,
3140 vm_object_print_static(addr, have_addr, count, modif);
3146 DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
3153 for (n = 0; n < VMOBJ_HSIZE; ++n) {
3154 for (object = TAILQ_FIRST(&vm_object_lists[n]);
3156 object = TAILQ_NEXT(object, object_list)) {
3157 vm_pindex_t idx, fidx;
3159 vm_paddr_t pa = -1, padiff;
3163 if (object->type == OBJT_MARKER)
3165 db_printf("new object: %p\n", (void *)object);
3175 osize = object->size;
3178 for (idx = 0; idx < osize; idx++) {
3179 m = vm_page_lookup(object, idx);
3182 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3183 (long)fidx, rcount, (long)pa);
3197 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
3202 padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m);
3203 padiff >>= PAGE_SHIFT;
3204 padiff &= PQ_L2_MASK;
3206 pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE;
3210 db_printf(" index(%ld)run(%d)pa(0x%lx)",
3211 (long)fidx, rcount, (long)pa);
3212 db_printf("pd(%ld)\n", (long)padiff);
3222 pa = VM_PAGE_TO_PHYS(m);
3226 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3227 (long)fidx, rcount, (long)pa);