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 object_collapses;
134 static long object_bypasses;
136 struct vm_object_hash vm_object_hash[VMOBJ_HSIZE];
138 MALLOC_DEFINE(M_VM_OBJECT, "vm_object", "vm_object structures");
140 #if defined(DEBUG_LOCKS)
142 #define vm_object_vndeallocate(obj, vpp) \
143 debugvm_object_vndeallocate(obj, vpp, __FILE__, __LINE__)
146 * Debug helper to track hold/drop/ref/deallocate calls.
149 debugvm_object_add(vm_object_t obj, char *file, int line, int addrem)
153 i = atomic_fetchadd_int(&obj->debug_index, 1);
154 i = i & (VMOBJ_DEBUG_ARRAY_SIZE - 1);
155 ksnprintf(obj->debug_hold_thrs[i],
156 sizeof(obj->debug_hold_thrs[i]),
158 (addrem == -1 ? '-' : (addrem == 1 ? '+' : '=')),
159 (curthread->td_proc ? curthread->td_proc->p_pid : -1),
162 obj->debug_hold_file[i] = file;
163 obj->debug_hold_line[i] = line;
165 /* Uncomment for debugging obj refs/derefs in reproducable cases */
166 if (strcmp(curthread->td_comm, "sshd") == 0) {
167 kprintf("%d %p refs=%d ar=%d file: %s/%d\n",
168 (curthread->td_proc ? curthread->td_proc->p_pid : -1),
169 obj, obj->ref_count, addrem, file, line);
177 * Misc low level routines
180 vm_object_lock_init(vm_object_t obj)
182 #if defined(DEBUG_LOCKS)
185 obj->debug_index = 0;
186 for (i = 0; i < VMOBJ_DEBUG_ARRAY_SIZE; i++) {
187 obj->debug_hold_thrs[i][0] = 0;
188 obj->debug_hold_file[i] = NULL;
189 obj->debug_hold_line[i] = 0;
195 vm_object_lock_swap(void)
201 vm_object_lock(vm_object_t obj)
203 lwkt_gettoken(&obj->token);
207 * Returns TRUE on sucesss
210 vm_object_lock_try(vm_object_t obj)
212 return(lwkt_trytoken(&obj->token));
216 vm_object_lock_shared(vm_object_t obj)
218 lwkt_gettoken_shared(&obj->token);
222 vm_object_unlock(vm_object_t obj)
224 lwkt_reltoken(&obj->token);
228 vm_object_upgrade(vm_object_t obj)
230 lwkt_reltoken(&obj->token);
231 lwkt_gettoken(&obj->token);
235 vm_object_downgrade(vm_object_t obj)
237 lwkt_reltoken(&obj->token);
238 lwkt_gettoken_shared(&obj->token);
242 vm_object_assert_held(vm_object_t obj)
244 ASSERT_LWKT_TOKEN_HELD(&obj->token);
250 globaldata_t gd = mycpu;
253 pg_color = (int)(intptr_t)gd->gd_curthread >> 10;
254 pg_color += gd->gd_quick_color;
255 gd->gd_quick_color += PQ_PRIME2;
261 VMOBJDEBUG(vm_object_hold)(vm_object_t obj VMOBJDBARGS)
263 KKASSERT(obj != NULL);
266 * Object must be held (object allocation is stable due to callers
267 * context, typically already holding the token on a parent object)
268 * prior to potentially blocking on the lock, otherwise the object
269 * can get ripped away from us.
271 refcount_acquire(&obj->hold_count);
274 #if defined(DEBUG_LOCKS)
275 debugvm_object_add(obj, file, line, 1);
280 VMOBJDEBUG(vm_object_hold_try)(vm_object_t obj VMOBJDBARGS)
282 KKASSERT(obj != NULL);
285 * Object must be held (object allocation is stable due to callers
286 * context, typically already holding the token on a parent object)
287 * prior to potentially blocking on the lock, otherwise the object
288 * can get ripped away from us.
290 refcount_acquire(&obj->hold_count);
291 if (vm_object_lock_try(obj) == 0) {
292 if (refcount_release(&obj->hold_count)) {
293 if (obj->ref_count == 0 && (obj->flags & OBJ_DEAD))
294 kfree(obj, M_VM_OBJECT);
299 #if defined(DEBUG_LOCKS)
300 debugvm_object_add(obj, file, line, 1);
306 VMOBJDEBUG(vm_object_hold_shared)(vm_object_t obj VMOBJDBARGS)
308 KKASSERT(obj != NULL);
311 * Object must be held (object allocation is stable due to callers
312 * context, typically already holding the token on a parent object)
313 * prior to potentially blocking on the lock, otherwise the object
314 * can get ripped away from us.
316 refcount_acquire(&obj->hold_count);
317 vm_object_lock_shared(obj);
319 #if defined(DEBUG_LOCKS)
320 debugvm_object_add(obj, file, line, 1);
325 * Drop the token and hold_count on the object.
327 * WARNING! Token might be shared.
330 VMOBJDEBUG(vm_object_drop)(vm_object_t obj VMOBJDBARGS)
336 * No new holders should be possible once we drop hold_count 1->0 as
337 * there is no longer any way to reference the object.
339 KKASSERT(obj->hold_count > 0);
340 if (refcount_release(&obj->hold_count)) {
341 #if defined(DEBUG_LOCKS)
342 debugvm_object_add(obj, file, line, -1);
345 if (obj->ref_count == 0 && (obj->flags & OBJ_DEAD)) {
346 vm_object_unlock(obj);
347 kfree(obj, M_VM_OBJECT);
349 vm_object_unlock(obj);
352 #if defined(DEBUG_LOCKS)
353 debugvm_object_add(obj, file, line, -1);
355 vm_object_unlock(obj);
360 * Initialize a freshly allocated object, returning a held object.
362 * Used only by vm_object_allocate() and zinitna().
367 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object)
369 struct vm_object_hash *hash;
371 RB_INIT(&object->rb_memq);
372 LIST_INIT(&object->shadow_head);
373 lwkt_token_init(&object->token, "vmobj");
377 object->ref_count = 1;
378 object->memattr = VM_MEMATTR_DEFAULT;
379 object->hold_count = 0;
381 if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP))
382 vm_object_set_flag(object, OBJ_ONEMAPPING);
383 object->paging_in_progress = 0;
384 object->resident_page_count = 0;
385 object->agg_pv_list_count = 0;
386 object->shadow_count = 0;
387 /* cpu localization twist */
388 object->pg_color = vm_quickcolor();
389 object->handle = NULL;
390 object->backing_object = NULL;
391 object->backing_object_offset = (vm_ooffset_t)0;
393 object->generation++;
394 object->swblock_count = 0;
395 RB_INIT(&object->swblock_root);
396 vm_object_lock_init(object);
397 pmap_object_init(object);
399 vm_object_hold(object);
401 hash = VMOBJ_HASH(object);
402 lwkt_gettoken(&hash->token);
403 TAILQ_INSERT_TAIL(&hash->list, object, object_list);
404 lwkt_reltoken(&hash->token);
408 * Initialize the VM objects module.
410 * Called from the low level boot code only. Note that this occurs before
411 * kmalloc is initialized so we cannot allocate any VM objects.
418 for (i = 0; i < VMOBJ_HSIZE; ++i) {
419 TAILQ_INIT(&vm_object_hash[i].list);
420 lwkt_token_init(&vm_object_hash[i].token, "vmobjlst");
423 _vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(KvaEnd),
425 vm_object_drop(&kernel_object);
429 vm_object_init2(void)
431 kmalloc_set_unlimited(M_VM_OBJECT);
435 * Allocate and return a new object of the specified type and size.
440 vm_object_allocate(objtype_t type, vm_pindex_t size)
444 obj = kmalloc(sizeof(*obj), M_VM_OBJECT, M_INTWAIT|M_ZERO);
445 _vm_object_allocate(type, size, obj);
452 * This version returns a held object, allowing further atomic initialization
456 vm_object_allocate_hold(objtype_t type, vm_pindex_t size)
460 obj = kmalloc(sizeof(*obj), M_VM_OBJECT, M_INTWAIT|M_ZERO);
461 _vm_object_allocate(type, size, obj);
467 * Add an additional reference to a vm_object. The object must already be
468 * held. The original non-lock version is no longer supported. The object
469 * must NOT be chain locked by anyone at the time the reference is added.
471 * Referencing a chain-locked object can blow up the fairly sensitive
472 * ref_count and shadow_count tests in the deallocator. Most callers
473 * will call vm_object_chain_wait() prior to calling
474 * vm_object_reference_locked() to avoid the case.
476 * The object must be held, but may be held shared if desired (hence why
477 * we use an atomic op).
480 VMOBJDEBUG(vm_object_reference_locked)(vm_object_t object VMOBJDBARGS)
482 KKASSERT(object != NULL);
483 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
484 KKASSERT((object->chainlk & (CHAINLK_EXCL | CHAINLK_MASK)) == 0);
485 atomic_add_int(&object->ref_count, 1);
486 if (object->type == OBJT_VNODE) {
487 vref(object->handle);
488 /* XXX what if the vnode is being destroyed? */
490 #if defined(DEBUG_LOCKS)
491 debugvm_object_add(object, file, line, 1);
496 * This version is only allowed for vnode objects.
499 VMOBJDEBUG(vm_object_reference_quick)(vm_object_t object VMOBJDBARGS)
501 KKASSERT(object->type == OBJT_VNODE);
502 atomic_add_int(&object->ref_count, 1);
503 vref(object->handle);
504 #if defined(DEBUG_LOCKS)
505 debugvm_object_add(object, file, line, 1);
510 * Object OBJ_CHAINLOCK lock handling.
512 * The caller can chain-lock backing objects recursively and then
513 * use vm_object_chain_release_all() to undo the whole chain.
515 * Chain locks are used to prevent collapses and are only applicable
516 * to OBJT_DEFAULT and OBJT_SWAP objects. Chain locking operations
517 * on other object types are ignored. This is also important because
518 * it allows e.g. the vnode underlying a memory mapping to take concurrent
521 * The object must usually be held on entry, though intermediate
522 * objects need not be held on release. The object must be held exclusively,
523 * NOT shared. Note that the prefault path checks the shared state and
524 * avoids using the chain functions.
527 vm_object_chain_wait(vm_object_t object, int shared)
529 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
531 uint32_t chainlk = object->chainlk;
535 if (chainlk & (CHAINLK_EXCL | CHAINLK_EXCLREQ)) {
536 tsleep_interlock(object, 0);
537 if (atomic_cmpset_int(&object->chainlk,
539 chainlk | CHAINLK_WAIT)) {
540 tsleep(object, PINTERLOCKED,
549 if (chainlk & (CHAINLK_MASK | CHAINLK_EXCL)) {
550 tsleep_interlock(object, 0);
551 if (atomic_cmpset_int(&object->chainlk,
553 chainlk | CHAINLK_WAIT))
555 tsleep(object, PINTERLOCKED,
560 if (atomic_cmpset_int(&object->chainlk,
562 chainlk & ~CHAINLK_WAIT))
564 if (chainlk & CHAINLK_WAIT)
576 vm_object_chain_acquire(vm_object_t object, int shared)
578 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP)
580 if (vm_shared_fault == 0)
584 uint32_t chainlk = object->chainlk;
588 if (chainlk & (CHAINLK_EXCL | CHAINLK_EXCLREQ)) {
589 tsleep_interlock(object, 0);
590 if (atomic_cmpset_int(&object->chainlk,
592 chainlk | CHAINLK_WAIT)) {
593 tsleep(object, PINTERLOCKED,
597 } else if (atomic_cmpset_int(&object->chainlk,
598 chainlk, chainlk + 1)) {
603 if (chainlk & (CHAINLK_MASK | CHAINLK_EXCL)) {
604 tsleep_interlock(object, 0);
605 if (atomic_cmpset_int(&object->chainlk,
610 tsleep(object, PINTERLOCKED,
615 if (atomic_cmpset_int(&object->chainlk,
617 (chainlk | CHAINLK_EXCL) &
620 if (chainlk & CHAINLK_WAIT)
632 vm_object_chain_release(vm_object_t object)
634 /*ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));*/
635 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP)
637 KKASSERT(object->chainlk & (CHAINLK_MASK | CHAINLK_EXCL));
639 uint32_t chainlk = object->chainlk;
642 if (chainlk & CHAINLK_MASK) {
643 if ((chainlk & CHAINLK_MASK) == 1 &&
644 atomic_cmpset_int(&object->chainlk,
646 (chainlk - 1) & ~CHAINLK_WAIT)) {
647 if (chainlk & CHAINLK_WAIT)
651 if ((chainlk & CHAINLK_MASK) > 1 &&
652 atomic_cmpset_int(&object->chainlk,
653 chainlk, chainlk - 1)) {
658 KKASSERT(chainlk & CHAINLK_EXCL);
659 if (atomic_cmpset_int(&object->chainlk,
661 chainlk & ~(CHAINLK_EXCL |
663 if (chainlk & CHAINLK_WAIT)
672 * Release the chain from first_object through and including stopobj.
673 * The caller is typically holding the first and last object locked
674 * (shared or exclusive) to prevent destruction races.
676 * We release stopobj first as an optimization as this object is most
677 * likely to be shared across multiple processes.
680 vm_object_chain_release_all(vm_object_t first_object, vm_object_t stopobj)
682 vm_object_t backing_object;
685 vm_object_chain_release(stopobj);
686 object = first_object;
688 while (object != stopobj) {
690 backing_object = object->backing_object;
691 vm_object_chain_release(object);
692 object = backing_object;
697 * Dereference an object and its underlying vnode. The object may be
698 * held shared. On return the object will remain held.
700 * This function may return a vnode in *vpp which the caller must release
701 * after the caller drops its own lock. If vpp is NULL, we assume that
702 * the caller was holding an exclusive lock on the object and we vrele()
706 VMOBJDEBUG(vm_object_vndeallocate)(vm_object_t object, struct vnode **vpp
709 struct vnode *vp = (struct vnode *) object->handle;
711 KASSERT(object->type == OBJT_VNODE,
712 ("vm_object_vndeallocate: not a vnode object"));
713 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
714 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
716 if (object->ref_count == 0) {
717 vprint("vm_object_vndeallocate", vp);
718 panic("vm_object_vndeallocate: bad object reference count");
722 int count = object->ref_count;
725 vm_object_upgrade(object);
726 if (atomic_cmpset_int(&object->ref_count, count, 0)) {
727 vclrflags(vp, VTEXT);
731 if (atomic_cmpset_int(&object->ref_count,
738 #if defined(DEBUG_LOCKS)
739 debugvm_object_add(object, file, line, -1);
743 * vrele or return the vp to vrele. We can only safely vrele(vp)
744 * if the object was locked exclusively. But there are two races
747 * We had to upgrade the object above to safely clear VTEXT
748 * but the alternative path where the shared lock is retained
749 * can STILL race to 0 in other paths and cause our own vrele()
750 * to terminate the vnode. We can't allow that if the VM object
751 * is still locked shared.
760 * Release a reference to the specified object, gained either through a
761 * vm_object_allocate or a vm_object_reference call. When all references
762 * are gone, storage associated with this object may be relinquished.
764 * The caller does not have to hold the object locked but must have control
765 * over the reference in question in order to guarantee that the object
766 * does not get ripped out from under us.
768 * XXX Currently all deallocations require an exclusive lock.
771 VMOBJDEBUG(vm_object_deallocate)(vm_object_t object VMOBJDBARGS)
780 count = object->ref_count;
784 * If decrementing the count enters into special handling
785 * territory (0, 1, or 2) we have to do it the hard way.
786 * Fortunate though, objects with only a few refs like this
787 * are not likely to be heavily contended anyway.
789 * For vnode objects we only care about 1->0 transitions.
791 if (count <= 3 || (object->type == OBJT_VNODE && count <= 1)) {
792 #if defined(DEBUG_LOCKS)
793 debugvm_object_add(object, file, line, 0);
795 vm_object_hold(object);
796 vm_object_deallocate_locked(object);
797 vm_object_drop(object);
802 * Try to decrement ref_count without acquiring a hold on
803 * the object. This is particularly important for the exec*()
804 * and exit*() code paths because the program binary may
805 * have a great deal of sharing and an exclusive lock will
806 * crowbar performance in those circumstances.
808 if (object->type == OBJT_VNODE) {
809 vp = (struct vnode *)object->handle;
810 if (atomic_cmpset_int(&object->ref_count,
812 #if defined(DEBUG_LOCKS)
813 debugvm_object_add(object, file, line, -1);
821 if (atomic_cmpset_int(&object->ref_count,
823 #if defined(DEBUG_LOCKS)
824 debugvm_object_add(object, file, line, -1);
835 VMOBJDEBUG(vm_object_deallocate_locked)(vm_object_t object VMOBJDBARGS)
837 struct vm_object_dealloc_list *dlist = NULL;
838 struct vm_object_dealloc_list *dtmp;
843 * We may chain deallocate object, but additional objects may
844 * collect on the dlist which also have to be deallocated. We
845 * must avoid a recursion, vm_object chains can get deep.
849 while (object != NULL) {
851 * vnode case, caller either locked the object exclusively
852 * or this is a recursion with must_drop != 0 and the vnode
853 * object will be locked shared.
855 * If locked shared we have to drop the object before we can
856 * call vrele() or risk a shared/exclusive livelock.
858 if (object->type == OBJT_VNODE) {
859 ASSERT_LWKT_TOKEN_HELD(&object->token);
861 struct vnode *tmp_vp;
863 vm_object_vndeallocate(object, &tmp_vp);
864 vm_object_drop(object);
869 vm_object_vndeallocate(object, NULL);
873 ASSERT_LWKT_TOKEN_HELD_EXCL(&object->token);
876 * Normal case (object is locked exclusively)
878 if (object->ref_count == 0) {
879 panic("vm_object_deallocate: object deallocated "
880 "too many times: %d", object->type);
882 if (object->ref_count > 2) {
883 atomic_add_int(&object->ref_count, -1);
884 #if defined(DEBUG_LOCKS)
885 debugvm_object_add(object, file, line, -1);
891 * Here on ref_count of one or two, which are special cases for
894 * Nominal ref_count > 1 case if the second ref is not from
897 * (ONEMAPPING only applies to DEFAULT AND SWAP objects)
899 if (object->ref_count == 2 && object->shadow_count == 0) {
900 if (object->type == OBJT_DEFAULT ||
901 object->type == OBJT_SWAP) {
902 vm_object_set_flag(object, OBJ_ONEMAPPING);
904 atomic_add_int(&object->ref_count, -1);
905 #if defined(DEBUG_LOCKS)
906 debugvm_object_add(object, file, line, -1);
912 * If the second ref is from a shadow we chain along it
913 * upwards if object's handle is exhausted.
915 * We have to decrement object->ref_count before potentially
916 * collapsing the first shadow object or the collapse code
917 * will not be able to handle the degenerate case to remove
918 * object. However, if we do it too early the object can
919 * get ripped out from under us.
921 if (object->ref_count == 2 && object->shadow_count == 1 &&
922 object->handle == NULL && (object->type == OBJT_DEFAULT ||
923 object->type == OBJT_SWAP)) {
924 temp = LIST_FIRST(&object->shadow_head);
925 KKASSERT(temp != NULL);
926 vm_object_hold(temp);
929 * Wait for any paging to complete so the collapse
930 * doesn't (or isn't likely to) qcollapse. pip
931 * waiting must occur before we acquire the
935 temp->paging_in_progress ||
936 object->paging_in_progress
938 vm_object_pip_wait(temp, "objde1");
939 vm_object_pip_wait(object, "objde2");
943 * If the parent is locked we have to give up, as
944 * otherwise we would be acquiring locks in the
945 * wrong order and potentially deadlock.
947 if (temp->chainlk & (CHAINLK_EXCL | CHAINLK_MASK)) {
948 vm_object_drop(temp);
951 vm_object_chain_acquire(temp, 0);
954 * Recheck/retry after the hold and the paging
955 * wait, both of which can block us.
957 if (object->ref_count != 2 ||
958 object->shadow_count != 1 ||
960 LIST_FIRST(&object->shadow_head) != temp ||
961 (object->type != OBJT_DEFAULT &&
962 object->type != OBJT_SWAP)) {
963 vm_object_chain_release(temp);
964 vm_object_drop(temp);
969 * We can safely drop object's ref_count now.
971 KKASSERT(object->ref_count == 2);
972 atomic_add_int(&object->ref_count, -1);
973 #if defined(DEBUG_LOCKS)
974 debugvm_object_add(object, file, line, -1);
978 * If our single parent is not collapseable just
979 * decrement ref_count (2->1) and stop.
981 if (temp->handle || (temp->type != OBJT_DEFAULT &&
982 temp->type != OBJT_SWAP)) {
983 vm_object_chain_release(temp);
984 vm_object_drop(temp);
989 * At this point we have already dropped object's
990 * ref_count so it is possible for a race to
991 * deallocate obj out from under us. Any collapse
992 * will re-check the situation. We must not block
993 * until we are able to collapse.
995 * Bump temp's ref_count to avoid an unwanted
996 * degenerate recursion (can't call
997 * vm_object_reference_locked() because it asserts
998 * that CHAINLOCK is not set).
1000 atomic_add_int(&temp->ref_count, 1);
1001 KKASSERT(temp->ref_count > 1);
1004 * Collapse temp, then deallocate the extra ref
1007 vm_object_collapse(temp, &dlist);
1008 vm_object_chain_release(temp);
1010 vm_object_lock_swap();
1011 vm_object_drop(object);
1019 * Drop the ref and handle termination on the 1->0 transition.
1020 * We may have blocked above so we have to recheck.
1023 KKASSERT(object->ref_count != 0);
1024 if (object->ref_count >= 2) {
1025 atomic_add_int(&object->ref_count, -1);
1026 #if defined(DEBUG_LOCKS)
1027 debugvm_object_add(object, file, line, -1);
1031 KKASSERT(object->ref_count == 1);
1034 * 1->0 transition. Chain through the backing_object.
1035 * Maintain the ref until we've located the backing object,
1038 while ((temp = object->backing_object) != NULL) {
1039 if (temp->type == OBJT_VNODE)
1040 vm_object_hold_shared(temp);
1042 vm_object_hold(temp);
1043 if (temp == object->backing_object)
1045 vm_object_drop(temp);
1049 * 1->0 transition verified, retry if ref_count is no longer
1050 * 1. Otherwise disconnect the backing_object (temp) and
1053 if (object->ref_count != 1) {
1054 vm_object_drop(temp);
1059 * It shouldn't be possible for the object to be chain locked
1060 * if we're removing the last ref on it.
1062 * Removing object from temp's shadow list requires dropping
1063 * temp, which we will do on loop.
1065 * NOTE! vnodes do not use the shadow list, but still have
1066 * the backing_object reference.
1068 KKASSERT((object->chainlk & (CHAINLK_EXCL|CHAINLK_MASK)) == 0);
1071 if (object->flags & OBJ_ONSHADOW) {
1072 LIST_REMOVE(object, shadow_list);
1073 temp->shadow_count--;
1075 vm_object_clear_flag(object, OBJ_ONSHADOW);
1077 object->backing_object = NULL;
1080 atomic_add_int(&object->ref_count, -1);
1081 if ((object->flags & OBJ_DEAD) == 0)
1082 vm_object_terminate(object);
1083 if (must_drop && temp)
1084 vm_object_lock_swap();
1086 vm_object_drop(object);
1091 if (must_drop && object)
1092 vm_object_drop(object);
1095 * Additional tail recursion on dlist. Avoid a recursion. Objects
1096 * on the dlist have a hold count but are not locked.
1098 if ((dtmp = dlist) != NULL) {
1100 object = dtmp->object;
1101 kfree(dtmp, M_TEMP);
1103 vm_object_lock(object); /* already held, add lock */
1104 must_drop = 1; /* and we're responsible for it */
1110 * Destroy the specified object, freeing up related resources.
1112 * The object must have zero references.
1114 * The object must held. The caller is responsible for dropping the object
1115 * after terminate returns. Terminate does NOT drop the object.
1117 static int vm_object_terminate_callback(vm_page_t p, void *data);
1120 vm_object_terminate(vm_object_t object)
1122 struct rb_vm_page_scan_info info;
1123 struct vm_object_hash *hash;
1126 * Make sure no one uses us. Once we set OBJ_DEAD we should be
1127 * able to safely block.
1129 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
1130 KKASSERT((object->flags & OBJ_DEAD) == 0);
1131 vm_object_set_flag(object, OBJ_DEAD);
1134 * Wait for the pageout daemon to be done with the object
1136 vm_object_pip_wait(object, "objtrm1");
1138 KASSERT(!object->paging_in_progress,
1139 ("vm_object_terminate: pageout in progress"));
1142 * Clean and free the pages, as appropriate. All references to the
1143 * object are gone, so we don't need to lock it.
1145 if (object->type == OBJT_VNODE) {
1149 * Clean pages and flush buffers.
1151 * NOTE! TMPFS buffer flushes do not typically flush the
1152 * actual page to swap as this would be highly
1153 * inefficient, and normal filesystems usually wrap
1154 * page flushes with buffer cache buffers.
1156 * To deal with this we have to call vinvalbuf() both
1157 * before and after the vm_object_page_clean().
1159 vp = (struct vnode *) object->handle;
1160 vinvalbuf(vp, V_SAVE, 0, 0);
1161 vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
1162 vinvalbuf(vp, V_SAVE, 0, 0);
1166 * Wait for any I/O to complete, after which there had better not
1167 * be any references left on the object.
1169 vm_object_pip_wait(object, "objtrm2");
1171 if (object->ref_count != 0) {
1172 panic("vm_object_terminate: object with references, "
1173 "ref_count=%d", object->ref_count);
1177 * Cleanup any shared pmaps associated with this object.
1179 pmap_object_free(object);
1182 * Now free any remaining pages. For internal objects, this also
1183 * removes them from paging queues. Don't free wired pages, just
1184 * remove them from the object.
1187 info.object = object;
1188 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL,
1189 vm_object_terminate_callback, &info);
1192 * Let the pager know object is dead.
1194 vm_pager_deallocate(object);
1197 * Wait for the object hold count to hit 1, clean out pages as
1198 * we go. vmobj_token interlocks any race conditions that might
1199 * pick the object up from the vm_object_list after we have cleared
1203 if (RB_ROOT(&object->rb_memq) == NULL)
1205 kprintf("vm_object_terminate: Warning, object %p "
1206 "still has %ld pages\n",
1207 object, object->resident_page_count);
1208 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL,
1209 vm_object_terminate_callback, &info);
1213 * There had better not be any pages left
1215 KKASSERT(object->resident_page_count == 0);
1218 * Remove the object from the global object list.
1220 hash = VMOBJ_HASH(object);
1221 lwkt_gettoken(&hash->token);
1222 TAILQ_REMOVE(&hash->list, object, object_list);
1223 lwkt_reltoken(&hash->token);
1225 if (object->ref_count != 0) {
1226 panic("vm_object_terminate2: object with references, "
1227 "ref_count=%d", object->ref_count);
1231 * NOTE: The object hold_count is at least 1, so we cannot kfree()
1232 * the object here. See vm_object_drop().
1237 * The caller must hold the object.
1240 vm_object_terminate_callback(vm_page_t p, void *data)
1242 struct rb_vm_page_scan_info *info = data;
1245 if ((++info->count & 63) == 0)
1248 if (object != info->object) {
1249 kprintf("vm_object_terminate_callback: obj/pg race %p/%p\n",
1253 vm_page_busy_wait(p, TRUE, "vmpgtrm");
1254 if (object != p->object) {
1255 kprintf("vm_object_terminate: Warning: Encountered "
1256 "busied page %p on queue %d\n", p, p->queue);
1258 } else if (p->wire_count == 0) {
1260 * NOTE: p->dirty and PG_NEED_COMMIT are ignored.
1263 mycpu->gd_cnt.v_pfree++;
1265 if (p->queue != PQ_NONE)
1266 kprintf("vm_object_terminate: Warning: Encountered "
1267 "wired page %p on queue %d\n", p, p->queue);
1275 * Clean all dirty pages in the specified range of object. Leaves page
1276 * on whatever queue it is currently on. If NOSYNC is set then do not
1277 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC),
1278 * leaving the object dirty.
1280 * When stuffing pages asynchronously, allow clustering. XXX we need a
1281 * synchronous clustering mode implementation.
1283 * Odd semantics: if start == end, we clean everything.
1285 * The object must be locked? XXX
1287 static int vm_object_page_clean_pass1(struct vm_page *p, void *data);
1288 static int vm_object_page_clean_pass2(struct vm_page *p, void *data);
1291 vm_object_page_clean(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
1294 struct rb_vm_page_scan_info info;
1300 vm_object_hold(object);
1301 if (object->type != OBJT_VNODE ||
1302 (object->flags & OBJ_MIGHTBEDIRTY) == 0) {
1303 vm_object_drop(object);
1307 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ?
1308 VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK;
1309 pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0;
1311 vp = object->handle;
1314 * Interlock other major object operations. This allows us to
1315 * temporarily clear OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY.
1317 vm_object_set_flag(object, OBJ_CLEANING);
1320 * Handle 'entire object' case
1322 info.start_pindex = start;
1324 info.end_pindex = object->size - 1;
1326 info.end_pindex = end - 1;
1328 wholescan = (start == 0 && info.end_pindex == object->size - 1);
1330 info.pagerflags = pagerflags;
1331 info.object = object;
1334 * If cleaning the entire object do a pass to mark the pages read-only.
1335 * If everything worked out ok, clear OBJ_WRITEABLE and
1341 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
1342 vm_object_page_clean_pass1, &info);
1343 if (info.error == 0) {
1344 vm_object_clear_flag(object,
1345 OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
1346 if (object->type == OBJT_VNODE &&
1347 (vp = (struct vnode *)object->handle) != NULL) {
1349 * Use new-style interface to clear VISDIRTY
1350 * because the vnode is not necessarily removed
1351 * from the syncer list(s) as often as it was
1352 * under the old interface, which can leave
1353 * the vnode on the syncer list after reclaim.
1361 * Do a pass to clean all the dirty pages we find.
1366 generation = object->generation;
1367 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
1368 vm_object_page_clean_pass2, &info);
1369 } while (info.error || generation != object->generation);
1371 vm_object_clear_flag(object, OBJ_CLEANING);
1372 vm_object_drop(object);
1376 * The caller must hold the object.
1380 vm_object_page_clean_pass1(struct vm_page *p, void *data)
1382 struct rb_vm_page_scan_info *info = data;
1384 if ((++info->count & 63) == 0)
1386 if (p->object != info->object ||
1387 p->pindex < info->start_pindex ||
1388 p->pindex > info->end_pindex) {
1389 kprintf("vm_object_page_clean_pass1: obj/pg race %p/%p\n",
1393 vm_page_flag_set(p, PG_CLEANCHK);
1394 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) {
1396 } else if (vm_page_busy_try(p, FALSE) == 0) {
1397 if (p->object == info->object)
1398 vm_page_protect(p, VM_PROT_READ);
1407 * The caller must hold the object
1411 vm_object_page_clean_pass2(struct vm_page *p, void *data)
1413 struct rb_vm_page_scan_info *info = data;
1416 if (p->object != info->object ||
1417 p->pindex < info->start_pindex ||
1418 p->pindex > info->end_pindex) {
1419 kprintf("vm_object_page_clean_pass2: obj/pg race %p/%p\n",
1425 * Do not mess with pages that were inserted after we started
1426 * the cleaning pass.
1428 if ((p->flags & PG_CLEANCHK) == 0)
1431 generation = info->object->generation;
1432 vm_page_busy_wait(p, TRUE, "vpcwai");
1434 if (p->object != info->object ||
1435 p->pindex < info->start_pindex ||
1436 p->pindex > info->end_pindex ||
1437 info->object->generation != generation) {
1444 * Before wasting time traversing the pmaps, check for trivial
1445 * cases where the page cannot be dirty.
1447 if (p->valid == 0 || (p->queue - p->pc) == PQ_CACHE) {
1448 KKASSERT((p->dirty & p->valid) == 0 &&
1449 (p->flags & PG_NEED_COMMIT) == 0);
1455 * Check whether the page is dirty or not. The page has been set
1456 * to be read-only so the check will not race a user dirtying the
1459 vm_page_test_dirty(p);
1460 if ((p->dirty & p->valid) == 0 && (p->flags & PG_NEED_COMMIT) == 0) {
1461 vm_page_flag_clear(p, PG_CLEANCHK);
1467 * If we have been asked to skip nosync pages and this is a
1468 * nosync page, skip it. Note that the object flags were
1469 * not cleared in this case (because pass1 will have returned an
1470 * error), so we do not have to set them.
1472 if ((info->limit & OBJPC_NOSYNC) && (p->flags & PG_NOSYNC)) {
1473 vm_page_flag_clear(p, PG_CLEANCHK);
1479 * Flush as many pages as we can. PG_CLEANCHK will be cleared on
1480 * the pages that get successfully flushed. Set info->error if
1481 * we raced an object modification.
1483 vm_object_page_collect_flush(info->object, p, info->pagerflags);
1484 /* vm_wait_nominal(); this can deadlock the system in syncer/pageout */
1486 if ((++info->count & 63) == 0)
1493 * Collect the specified page and nearby pages and flush them out.
1494 * The number of pages flushed is returned. The passed page is busied
1495 * by the caller and we are responsible for its disposition.
1497 * The caller must hold the object.
1500 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags)
1508 vm_page_t ma[BLIST_MAX_ALLOC];
1510 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
1513 page_base = pi % BLIST_MAX_ALLOC;
1521 tp = vm_page_lookup_busy_try(object, pi - page_base + ib,
1527 if ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 &&
1528 (tp->flags & PG_CLEANCHK) == 0) {
1532 if ((tp->queue - tp->pc) == PQ_CACHE) {
1533 vm_page_flag_clear(tp, PG_CLEANCHK);
1537 vm_page_test_dirty(tp);
1538 if ((tp->dirty & tp->valid) == 0 &&
1539 (tp->flags & PG_NEED_COMMIT) == 0) {
1540 vm_page_flag_clear(tp, PG_CLEANCHK);
1549 while (is < BLIST_MAX_ALLOC &&
1550 pi - page_base + is < object->size) {
1553 tp = vm_page_lookup_busy_try(object, pi - page_base + is,
1559 if ((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 &&
1560 (tp->flags & PG_CLEANCHK) == 0) {
1564 if ((tp->queue - tp->pc) == PQ_CACHE) {
1565 vm_page_flag_clear(tp, PG_CLEANCHK);
1569 vm_page_test_dirty(tp);
1570 if ((tp->dirty & tp->valid) == 0 &&
1571 (tp->flags & PG_NEED_COMMIT) == 0) {
1572 vm_page_flag_clear(tp, PG_CLEANCHK);
1581 * All pages in the ma[] array are busied now
1583 for (i = ib; i < is; ++i) {
1584 vm_page_flag_clear(ma[i], PG_CLEANCHK);
1585 vm_page_hold(ma[i]); /* XXX need this any more? */
1587 vm_pageout_flush(&ma[ib], is - ib, pagerflags);
1588 for (i = ib; i < is; ++i) /* XXX need this any more? */
1589 vm_page_unhold(ma[i]);
1593 * Same as vm_object_pmap_copy, except range checking really
1594 * works, and is meant for small sections of an object.
1596 * This code protects resident pages by making them read-only
1597 * and is typically called on a fork or split when a page
1598 * is converted to copy-on-write.
1600 * NOTE: If the page is already at VM_PROT_NONE, calling
1601 * vm_page_protect will have no effect.
1604 vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
1609 if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
1612 vm_object_hold(object);
1613 for (idx = start; idx < end; idx++) {
1614 p = vm_page_lookup(object, idx);
1617 vm_page_protect(p, VM_PROT_READ);
1619 vm_object_drop(object);
1623 * Removes all physical pages in the specified object range from all
1626 * The object must *not* be locked.
1629 static int vm_object_pmap_remove_callback(vm_page_t p, void *data);
1632 vm_object_pmap_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
1634 struct rb_vm_page_scan_info info;
1638 info.start_pindex = start;
1639 info.end_pindex = end - 1;
1641 info.object = object;
1643 vm_object_hold(object);
1644 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
1645 vm_object_pmap_remove_callback, &info);
1646 if (start == 0 && end == object->size)
1647 vm_object_clear_flag(object, OBJ_WRITEABLE);
1648 vm_object_drop(object);
1652 * The caller must hold the object
1655 vm_object_pmap_remove_callback(vm_page_t p, void *data)
1657 struct rb_vm_page_scan_info *info = data;
1659 if ((++info->count & 63) == 0)
1662 if (info->object != p->object ||
1663 p->pindex < info->start_pindex ||
1664 p->pindex > info->end_pindex) {
1665 kprintf("vm_object_pmap_remove_callback: obj/pg race %p/%p\n",
1670 vm_page_protect(p, VM_PROT_NONE);
1676 * Implements the madvise function at the object/page level.
1678 * MADV_WILLNEED (any object)
1680 * Activate the specified pages if they are resident.
1682 * MADV_DONTNEED (any object)
1684 * Deactivate the specified pages if they are resident.
1686 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, OBJ_ONEMAPPING only)
1688 * Deactivate and clean the specified pages if they are
1689 * resident. This permits the process to reuse the pages
1690 * without faulting or the kernel to reclaim the pages
1696 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, int count, int advise)
1698 vm_pindex_t end, tpindex;
1699 vm_object_t tobject;
1707 end = pindex + count;
1709 vm_object_hold(object);
1713 * Locate and adjust resident pages
1715 for (; pindex < end; pindex += 1) {
1717 if (tobject != object)
1718 vm_object_drop(tobject);
1723 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
1724 * and those pages must be OBJ_ONEMAPPING.
1726 if (advise == MADV_FREE) {
1727 if ((tobject->type != OBJT_DEFAULT &&
1728 tobject->type != OBJT_SWAP) ||
1729 (tobject->flags & OBJ_ONEMAPPING) == 0) {
1734 m = vm_page_lookup_busy_try(tobject, tpindex, TRUE, &error);
1737 vm_page_sleep_busy(m, TRUE, "madvpo");
1742 * There may be swap even if there is no backing page
1744 if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
1745 swap_pager_freespace(tobject, tpindex, 1);
1750 while ((xobj = tobject->backing_object) != NULL) {
1751 KKASSERT(xobj != object);
1752 vm_object_hold(xobj);
1753 if (xobj == tobject->backing_object)
1755 vm_object_drop(xobj);
1759 tpindex += OFF_TO_IDX(tobject->backing_object_offset);
1760 if (tobject != object) {
1761 vm_object_lock_swap();
1762 vm_object_drop(tobject);
1769 * If the page is not in a normal active state, we skip it.
1770 * If the page is not managed there are no page queues to
1771 * mess with. Things can break if we mess with pages in
1772 * any of the below states.
1774 if (m->wire_count ||
1775 (m->flags & (PG_UNMANAGED | PG_NEED_COMMIT)) ||
1776 m->valid != VM_PAGE_BITS_ALL
1783 * Theoretically once a page is known not to be busy, an
1784 * interrupt cannot come along and rip it out from under us.
1787 if (advise == MADV_WILLNEED) {
1788 vm_page_activate(m);
1789 } else if (advise == MADV_DONTNEED) {
1790 vm_page_dontneed(m);
1791 } else if (advise == MADV_FREE) {
1793 * Mark the page clean. This will allow the page
1794 * to be freed up by the system. However, such pages
1795 * are often reused quickly by malloc()/free()
1796 * so we do not do anything that would cause
1797 * a page fault if we can help it.
1799 * Specifically, we do not try to actually free
1800 * the page now nor do we try to put it in the
1801 * cache (which would cause a page fault on reuse).
1803 * But we do make the page is freeable as we
1804 * can without actually taking the step of unmapping
1807 pmap_clear_modify(m);
1810 vm_page_dontneed(m);
1811 if (tobject->type == OBJT_SWAP)
1812 swap_pager_freespace(tobject, tpindex, 1);
1816 if (tobject != object)
1817 vm_object_drop(tobject);
1818 vm_object_drop(object);
1822 * Create a new object which is backed by the specified existing object
1823 * range. Replace the pointer and offset that was pointing at the existing
1824 * object with the pointer/offset for the new object.
1826 * If addref is non-zero the returned object is given an additional reference.
1827 * This mechanic exists to avoid the situation where refs might be 1 and
1828 * race against a collapse when the caller intends to bump it. So the
1829 * caller cannot add the ref after the fact. Used when the caller is
1830 * duplicating a vm_map_entry.
1832 * No other requirements.
1835 vm_object_shadow(vm_object_t *objectp, vm_ooffset_t *offset, vm_size_t length,
1845 * Don't create the new object if the old object isn't shared.
1846 * We have to chain wait before adding the reference to avoid
1847 * racing a collapse or deallocation.
1849 * Clear OBJ_ONEMAPPING flag when shadowing.
1851 * The caller owns a ref on source via *objectp which we are going
1852 * to replace. This ref is inherited by the backing_object assignment.
1853 * from nobject and does not need to be incremented here.
1855 * However, we add a temporary extra reference to the original source
1856 * prior to holding nobject in case we block, to avoid races where
1857 * someone else might believe that the source can be collapsed.
1861 if (source->type != OBJT_VNODE) {
1863 vm_object_hold(source);
1864 vm_object_chain_wait(source, 0);
1865 if (source->ref_count == 1 &&
1866 source->handle == NULL &&
1867 (source->type == OBJT_DEFAULT ||
1868 source->type == OBJT_SWAP)) {
1870 vm_object_reference_locked(source);
1871 vm_object_clear_flag(source,
1874 vm_object_drop(source);
1877 vm_object_reference_locked(source);
1878 vm_object_clear_flag(source, OBJ_ONEMAPPING);
1880 vm_object_reference_quick(source);
1881 vm_object_clear_flag(source, OBJ_ONEMAPPING);
1886 * Allocate a new object with the given length. The new object
1887 * is returned referenced but we may have to add another one.
1888 * If we are adding a second reference we must clear OBJ_ONEMAPPING.
1889 * (typically because the caller is about to clone a vm_map_entry).
1891 * The source object currently has an extra reference to prevent
1892 * collapses into it while we mess with its shadow list, which
1893 * we will remove later in this routine.
1895 * The target object may require a second reference if asked for one
1898 result = vm_object_allocate(OBJT_DEFAULT, length);
1900 panic("vm_object_shadow: no object for shadowing");
1901 vm_object_hold(result);
1903 vm_object_reference_locked(result);
1904 vm_object_clear_flag(result, OBJ_ONEMAPPING);
1908 * The new object shadows the source object. Chain wait before
1909 * adjusting shadow_count or the shadow list to avoid races.
1911 * Try to optimize the result object's page color when shadowing
1912 * in order to maintain page coloring consistency in the combined
1915 * The backing_object reference to source requires adding a ref to
1916 * source. We simply inherit the ref from the original *objectp
1917 * (which we are replacing) so no additional refs need to be added.
1918 * (we must still clean up the extra ref we had to prevent collapse
1921 * SHADOWING IS NOT APPLICABLE TO OBJT_VNODE OBJECTS
1923 KKASSERT(result->backing_object == NULL);
1924 result->backing_object = source;
1926 if (useshadowlist) {
1927 vm_object_chain_wait(source, 0);
1928 LIST_INSERT_HEAD(&source->shadow_head,
1929 result, shadow_list);
1930 source->shadow_count++;
1931 source->generation++;
1932 vm_object_set_flag(result, OBJ_ONSHADOW);
1934 /* cpu localization twist */
1935 result->pg_color = vm_quickcolor();
1939 * Adjust the return storage. Drop the ref on source before
1942 result->backing_object_offset = *offset;
1943 vm_object_drop(result);
1946 if (useshadowlist) {
1947 vm_object_deallocate_locked(source);
1948 vm_object_drop(source);
1950 vm_object_deallocate(source);
1955 * Return the new things
1960 #define OBSC_TEST_ALL_SHADOWED 0x0001
1961 #define OBSC_COLLAPSE_NOWAIT 0x0002
1962 #define OBSC_COLLAPSE_WAIT 0x0004
1964 static int vm_object_backing_scan_callback(vm_page_t p, void *data);
1967 * The caller must hold the object.
1970 vm_object_backing_scan(vm_object_t object, vm_object_t backing_object, int op)
1972 struct rb_vm_page_scan_info info;
1973 struct vm_object_hash *hash;
1975 vm_object_assert_held(object);
1976 vm_object_assert_held(backing_object);
1978 KKASSERT(backing_object == object->backing_object);
1979 info.backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
1982 * Initial conditions
1984 if (op & OBSC_TEST_ALL_SHADOWED) {
1986 * We do not want to have to test for the existence of
1987 * swap pages in the backing object. XXX but with the
1988 * new swapper this would be pretty easy to do.
1990 * XXX what about anonymous MAP_SHARED memory that hasn't
1991 * been ZFOD faulted yet? If we do not test for this, the
1992 * shadow test may succeed! XXX
1994 if (backing_object->type != OBJT_DEFAULT)
1997 if (op & OBSC_COLLAPSE_WAIT) {
1998 KKASSERT((backing_object->flags & OBJ_DEAD) == 0);
1999 vm_object_set_flag(backing_object, OBJ_DEAD);
2001 hash = VMOBJ_HASH(backing_object);
2002 lwkt_gettoken(&hash->token);
2003 TAILQ_REMOVE(&hash->list, backing_object, object_list);
2004 lwkt_reltoken(&hash->token);
2008 * Our scan. We have to retry if a negative error code is returned,
2009 * otherwise 0 or 1 will be returned in info.error. 0 Indicates that
2010 * the scan had to be stopped because the parent does not completely
2013 info.object = object;
2014 info.backing_object = backing_object;
2019 vm_page_rb_tree_RB_SCAN(&backing_object->rb_memq, NULL,
2020 vm_object_backing_scan_callback,
2022 } while (info.error < 0);
2028 * The caller must hold the object.
2031 vm_object_backing_scan_callback(vm_page_t p, void *data)
2033 struct rb_vm_page_scan_info *info = data;
2034 vm_object_t backing_object;
2037 vm_pindex_t new_pindex;
2038 vm_pindex_t backing_offset_index;
2042 new_pindex = pindex - info->backing_offset_index;
2044 object = info->object;
2045 backing_object = info->backing_object;
2046 backing_offset_index = info->backing_offset_index;
2048 if (op & OBSC_TEST_ALL_SHADOWED) {
2052 * Ignore pages outside the parent object's range
2053 * and outside the parent object's mapping of the
2056 * note that we do not busy the backing object's
2059 if (pindex < backing_offset_index ||
2060 new_pindex >= object->size
2066 * See if the parent has the page or if the parent's
2067 * object pager has the page. If the parent has the
2068 * page but the page is not valid, the parent's
2069 * object pager must have the page.
2071 * If this fails, the parent does not completely shadow
2072 * the object and we might as well give up now.
2074 pp = vm_page_lookup(object, new_pindex);
2075 if ((pp == NULL || pp->valid == 0) &&
2076 !vm_pager_has_page(object, new_pindex)
2078 info->error = 0; /* problemo */
2079 return(-1); /* stop the scan */
2084 * Check for busy page. Note that we may have lost (p) when we
2085 * possibly blocked above.
2087 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
2090 if (vm_page_busy_try(p, TRUE)) {
2091 if (op & OBSC_COLLAPSE_NOWAIT) {
2095 * If we slept, anything could have
2096 * happened. Ask that the scan be restarted.
2098 * Since the object is marked dead, the
2099 * backing offset should not have changed.
2101 vm_page_sleep_busy(p, TRUE, "vmocol");
2108 * If (p) is no longer valid restart the scan.
2110 if (p->object != backing_object || p->pindex != pindex) {
2111 kprintf("vm_object_backing_scan: Warning: page "
2112 "%p ripped out from under us\n", p);
2118 if (op & OBSC_COLLAPSE_NOWAIT) {
2119 if (p->valid == 0 ||
2121 (p->flags & PG_NEED_COMMIT)) {
2126 /* XXX what if p->valid == 0 , hold_count, etc? */
2130 p->object == backing_object,
2131 ("vm_object_qcollapse(): object mismatch")
2135 * Destroy any associated swap
2137 if (backing_object->type == OBJT_SWAP)
2138 swap_pager_freespace(backing_object, p->pindex, 1);
2141 p->pindex < backing_offset_index ||
2142 new_pindex >= object->size
2145 * Page is out of the parent object's range, we
2146 * can simply destroy it.
2148 vm_page_protect(p, VM_PROT_NONE);
2153 pp = vm_page_lookup(object, new_pindex);
2154 if (pp != NULL || vm_pager_has_page(object, new_pindex)) {
2156 * page already exists in parent OR swap exists
2157 * for this location in the parent. Destroy
2158 * the original page from the backing object.
2160 * Leave the parent's page alone
2162 vm_page_protect(p, VM_PROT_NONE);
2168 * Page does not exist in parent, rename the
2169 * page from the backing object to the main object.
2171 * If the page was mapped to a process, it can remain
2172 * mapped through the rename.
2174 if ((p->queue - p->pc) == PQ_CACHE)
2175 vm_page_deactivate(p);
2177 vm_page_rename(p, object, new_pindex);
2179 /* page automatically made dirty by rename */
2185 * This version of collapse allows the operation to occur earlier and
2186 * when paging_in_progress is true for an object... This is not a complete
2187 * operation, but should plug 99.9% of the rest of the leaks.
2189 * The caller must hold the object and backing_object and both must be
2192 * (only called from vm_object_collapse)
2195 vm_object_qcollapse(vm_object_t object, vm_object_t backing_object)
2197 if (backing_object->ref_count == 1) {
2198 atomic_add_int(&backing_object->ref_count, 2);
2199 #if defined(DEBUG_LOCKS)
2200 debugvm_object_add(backing_object, "qcollapse", 1, 2);
2202 vm_object_backing_scan(object, backing_object,
2203 OBSC_COLLAPSE_NOWAIT);
2204 atomic_add_int(&backing_object->ref_count, -2);
2205 #if defined(DEBUG_LOCKS)
2206 debugvm_object_add(backing_object, "qcollapse", 2, -2);
2212 * Collapse an object with the object backing it. Pages in the backing
2213 * object are moved into the parent, and the backing object is deallocated.
2214 * Any conflict is resolved in favor of the parent's existing pages.
2216 * object must be held and chain-locked on call.
2218 * The caller must have an extra ref on object to prevent a race from
2219 * destroying it during the collapse.
2222 vm_object_collapse(vm_object_t object, struct vm_object_dealloc_list **dlistp)
2224 struct vm_object_dealloc_list *dlist = NULL;
2225 vm_object_t backing_object;
2228 * Only one thread is attempting a collapse at any given moment.
2229 * There are few restrictions for (object) that callers of this
2230 * function check so reentrancy is likely.
2232 KKASSERT(object != NULL);
2233 vm_object_assert_held(object);
2234 KKASSERT(object->chainlk & (CHAINLK_MASK | CHAINLK_EXCL));
2241 * We can only collapse a DEFAULT/SWAP object with a
2242 * DEFAULT/SWAP object.
2244 if (object->type != OBJT_DEFAULT && object->type != OBJT_SWAP) {
2245 backing_object = NULL;
2249 backing_object = object->backing_object;
2250 if (backing_object == NULL)
2252 if (backing_object->type != OBJT_DEFAULT &&
2253 backing_object->type != OBJT_SWAP) {
2254 backing_object = NULL;
2259 * Hold the backing_object and check for races
2261 vm_object_hold(backing_object);
2262 if (backing_object != object->backing_object ||
2263 (backing_object->type != OBJT_DEFAULT &&
2264 backing_object->type != OBJT_SWAP)) {
2265 vm_object_drop(backing_object);
2270 * Chain-lock the backing object too because if we
2271 * successfully merge its pages into the top object we
2272 * will collapse backing_object->backing_object as the
2273 * new backing_object. Re-check that it is still our
2276 vm_object_chain_acquire(backing_object, 0);
2277 if (backing_object != object->backing_object) {
2278 vm_object_chain_release(backing_object);
2279 vm_object_drop(backing_object);
2284 * we check the backing object first, because it is most likely
2287 if (backing_object->handle != NULL ||
2288 (backing_object->type != OBJT_DEFAULT &&
2289 backing_object->type != OBJT_SWAP) ||
2290 (backing_object->flags & OBJ_DEAD) ||
2291 object->handle != NULL ||
2292 (object->type != OBJT_DEFAULT &&
2293 object->type != OBJT_SWAP) ||
2294 (object->flags & OBJ_DEAD)) {
2299 * If paging is in progress we can't do a normal collapse.
2302 object->paging_in_progress != 0 ||
2303 backing_object->paging_in_progress != 0
2305 vm_object_qcollapse(object, backing_object);
2310 * We know that we can either collapse the backing object (if
2311 * the parent is the only reference to it) or (perhaps) have
2312 * the parent bypass the object if the parent happens to shadow
2313 * all the resident pages in the entire backing object.
2315 * This is ignoring pager-backed pages such as swap pages.
2316 * vm_object_backing_scan fails the shadowing test in this
2319 if (backing_object->ref_count == 1) {
2321 * If there is exactly one reference to the backing
2322 * object, we can collapse it into the parent.
2324 KKASSERT(object->backing_object == backing_object);
2325 vm_object_backing_scan(object, backing_object,
2326 OBSC_COLLAPSE_WAIT);
2329 * Move the pager from backing_object to object.
2331 if (backing_object->type == OBJT_SWAP) {
2332 vm_object_pip_add(backing_object, 1);
2335 * scrap the paging_offset junk and do a
2336 * discrete copy. This also removes major
2337 * assumptions about how the swap-pager
2338 * works from where it doesn't belong. The
2339 * new swapper is able to optimize the
2340 * destroy-source case.
2342 vm_object_pip_add(object, 1);
2343 swap_pager_copy(backing_object, object,
2344 OFF_TO_IDX(object->backing_object_offset),
2346 vm_object_pip_wakeup(object);
2347 vm_object_pip_wakeup(backing_object);
2351 * Object now shadows whatever backing_object did.
2352 * Remove object from backing_object's shadow_list.
2354 * Removing object from backing_objects shadow list
2355 * requires releasing object, which we will do below.
2357 KKASSERT(object->backing_object == backing_object);
2358 if (object->flags & OBJ_ONSHADOW) {
2359 LIST_REMOVE(object, shadow_list);
2360 backing_object->shadow_count--;
2361 backing_object->generation++;
2362 vm_object_clear_flag(object, OBJ_ONSHADOW);
2366 * backing_object->backing_object moves from within
2367 * backing_object to within object.
2369 * OBJT_VNODE bbobj's should have empty shadow lists.
2371 while ((bbobj = backing_object->backing_object) != NULL) {
2372 if (bbobj->type == OBJT_VNODE)
2373 vm_object_hold_shared(bbobj);
2375 vm_object_hold(bbobj);
2376 if (bbobj == backing_object->backing_object)
2378 vm_object_drop(bbobj);
2382 * We are removing backing_object from bbobj's
2383 * shadow list and adding object to bbobj's shadow
2384 * list, so the ref_count on bbobj is unchanged.
2387 if (backing_object->flags & OBJ_ONSHADOW) {
2388 /* not locked exclusively if vnode */
2389 KKASSERT(bbobj->type != OBJT_VNODE);
2390 LIST_REMOVE(backing_object,
2392 bbobj->shadow_count--;
2393 bbobj->generation++;
2394 vm_object_clear_flag(backing_object,
2397 backing_object->backing_object = NULL;
2399 object->backing_object = bbobj;
2401 if (bbobj->type != OBJT_VNODE) {
2402 LIST_INSERT_HEAD(&bbobj->shadow_head,
2403 object, shadow_list);
2404 bbobj->shadow_count++;
2405 bbobj->generation++;
2406 vm_object_set_flag(object,
2411 object->backing_object_offset +=
2412 backing_object->backing_object_offset;
2414 vm_object_drop(bbobj);
2417 * Discard the old backing_object. Nothing should be
2418 * able to ref it, other than a vm_map_split(),
2419 * and vm_map_split() will stall on our chain lock.
2420 * And we control the parent so it shouldn't be
2421 * possible for it to go away either.
2423 * Since the backing object has no pages, no pager
2424 * left, and no object references within it, all
2425 * that is necessary is to dispose of it.
2427 KASSERT(backing_object->ref_count == 1,
2428 ("backing_object %p was somehow "
2429 "re-referenced during collapse!",
2431 KASSERT(RB_EMPTY(&backing_object->rb_memq),
2432 ("backing_object %p somehow has left "
2433 "over pages during collapse!",
2437 * The object can be destroyed.
2439 * XXX just fall through and dodealloc instead
2440 * of forcing destruction?
2442 atomic_add_int(&backing_object->ref_count, -1);
2443 #if defined(DEBUG_LOCKS)
2444 debugvm_object_add(backing_object, "collapse", 1, -1);
2446 if ((backing_object->flags & OBJ_DEAD) == 0)
2447 vm_object_terminate(backing_object);
2452 * If we do not entirely shadow the backing object,
2453 * there is nothing we can do so we give up.
2455 if (vm_object_backing_scan(object, backing_object,
2456 OBSC_TEST_ALL_SHADOWED) == 0) {
2461 * bbobj is backing_object->backing_object. Since
2462 * object completely shadows backing_object we can
2463 * bypass it and become backed by bbobj instead.
2465 * The shadow list for vnode backing objects is not
2466 * used and a shared hold is allowed.
2468 while ((bbobj = backing_object->backing_object) != NULL) {
2469 if (bbobj->type == OBJT_VNODE)
2470 vm_object_hold_shared(bbobj);
2472 vm_object_hold(bbobj);
2473 if (bbobj == backing_object->backing_object)
2475 vm_object_drop(bbobj);
2479 * Make object shadow bbobj instead of backing_object.
2480 * Remove object from backing_object's shadow list.
2482 * Deallocating backing_object will not remove
2483 * it, since its reference count is at least 2.
2485 * Removing object from backing_object's shadow
2486 * list requires releasing a ref, which we do
2487 * below by setting dodealloc to 1.
2489 KKASSERT(object->backing_object == backing_object);
2490 if (object->flags & OBJ_ONSHADOW) {
2491 LIST_REMOVE(object, shadow_list);
2492 backing_object->shadow_count--;
2493 backing_object->generation++;
2494 vm_object_clear_flag(object, OBJ_ONSHADOW);
2498 * Add a ref to bbobj, bbobj now shadows object.
2500 * NOTE: backing_object->backing_object still points
2501 * to bbobj. That relationship remains intact
2502 * because backing_object has > 1 ref, so
2503 * someone else is pointing to it (hence why
2504 * we can't collapse it into object and can
2505 * only handle the all-shadowed bypass case).
2508 if (bbobj->type != OBJT_VNODE) {
2509 vm_object_chain_wait(bbobj, 0);
2510 vm_object_reference_locked(bbobj);
2511 LIST_INSERT_HEAD(&bbobj->shadow_head,
2512 object, shadow_list);
2513 bbobj->shadow_count++;
2514 bbobj->generation++;
2515 vm_object_set_flag(object,
2518 vm_object_reference_quick(bbobj);
2520 object->backing_object_offset +=
2521 backing_object->backing_object_offset;
2522 object->backing_object = bbobj;
2523 vm_object_drop(bbobj);
2525 object->backing_object = NULL;
2529 * Drop the reference count on backing_object. To
2530 * handle ref_count races properly we can't assume
2531 * that the ref_count is still at least 2 so we
2532 * have to actually call vm_object_deallocate()
2533 * (after clearing the chainlock).
2540 * Ok, we want to loop on the new object->bbobj association,
2541 * possibly collapsing it further. However if dodealloc is
2542 * non-zero we have to deallocate the backing_object which
2543 * itself can potentially undergo a collapse, creating a
2544 * recursion depth issue with the LWKT token subsystem.
2546 * In the case where we must deallocate the backing_object
2547 * it is possible now that the backing_object has a single
2548 * shadow count on some other object (not represented here
2549 * as yet), since it no longer shadows us. Thus when we
2550 * call vm_object_deallocate() it may attempt to collapse
2551 * itself into its remaining parent.
2554 struct vm_object_dealloc_list *dtmp;
2556 vm_object_chain_release(backing_object);
2557 vm_object_unlock(backing_object);
2558 /* backing_object remains held */
2561 * Auto-deallocation list for caller convenience.
2566 dtmp = kmalloc(sizeof(*dtmp), M_TEMP, M_WAITOK);
2567 dtmp->object = backing_object;
2568 dtmp->next = *dlistp;
2571 vm_object_chain_release(backing_object);
2572 vm_object_drop(backing_object);
2574 /* backing_object = NULL; not needed */
2579 * Clean up any left over backing_object
2581 if (backing_object) {
2582 vm_object_chain_release(backing_object);
2583 vm_object_drop(backing_object);
2587 * Clean up any auto-deallocation list. This is a convenience
2588 * for top-level callers so they don't have to pass &dlist.
2589 * Do not clean up any caller-passed dlistp, the caller will
2593 vm_object_deallocate_list(&dlist);
2598 * vm_object_collapse() may collect additional objects in need of
2599 * deallocation. This routine deallocates these objects. The
2600 * deallocation itself can trigger additional collapses (which the
2601 * deallocate function takes care of). This procedure is used to
2602 * reduce procedural recursion since these vm_object shadow chains
2603 * can become quite long.
2606 vm_object_deallocate_list(struct vm_object_dealloc_list **dlistp)
2608 struct vm_object_dealloc_list *dlist;
2610 while ((dlist = *dlistp) != NULL) {
2611 *dlistp = dlist->next;
2612 vm_object_lock(dlist->object);
2613 vm_object_deallocate_locked(dlist->object);
2614 vm_object_drop(dlist->object);
2615 kfree(dlist, M_TEMP);
2620 * Removes all physical pages in the specified object range from the
2621 * object's list of pages.
2625 static int vm_object_page_remove_callback(vm_page_t p, void *data);
2628 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
2629 boolean_t clean_only)
2631 struct rb_vm_page_scan_info info;
2635 * Degenerate cases and assertions
2637 vm_object_hold(object);
2638 if (object == NULL ||
2639 (object->resident_page_count == 0 && object->swblock_count == 0)) {
2640 vm_object_drop(object);
2643 KASSERT(object->type != OBJT_PHYS,
2644 ("attempt to remove pages from a physical object"));
2647 * Indicate that paging is occuring on the object
2649 vm_object_pip_add(object, 1);
2652 * Figure out the actual removal range and whether we are removing
2653 * the entire contents of the object or not. If removing the entire
2654 * contents, be sure to get all pages, even those that might be
2655 * beyond the end of the object.
2657 info.object = object;
2658 info.start_pindex = start;
2660 info.end_pindex = (vm_pindex_t)-1;
2662 info.end_pindex = end - 1;
2663 info.limit = clean_only;
2665 all = (start == 0 && info.end_pindex >= object->size - 1);
2668 * Loop until we are sure we have gotten them all.
2672 vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
2673 vm_object_page_remove_callback, &info);
2674 } while (info.error);
2677 * Remove any related swap if throwing away pages, or for
2678 * non-swap objects (the swap is a clean copy in that case).
2680 if (object->type != OBJT_SWAP || clean_only == FALSE) {
2682 swap_pager_freespace_all(object);
2684 swap_pager_freespace(object, info.start_pindex,
2685 info.end_pindex - info.start_pindex + 1);
2691 vm_object_pip_wakeup(object);
2692 vm_object_drop(object);
2696 * The caller must hold the object.
2698 * NOTE: User yields are allowed when removing more than one page, but not
2699 * allowed if only removing one page (the path for single page removals
2700 * might hold a spinlock).
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)
3036 struct vm_object_hash *hash;
3041 * make sure that internal objs are in a map somewhere
3042 * and none have zero ref counts.
3044 for (n = 0; n < VMOBJ_HSIZE; ++n) {
3045 hash = &vm_object_hash[n];
3046 for (object = TAILQ_FIRST(&hash->list);
3048 object = TAILQ_NEXT(object, object_list)) {
3049 if (object->type == OBJT_MARKER)
3051 if (object->handle != NULL ||
3052 (object->type != OBJT_DEFAULT &&
3053 object->type != OBJT_SWAP)) {
3056 if (object->ref_count == 0) {
3057 db_printf("vmochk: internal obj has "
3058 "zero ref count: %ld\n",
3059 (long)object->size);
3061 if (vm_object_in_map(object))
3063 db_printf("vmochk: internal obj is not in a map: "
3064 "ref: %d, size: %lu: 0x%lx, "
3065 "backing_object: %p\n",
3066 object->ref_count, (u_long)object->size,
3067 (u_long)object->size,
3068 (void *)object->backing_object);
3076 DB_SHOW_COMMAND(object, vm_object_print_static)
3078 /* XXX convert args. */
3079 vm_object_t object = (vm_object_t)addr;
3080 boolean_t full = have_addr;
3084 /* XXX count is an (unused) arg. Avoid shadowing it. */
3085 #define count was_count
3093 "Object %p: type=%d, size=0x%lx, res=%ld, ref=%d, flags=0x%x\n",
3094 object, (int)object->type, (u_long)object->size,
3095 object->resident_page_count, object->ref_count, object->flags);
3097 * XXX no %qd in kernel. Truncate object->backing_object_offset.
3099 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n",
3100 object->shadow_count,
3101 object->backing_object ? object->backing_object->ref_count : 0,
3102 object->backing_object, (long)object->backing_object_offset);
3109 RB_FOREACH(p, vm_page_rb_tree, &object->rb_memq) {
3111 db_iprintf("memory:=");
3112 else if (count == 6) {
3120 db_printf("(off=0x%lx,page=0x%lx)",
3121 (u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p));
3132 * XXX need this non-static entry for calling from vm_map_print.
3137 vm_object_print(/* db_expr_t */ long addr,
3138 boolean_t have_addr,
3139 /* db_expr_t */ long count,
3142 vm_object_print_static(addr, have_addr, count, modif);
3148 DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
3150 struct vm_object_hash *hash;
3156 for (n = 0; n < VMOBJ_HSIZE; ++n) {
3157 hash = &vm_object_hash[n];
3158 for (object = TAILQ_FIRST(&hash->list);
3160 object = TAILQ_NEXT(object, object_list)) {
3161 vm_pindex_t idx, fidx;
3163 vm_paddr_t pa = -1, padiff;
3167 if (object->type == OBJT_MARKER)
3169 db_printf("new object: %p\n", (void *)object);
3179 osize = object->size;
3182 for (idx = 0; idx < osize; idx++) {
3183 m = vm_page_lookup(object, idx);
3186 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3187 (long)fidx, rcount, (long)pa);
3201 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
3206 padiff = pa + rcount * PAGE_SIZE - VM_PAGE_TO_PHYS(m);
3207 padiff >>= PAGE_SHIFT;
3208 padiff &= PQ_L2_MASK;
3210 pa = VM_PAGE_TO_PHYS(m) - rcount * PAGE_SIZE;
3214 db_printf(" index(%ld)run(%d)pa(0x%lx)",
3215 (long)fidx, rcount, (long)pa);
3216 db_printf("pd(%ld)\n", (long)padiff);
3226 pa = VM_PAGE_TO_PHYS(m);
3230 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3231 (long)fidx, rcount, (long)pa);