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(), zinitna() and vm_object_init().
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
->shadow_count
= 0;
386 /* cpu localization twist */
387 object
->pg_color
= vm_quickcolor();
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 hash
= VMOBJ_HASH(object
);
401 lwkt_gettoken(&hash
->token
);
402 TAILQ_INSERT_TAIL(&hash
->list
, object
, object_list
);
403 lwkt_reltoken(&hash
->token
);
407 * Initialize a VM object.
410 vm_object_init(vm_object_t object
, vm_pindex_t size
)
412 _vm_object_allocate(OBJT_DEFAULT
, size
, object
);
413 vm_object_drop(object
);
417 * Initialize the VM objects module.
419 * Called from the low level boot code only. Note that this occurs before
420 * kmalloc is initialized so we cannot allocate any VM objects.
423 vm_object_init1(void)
427 for (i
= 0; i
< VMOBJ_HSIZE
; ++i
) {
428 TAILQ_INIT(&vm_object_hash
[i
].list
);
429 lwkt_token_init(&vm_object_hash
[i
].token
, "vmobjlst");
432 _vm_object_allocate(OBJT_DEFAULT
, OFF_TO_IDX(KvaEnd
),
434 vm_object_drop(&kernel_object
);
438 vm_object_init2(void)
440 kmalloc_set_unlimited(M_VM_OBJECT
);
444 * Allocate and return a new object of the specified type and size.
449 vm_object_allocate(objtype_t type
, vm_pindex_t size
)
453 obj
= kmalloc(sizeof(*obj
), M_VM_OBJECT
, M_INTWAIT
|M_ZERO
);
454 _vm_object_allocate(type
, size
, obj
);
461 * This version returns a held object, allowing further atomic initialization
465 vm_object_allocate_hold(objtype_t type
, vm_pindex_t size
)
469 obj
= kmalloc(sizeof(*obj
), M_VM_OBJECT
, M_INTWAIT
|M_ZERO
);
470 _vm_object_allocate(type
, size
, obj
);
476 * Add an additional reference to a vm_object. The object must already be
477 * held. The original non-lock version is no longer supported. The object
478 * must NOT be chain locked by anyone at the time the reference is added.
480 * Referencing a chain-locked object can blow up the fairly sensitive
481 * ref_count and shadow_count tests in the deallocator. Most callers
482 * will call vm_object_chain_wait() prior to calling
483 * vm_object_reference_locked() to avoid the case.
485 * The object must be held, but may be held shared if desired (hence why
486 * we use an atomic op).
489 VMOBJDEBUG(vm_object_reference_locked
)(vm_object_t object VMOBJDBARGS
)
491 KKASSERT(object
!= NULL
);
492 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
493 KKASSERT((object
->chainlk
& (CHAINLK_EXCL
| CHAINLK_MASK
)) == 0);
494 atomic_add_int(&object
->ref_count
, 1);
495 if (object
->type
== OBJT_VNODE
) {
496 vref(object
->handle
);
497 /* XXX what if the vnode is being destroyed? */
499 #if defined(DEBUG_LOCKS)
500 debugvm_object_add(object
, file
, line
, 1);
505 * This version is only allowed for vnode objects.
508 VMOBJDEBUG(vm_object_reference_quick
)(vm_object_t object VMOBJDBARGS
)
510 KKASSERT(object
->type
== OBJT_VNODE
);
511 atomic_add_int(&object
->ref_count
, 1);
512 vref(object
->handle
);
513 #if defined(DEBUG_LOCKS)
514 debugvm_object_add(object
, file
, line
, 1);
519 * Object OBJ_CHAINLOCK lock handling.
521 * The caller can chain-lock backing objects recursively and then
522 * use vm_object_chain_release_all() to undo the whole chain.
524 * Chain locks are used to prevent collapses and are only applicable
525 * to OBJT_DEFAULT and OBJT_SWAP objects. Chain locking operations
526 * on other object types are ignored. This is also important because
527 * it allows e.g. the vnode underlying a memory mapping to take concurrent
530 * The object must usually be held on entry, though intermediate
531 * objects need not be held on release. The object must be held exclusively,
532 * NOT shared. Note that the prefault path checks the shared state and
533 * avoids using the chain functions.
536 vm_object_chain_wait(vm_object_t object
, int shared
)
538 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
540 uint32_t chainlk
= object
->chainlk
;
544 if (chainlk
& (CHAINLK_EXCL
| CHAINLK_EXCLREQ
)) {
545 tsleep_interlock(object
, 0);
546 if (atomic_cmpset_int(&object
->chainlk
,
548 chainlk
| CHAINLK_WAIT
)) {
549 tsleep(object
, PINTERLOCKED
,
558 if (chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
)) {
559 tsleep_interlock(object
, 0);
560 if (atomic_cmpset_int(&object
->chainlk
,
562 chainlk
| CHAINLK_WAIT
))
564 tsleep(object
, PINTERLOCKED
,
569 if (atomic_cmpset_int(&object
->chainlk
,
571 chainlk
& ~CHAINLK_WAIT
))
573 if (chainlk
& CHAINLK_WAIT
)
585 vm_object_chain_acquire(vm_object_t object
, int shared
)
587 if (object
->type
!= OBJT_DEFAULT
&& object
->type
!= OBJT_SWAP
)
589 if (vm_shared_fault
== 0)
593 uint32_t chainlk
= object
->chainlk
;
597 if (chainlk
& (CHAINLK_EXCL
| CHAINLK_EXCLREQ
)) {
598 tsleep_interlock(object
, 0);
599 if (atomic_cmpset_int(&object
->chainlk
,
601 chainlk
| CHAINLK_WAIT
)) {
602 tsleep(object
, PINTERLOCKED
,
606 } else if (atomic_cmpset_int(&object
->chainlk
,
607 chainlk
, chainlk
+ 1)) {
612 if (chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
)) {
613 tsleep_interlock(object
, 0);
614 if (atomic_cmpset_int(&object
->chainlk
,
619 tsleep(object
, PINTERLOCKED
,
624 if (atomic_cmpset_int(&object
->chainlk
,
626 (chainlk
| CHAINLK_EXCL
) &
629 if (chainlk
& CHAINLK_WAIT
)
641 vm_object_chain_release(vm_object_t object
)
643 /*ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));*/
644 if (object
->type
!= OBJT_DEFAULT
&& object
->type
!= OBJT_SWAP
)
646 KKASSERT(object
->chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
));
648 uint32_t chainlk
= object
->chainlk
;
651 if (chainlk
& CHAINLK_MASK
) {
652 if ((chainlk
& CHAINLK_MASK
) == 1 &&
653 atomic_cmpset_int(&object
->chainlk
,
655 (chainlk
- 1) & ~CHAINLK_WAIT
)) {
656 if (chainlk
& CHAINLK_WAIT
)
660 if ((chainlk
& CHAINLK_MASK
) > 1 &&
661 atomic_cmpset_int(&object
->chainlk
,
662 chainlk
, chainlk
- 1)) {
667 KKASSERT(chainlk
& CHAINLK_EXCL
);
668 if (atomic_cmpset_int(&object
->chainlk
,
670 chainlk
& ~(CHAINLK_EXCL
|
672 if (chainlk
& CHAINLK_WAIT
)
681 * Release the chain from first_object through and including stopobj.
682 * The caller is typically holding the first and last object locked
683 * (shared or exclusive) to prevent destruction races.
685 * We release stopobj first as an optimization as this object is most
686 * likely to be shared across multiple processes.
689 vm_object_chain_release_all(vm_object_t first_object
, vm_object_t stopobj
)
691 vm_object_t backing_object
;
694 vm_object_chain_release(stopobj
);
695 object
= first_object
;
697 while (object
!= stopobj
) {
699 backing_object
= object
->backing_object
;
700 vm_object_chain_release(object
);
701 object
= backing_object
;
706 * Dereference an object and its underlying vnode. The object may be
707 * held shared. On return the object will remain held.
709 * This function may return a vnode in *vpp which the caller must release
710 * after the caller drops its own lock. If vpp is NULL, we assume that
711 * the caller was holding an exclusive lock on the object and we vrele()
715 VMOBJDEBUG(vm_object_vndeallocate
)(vm_object_t object
, struct vnode
**vpp
718 struct vnode
*vp
= (struct vnode
*) object
->handle
;
720 KASSERT(object
->type
== OBJT_VNODE
,
721 ("vm_object_vndeallocate: not a vnode object"));
722 KASSERT(vp
!= NULL
, ("vm_object_vndeallocate: missing vp"));
723 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
725 if (object
->ref_count
== 0) {
726 vprint("vm_object_vndeallocate", vp
);
727 panic("vm_object_vndeallocate: bad object reference count");
731 int count
= object
->ref_count
;
734 vm_object_upgrade(object
);
735 if (atomic_cmpset_int(&object
->ref_count
, count
, 0)) {
736 vclrflags(vp
, VTEXT
);
740 if (atomic_cmpset_int(&object
->ref_count
,
747 #if defined(DEBUG_LOCKS)
748 debugvm_object_add(object
, file
, line
, -1);
752 * vrele or return the vp to vrele. We can only safely vrele(vp)
753 * if the object was locked exclusively. But there are two races
756 * We had to upgrade the object above to safely clear VTEXT
757 * but the alternative path where the shared lock is retained
758 * can STILL race to 0 in other paths and cause our own vrele()
759 * to terminate the vnode. We can't allow that if the VM object
760 * is still locked shared.
769 * Release a reference to the specified object, gained either through a
770 * vm_object_allocate or a vm_object_reference call. When all references
771 * are gone, storage associated with this object may be relinquished.
773 * The caller does not have to hold the object locked but must have control
774 * over the reference in question in order to guarantee that the object
775 * does not get ripped out from under us.
777 * XXX Currently all deallocations require an exclusive lock.
780 VMOBJDEBUG(vm_object_deallocate
)(vm_object_t object VMOBJDBARGS
)
789 count
= object
->ref_count
;
793 * If decrementing the count enters into special handling
794 * territory (0, 1, or 2) we have to do it the hard way.
795 * Fortunate though, objects with only a few refs like this
796 * are not likely to be heavily contended anyway.
798 * For vnode objects we only care about 1->0 transitions.
800 if (count
<= 3 || (object
->type
== OBJT_VNODE
&& count
<= 1)) {
801 #if defined(DEBUG_LOCKS)
802 debugvm_object_add(object
, file
, line
, 0);
804 vm_object_hold(object
);
805 vm_object_deallocate_locked(object
);
806 vm_object_drop(object
);
811 * Try to decrement ref_count without acquiring a hold on
812 * the object. This is particularly important for the exec*()
813 * and exit*() code paths because the program binary may
814 * have a great deal of sharing and an exclusive lock will
815 * crowbar performance in those circumstances.
817 if (object
->type
== OBJT_VNODE
) {
818 vp
= (struct vnode
*)object
->handle
;
819 if (atomic_cmpset_int(&object
->ref_count
,
821 #if defined(DEBUG_LOCKS)
822 debugvm_object_add(object
, file
, line
, -1);
830 if (atomic_cmpset_int(&object
->ref_count
,
832 #if defined(DEBUG_LOCKS)
833 debugvm_object_add(object
, file
, line
, -1);
844 VMOBJDEBUG(vm_object_deallocate_locked
)(vm_object_t object VMOBJDBARGS
)
846 struct vm_object_dealloc_list
*dlist
= NULL
;
847 struct vm_object_dealloc_list
*dtmp
;
852 * We may chain deallocate object, but additional objects may
853 * collect on the dlist which also have to be deallocated. We
854 * must avoid a recursion, vm_object chains can get deep.
858 while (object
!= NULL
) {
860 * vnode case, caller either locked the object exclusively
861 * or this is a recursion with must_drop != 0 and the vnode
862 * object will be locked shared.
864 * If locked shared we have to drop the object before we can
865 * call vrele() or risk a shared/exclusive livelock.
867 if (object
->type
== OBJT_VNODE
) {
868 ASSERT_LWKT_TOKEN_HELD(&object
->token
);
870 struct vnode
*tmp_vp
;
872 vm_object_vndeallocate(object
, &tmp_vp
);
873 vm_object_drop(object
);
878 vm_object_vndeallocate(object
, NULL
);
882 ASSERT_LWKT_TOKEN_HELD_EXCL(&object
->token
);
885 * Normal case (object is locked exclusively)
887 if (object
->ref_count
== 0) {
888 panic("vm_object_deallocate: object deallocated "
889 "too many times: %d", object
->type
);
891 if (object
->ref_count
> 2) {
892 atomic_add_int(&object
->ref_count
, -1);
893 #if defined(DEBUG_LOCKS)
894 debugvm_object_add(object
, file
, line
, -1);
900 * Here on ref_count of one or two, which are special cases for
903 * Nominal ref_count > 1 case if the second ref is not from
906 * (ONEMAPPING only applies to DEFAULT AND SWAP objects)
908 if (object
->ref_count
== 2 && object
->shadow_count
== 0) {
909 if (object
->type
== OBJT_DEFAULT
||
910 object
->type
== OBJT_SWAP
) {
911 vm_object_set_flag(object
, OBJ_ONEMAPPING
);
913 atomic_add_int(&object
->ref_count
, -1);
914 #if defined(DEBUG_LOCKS)
915 debugvm_object_add(object
, file
, line
, -1);
921 * If the second ref is from a shadow we chain along it
922 * upwards if object's handle is exhausted.
924 * We have to decrement object->ref_count before potentially
925 * collapsing the first shadow object or the collapse code
926 * will not be able to handle the degenerate case to remove
927 * object. However, if we do it too early the object can
928 * get ripped out from under us.
930 if (object
->ref_count
== 2 && object
->shadow_count
== 1 &&
931 object
->handle
== NULL
&& (object
->type
== OBJT_DEFAULT
||
932 object
->type
== OBJT_SWAP
)) {
933 temp
= LIST_FIRST(&object
->shadow_head
);
934 KKASSERT(temp
!= NULL
);
935 vm_object_hold(temp
);
938 * Wait for any paging to complete so the collapse
939 * doesn't (or isn't likely to) qcollapse. pip
940 * waiting must occur before we acquire the
944 temp
->paging_in_progress
||
945 object
->paging_in_progress
947 vm_object_pip_wait(temp
, "objde1");
948 vm_object_pip_wait(object
, "objde2");
952 * If the parent is locked we have to give up, as
953 * otherwise we would be acquiring locks in the
954 * wrong order and potentially deadlock.
956 if (temp
->chainlk
& (CHAINLK_EXCL
| CHAINLK_MASK
)) {
957 vm_object_drop(temp
);
960 vm_object_chain_acquire(temp
, 0);
963 * Recheck/retry after the hold and the paging
964 * wait, both of which can block us.
966 if (object
->ref_count
!= 2 ||
967 object
->shadow_count
!= 1 ||
969 LIST_FIRST(&object
->shadow_head
) != temp
||
970 (object
->type
!= OBJT_DEFAULT
&&
971 object
->type
!= OBJT_SWAP
)) {
972 vm_object_chain_release(temp
);
973 vm_object_drop(temp
);
978 * We can safely drop object's ref_count now.
980 KKASSERT(object
->ref_count
== 2);
981 atomic_add_int(&object
->ref_count
, -1);
982 #if defined(DEBUG_LOCKS)
983 debugvm_object_add(object
, file
, line
, -1);
987 * If our single parent is not collapseable just
988 * decrement ref_count (2->1) and stop.
990 if (temp
->handle
|| (temp
->type
!= OBJT_DEFAULT
&&
991 temp
->type
!= OBJT_SWAP
)) {
992 vm_object_chain_release(temp
);
993 vm_object_drop(temp
);
998 * At this point we have already dropped object's
999 * ref_count so it is possible for a race to
1000 * deallocate obj out from under us. Any collapse
1001 * will re-check the situation. We must not block
1002 * until we are able to collapse.
1004 * Bump temp's ref_count to avoid an unwanted
1005 * degenerate recursion (can't call
1006 * vm_object_reference_locked() because it asserts
1007 * that CHAINLOCK is not set).
1009 atomic_add_int(&temp
->ref_count
, 1);
1010 KKASSERT(temp
->ref_count
> 1);
1013 * Collapse temp, then deallocate the extra ref
1016 vm_object_collapse(temp
, &dlist
);
1017 vm_object_chain_release(temp
);
1019 vm_object_lock_swap();
1020 vm_object_drop(object
);
1028 * Drop the ref and handle termination on the 1->0 transition.
1029 * We may have blocked above so we have to recheck.
1032 KKASSERT(object
->ref_count
!= 0);
1033 if (object
->ref_count
>= 2) {
1034 atomic_add_int(&object
->ref_count
, -1);
1035 #if defined(DEBUG_LOCKS)
1036 debugvm_object_add(object
, file
, line
, -1);
1040 KKASSERT(object
->ref_count
== 1);
1043 * 1->0 transition. Chain through the backing_object.
1044 * Maintain the ref until we've located the backing object,
1047 while ((temp
= object
->backing_object
) != NULL
) {
1048 if (temp
->type
== OBJT_VNODE
)
1049 vm_object_hold_shared(temp
);
1051 vm_object_hold(temp
);
1052 if (temp
== object
->backing_object
)
1054 vm_object_drop(temp
);
1058 * 1->0 transition verified, retry if ref_count is no longer
1059 * 1. Otherwise disconnect the backing_object (temp) and
1062 if (object
->ref_count
!= 1) {
1063 vm_object_drop(temp
);
1068 * It shouldn't be possible for the object to be chain locked
1069 * if we're removing the last ref on it.
1071 * Removing object from temp's shadow list requires dropping
1072 * temp, which we will do on loop.
1074 * NOTE! vnodes do not use the shadow list, but still have
1075 * the backing_object reference.
1077 KKASSERT((object
->chainlk
& (CHAINLK_EXCL
|CHAINLK_MASK
)) == 0);
1080 if (object
->flags
& OBJ_ONSHADOW
) {
1081 LIST_REMOVE(object
, shadow_list
);
1082 temp
->shadow_count
--;
1084 vm_object_clear_flag(object
, OBJ_ONSHADOW
);
1086 object
->backing_object
= NULL
;
1089 atomic_add_int(&object
->ref_count
, -1);
1090 if ((object
->flags
& OBJ_DEAD
) == 0)
1091 vm_object_terminate(object
);
1092 if (must_drop
&& temp
)
1093 vm_object_lock_swap();
1095 vm_object_drop(object
);
1100 if (must_drop
&& object
)
1101 vm_object_drop(object
);
1104 * Additional tail recursion on dlist. Avoid a recursion. Objects
1105 * on the dlist have a hold count but are not locked.
1107 if ((dtmp
= dlist
) != NULL
) {
1109 object
= dtmp
->object
;
1110 kfree(dtmp
, M_TEMP
);
1112 vm_object_lock(object
); /* already held, add lock */
1113 must_drop
= 1; /* and we're responsible for it */
1119 * Destroy the specified object, freeing up related resources.
1121 * The object must have zero references.
1123 * The object must held. The caller is responsible for dropping the object
1124 * after terminate returns. Terminate does NOT drop the object.
1126 static int vm_object_terminate_callback(vm_page_t p
, void *data
);
1129 vm_object_terminate(vm_object_t object
)
1131 struct rb_vm_page_scan_info info
;
1132 struct vm_object_hash
*hash
;
1135 * Make sure no one uses us. Once we set OBJ_DEAD we should be
1136 * able to safely block.
1138 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
1139 KKASSERT((object
->flags
& OBJ_DEAD
) == 0);
1140 vm_object_set_flag(object
, OBJ_DEAD
);
1143 * Wait for the pageout daemon to be done with the object
1145 vm_object_pip_wait(object
, "objtrm1");
1147 KASSERT(!object
->paging_in_progress
,
1148 ("vm_object_terminate: pageout in progress"));
1151 * Clean and free the pages, as appropriate. All references to the
1152 * object are gone, so we don't need to lock it.
1154 if (object
->type
== OBJT_VNODE
) {
1158 * Clean pages and flush buffers.
1160 * NOTE! TMPFS buffer flushes do not typically flush the
1161 * actual page to swap as this would be highly
1162 * inefficient, and normal filesystems usually wrap
1163 * page flushes with buffer cache buffers.
1165 * To deal with this we have to call vinvalbuf() both
1166 * before and after the vm_object_page_clean().
1168 vp
= (struct vnode
*) object
->handle
;
1169 vinvalbuf(vp
, V_SAVE
, 0, 0);
1170 vm_object_page_clean(object
, 0, 0, OBJPC_SYNC
);
1171 vinvalbuf(vp
, V_SAVE
, 0, 0);
1175 * Wait for any I/O to complete, after which there had better not
1176 * be any references left on the object.
1178 vm_object_pip_wait(object
, "objtrm2");
1180 if (object
->ref_count
!= 0) {
1181 panic("vm_object_terminate: object with references, "
1182 "ref_count=%d", object
->ref_count
);
1186 * Cleanup any shared pmaps associated with this object.
1188 pmap_object_free(object
);
1191 * Now free any remaining pages. For internal objects, this also
1192 * removes them from paging queues. Don't free wired pages, just
1193 * remove them from the object.
1196 info
.object
= object
;
1197 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, NULL
,
1198 vm_object_terminate_callback
, &info
);
1201 * Let the pager know object is dead.
1203 vm_pager_deallocate(object
);
1206 * Wait for the object hold count to hit 1, clean out pages as
1207 * we go. vmobj_token interlocks any race conditions that might
1208 * pick the object up from the vm_object_list after we have cleared
1212 if (RB_ROOT(&object
->rb_memq
) == NULL
)
1214 kprintf("vm_object_terminate: Warning, object %p "
1215 "still has %ld pages\n",
1216 object
, object
->resident_page_count
);
1217 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, NULL
,
1218 vm_object_terminate_callback
, &info
);
1222 * There had better not be any pages left
1224 KKASSERT(object
->resident_page_count
== 0);
1227 * Remove the object from the global object list.
1229 hash
= VMOBJ_HASH(object
);
1230 lwkt_gettoken(&hash
->token
);
1231 TAILQ_REMOVE(&hash
->list
, object
, object_list
);
1232 lwkt_reltoken(&hash
->token
);
1234 if (object
->ref_count
!= 0) {
1235 panic("vm_object_terminate2: object with references, "
1236 "ref_count=%d", object
->ref_count
);
1240 * NOTE: The object hold_count is at least 1, so we cannot kfree()
1241 * the object here. See vm_object_drop().
1246 * The caller must hold the object.
1249 vm_object_terminate_callback(vm_page_t p
, void *data
)
1251 struct rb_vm_page_scan_info
*info
= data
;
1254 if ((++info
->count
& 63) == 0)
1257 if (object
!= info
->object
) {
1258 kprintf("vm_object_terminate_callback: obj/pg race %p/%p\n",
1262 vm_page_busy_wait(p
, TRUE
, "vmpgtrm");
1263 if (object
!= p
->object
) {
1264 kprintf("vm_object_terminate: Warning: Encountered "
1265 "busied page %p on queue %d\n", p
, p
->queue
);
1267 } else if (p
->wire_count
== 0) {
1269 * NOTE: p->dirty and PG_NEED_COMMIT are ignored.
1272 mycpu
->gd_cnt
.v_pfree
++;
1274 if (p
->queue
!= PQ_NONE
)
1275 kprintf("vm_object_terminate: Warning: Encountered "
1276 "wired page %p on queue %d\n", p
, p
->queue
);
1284 * Clean all dirty pages in the specified range of object. Leaves page
1285 * on whatever queue it is currently on. If NOSYNC is set then do not
1286 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC),
1287 * leaving the object dirty.
1289 * When stuffing pages asynchronously, allow clustering. XXX we need a
1290 * synchronous clustering mode implementation.
1292 * Odd semantics: if start == end, we clean everything.
1294 * The object must be locked? XXX
1296 static int vm_object_page_clean_pass1(struct vm_page
*p
, void *data
);
1297 static int vm_object_page_clean_pass2(struct vm_page
*p
, void *data
);
1300 vm_object_page_clean(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
,
1303 struct rb_vm_page_scan_info info
;
1309 vm_object_hold(object
);
1310 if (object
->type
!= OBJT_VNODE
||
1311 (object
->flags
& OBJ_MIGHTBEDIRTY
) == 0) {
1312 vm_object_drop(object
);
1316 pagerflags
= (flags
& (OBJPC_SYNC
| OBJPC_INVAL
)) ?
1317 VM_PAGER_PUT_SYNC
: VM_PAGER_CLUSTER_OK
;
1318 pagerflags
|= (flags
& OBJPC_INVAL
) ? VM_PAGER_PUT_INVAL
: 0;
1320 vp
= object
->handle
;
1323 * Interlock other major object operations. This allows us to
1324 * temporarily clear OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY.
1326 vm_object_set_flag(object
, OBJ_CLEANING
);
1329 * Handle 'entire object' case
1331 info
.start_pindex
= start
;
1333 info
.end_pindex
= object
->size
- 1;
1335 info
.end_pindex
= end
- 1;
1337 wholescan
= (start
== 0 && info
.end_pindex
== object
->size
- 1);
1339 info
.pagerflags
= pagerflags
;
1340 info
.object
= object
;
1343 * If cleaning the entire object do a pass to mark the pages read-only.
1344 * If everything worked out ok, clear OBJ_WRITEABLE and
1350 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
1351 vm_object_page_clean_pass1
, &info
);
1352 if (info
.error
== 0) {
1353 vm_object_clear_flag(object
,
1354 OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
);
1355 if (object
->type
== OBJT_VNODE
&&
1356 (vp
= (struct vnode
*)object
->handle
) != NULL
) {
1358 * Use new-style interface to clear VISDIRTY
1359 * because the vnode is not necessarily removed
1360 * from the syncer list(s) as often as it was
1361 * under the old interface, which can leave
1362 * the vnode on the syncer list after reclaim.
1370 * Do a pass to clean all the dirty pages we find.
1375 generation
= object
->generation
;
1376 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
1377 vm_object_page_clean_pass2
, &info
);
1378 } while (info
.error
|| generation
!= object
->generation
);
1380 vm_object_clear_flag(object
, OBJ_CLEANING
);
1381 vm_object_drop(object
);
1385 * The caller must hold the object.
1389 vm_object_page_clean_pass1(struct vm_page
*p
, void *data
)
1391 struct rb_vm_page_scan_info
*info
= data
;
1393 if ((++info
->count
& 63) == 0)
1395 if (p
->object
!= info
->object
||
1396 p
->pindex
< info
->start_pindex
||
1397 p
->pindex
> info
->end_pindex
) {
1398 kprintf("vm_object_page_clean_pass1: obj/pg race %p/%p\n",
1402 vm_page_flag_set(p
, PG_CLEANCHK
);
1403 if ((info
->limit
& OBJPC_NOSYNC
) && (p
->flags
& PG_NOSYNC
)) {
1405 } else if (vm_page_busy_try(p
, FALSE
) == 0) {
1406 if (p
->object
== info
->object
)
1407 vm_page_protect(p
, VM_PROT_READ
);
1416 * The caller must hold the object
1420 vm_object_page_clean_pass2(struct vm_page
*p
, void *data
)
1422 struct rb_vm_page_scan_info
*info
= data
;
1425 if (p
->object
!= info
->object
||
1426 p
->pindex
< info
->start_pindex
||
1427 p
->pindex
> info
->end_pindex
) {
1428 kprintf("vm_object_page_clean_pass2: obj/pg race %p/%p\n",
1434 * Do not mess with pages that were inserted after we started
1435 * the cleaning pass.
1437 if ((p
->flags
& PG_CLEANCHK
) == 0)
1440 generation
= info
->object
->generation
;
1441 vm_page_busy_wait(p
, TRUE
, "vpcwai");
1443 if (p
->object
!= info
->object
||
1444 p
->pindex
< info
->start_pindex
||
1445 p
->pindex
> info
->end_pindex
||
1446 info
->object
->generation
!= generation
) {
1453 * Before wasting time traversing the pmaps, check for trivial
1454 * cases where the page cannot be dirty.
1456 if (p
->valid
== 0 || (p
->queue
- p
->pc
) == PQ_CACHE
) {
1457 KKASSERT((p
->dirty
& p
->valid
) == 0 &&
1458 (p
->flags
& PG_NEED_COMMIT
) == 0);
1464 * Check whether the page is dirty or not. The page has been set
1465 * to be read-only so the check will not race a user dirtying the
1468 vm_page_test_dirty(p
);
1469 if ((p
->dirty
& p
->valid
) == 0 && (p
->flags
& PG_NEED_COMMIT
) == 0) {
1470 vm_page_flag_clear(p
, PG_CLEANCHK
);
1476 * If we have been asked to skip nosync pages and this is a
1477 * nosync page, skip it. Note that the object flags were
1478 * not cleared in this case (because pass1 will have returned an
1479 * error), so we do not have to set them.
1481 if ((info
->limit
& OBJPC_NOSYNC
) && (p
->flags
& PG_NOSYNC
)) {
1482 vm_page_flag_clear(p
, PG_CLEANCHK
);
1488 * Flush as many pages as we can. PG_CLEANCHK will be cleared on
1489 * the pages that get successfully flushed. Set info->error if
1490 * we raced an object modification.
1492 vm_object_page_collect_flush(info
->object
, p
, info
->pagerflags
);
1493 /* vm_wait_nominal(); this can deadlock the system in syncer/pageout */
1495 if ((++info
->count
& 63) == 0)
1502 * Collect the specified page and nearby pages and flush them out.
1503 * The number of pages flushed is returned. The passed page is busied
1504 * by the caller and we are responsible for its disposition.
1506 * The caller must hold the object.
1509 vm_object_page_collect_flush(vm_object_t object
, vm_page_t p
, int pagerflags
)
1517 vm_page_t ma
[BLIST_MAX_ALLOC
];
1519 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
1522 page_base
= pi
% BLIST_MAX_ALLOC
;
1530 tp
= vm_page_lookup_busy_try(object
, pi
- page_base
+ ib
,
1536 if ((pagerflags
& VM_PAGER_IGNORE_CLEANCHK
) == 0 &&
1537 (tp
->flags
& PG_CLEANCHK
) == 0) {
1541 if ((tp
->queue
- tp
->pc
) == PQ_CACHE
) {
1542 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1546 vm_page_test_dirty(tp
);
1547 if ((tp
->dirty
& tp
->valid
) == 0 &&
1548 (tp
->flags
& PG_NEED_COMMIT
) == 0) {
1549 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1558 while (is
< BLIST_MAX_ALLOC
&&
1559 pi
- page_base
+ is
< object
->size
) {
1562 tp
= vm_page_lookup_busy_try(object
, pi
- page_base
+ is
,
1568 if ((pagerflags
& VM_PAGER_IGNORE_CLEANCHK
) == 0 &&
1569 (tp
->flags
& PG_CLEANCHK
) == 0) {
1573 if ((tp
->queue
- tp
->pc
) == PQ_CACHE
) {
1574 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1578 vm_page_test_dirty(tp
);
1579 if ((tp
->dirty
& tp
->valid
) == 0 &&
1580 (tp
->flags
& PG_NEED_COMMIT
) == 0) {
1581 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1590 * All pages in the ma[] array are busied now
1592 for (i
= ib
; i
< is
; ++i
) {
1593 vm_page_flag_clear(ma
[i
], PG_CLEANCHK
);
1594 vm_page_hold(ma
[i
]); /* XXX need this any more? */
1596 vm_pageout_flush(&ma
[ib
], is
- ib
, pagerflags
);
1597 for (i
= ib
; i
< is
; ++i
) /* XXX need this any more? */
1598 vm_page_unhold(ma
[i
]);
1602 * Same as vm_object_pmap_copy, except range checking really
1603 * works, and is meant for small sections of an object.
1605 * This code protects resident pages by making them read-only
1606 * and is typically called on a fork or split when a page
1607 * is converted to copy-on-write.
1609 * NOTE: If the page is already at VM_PROT_NONE, calling
1610 * vm_page_protect will have no effect.
1613 vm_object_pmap_copy_1(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
)
1618 if (object
== NULL
|| (object
->flags
& OBJ_WRITEABLE
) == 0)
1621 vm_object_hold(object
);
1622 for (idx
= start
; idx
< end
; idx
++) {
1623 p
= vm_page_lookup(object
, idx
);
1626 vm_page_protect(p
, VM_PROT_READ
);
1628 vm_object_drop(object
);
1632 * Removes all physical pages in the specified object range from all
1635 * The object must *not* be locked.
1638 static int vm_object_pmap_remove_callback(vm_page_t p
, void *data
);
1641 vm_object_pmap_remove(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
)
1643 struct rb_vm_page_scan_info info
;
1647 info
.start_pindex
= start
;
1648 info
.end_pindex
= end
- 1;
1650 info
.object
= object
;
1652 vm_object_hold(object
);
1653 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
1654 vm_object_pmap_remove_callback
, &info
);
1655 if (start
== 0 && end
== object
->size
)
1656 vm_object_clear_flag(object
, OBJ_WRITEABLE
);
1657 vm_object_drop(object
);
1661 * The caller must hold the object
1664 vm_object_pmap_remove_callback(vm_page_t p
, void *data
)
1666 struct rb_vm_page_scan_info
*info
= data
;
1668 if ((++info
->count
& 63) == 0)
1671 if (info
->object
!= p
->object
||
1672 p
->pindex
< info
->start_pindex
||
1673 p
->pindex
> info
->end_pindex
) {
1674 kprintf("vm_object_pmap_remove_callback: obj/pg race %p/%p\n",
1679 vm_page_protect(p
, VM_PROT_NONE
);
1685 * Implements the madvise function at the object/page level.
1687 * MADV_WILLNEED (any object)
1689 * Activate the specified pages if they are resident.
1691 * MADV_DONTNEED (any object)
1693 * Deactivate the specified pages if they are resident.
1695 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, OBJ_ONEMAPPING only)
1697 * Deactivate and clean the specified pages if they are
1698 * resident. This permits the process to reuse the pages
1699 * without faulting or the kernel to reclaim the pages
1705 vm_object_madvise(vm_object_t object
, vm_pindex_t pindex
,
1706 vm_pindex_t count
, int advise
)
1708 vm_pindex_t end
, tpindex
;
1709 vm_object_t tobject
;
1717 end
= pindex
+ count
;
1719 vm_object_hold(object
);
1723 * Locate and adjust resident pages
1725 for (; pindex
< end
; pindex
+= 1) {
1727 if (tobject
!= object
)
1728 vm_object_drop(tobject
);
1733 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
1734 * and those pages must be OBJ_ONEMAPPING.
1736 if (advise
== MADV_FREE
) {
1737 if ((tobject
->type
!= OBJT_DEFAULT
&&
1738 tobject
->type
!= OBJT_SWAP
) ||
1739 (tobject
->flags
& OBJ_ONEMAPPING
) == 0) {
1744 m
= vm_page_lookup_busy_try(tobject
, tpindex
, TRUE
, &error
);
1747 vm_page_sleep_busy(m
, TRUE
, "madvpo");
1752 * There may be swap even if there is no backing page
1754 if (advise
== MADV_FREE
&& tobject
->type
== OBJT_SWAP
)
1755 swap_pager_freespace(tobject
, tpindex
, 1);
1760 while ((xobj
= tobject
->backing_object
) != NULL
) {
1761 KKASSERT(xobj
!= object
);
1762 vm_object_hold(xobj
);
1763 if (xobj
== tobject
->backing_object
)
1765 vm_object_drop(xobj
);
1769 tpindex
+= OFF_TO_IDX(tobject
->backing_object_offset
);
1770 if (tobject
!= object
) {
1771 vm_object_lock_swap();
1772 vm_object_drop(tobject
);
1779 * If the page is not in a normal active state, we skip it.
1780 * If the page is not managed there are no page queues to
1781 * mess with. Things can break if we mess with pages in
1782 * any of the below states.
1784 if (m
->wire_count
||
1785 (m
->flags
& (PG_UNMANAGED
| PG_NEED_COMMIT
)) ||
1786 m
->valid
!= VM_PAGE_BITS_ALL
1793 * Theoretically once a page is known not to be busy, an
1794 * interrupt cannot come along and rip it out from under us.
1797 if (advise
== MADV_WILLNEED
) {
1798 vm_page_activate(m
);
1799 } else if (advise
== MADV_DONTNEED
) {
1800 vm_page_dontneed(m
);
1801 } else if (advise
== MADV_FREE
) {
1803 * Mark the page clean. This will allow the page
1804 * to be freed up by the system. However, such pages
1805 * are often reused quickly by malloc()/free()
1806 * so we do not do anything that would cause
1807 * a page fault if we can help it.
1809 * Specifically, we do not try to actually free
1810 * the page now nor do we try to put it in the
1811 * cache (which would cause a page fault on reuse).
1813 * But we do make the page is freeable as we
1814 * can without actually taking the step of unmapping
1817 pmap_clear_modify(m
);
1820 vm_page_dontneed(m
);
1821 if (tobject
->type
== OBJT_SWAP
)
1822 swap_pager_freespace(tobject
, tpindex
, 1);
1826 if (tobject
!= object
)
1827 vm_object_drop(tobject
);
1828 vm_object_drop(object
);
1832 * Create a new object which is backed by the specified existing object
1833 * range. Replace the pointer and offset that was pointing at the existing
1834 * object with the pointer/offset for the new object.
1836 * If addref is non-zero the returned object is given an additional reference.
1837 * This mechanic exists to avoid the situation where refs might be 1 and
1838 * race against a collapse when the caller intends to bump it. So the
1839 * caller cannot add the ref after the fact. Used when the caller is
1840 * duplicating a vm_map_entry.
1842 * No other requirements.
1845 vm_object_shadow(vm_object_t
*objectp
, vm_ooffset_t
*offset
, vm_size_t length
,
1855 * Don't create the new object if the old object isn't shared.
1856 * We have to chain wait before adding the reference to avoid
1857 * racing a collapse or deallocation.
1859 * Clear OBJ_ONEMAPPING flag when shadowing.
1861 * The caller owns a ref on source via *objectp which we are going
1862 * to replace. This ref is inherited by the backing_object assignment.
1863 * from nobject and does not need to be incremented here.
1865 * However, we add a temporary extra reference to the original source
1866 * prior to holding nobject in case we block, to avoid races where
1867 * someone else might believe that the source can be collapsed.
1871 if (source
->type
!= OBJT_VNODE
) {
1873 vm_object_hold(source
);
1874 vm_object_chain_wait(source
, 0);
1875 if (source
->ref_count
== 1 &&
1876 source
->handle
== NULL
&&
1877 (source
->type
== OBJT_DEFAULT
||
1878 source
->type
== OBJT_SWAP
)) {
1880 vm_object_reference_locked(source
);
1881 vm_object_clear_flag(source
,
1884 vm_object_drop(source
);
1887 vm_object_reference_locked(source
);
1888 vm_object_clear_flag(source
, OBJ_ONEMAPPING
);
1890 vm_object_reference_quick(source
);
1891 vm_object_clear_flag(source
, OBJ_ONEMAPPING
);
1896 * Allocate a new object with the given length. The new object
1897 * is returned referenced but we may have to add another one.
1898 * If we are adding a second reference we must clear OBJ_ONEMAPPING.
1899 * (typically because the caller is about to clone a vm_map_entry).
1901 * The source object currently has an extra reference to prevent
1902 * collapses into it while we mess with its shadow list, which
1903 * we will remove later in this routine.
1905 * The target object may require a second reference if asked for one
1908 result
= vm_object_allocate(OBJT_DEFAULT
, length
);
1910 panic("vm_object_shadow: no object for shadowing");
1911 vm_object_hold(result
);
1913 vm_object_reference_locked(result
);
1914 vm_object_clear_flag(result
, OBJ_ONEMAPPING
);
1918 * The new object shadows the source object. Chain wait before
1919 * adjusting shadow_count or the shadow list to avoid races.
1921 * Try to optimize the result object's page color when shadowing
1922 * in order to maintain page coloring consistency in the combined
1925 * The backing_object reference to source requires adding a ref to
1926 * source. We simply inherit the ref from the original *objectp
1927 * (which we are replacing) so no additional refs need to be added.
1928 * (we must still clean up the extra ref we had to prevent collapse
1931 * SHADOWING IS NOT APPLICABLE TO OBJT_VNODE OBJECTS
1933 KKASSERT(result
->backing_object
== NULL
);
1934 result
->backing_object
= source
;
1936 if (useshadowlist
) {
1937 vm_object_chain_wait(source
, 0);
1938 LIST_INSERT_HEAD(&source
->shadow_head
,
1939 result
, shadow_list
);
1940 source
->shadow_count
++;
1941 source
->generation
++;
1942 vm_object_set_flag(result
, OBJ_ONSHADOW
);
1944 /* cpu localization twist */
1945 result
->pg_color
= vm_quickcolor();
1949 * Adjust the return storage. Drop the ref on source before
1952 result
->backing_object_offset
= *offset
;
1953 vm_object_drop(result
);
1956 if (useshadowlist
) {
1957 vm_object_deallocate_locked(source
);
1958 vm_object_drop(source
);
1960 vm_object_deallocate(source
);
1965 * Return the new things
1970 #define OBSC_TEST_ALL_SHADOWED 0x0001
1971 #define OBSC_COLLAPSE_NOWAIT 0x0002
1972 #define OBSC_COLLAPSE_WAIT 0x0004
1974 static int vm_object_backing_scan_callback(vm_page_t p
, void *data
);
1977 * The caller must hold the object.
1980 vm_object_backing_scan(vm_object_t object
, vm_object_t backing_object
, int op
)
1982 struct rb_vm_page_scan_info info
;
1983 struct vm_object_hash
*hash
;
1985 vm_object_assert_held(object
);
1986 vm_object_assert_held(backing_object
);
1988 KKASSERT(backing_object
== object
->backing_object
);
1989 info
.backing_offset_index
= OFF_TO_IDX(object
->backing_object_offset
);
1992 * Initial conditions
1994 if (op
& OBSC_TEST_ALL_SHADOWED
) {
1996 * We do not want to have to test for the existence of
1997 * swap pages in the backing object. XXX but with the
1998 * new swapper this would be pretty easy to do.
2000 * XXX what about anonymous MAP_SHARED memory that hasn't
2001 * been ZFOD faulted yet? If we do not test for this, the
2002 * shadow test may succeed! XXX
2004 if (backing_object
->type
!= OBJT_DEFAULT
)
2007 if (op
& OBSC_COLLAPSE_WAIT
) {
2008 KKASSERT((backing_object
->flags
& OBJ_DEAD
) == 0);
2009 vm_object_set_flag(backing_object
, OBJ_DEAD
);
2011 hash
= VMOBJ_HASH(backing_object
);
2012 lwkt_gettoken(&hash
->token
);
2013 TAILQ_REMOVE(&hash
->list
, backing_object
, object_list
);
2014 lwkt_reltoken(&hash
->token
);
2018 * Our scan. We have to retry if a negative error code is returned,
2019 * otherwise 0 or 1 will be returned in info.error. 0 Indicates that
2020 * the scan had to be stopped because the parent does not completely
2023 info
.object
= object
;
2024 info
.backing_object
= backing_object
;
2029 vm_page_rb_tree_RB_SCAN(&backing_object
->rb_memq
, NULL
,
2030 vm_object_backing_scan_callback
,
2032 } while (info
.error
< 0);
2038 * The caller must hold the object.
2041 vm_object_backing_scan_callback(vm_page_t p
, void *data
)
2043 struct rb_vm_page_scan_info
*info
= data
;
2044 vm_object_t backing_object
;
2047 vm_pindex_t new_pindex
;
2048 vm_pindex_t backing_offset_index
;
2052 new_pindex
= pindex
- info
->backing_offset_index
;
2054 object
= info
->object
;
2055 backing_object
= info
->backing_object
;
2056 backing_offset_index
= info
->backing_offset_index
;
2058 if (op
& OBSC_TEST_ALL_SHADOWED
) {
2062 * Ignore pages outside the parent object's range
2063 * and outside the parent object's mapping of the
2066 * note that we do not busy the backing object's
2069 if (pindex
< backing_offset_index
||
2070 new_pindex
>= object
->size
2076 * See if the parent has the page or if the parent's
2077 * object pager has the page. If the parent has the
2078 * page but the page is not valid, the parent's
2079 * object pager must have the page.
2081 * If this fails, the parent does not completely shadow
2082 * the object and we might as well give up now.
2084 pp
= vm_page_lookup(object
, new_pindex
);
2085 if ((pp
== NULL
|| pp
->valid
== 0) &&
2086 !vm_pager_has_page(object
, new_pindex
)
2088 info
->error
= 0; /* problemo */
2089 return(-1); /* stop the scan */
2094 * Check for busy page. Note that we may have lost (p) when we
2095 * possibly blocked above.
2097 if (op
& (OBSC_COLLAPSE_WAIT
| OBSC_COLLAPSE_NOWAIT
)) {
2100 if (vm_page_busy_try(p
, TRUE
)) {
2101 if (op
& OBSC_COLLAPSE_NOWAIT
) {
2105 * If we slept, anything could have
2106 * happened. Ask that the scan be restarted.
2108 * Since the object is marked dead, the
2109 * backing offset should not have changed.
2111 vm_page_sleep_busy(p
, TRUE
, "vmocol");
2118 * If (p) is no longer valid restart the scan.
2120 if (p
->object
!= backing_object
|| p
->pindex
!= pindex
) {
2121 kprintf("vm_object_backing_scan: Warning: page "
2122 "%p ripped out from under us\n", p
);
2128 if (op
& OBSC_COLLAPSE_NOWAIT
) {
2129 if (p
->valid
== 0 ||
2131 (p
->flags
& PG_NEED_COMMIT
)) {
2136 /* XXX what if p->valid == 0 , hold_count, etc? */
2140 p
->object
== backing_object
,
2141 ("vm_object_qcollapse(): object mismatch")
2145 * Destroy any associated swap
2147 if (backing_object
->type
== OBJT_SWAP
)
2148 swap_pager_freespace(backing_object
, p
->pindex
, 1);
2151 p
->pindex
< backing_offset_index
||
2152 new_pindex
>= object
->size
2155 * Page is out of the parent object's range, we
2156 * can simply destroy it.
2158 vm_page_protect(p
, VM_PROT_NONE
);
2163 pp
= vm_page_lookup(object
, new_pindex
);
2164 if (pp
!= NULL
|| vm_pager_has_page(object
, new_pindex
)) {
2166 * page already exists in parent OR swap exists
2167 * for this location in the parent. Destroy
2168 * the original page from the backing object.
2170 * Leave the parent's page alone
2172 vm_page_protect(p
, VM_PROT_NONE
);
2178 * Page does not exist in parent, rename the
2179 * page from the backing object to the main object.
2181 * If the page was mapped to a process, it can remain
2182 * mapped through the rename.
2184 if ((p
->queue
- p
->pc
) == PQ_CACHE
)
2185 vm_page_deactivate(p
);
2187 vm_page_rename(p
, object
, new_pindex
);
2189 /* page automatically made dirty by rename */
2195 * This version of collapse allows the operation to occur earlier and
2196 * when paging_in_progress is true for an object... This is not a complete
2197 * operation, but should plug 99.9% of the rest of the leaks.
2199 * The caller must hold the object and backing_object and both must be
2202 * (only called from vm_object_collapse)
2205 vm_object_qcollapse(vm_object_t object
, vm_object_t backing_object
)
2207 if (backing_object
->ref_count
== 1) {
2208 atomic_add_int(&backing_object
->ref_count
, 2);
2209 #if defined(DEBUG_LOCKS)
2210 debugvm_object_add(backing_object
, "qcollapse", 1, 2);
2212 vm_object_backing_scan(object
, backing_object
,
2213 OBSC_COLLAPSE_NOWAIT
);
2214 atomic_add_int(&backing_object
->ref_count
, -2);
2215 #if defined(DEBUG_LOCKS)
2216 debugvm_object_add(backing_object
, "qcollapse", 2, -2);
2222 * Collapse an object with the object backing it. Pages in the backing
2223 * object are moved into the parent, and the backing object is deallocated.
2224 * Any conflict is resolved in favor of the parent's existing pages.
2226 * object must be held and chain-locked on call.
2228 * The caller must have an extra ref on object to prevent a race from
2229 * destroying it during the collapse.
2232 vm_object_collapse(vm_object_t object
, struct vm_object_dealloc_list
**dlistp
)
2234 struct vm_object_dealloc_list
*dlist
= NULL
;
2235 vm_object_t backing_object
;
2238 * Only one thread is attempting a collapse at any given moment.
2239 * There are few restrictions for (object) that callers of this
2240 * function check so reentrancy is likely.
2242 KKASSERT(object
!= NULL
);
2243 vm_object_assert_held(object
);
2244 KKASSERT(object
->chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
));
2251 * We can only collapse a DEFAULT/SWAP object with a
2252 * DEFAULT/SWAP object.
2254 if (object
->type
!= OBJT_DEFAULT
&& object
->type
!= OBJT_SWAP
) {
2255 backing_object
= NULL
;
2259 backing_object
= object
->backing_object
;
2260 if (backing_object
== NULL
)
2262 if (backing_object
->type
!= OBJT_DEFAULT
&&
2263 backing_object
->type
!= OBJT_SWAP
) {
2264 backing_object
= NULL
;
2269 * Hold the backing_object and check for races
2271 vm_object_hold(backing_object
);
2272 if (backing_object
!= object
->backing_object
||
2273 (backing_object
->type
!= OBJT_DEFAULT
&&
2274 backing_object
->type
!= OBJT_SWAP
)) {
2275 vm_object_drop(backing_object
);
2280 * Chain-lock the backing object too because if we
2281 * successfully merge its pages into the top object we
2282 * will collapse backing_object->backing_object as the
2283 * new backing_object. Re-check that it is still our
2286 vm_object_chain_acquire(backing_object
, 0);
2287 if (backing_object
!= object
->backing_object
) {
2288 vm_object_chain_release(backing_object
);
2289 vm_object_drop(backing_object
);
2294 * we check the backing object first, because it is most likely
2297 if (backing_object
->handle
!= NULL
||
2298 (backing_object
->type
!= OBJT_DEFAULT
&&
2299 backing_object
->type
!= OBJT_SWAP
) ||
2300 (backing_object
->flags
& OBJ_DEAD
) ||
2301 object
->handle
!= NULL
||
2302 (object
->type
!= OBJT_DEFAULT
&&
2303 object
->type
!= OBJT_SWAP
) ||
2304 (object
->flags
& OBJ_DEAD
)) {
2309 * If paging is in progress we can't do a normal collapse.
2312 object
->paging_in_progress
!= 0 ||
2313 backing_object
->paging_in_progress
!= 0
2315 vm_object_qcollapse(object
, backing_object
);
2320 * We know that we can either collapse the backing object (if
2321 * the parent is the only reference to it) or (perhaps) have
2322 * the parent bypass the object if the parent happens to shadow
2323 * all the resident pages in the entire backing object.
2325 * This is ignoring pager-backed pages such as swap pages.
2326 * vm_object_backing_scan fails the shadowing test in this
2329 if (backing_object
->ref_count
== 1) {
2331 * If there is exactly one reference to the backing
2332 * object, we can collapse it into the parent.
2334 KKASSERT(object
->backing_object
== backing_object
);
2335 vm_object_backing_scan(object
, backing_object
,
2336 OBSC_COLLAPSE_WAIT
);
2339 * Move the pager from backing_object to object.
2341 if (backing_object
->type
== OBJT_SWAP
) {
2342 vm_object_pip_add(backing_object
, 1);
2345 * scrap the paging_offset junk and do a
2346 * discrete copy. This also removes major
2347 * assumptions about how the swap-pager
2348 * works from where it doesn't belong. The
2349 * new swapper is able to optimize the
2350 * destroy-source case.
2352 vm_object_pip_add(object
, 1);
2353 swap_pager_copy(backing_object
, object
,
2354 OFF_TO_IDX(object
->backing_object_offset
),
2356 vm_object_pip_wakeup(object
);
2357 vm_object_pip_wakeup(backing_object
);
2361 * Object now shadows whatever backing_object did.
2362 * Remove object from backing_object's shadow_list.
2364 * Removing object from backing_objects shadow list
2365 * requires releasing object, which we will do below.
2367 KKASSERT(object
->backing_object
== backing_object
);
2368 if (object
->flags
& OBJ_ONSHADOW
) {
2369 LIST_REMOVE(object
, shadow_list
);
2370 backing_object
->shadow_count
--;
2371 backing_object
->generation
++;
2372 vm_object_clear_flag(object
, OBJ_ONSHADOW
);
2376 * backing_object->backing_object moves from within
2377 * backing_object to within object.
2379 * OBJT_VNODE bbobj's should have empty shadow lists.
2381 while ((bbobj
= backing_object
->backing_object
) != NULL
) {
2382 if (bbobj
->type
== OBJT_VNODE
)
2383 vm_object_hold_shared(bbobj
);
2385 vm_object_hold(bbobj
);
2386 if (bbobj
== backing_object
->backing_object
)
2388 vm_object_drop(bbobj
);
2392 * We are removing backing_object from bbobj's
2393 * shadow list and adding object to bbobj's shadow
2394 * list, so the ref_count on bbobj is unchanged.
2397 if (backing_object
->flags
& OBJ_ONSHADOW
) {
2398 /* not locked exclusively if vnode */
2399 KKASSERT(bbobj
->type
!= OBJT_VNODE
);
2400 LIST_REMOVE(backing_object
,
2402 bbobj
->shadow_count
--;
2403 bbobj
->generation
++;
2404 vm_object_clear_flag(backing_object
,
2407 backing_object
->backing_object
= NULL
;
2409 object
->backing_object
= bbobj
;
2411 if (bbobj
->type
!= OBJT_VNODE
) {
2412 LIST_INSERT_HEAD(&bbobj
->shadow_head
,
2413 object
, shadow_list
);
2414 bbobj
->shadow_count
++;
2415 bbobj
->generation
++;
2416 vm_object_set_flag(object
,
2421 object
->backing_object_offset
+=
2422 backing_object
->backing_object_offset
;
2424 vm_object_drop(bbobj
);
2427 * Discard the old backing_object. Nothing should be
2428 * able to ref it, other than a vm_map_split(),
2429 * and vm_map_split() will stall on our chain lock.
2430 * And we control the parent so it shouldn't be
2431 * possible for it to go away either.
2433 * Since the backing object has no pages, no pager
2434 * left, and no object references within it, all
2435 * that is necessary is to dispose of it.
2437 KASSERT(backing_object
->ref_count
== 1,
2438 ("backing_object %p was somehow "
2439 "re-referenced during collapse!",
2441 KASSERT(RB_EMPTY(&backing_object
->rb_memq
),
2442 ("backing_object %p somehow has left "
2443 "over pages during collapse!",
2447 * The object can be destroyed.
2449 * XXX just fall through and dodealloc instead
2450 * of forcing destruction?
2452 atomic_add_int(&backing_object
->ref_count
, -1);
2453 #if defined(DEBUG_LOCKS)
2454 debugvm_object_add(backing_object
, "collapse", 1, -1);
2456 if ((backing_object
->flags
& OBJ_DEAD
) == 0)
2457 vm_object_terminate(backing_object
);
2462 * If we do not entirely shadow the backing object,
2463 * there is nothing we can do so we give up.
2465 if (vm_object_backing_scan(object
, backing_object
,
2466 OBSC_TEST_ALL_SHADOWED
) == 0) {
2471 * bbobj is backing_object->backing_object. Since
2472 * object completely shadows backing_object we can
2473 * bypass it and become backed by bbobj instead.
2475 * The shadow list for vnode backing objects is not
2476 * used and a shared hold is allowed.
2478 while ((bbobj
= backing_object
->backing_object
) != NULL
) {
2479 if (bbobj
->type
== OBJT_VNODE
)
2480 vm_object_hold_shared(bbobj
);
2482 vm_object_hold(bbobj
);
2483 if (bbobj
== backing_object
->backing_object
)
2485 vm_object_drop(bbobj
);
2489 * Make object shadow bbobj instead of backing_object.
2490 * Remove object from backing_object's shadow list.
2492 * Deallocating backing_object will not remove
2493 * it, since its reference count is at least 2.
2495 * Removing object from backing_object's shadow
2496 * list requires releasing a ref, which we do
2497 * below by setting dodealloc to 1.
2499 KKASSERT(object
->backing_object
== backing_object
);
2500 if (object
->flags
& OBJ_ONSHADOW
) {
2501 LIST_REMOVE(object
, shadow_list
);
2502 backing_object
->shadow_count
--;
2503 backing_object
->generation
++;
2504 vm_object_clear_flag(object
, OBJ_ONSHADOW
);
2508 * Add a ref to bbobj, bbobj now shadows object.
2510 * NOTE: backing_object->backing_object still points
2511 * to bbobj. That relationship remains intact
2512 * because backing_object has > 1 ref, so
2513 * someone else is pointing to it (hence why
2514 * we can't collapse it into object and can
2515 * only handle the all-shadowed bypass case).
2518 if (bbobj
->type
!= OBJT_VNODE
) {
2519 vm_object_chain_wait(bbobj
, 0);
2520 vm_object_reference_locked(bbobj
);
2521 LIST_INSERT_HEAD(&bbobj
->shadow_head
,
2522 object
, shadow_list
);
2523 bbobj
->shadow_count
++;
2524 bbobj
->generation
++;
2525 vm_object_set_flag(object
,
2528 vm_object_reference_quick(bbobj
);
2530 object
->backing_object_offset
+=
2531 backing_object
->backing_object_offset
;
2532 object
->backing_object
= bbobj
;
2533 vm_object_drop(bbobj
);
2535 object
->backing_object
= NULL
;
2539 * Drop the reference count on backing_object. To
2540 * handle ref_count races properly we can't assume
2541 * that the ref_count is still at least 2 so we
2542 * have to actually call vm_object_deallocate()
2543 * (after clearing the chainlock).
2550 * Ok, we want to loop on the new object->bbobj association,
2551 * possibly collapsing it further. However if dodealloc is
2552 * non-zero we have to deallocate the backing_object which
2553 * itself can potentially undergo a collapse, creating a
2554 * recursion depth issue with the LWKT token subsystem.
2556 * In the case where we must deallocate the backing_object
2557 * it is possible now that the backing_object has a single
2558 * shadow count on some other object (not represented here
2559 * as yet), since it no longer shadows us. Thus when we
2560 * call vm_object_deallocate() it may attempt to collapse
2561 * itself into its remaining parent.
2564 struct vm_object_dealloc_list
*dtmp
;
2566 vm_object_chain_release(backing_object
);
2567 vm_object_unlock(backing_object
);
2568 /* backing_object remains held */
2571 * Auto-deallocation list for caller convenience.
2576 dtmp
= kmalloc(sizeof(*dtmp
), M_TEMP
, M_WAITOK
);
2577 dtmp
->object
= backing_object
;
2578 dtmp
->next
= *dlistp
;
2581 vm_object_chain_release(backing_object
);
2582 vm_object_drop(backing_object
);
2584 /* backing_object = NULL; not needed */
2589 * Clean up any left over backing_object
2591 if (backing_object
) {
2592 vm_object_chain_release(backing_object
);
2593 vm_object_drop(backing_object
);
2597 * Clean up any auto-deallocation list. This is a convenience
2598 * for top-level callers so they don't have to pass &dlist.
2599 * Do not clean up any caller-passed dlistp, the caller will
2603 vm_object_deallocate_list(&dlist
);
2608 * vm_object_collapse() may collect additional objects in need of
2609 * deallocation. This routine deallocates these objects. The
2610 * deallocation itself can trigger additional collapses (which the
2611 * deallocate function takes care of). This procedure is used to
2612 * reduce procedural recursion since these vm_object shadow chains
2613 * can become quite long.
2616 vm_object_deallocate_list(struct vm_object_dealloc_list
**dlistp
)
2618 struct vm_object_dealloc_list
*dlist
;
2620 while ((dlist
= *dlistp
) != NULL
) {
2621 *dlistp
= dlist
->next
;
2622 vm_object_lock(dlist
->object
);
2623 vm_object_deallocate_locked(dlist
->object
);
2624 vm_object_drop(dlist
->object
);
2625 kfree(dlist
, M_TEMP
);
2630 * Removes all physical pages in the specified object range from the
2631 * object's list of pages.
2635 static int vm_object_page_remove_callback(vm_page_t p
, void *data
);
2638 vm_object_page_remove(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
,
2639 boolean_t clean_only
)
2641 struct rb_vm_page_scan_info info
;
2645 * Degenerate cases and assertions
2647 vm_object_hold(object
);
2648 if (object
== NULL
||
2649 (object
->resident_page_count
== 0 && object
->swblock_count
== 0)) {
2650 vm_object_drop(object
);
2653 KASSERT(object
->type
!= OBJT_PHYS
,
2654 ("attempt to remove pages from a physical object"));
2657 * Indicate that paging is occuring on the object
2659 vm_object_pip_add(object
, 1);
2662 * Figure out the actual removal range and whether we are removing
2663 * the entire contents of the object or not. If removing the entire
2664 * contents, be sure to get all pages, even those that might be
2665 * beyond the end of the object.
2667 info
.object
= object
;
2668 info
.start_pindex
= start
;
2670 info
.end_pindex
= (vm_pindex_t
)-1;
2672 info
.end_pindex
= end
- 1;
2673 info
.limit
= clean_only
;
2675 all
= (start
== 0 && info
.end_pindex
>= object
->size
- 1);
2678 * Loop until we are sure we have gotten them all.
2682 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
2683 vm_object_page_remove_callback
, &info
);
2684 } while (info
.error
);
2687 * Remove any related swap if throwing away pages, or for
2688 * non-swap objects (the swap is a clean copy in that case).
2690 if (object
->type
!= OBJT_SWAP
|| clean_only
== FALSE
) {
2692 swap_pager_freespace_all(object
);
2694 swap_pager_freespace(object
, info
.start_pindex
,
2695 info
.end_pindex
- info
.start_pindex
+ 1);
2701 vm_object_pip_wakeup(object
);
2702 vm_object_drop(object
);
2706 * The caller must hold the object.
2708 * NOTE: User yields are allowed when removing more than one page, but not
2709 * allowed if only removing one page (the path for single page removals
2710 * might hold a spinlock).
2713 vm_object_page_remove_callback(vm_page_t p
, void *data
)
2715 struct rb_vm_page_scan_info
*info
= data
;
2717 if ((++info
->count
& 63) == 0)
2720 if (info
->object
!= p
->object
||
2721 p
->pindex
< info
->start_pindex
||
2722 p
->pindex
> info
->end_pindex
) {
2723 kprintf("vm_object_page_remove_callbackA: obj/pg race %p/%p\n",
2727 if (vm_page_busy_try(p
, TRUE
)) {
2728 vm_page_sleep_busy(p
, TRUE
, "vmopar");
2732 if (info
->object
!= p
->object
) {
2733 /* this should never happen */
2734 kprintf("vm_object_page_remove_callbackB: obj/pg race %p/%p\n",
2741 * Wired pages cannot be destroyed, but they can be invalidated
2742 * and we do so if clean_only (limit) is not set.
2744 * WARNING! The page may be wired due to being part of a buffer
2745 * cache buffer, and the buffer might be marked B_CACHE.
2746 * This is fine as part of a truncation but VFSs must be
2747 * sure to fix the buffer up when re-extending the file.
2749 * NOTE! PG_NEED_COMMIT is ignored.
2751 if (p
->wire_count
!= 0) {
2752 vm_page_protect(p
, VM_PROT_NONE
);
2753 if (info
->limit
== 0)
2760 * limit is our clean_only flag. If set and the page is dirty or
2761 * requires a commit, do not free it. If set and the page is being
2762 * held by someone, do not free it.
2764 if (info
->limit
&& p
->valid
) {
2765 vm_page_test_dirty(p
);
2766 if ((p
->valid
& p
->dirty
) || (p
->flags
& PG_NEED_COMMIT
)) {
2775 vm_page_protect(p
, VM_PROT_NONE
);
2782 * Coalesces two objects backing up adjoining regions of memory into a
2785 * returns TRUE if objects were combined.
2787 * NOTE: Only works at the moment if the second object is NULL -
2788 * if it's not, which object do we lock first?
2791 * prev_object First object to coalesce
2792 * prev_offset Offset into prev_object
2793 * next_object Second object into coalesce
2794 * next_offset Offset into next_object
2796 * prev_size Size of reference to prev_object
2797 * next_size Size of reference to next_object
2799 * The caller does not need to hold (prev_object) but must have a stable
2800 * pointer to it (typically by holding the vm_map locked).
2803 vm_object_coalesce(vm_object_t prev_object
, vm_pindex_t prev_pindex
,
2804 vm_size_t prev_size
, vm_size_t next_size
)
2806 vm_pindex_t next_pindex
;
2808 if (prev_object
== NULL
)
2811 vm_object_hold(prev_object
);
2813 if (prev_object
->type
!= OBJT_DEFAULT
&&
2814 prev_object
->type
!= OBJT_SWAP
) {
2815 vm_object_drop(prev_object
);
2820 * Try to collapse the object first
2822 vm_object_chain_acquire(prev_object
, 0);
2823 vm_object_collapse(prev_object
, NULL
);
2826 * Can't coalesce if: . more than one reference . paged out . shadows
2827 * another object . has a copy elsewhere (any of which mean that the
2828 * pages not mapped to prev_entry may be in use anyway)
2831 if (prev_object
->backing_object
!= NULL
) {
2832 vm_object_chain_release(prev_object
);
2833 vm_object_drop(prev_object
);
2837 prev_size
>>= PAGE_SHIFT
;
2838 next_size
>>= PAGE_SHIFT
;
2839 next_pindex
= prev_pindex
+ prev_size
;
2841 if ((prev_object
->ref_count
> 1) &&
2842 (prev_object
->size
!= next_pindex
)) {
2843 vm_object_chain_release(prev_object
);
2844 vm_object_drop(prev_object
);
2849 * Remove any pages that may still be in the object from a previous
2852 if (next_pindex
< prev_object
->size
) {
2853 vm_object_page_remove(prev_object
,
2855 next_pindex
+ next_size
, FALSE
);
2856 if (prev_object
->type
== OBJT_SWAP
)
2857 swap_pager_freespace(prev_object
,
2858 next_pindex
, next_size
);
2862 * Extend the object if necessary.
2864 if (next_pindex
+ next_size
> prev_object
->size
)
2865 prev_object
->size
= next_pindex
+ next_size
;
2867 vm_object_chain_release(prev_object
);
2868 vm_object_drop(prev_object
);
2873 * Make the object writable and flag is being possibly dirty.
2875 * The object might not be held (or might be held but held shared),
2876 * the related vnode is probably not held either. Object and vnode are
2877 * stable by virtue of the vm_page busied by the caller preventing
2880 * If the related mount is flagged MNTK_THR_SYNC we need to call
2881 * vsetobjdirty(). Filesystems using this option usually shortcut
2882 * synchronization by only scanning the syncer list.
2885 vm_object_set_writeable_dirty(vm_object_t object
)
2889 /*vm_object_assert_held(object);*/
2891 * Avoid contention in vm fault path by checking the state before
2892 * issuing an atomic op on it.
2894 if ((object
->flags
& (OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
)) !=
2895 (OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
)) {
2896 vm_object_set_flag(object
, OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
);
2898 if (object
->type
== OBJT_VNODE
&&
2899 (vp
= (struct vnode
*)object
->handle
) != NULL
) {
2900 if ((vp
->v_flag
& VOBJDIRTY
) == 0) {
2902 (vp
->v_mount
->mnt_kern_flag
& MNTK_THR_SYNC
)) {
2904 * New style THR_SYNC places vnodes on the
2905 * syncer list more deterministically.
2910 * Old style scan would not necessarily place
2911 * a vnode on the syncer list when possibly
2912 * modified via mmap.
2914 vsetflags(vp
, VOBJDIRTY
);
2920 #include "opt_ddb.h"
2922 #include <sys/kernel.h>
2924 #include <sys/cons.h>
2926 #include <ddb/ddb.h>
2928 static int _vm_object_in_map (vm_map_t map
, vm_object_t object
,
2929 vm_map_entry_t entry
);
2930 static int vm_object_in_map (vm_object_t object
);
2933 * The caller must hold the object.
2936 _vm_object_in_map(vm_map_t map
, vm_object_t object
, vm_map_entry_t entry
)
2939 vm_map_entry_t tmpe
;
2940 vm_object_t obj
, nobj
;
2946 tmpe
= map
->header
.next
;
2947 entcount
= map
->nentries
;
2948 while (entcount
-- && (tmpe
!= &map
->header
)) {
2949 if( _vm_object_in_map(map
, object
, tmpe
)) {
2956 switch(entry
->maptype
) {
2957 case VM_MAPTYPE_SUBMAP
:
2958 tmpm
= entry
->object
.sub_map
;
2959 tmpe
= tmpm
->header
.next
;
2960 entcount
= tmpm
->nentries
;
2961 while (entcount
-- && tmpe
!= &tmpm
->header
) {
2962 if( _vm_object_in_map(tmpm
, object
, tmpe
)) {
2968 case VM_MAPTYPE_NORMAL
:
2969 case VM_MAPTYPE_VPAGETABLE
:
2970 obj
= entry
->object
.vm_object
;
2972 if (obj
== object
) {
2973 if (obj
!= entry
->object
.vm_object
)
2974 vm_object_drop(obj
);
2977 while ((nobj
= obj
->backing_object
) != NULL
) {
2978 vm_object_hold(nobj
);
2979 if (nobj
== obj
->backing_object
)
2981 vm_object_drop(nobj
);
2983 if (obj
!= entry
->object
.vm_object
) {
2985 vm_object_lock_swap();
2986 vm_object_drop(obj
);
2997 static int vm_object_in_map_callback(struct proc
*p
, void *data
);
2999 struct vm_object_in_map_info
{
3008 vm_object_in_map(vm_object_t object
)
3010 struct vm_object_in_map_info info
;
3013 info
.object
= object
;
3015 allproc_scan(vm_object_in_map_callback
, &info
);
3018 if( _vm_object_in_map(&kernel_map
, object
, 0))
3020 if( _vm_object_in_map(&pager_map
, object
, 0))
3022 if( _vm_object_in_map(&buffer_map
, object
, 0))
3031 vm_object_in_map_callback(struct proc
*p
, void *data
)
3033 struct vm_object_in_map_info
*info
= data
;
3036 if (_vm_object_in_map(&p
->p_vmspace
->vm_map
, info
->object
, 0)) {
3044 DB_SHOW_COMMAND(vmochk
, vm_object_check
)
3046 struct vm_object_hash
*hash
;
3051 * make sure that internal objs are in a map somewhere
3052 * and none have zero ref counts.
3054 for (n
= 0; n
< VMOBJ_HSIZE
; ++n
) {
3055 hash
= &vm_object_hash
[n
];
3056 for (object
= TAILQ_FIRST(&hash
->list
);
3058 object
= TAILQ_NEXT(object
, object_list
)) {
3059 if (object
->type
== OBJT_MARKER
)
3061 if (object
->handle
!= NULL
||
3062 (object
->type
!= OBJT_DEFAULT
&&
3063 object
->type
!= OBJT_SWAP
)) {
3066 if (object
->ref_count
== 0) {
3067 db_printf("vmochk: internal obj has "
3068 "zero ref count: %ld\n",
3069 (long)object
->size
);
3071 if (vm_object_in_map(object
))
3073 db_printf("vmochk: internal obj is not in a map: "
3074 "ref: %d, size: %lu: 0x%lx, "
3075 "backing_object: %p\n",
3076 object
->ref_count
, (u_long
)object
->size
,
3077 (u_long
)object
->size
,
3078 (void *)object
->backing_object
);
3086 DB_SHOW_COMMAND(object
, vm_object_print_static
)
3088 /* XXX convert args. */
3089 vm_object_t object
= (vm_object_t
)addr
;
3090 boolean_t full
= have_addr
;
3094 /* XXX count is an (unused) arg. Avoid shadowing it. */
3095 #define count was_count
3103 "Object %p: type=%d, size=0x%lx, res=%ld, ref=%d, flags=0x%x\n",
3104 object
, (int)object
->type
, (u_long
)object
->size
,
3105 object
->resident_page_count
, object
->ref_count
, object
->flags
);
3107 * XXX no %qd in kernel. Truncate object->backing_object_offset.
3109 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n",
3110 object
->shadow_count
,
3111 object
->backing_object
? object
->backing_object
->ref_count
: 0,
3112 object
->backing_object
, (long)object
->backing_object_offset
);
3119 RB_FOREACH(p
, vm_page_rb_tree
, &object
->rb_memq
) {
3121 db_iprintf("memory:=");
3122 else if (count
== 6) {
3130 db_printf("(off=0x%lx,page=0x%lx)",
3131 (u_long
) p
->pindex
, (u_long
) VM_PAGE_TO_PHYS(p
));
3142 * XXX need this non-static entry for calling from vm_map_print.
3147 vm_object_print(/* db_expr_t */ long addr
,
3148 boolean_t have_addr
,
3149 /* db_expr_t */ long count
,
3152 vm_object_print_static(addr
, have_addr
, count
, modif
);
3158 DB_SHOW_COMMAND(vmopag
, vm_object_print_pages
)
3160 struct vm_object_hash
*hash
;
3166 for (n
= 0; n
< VMOBJ_HSIZE
; ++n
) {
3167 hash
= &vm_object_hash
[n
];
3168 for (object
= TAILQ_FIRST(&hash
->list
);
3170 object
= TAILQ_NEXT(object
, object_list
)) {
3171 vm_pindex_t idx
, fidx
;
3173 vm_paddr_t pa
= -1, padiff
;
3177 if (object
->type
== OBJT_MARKER
)
3179 db_printf("new object: %p\n", (void *)object
);
3189 osize
= object
->size
;
3192 for (idx
= 0; idx
< osize
; idx
++) {
3193 m
= vm_page_lookup(object
, idx
);
3196 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3197 (long)fidx
, rcount
, (long)pa
);
3211 (VM_PAGE_TO_PHYS(m
) == pa
+ rcount
* PAGE_SIZE
)) {
3216 padiff
= pa
+ rcount
* PAGE_SIZE
- VM_PAGE_TO_PHYS(m
);
3217 padiff
>>= PAGE_SHIFT
;
3218 padiff
&= PQ_L2_MASK
;
3220 pa
= VM_PAGE_TO_PHYS(m
) - rcount
* PAGE_SIZE
;
3224 db_printf(" index(%ld)run(%d)pa(0x%lx)",
3225 (long)fidx
, rcount
, (long)pa
);
3226 db_printf("pd(%ld)\n", (long)padiff
);
3236 pa
= VM_PAGE_TO_PHYS(m
);
3240 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3241 (long)fidx
, rcount
, (long)pa
);