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 atomic_add_int(&object
->generation
, 1);
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. The held token
484 * allows the caller to pair the wait and ref.
486 * The object must be held, but may be held shared if desired (hence why
487 * we use an atomic op).
490 VMOBJDEBUG(vm_object_reference_locked
)(vm_object_t object VMOBJDBARGS
)
492 KKASSERT(object
!= NULL
);
493 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
494 KKASSERT((object
->chainlk
& (CHAINLK_EXCL
| CHAINLK_MASK
)) == 0);
495 atomic_add_int(&object
->ref_count
, 1);
496 if (object
->type
== OBJT_VNODE
) {
497 vref(object
->handle
);
498 /* XXX what if the vnode is being destroyed? */
500 #if defined(DEBUG_LOCKS)
501 debugvm_object_add(object
, file
, line
, 1);
506 * This version explicitly allows the chain to be held (i.e. by the
507 * caller). The token must also be held.
510 VMOBJDEBUG(vm_object_reference_locked_chain_held
)(vm_object_t object
513 KKASSERT(object
!= NULL
);
514 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
515 atomic_add_int(&object
->ref_count
, 1);
516 if (object
->type
== OBJT_VNODE
) {
517 vref(object
->handle
);
518 /* XXX what if the vnode is being destroyed? */
520 #if defined(DEBUG_LOCKS)
521 debugvm_object_add(object
, file
, line
, 1);
526 * This version is only allowed for vnode objects.
529 VMOBJDEBUG(vm_object_reference_quick
)(vm_object_t object VMOBJDBARGS
)
531 KKASSERT(object
->type
== OBJT_VNODE
);
532 atomic_add_int(&object
->ref_count
, 1);
533 vref(object
->handle
);
534 #if defined(DEBUG_LOCKS)
535 debugvm_object_add(object
, file
, line
, 1);
540 * Object OBJ_CHAINLOCK lock handling.
542 * The caller can chain-lock backing objects recursively and then
543 * use vm_object_chain_release_all() to undo the whole chain.
545 * Chain locks are used to prevent collapses and are only applicable
546 * to OBJT_DEFAULT and OBJT_SWAP objects. Chain locking operations
547 * on other object types are ignored. This is also important because
548 * it allows e.g. the vnode underlying a memory mapping to take concurrent
551 * The object must usually be held on entry, though intermediate
552 * objects need not be held on release. The object must be held exclusively,
553 * NOT shared. Note that the prefault path checks the shared state and
554 * avoids using the chain functions.
557 vm_object_chain_wait(vm_object_t object
, int shared
)
559 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
561 uint32_t chainlk
= object
->chainlk
;
565 if (chainlk
& (CHAINLK_EXCL
| CHAINLK_EXCLREQ
)) {
566 tsleep_interlock(object
, 0);
567 if (atomic_cmpset_int(&object
->chainlk
,
569 chainlk
| CHAINLK_WAIT
)) {
570 tsleep(object
, PINTERLOCKED
,
579 if (chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
)) {
580 tsleep_interlock(object
, 0);
581 if (atomic_cmpset_int(&object
->chainlk
,
583 chainlk
| CHAINLK_WAIT
))
585 tsleep(object
, PINTERLOCKED
,
590 if (atomic_cmpset_int(&object
->chainlk
,
592 chainlk
& ~CHAINLK_WAIT
))
594 if (chainlk
& CHAINLK_WAIT
)
606 vm_object_chain_acquire(vm_object_t object
, int shared
)
608 if (object
->type
!= OBJT_DEFAULT
&& object
->type
!= OBJT_SWAP
)
610 if (vm_shared_fault
== 0)
614 uint32_t chainlk
= object
->chainlk
;
618 if (chainlk
& (CHAINLK_EXCL
| CHAINLK_EXCLREQ
)) {
619 tsleep_interlock(object
, 0);
620 if (atomic_cmpset_int(&object
->chainlk
,
622 chainlk
| CHAINLK_WAIT
)) {
623 tsleep(object
, PINTERLOCKED
,
627 } else if (atomic_cmpset_int(&object
->chainlk
,
628 chainlk
, chainlk
+ 1)) {
633 if (chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
)) {
634 tsleep_interlock(object
, 0);
635 if (atomic_cmpset_int(&object
->chainlk
,
640 tsleep(object
, PINTERLOCKED
,
645 if (atomic_cmpset_int(&object
->chainlk
,
647 (chainlk
| CHAINLK_EXCL
) &
650 if (chainlk
& CHAINLK_WAIT
)
662 vm_object_chain_release(vm_object_t object
)
664 /*ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));*/
665 if (object
->type
!= OBJT_DEFAULT
&& object
->type
!= OBJT_SWAP
)
667 KKASSERT(object
->chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
));
669 uint32_t chainlk
= object
->chainlk
;
672 if (chainlk
& CHAINLK_MASK
) {
673 if ((chainlk
& CHAINLK_MASK
) == 1 &&
674 atomic_cmpset_int(&object
->chainlk
,
676 (chainlk
- 1) & ~CHAINLK_WAIT
)) {
677 if (chainlk
& CHAINLK_WAIT
)
681 if ((chainlk
& CHAINLK_MASK
) > 1 &&
682 atomic_cmpset_int(&object
->chainlk
,
683 chainlk
, chainlk
- 1)) {
688 KKASSERT(chainlk
& CHAINLK_EXCL
);
689 if (atomic_cmpset_int(&object
->chainlk
,
691 chainlk
& ~(CHAINLK_EXCL
|
693 if (chainlk
& CHAINLK_WAIT
)
702 * Release the chain from first_object through and including stopobj.
703 * The caller is typically holding the first and last object locked
704 * (shared or exclusive) to prevent destruction races.
706 * We release stopobj first as an optimization as this object is most
707 * likely to be shared across multiple processes.
710 vm_object_chain_release_all(vm_object_t first_object
, vm_object_t stopobj
)
712 vm_object_t backing_object
;
715 vm_object_chain_release(stopobj
);
716 object
= first_object
;
718 while (object
!= stopobj
) {
720 backing_object
= object
->backing_object
;
721 vm_object_chain_release(object
);
722 object
= backing_object
;
727 * Dereference an object and its underlying vnode. The object may be
728 * held shared. On return the object will remain held.
730 * This function may return a vnode in *vpp which the caller must release
731 * after the caller drops its own lock. If vpp is NULL, we assume that
732 * the caller was holding an exclusive lock on the object and we vrele()
736 VMOBJDEBUG(vm_object_vndeallocate
)(vm_object_t object
, struct vnode
**vpp
739 struct vnode
*vp
= (struct vnode
*) object
->handle
;
741 KASSERT(object
->type
== OBJT_VNODE
,
742 ("vm_object_vndeallocate: not a vnode object"));
743 KASSERT(vp
!= NULL
, ("vm_object_vndeallocate: missing vp"));
744 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
746 if (object
->ref_count
== 0) {
747 vprint("vm_object_vndeallocate", vp
);
748 panic("vm_object_vndeallocate: bad object reference count");
752 int count
= object
->ref_count
;
755 vm_object_upgrade(object
);
756 if (atomic_cmpset_int(&object
->ref_count
, count
, 0)) {
757 vclrflags(vp
, VTEXT
);
761 if (atomic_cmpset_int(&object
->ref_count
,
768 #if defined(DEBUG_LOCKS)
769 debugvm_object_add(object
, file
, line
, -1);
773 * vrele or return the vp to vrele. We can only safely vrele(vp)
774 * if the object was locked exclusively. But there are two races
777 * We had to upgrade the object above to safely clear VTEXT
778 * but the alternative path where the shared lock is retained
779 * can STILL race to 0 in other paths and cause our own vrele()
780 * to terminate the vnode. We can't allow that if the VM object
781 * is still locked shared.
790 * Release a reference to the specified object, gained either through a
791 * vm_object_allocate or a vm_object_reference call. When all references
792 * are gone, storage associated with this object may be relinquished.
794 * The caller does not have to hold the object locked but must have control
795 * over the reference in question in order to guarantee that the object
796 * does not get ripped out from under us.
798 * XXX Currently all deallocations require an exclusive lock.
801 VMOBJDEBUG(vm_object_deallocate
)(vm_object_t object VMOBJDBARGS
)
810 count
= object
->ref_count
;
814 * If decrementing the count enters into special handling
815 * territory (0, 1, or 2) we have to do it the hard way.
816 * Fortunate though, objects with only a few refs like this
817 * are not likely to be heavily contended anyway.
819 * For vnode objects we only care about 1->0 transitions.
821 if (count
<= 3 || (object
->type
== OBJT_VNODE
&& count
<= 1)) {
822 #if defined(DEBUG_LOCKS)
823 debugvm_object_add(object
, file
, line
, 0);
825 vm_object_hold(object
);
826 vm_object_deallocate_locked(object
);
827 vm_object_drop(object
);
832 * Try to decrement ref_count without acquiring a hold on
833 * the object. This is particularly important for the exec*()
834 * and exit*() code paths because the program binary may
835 * have a great deal of sharing and an exclusive lock will
836 * crowbar performance in those circumstances.
838 if (object
->type
== OBJT_VNODE
) {
839 vp
= (struct vnode
*)object
->handle
;
840 if (atomic_cmpset_int(&object
->ref_count
,
842 #if defined(DEBUG_LOCKS)
843 debugvm_object_add(object
, file
, line
, -1);
851 if (atomic_cmpset_int(&object
->ref_count
,
853 #if defined(DEBUG_LOCKS)
854 debugvm_object_add(object
, file
, line
, -1);
865 VMOBJDEBUG(vm_object_deallocate_locked
)(vm_object_t object VMOBJDBARGS
)
867 struct vm_object_dealloc_list
*dlist
= NULL
;
868 struct vm_object_dealloc_list
*dtmp
;
873 * We may chain deallocate object, but additional objects may
874 * collect on the dlist which also have to be deallocated. We
875 * must avoid a recursion, vm_object chains can get deep.
879 while (object
!= NULL
) {
881 * vnode case, caller either locked the object exclusively
882 * or this is a recursion with must_drop != 0 and the vnode
883 * object will be locked shared.
885 * If locked shared we have to drop the object before we can
886 * call vrele() or risk a shared/exclusive livelock.
888 if (object
->type
== OBJT_VNODE
) {
889 ASSERT_LWKT_TOKEN_HELD(&object
->token
);
891 struct vnode
*tmp_vp
;
893 vm_object_vndeallocate(object
, &tmp_vp
);
894 vm_object_drop(object
);
899 vm_object_vndeallocate(object
, NULL
);
903 ASSERT_LWKT_TOKEN_HELD_EXCL(&object
->token
);
906 * Normal case (object is locked exclusively)
908 if (object
->ref_count
== 0) {
909 panic("vm_object_deallocate: object deallocated "
910 "too many times: %d", object
->type
);
912 if (object
->ref_count
> 2) {
913 atomic_add_int(&object
->ref_count
, -1);
914 #if defined(DEBUG_LOCKS)
915 debugvm_object_add(object
, file
, line
, -1);
921 * Here on ref_count of one or two, which are special cases for
924 * Nominal ref_count > 1 case if the second ref is not from
927 * (ONEMAPPING only applies to DEFAULT AND SWAP objects)
929 if (object
->ref_count
== 2 && object
->shadow_count
== 0) {
930 if (object
->type
== OBJT_DEFAULT
||
931 object
->type
== OBJT_SWAP
) {
932 vm_object_set_flag(object
, OBJ_ONEMAPPING
);
934 atomic_add_int(&object
->ref_count
, -1);
935 #if defined(DEBUG_LOCKS)
936 debugvm_object_add(object
, file
, line
, -1);
942 * If the second ref is from a shadow we chain along it
943 * upwards if object's handle is exhausted.
945 * We have to decrement object->ref_count before potentially
946 * collapsing the first shadow object or the collapse code
947 * will not be able to handle the degenerate case to remove
948 * object. However, if we do it too early the object can
949 * get ripped out from under us.
951 if (object
->ref_count
== 2 && object
->shadow_count
== 1 &&
952 object
->handle
== NULL
&& (object
->type
== OBJT_DEFAULT
||
953 object
->type
== OBJT_SWAP
)) {
954 temp
= LIST_FIRST(&object
->shadow_head
);
955 KKASSERT(temp
!= NULL
);
956 vm_object_hold(temp
);
959 * Wait for any paging to complete so the collapse
960 * doesn't (or isn't likely to) qcollapse. pip
961 * waiting must occur before we acquire the
965 temp
->paging_in_progress
||
966 object
->paging_in_progress
968 vm_object_pip_wait(temp
, "objde1");
969 vm_object_pip_wait(object
, "objde2");
973 * If the parent is locked we have to give up, as
974 * otherwise we would be acquiring locks in the
975 * wrong order and potentially deadlock.
977 if (temp
->chainlk
& (CHAINLK_EXCL
| CHAINLK_MASK
)) {
978 vm_object_drop(temp
);
981 vm_object_chain_acquire(temp
, 0);
984 * Recheck/retry after the hold and the paging
985 * wait, both of which can block us.
987 if (object
->ref_count
!= 2 ||
988 object
->shadow_count
!= 1 ||
990 LIST_FIRST(&object
->shadow_head
) != temp
||
991 (object
->type
!= OBJT_DEFAULT
&&
992 object
->type
!= OBJT_SWAP
)) {
993 vm_object_chain_release(temp
);
994 vm_object_drop(temp
);
999 * We can safely drop object's ref_count now.
1001 KKASSERT(object
->ref_count
== 2);
1002 atomic_add_int(&object
->ref_count
, -1);
1003 #if defined(DEBUG_LOCKS)
1004 debugvm_object_add(object
, file
, line
, -1);
1008 * If our single parent is not collapseable just
1009 * decrement ref_count (2->1) and stop.
1011 if (temp
->handle
|| (temp
->type
!= OBJT_DEFAULT
&&
1012 temp
->type
!= OBJT_SWAP
)) {
1013 vm_object_chain_release(temp
);
1014 vm_object_drop(temp
);
1019 * At this point we have already dropped object's
1020 * ref_count so it is possible for a race to
1021 * deallocate obj out from under us. Any collapse
1022 * will re-check the situation. We must not block
1023 * until we are able to collapse.
1025 * Bump temp's ref_count to avoid an unwanted
1026 * degenerate recursion (can't call
1027 * vm_object_reference_locked() because it asserts
1028 * that CHAINLOCK is not set).
1030 atomic_add_int(&temp
->ref_count
, 1);
1031 KKASSERT(temp
->ref_count
> 1);
1034 * Collapse temp, then deallocate the extra ref
1037 vm_object_collapse(temp
, &dlist
);
1038 vm_object_chain_release(temp
);
1040 vm_object_lock_swap();
1041 vm_object_drop(object
);
1049 * Drop the ref and handle termination on the 1->0 transition.
1050 * We may have blocked above so we have to recheck.
1053 KKASSERT(object
->ref_count
!= 0);
1054 if (object
->ref_count
>= 2) {
1055 atomic_add_int(&object
->ref_count
, -1);
1056 #if defined(DEBUG_LOCKS)
1057 debugvm_object_add(object
, file
, line
, -1);
1061 KKASSERT(object
->ref_count
== 1);
1064 * 1->0 transition. Chain through the backing_object.
1065 * Maintain the ref until we've located the backing object,
1068 while ((temp
= object
->backing_object
) != NULL
) {
1069 if (temp
->type
== OBJT_VNODE
)
1070 vm_object_hold_shared(temp
);
1072 vm_object_hold(temp
);
1073 if (temp
== object
->backing_object
)
1075 vm_object_drop(temp
);
1079 * 1->0 transition verified, retry if ref_count is no longer
1080 * 1. Otherwise disconnect the backing_object (temp) and
1083 if (object
->ref_count
!= 1) {
1084 vm_object_drop(temp
);
1089 * It shouldn't be possible for the object to be chain locked
1090 * if we're removing the last ref on it.
1092 * Removing object from temp's shadow list requires dropping
1093 * temp, which we will do on loop.
1095 * NOTE! vnodes do not use the shadow list, but still have
1096 * the backing_object reference.
1098 KKASSERT((object
->chainlk
& (CHAINLK_EXCL
|CHAINLK_MASK
)) == 0);
1101 if (object
->flags
& OBJ_ONSHADOW
) {
1102 LIST_REMOVE(object
, shadow_list
);
1103 temp
->shadow_count
--;
1104 atomic_add_int(&temp
->generation
, 1);
1105 vm_object_clear_flag(object
, OBJ_ONSHADOW
);
1107 object
->backing_object
= NULL
;
1110 atomic_add_int(&object
->ref_count
, -1);
1111 if ((object
->flags
& OBJ_DEAD
) == 0)
1112 vm_object_terminate(object
);
1113 if (must_drop
&& temp
)
1114 vm_object_lock_swap();
1116 vm_object_drop(object
);
1121 if (must_drop
&& object
)
1122 vm_object_drop(object
);
1125 * Additional tail recursion on dlist. Avoid a recursion. Objects
1126 * on the dlist have a hold count but are not locked.
1128 if ((dtmp
= dlist
) != NULL
) {
1130 object
= dtmp
->object
;
1131 kfree(dtmp
, M_TEMP
);
1133 vm_object_lock(object
); /* already held, add lock */
1134 must_drop
= 1; /* and we're responsible for it */
1140 * Destroy the specified object, freeing up related resources.
1142 * The object must have zero references.
1144 * The object must held. The caller is responsible for dropping the object
1145 * after terminate returns. Terminate does NOT drop the object.
1147 static int vm_object_terminate_callback(vm_page_t p
, void *data
);
1150 vm_object_terminate(vm_object_t object
)
1152 struct rb_vm_page_scan_info info
;
1153 struct vm_object_hash
*hash
;
1156 * Make sure no one uses us. Once we set OBJ_DEAD we should be
1157 * able to safely block.
1159 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
1160 KKASSERT((object
->flags
& OBJ_DEAD
) == 0);
1161 vm_object_set_flag(object
, OBJ_DEAD
);
1164 * Wait for the pageout daemon to be done with the object
1166 vm_object_pip_wait(object
, "objtrm1");
1168 KASSERT(!object
->paging_in_progress
,
1169 ("vm_object_terminate: pageout in progress"));
1172 * Clean and free the pages, as appropriate. All references to the
1173 * object are gone, so we don't need to lock it.
1175 if (object
->type
== OBJT_VNODE
) {
1179 * Clean pages and flush buffers.
1181 * NOTE! TMPFS buffer flushes do not typically flush the
1182 * actual page to swap as this would be highly
1183 * inefficient, and normal filesystems usually wrap
1184 * page flushes with buffer cache buffers.
1186 * To deal with this we have to call vinvalbuf() both
1187 * before and after the vm_object_page_clean().
1189 vp
= (struct vnode
*) object
->handle
;
1190 vinvalbuf(vp
, V_SAVE
, 0, 0);
1191 vm_object_page_clean(object
, 0, 0, OBJPC_SYNC
);
1192 vinvalbuf(vp
, V_SAVE
, 0, 0);
1196 * Wait for any I/O to complete, after which there had better not
1197 * be any references left on the object.
1199 vm_object_pip_wait(object
, "objtrm2");
1201 if (object
->ref_count
!= 0) {
1202 panic("vm_object_terminate: object with references, "
1203 "ref_count=%d", object
->ref_count
);
1207 * Cleanup any shared pmaps associated with this object.
1209 pmap_object_free(object
);
1212 * Now free any remaining pages. For internal objects, this also
1213 * removes them from paging queues. Don't free wired pages, just
1214 * remove them from the object.
1217 info
.object
= object
;
1220 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, NULL
,
1221 vm_object_terminate_callback
, &info
);
1222 } while (info
.error
);
1225 * Let the pager know object is dead.
1227 vm_pager_deallocate(object
);
1230 * Wait for the object hold count to hit 1, clean out pages as
1231 * we go. vmobj_token interlocks any race conditions that might
1232 * pick the object up from the vm_object_list after we have cleared
1236 if (RB_ROOT(&object
->rb_memq
) == NULL
)
1238 kprintf("vm_object_terminate: Warning, object %p "
1239 "still has %ld pages\n",
1240 object
, object
->resident_page_count
);
1241 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, NULL
,
1242 vm_object_terminate_callback
, &info
);
1246 * There had better not be any pages left
1248 KKASSERT(object
->resident_page_count
== 0);
1251 * Remove the object from the global object list.
1253 hash
= VMOBJ_HASH(object
);
1254 lwkt_gettoken(&hash
->token
);
1255 TAILQ_REMOVE(&hash
->list
, object
, object_list
);
1256 lwkt_reltoken(&hash
->token
);
1258 if (object
->ref_count
!= 0) {
1259 panic("vm_object_terminate2: object with references, "
1260 "ref_count=%d", object
->ref_count
);
1264 * NOTE: The object hold_count is at least 1, so we cannot kfree()
1265 * the object here. See vm_object_drop().
1270 * The caller must hold the object.
1273 vm_object_terminate_callback(vm_page_t p
, void *data
)
1275 struct rb_vm_page_scan_info
*info
= data
;
1279 KKASSERT(object
== info
->object
);
1280 if (vm_page_busy_try(p
, TRUE
)) {
1281 vm_page_sleep_busy(p
, TRUE
, "vmotrm");
1285 if (object
!= p
->object
) {
1286 /* XXX remove once we determine it can't happen */
1287 kprintf("vm_object_terminate: Warning: Encountered "
1288 "busied page %p on queue %d\n", p
, p
->queue
);
1291 } else if (p
->wire_count
== 0) {
1293 * NOTE: p->dirty and PG_NEED_COMMIT are ignored.
1296 mycpu
->gd_cnt
.v_pfree
++;
1298 if (p
->queue
!= PQ_NONE
)
1299 kprintf("vm_object_terminate: Warning: Encountered "
1300 "wired page %p on queue %d\n", p
, p
->queue
);
1306 * Must be at end to avoid SMP races, caller holds object token
1308 if ((++info
->count
& 63) == 0)
1314 * Clean all dirty pages in the specified range of object. Leaves page
1315 * on whatever queue it is currently on. If NOSYNC is set then do not
1316 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC),
1317 * leaving the object dirty.
1319 * When stuffing pages asynchronously, allow clustering. XXX we need a
1320 * synchronous clustering mode implementation.
1322 * Odd semantics: if start == end, we clean everything.
1324 * The object must be locked? XXX
1326 static int vm_object_page_clean_pass1(struct vm_page
*p
, void *data
);
1327 static int vm_object_page_clean_pass2(struct vm_page
*p
, void *data
);
1330 vm_object_page_clean(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
,
1333 struct rb_vm_page_scan_info info
;
1339 vm_object_hold(object
);
1340 if (object
->type
!= OBJT_VNODE
||
1341 (object
->flags
& OBJ_MIGHTBEDIRTY
) == 0) {
1342 vm_object_drop(object
);
1346 pagerflags
= (flags
& (OBJPC_SYNC
| OBJPC_INVAL
)) ?
1347 VM_PAGER_PUT_SYNC
: VM_PAGER_CLUSTER_OK
;
1348 pagerflags
|= (flags
& OBJPC_INVAL
) ? VM_PAGER_PUT_INVAL
: 0;
1350 vp
= object
->handle
;
1353 * Interlock other major object operations. This allows us to
1354 * temporarily clear OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY.
1356 vm_object_set_flag(object
, OBJ_CLEANING
);
1359 * Handle 'entire object' case
1361 info
.start_pindex
= start
;
1363 info
.end_pindex
= object
->size
- 1;
1365 info
.end_pindex
= end
- 1;
1367 wholescan
= (start
== 0 && info
.end_pindex
== object
->size
- 1);
1369 info
.pagerflags
= pagerflags
;
1370 info
.object
= object
;
1373 * If cleaning the entire object do a pass to mark the pages read-only.
1374 * If everything worked out ok, clear OBJ_WRITEABLE and
1380 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
1381 vm_object_page_clean_pass1
, &info
);
1382 if (info
.error
== 0) {
1383 vm_object_clear_flag(object
,
1384 OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
);
1385 if (object
->type
== OBJT_VNODE
&&
1386 (vp
= (struct vnode
*)object
->handle
) != NULL
) {
1388 * Use new-style interface to clear VISDIRTY
1389 * because the vnode is not necessarily removed
1390 * from the syncer list(s) as often as it was
1391 * under the old interface, which can leave
1392 * the vnode on the syncer list after reclaim.
1400 * Do a pass to clean all the dirty pages we find.
1405 generation
= object
->generation
;
1406 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
1407 vm_object_page_clean_pass2
, &info
);
1408 } while (info
.error
|| generation
!= object
->generation
);
1410 vm_object_clear_flag(object
, OBJ_CLEANING
);
1411 vm_object_drop(object
);
1415 * The caller must hold the object.
1419 vm_object_page_clean_pass1(struct vm_page
*p
, void *data
)
1421 struct rb_vm_page_scan_info
*info
= data
;
1423 KKASSERT(p
->object
== info
->object
);
1425 vm_page_flag_set(p
, PG_CLEANCHK
);
1426 if ((info
->limit
& OBJPC_NOSYNC
) && (p
->flags
& PG_NOSYNC
)) {
1428 } else if (vm_page_busy_try(p
, FALSE
)) {
1431 KKASSERT(p
->object
== info
->object
);
1432 vm_page_protect(p
, VM_PROT_READ
);
1437 * Must be at end to avoid SMP races, caller holds object token
1439 if ((++info
->count
& 63) == 0)
1445 * The caller must hold the object
1449 vm_object_page_clean_pass2(struct vm_page
*p
, void *data
)
1451 struct rb_vm_page_scan_info
*info
= data
;
1454 KKASSERT(p
->object
== info
->object
);
1457 * Do not mess with pages that were inserted after we started
1458 * the cleaning pass.
1460 if ((p
->flags
& PG_CLEANCHK
) == 0)
1463 generation
= info
->object
->generation
;
1465 if (vm_page_busy_try(p
, TRUE
)) {
1466 vm_page_sleep_busy(p
, TRUE
, "vpcwai");
1471 KKASSERT(p
->object
== info
->object
&&
1472 info
->object
->generation
== generation
);
1475 * Before wasting time traversing the pmaps, check for trivial
1476 * cases where the page cannot be dirty.
1478 if (p
->valid
== 0 || (p
->queue
- p
->pc
) == PQ_CACHE
) {
1479 KKASSERT((p
->dirty
& p
->valid
) == 0 &&
1480 (p
->flags
& PG_NEED_COMMIT
) == 0);
1486 * Check whether the page is dirty or not. The page has been set
1487 * to be read-only so the check will not race a user dirtying the
1490 vm_page_test_dirty(p
);
1491 if ((p
->dirty
& p
->valid
) == 0 && (p
->flags
& PG_NEED_COMMIT
) == 0) {
1492 vm_page_flag_clear(p
, PG_CLEANCHK
);
1498 * If we have been asked to skip nosync pages and this is a
1499 * nosync page, skip it. Note that the object flags were
1500 * not cleared in this case (because pass1 will have returned an
1501 * error), so we do not have to set them.
1503 if ((info
->limit
& OBJPC_NOSYNC
) && (p
->flags
& PG_NOSYNC
)) {
1504 vm_page_flag_clear(p
, PG_CLEANCHK
);
1510 * Flush as many pages as we can. PG_CLEANCHK will be cleared on
1511 * the pages that get successfully flushed. Set info->error if
1512 * we raced an object modification.
1514 vm_object_page_collect_flush(info
->object
, p
, info
->pagerflags
);
1515 /* vm_wait_nominal(); this can deadlock the system in syncer/pageout */
1518 * Must be at end to avoid SMP races, caller holds object token
1521 if ((++info
->count
& 63) == 0)
1527 * Collect the specified page and nearby pages and flush them out.
1528 * The number of pages flushed is returned. The passed page is busied
1529 * by the caller and we are responsible for its disposition.
1531 * The caller must hold the object.
1534 vm_object_page_collect_flush(vm_object_t object
, vm_page_t p
, int pagerflags
)
1542 vm_page_t ma
[BLIST_MAX_ALLOC
];
1544 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
1547 page_base
= pi
% BLIST_MAX_ALLOC
;
1555 tp
= vm_page_lookup_busy_try(object
, pi
- page_base
+ ib
,
1561 if ((pagerflags
& VM_PAGER_IGNORE_CLEANCHK
) == 0 &&
1562 (tp
->flags
& PG_CLEANCHK
) == 0) {
1566 if ((tp
->queue
- tp
->pc
) == PQ_CACHE
) {
1567 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1571 vm_page_test_dirty(tp
);
1572 if ((tp
->dirty
& tp
->valid
) == 0 &&
1573 (tp
->flags
& PG_NEED_COMMIT
) == 0) {
1574 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1583 while (is
< BLIST_MAX_ALLOC
&&
1584 pi
- page_base
+ is
< object
->size
) {
1587 tp
= vm_page_lookup_busy_try(object
, pi
- page_base
+ is
,
1593 if ((pagerflags
& VM_PAGER_IGNORE_CLEANCHK
) == 0 &&
1594 (tp
->flags
& PG_CLEANCHK
) == 0) {
1598 if ((tp
->queue
- tp
->pc
) == PQ_CACHE
) {
1599 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1603 vm_page_test_dirty(tp
);
1604 if ((tp
->dirty
& tp
->valid
) == 0 &&
1605 (tp
->flags
& PG_NEED_COMMIT
) == 0) {
1606 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1615 * All pages in the ma[] array are busied now
1617 for (i
= ib
; i
< is
; ++i
) {
1618 vm_page_flag_clear(ma
[i
], PG_CLEANCHK
);
1619 vm_page_hold(ma
[i
]); /* XXX need this any more? */
1621 vm_pageout_flush(&ma
[ib
], is
- ib
, pagerflags
);
1622 for (i
= ib
; i
< is
; ++i
) /* XXX need this any more? */
1623 vm_page_unhold(ma
[i
]);
1627 * Same as vm_object_pmap_copy, except range checking really
1628 * works, and is meant for small sections of an object.
1630 * This code protects resident pages by making them read-only
1631 * and is typically called on a fork or split when a page
1632 * is converted to copy-on-write.
1634 * NOTE: If the page is already at VM_PROT_NONE, calling
1635 * vm_page_protect will have no effect.
1638 vm_object_pmap_copy_1(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
)
1643 if (object
== NULL
|| (object
->flags
& OBJ_WRITEABLE
) == 0)
1646 vm_object_hold(object
);
1647 for (idx
= start
; idx
< end
; idx
++) {
1648 p
= vm_page_lookup(object
, idx
);
1651 vm_page_protect(p
, VM_PROT_READ
);
1653 vm_object_drop(object
);
1657 * Removes all physical pages in the specified object range from all
1660 * The object must *not* be locked.
1663 static int vm_object_pmap_remove_callback(vm_page_t p
, void *data
);
1666 vm_object_pmap_remove(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
)
1668 struct rb_vm_page_scan_info info
;
1674 info
.start_pindex
= start
;
1675 info
.end_pindex
= end
- 1;
1677 info
.object
= object
;
1679 vm_object_hold(object
);
1682 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
1683 vm_object_pmap_remove_callback
, &info
);
1684 } while (info
.error
);
1685 if (start
== 0 && end
== object
->size
)
1686 vm_object_clear_flag(object
, OBJ_WRITEABLE
);
1687 vm_object_drop(object
);
1691 * The caller must hold the object
1694 vm_object_pmap_remove_callback(vm_page_t p
, void *data
)
1696 struct rb_vm_page_scan_info
*info
= data
;
1698 if (info
->object
!= p
->object
||
1699 p
->pindex
< info
->start_pindex
||
1700 p
->pindex
> info
->end_pindex
) {
1701 kprintf("vm_object_pmap_remove_callback: obj/pg race %p/%p\n",
1707 vm_page_protect(p
, VM_PROT_NONE
);
1710 * Must be at end to avoid SMP races, caller holds object token
1712 if ((++info
->count
& 63) == 0)
1718 * Implements the madvise function at the object/page level.
1720 * MADV_WILLNEED (any object)
1722 * Activate the specified pages if they are resident.
1724 * MADV_DONTNEED (any object)
1726 * Deactivate the specified pages if they are resident.
1728 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, OBJ_ONEMAPPING only)
1730 * Deactivate and clean the specified pages if they are
1731 * resident. This permits the process to reuse the pages
1732 * without faulting or the kernel to reclaim the pages
1738 vm_object_madvise(vm_object_t object
, vm_pindex_t pindex
,
1739 vm_pindex_t count
, int advise
)
1741 vm_pindex_t end
, tpindex
;
1742 vm_object_t tobject
;
1750 end
= pindex
+ count
;
1752 vm_object_hold(object
);
1756 * Locate and adjust resident pages
1758 for (; pindex
< end
; pindex
+= 1) {
1760 if (tobject
!= object
)
1761 vm_object_drop(tobject
);
1766 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
1767 * and those pages must be OBJ_ONEMAPPING.
1769 if (advise
== MADV_FREE
) {
1770 if ((tobject
->type
!= OBJT_DEFAULT
&&
1771 tobject
->type
!= OBJT_SWAP
) ||
1772 (tobject
->flags
& OBJ_ONEMAPPING
) == 0) {
1777 m
= vm_page_lookup_busy_try(tobject
, tpindex
, TRUE
, &error
);
1780 vm_page_sleep_busy(m
, TRUE
, "madvpo");
1785 * There may be swap even if there is no backing page
1787 if (advise
== MADV_FREE
&& tobject
->type
== OBJT_SWAP
)
1788 swap_pager_freespace(tobject
, tpindex
, 1);
1793 while ((xobj
= tobject
->backing_object
) != NULL
) {
1794 KKASSERT(xobj
!= object
);
1795 vm_object_hold(xobj
);
1796 if (xobj
== tobject
->backing_object
)
1798 vm_object_drop(xobj
);
1802 tpindex
+= OFF_TO_IDX(tobject
->backing_object_offset
);
1803 if (tobject
!= object
) {
1804 vm_object_lock_swap();
1805 vm_object_drop(tobject
);
1812 * If the page is not in a normal active state, we skip it.
1813 * If the page is not managed there are no page queues to
1814 * mess with. Things can break if we mess with pages in
1815 * any of the below states.
1817 if (m
->wire_count
||
1818 (m
->flags
& (PG_UNMANAGED
| PG_NEED_COMMIT
)) ||
1819 m
->valid
!= VM_PAGE_BITS_ALL
1826 * Theoretically once a page is known not to be busy, an
1827 * interrupt cannot come along and rip it out from under us.
1830 if (advise
== MADV_WILLNEED
) {
1831 vm_page_activate(m
);
1832 } else if (advise
== MADV_DONTNEED
) {
1833 vm_page_dontneed(m
);
1834 } else if (advise
== MADV_FREE
) {
1836 * Mark the page clean. This will allow the page
1837 * to be freed up by the system. However, such pages
1838 * are often reused quickly by malloc()/free()
1839 * so we do not do anything that would cause
1840 * a page fault if we can help it.
1842 * Specifically, we do not try to actually free
1843 * the page now nor do we try to put it in the
1844 * cache (which would cause a page fault on reuse).
1846 * But we do make the page is freeable as we
1847 * can without actually taking the step of unmapping
1850 pmap_clear_modify(m
);
1853 vm_page_dontneed(m
);
1854 if (tobject
->type
== OBJT_SWAP
)
1855 swap_pager_freespace(tobject
, tpindex
, 1);
1859 if (tobject
!= object
)
1860 vm_object_drop(tobject
);
1861 vm_object_drop(object
);
1865 * Create a new object which is backed by the specified existing object
1866 * range. Replace the pointer and offset that was pointing at the existing
1867 * object with the pointer/offset for the new object.
1869 * If addref is non-zero the returned object is given an additional reference.
1870 * This mechanic exists to avoid the situation where refs might be 1 and
1871 * race against a collapse when the caller intends to bump it. So the
1872 * caller cannot add the ref after the fact. Used when the caller is
1873 * duplicating a vm_map_entry.
1875 * No other requirements.
1878 vm_object_shadow(vm_object_t
*objectp
, vm_ooffset_t
*offset
, vm_size_t length
,
1888 * Don't create the new object if the old object isn't shared.
1889 * We have to chain wait before adding the reference to avoid
1890 * racing a collapse or deallocation.
1892 * Clear OBJ_ONEMAPPING flag when shadowing.
1894 * The caller owns a ref on source via *objectp which we are going
1895 * to replace. This ref is inherited by the backing_object assignment.
1896 * from nobject and does not need to be incremented here.
1898 * However, we add a temporary extra reference to the original source
1899 * prior to holding nobject in case we block, to avoid races where
1900 * someone else might believe that the source can be collapsed.
1904 if (source
->type
!= OBJT_VNODE
) {
1906 vm_object_hold(source
);
1907 vm_object_chain_wait(source
, 0);
1908 if (source
->ref_count
== 1 &&
1909 source
->handle
== NULL
&&
1910 (source
->type
== OBJT_DEFAULT
||
1911 source
->type
== OBJT_SWAP
)) {
1913 vm_object_reference_locked(source
);
1914 vm_object_clear_flag(source
,
1917 vm_object_drop(source
);
1920 vm_object_reference_locked(source
);
1921 vm_object_clear_flag(source
, OBJ_ONEMAPPING
);
1923 vm_object_reference_quick(source
);
1924 vm_object_clear_flag(source
, OBJ_ONEMAPPING
);
1929 * Allocate a new object with the given length. The new object
1930 * is returned referenced but we may have to add another one.
1931 * If we are adding a second reference we must clear OBJ_ONEMAPPING.
1932 * (typically because the caller is about to clone a vm_map_entry).
1934 * The source object currently has an extra reference to prevent
1935 * collapses into it while we mess with its shadow list, which
1936 * we will remove later in this routine.
1938 * The target object may require a second reference if asked for one
1941 result
= vm_object_allocate(OBJT_DEFAULT
, length
);
1943 panic("vm_object_shadow: no object for shadowing");
1944 vm_object_hold(result
);
1946 vm_object_reference_locked(result
);
1947 vm_object_clear_flag(result
, OBJ_ONEMAPPING
);
1951 * The new object shadows the source object. Chain wait before
1952 * adjusting shadow_count or the shadow list to avoid races.
1954 * Try to optimize the result object's page color when shadowing
1955 * in order to maintain page coloring consistency in the combined
1958 * The backing_object reference to source requires adding a ref to
1959 * source. We simply inherit the ref from the original *objectp
1960 * (which we are replacing) so no additional refs need to be added.
1961 * (we must still clean up the extra ref we had to prevent collapse
1964 * SHADOWING IS NOT APPLICABLE TO OBJT_VNODE OBJECTS
1966 KKASSERT(result
->backing_object
== NULL
);
1967 result
->backing_object
= source
;
1969 if (useshadowlist
) {
1970 vm_object_chain_wait(source
, 0);
1971 LIST_INSERT_HEAD(&source
->shadow_head
,
1972 result
, shadow_list
);
1973 source
->shadow_count
++;
1974 atomic_add_int(&source
->generation
, 1);
1975 vm_object_set_flag(result
, OBJ_ONSHADOW
);
1977 /* cpu localization twist */
1978 result
->pg_color
= vm_quickcolor();
1982 * Adjust the return storage. Drop the ref on source before
1985 result
->backing_object_offset
= *offset
;
1986 vm_object_drop(result
);
1989 if (useshadowlist
) {
1990 vm_object_deallocate_locked(source
);
1991 vm_object_drop(source
);
1993 vm_object_deallocate(source
);
1998 * Return the new things
2003 #define OBSC_TEST_ALL_SHADOWED 0x0001
2004 #define OBSC_COLLAPSE_NOWAIT 0x0002
2005 #define OBSC_COLLAPSE_WAIT 0x0004
2007 static int vm_object_backing_scan_callback(vm_page_t p
, void *data
);
2010 * The caller must hold the object.
2013 vm_object_backing_scan(vm_object_t object
, vm_object_t backing_object
, int op
)
2015 struct rb_vm_page_scan_info info
;
2016 struct vm_object_hash
*hash
;
2018 vm_object_assert_held(object
);
2019 vm_object_assert_held(backing_object
);
2021 KKASSERT(backing_object
== object
->backing_object
);
2022 info
.backing_offset_index
= OFF_TO_IDX(object
->backing_object_offset
);
2025 * Initial conditions
2027 if (op
& OBSC_TEST_ALL_SHADOWED
) {
2029 * We do not want to have to test for the existence of
2030 * swap pages in the backing object. XXX but with the
2031 * new swapper this would be pretty easy to do.
2033 * XXX what about anonymous MAP_SHARED memory that hasn't
2034 * been ZFOD faulted yet? If we do not test for this, the
2035 * shadow test may succeed! XXX
2037 if (backing_object
->type
!= OBJT_DEFAULT
)
2040 if (op
& OBSC_COLLAPSE_WAIT
) {
2041 KKASSERT((backing_object
->flags
& OBJ_DEAD
) == 0);
2042 vm_object_set_flag(backing_object
, OBJ_DEAD
);
2044 hash
= VMOBJ_HASH(backing_object
);
2045 lwkt_gettoken(&hash
->token
);
2046 TAILQ_REMOVE(&hash
->list
, backing_object
, object_list
);
2047 lwkt_reltoken(&hash
->token
);
2051 * Our scan. We have to retry if a negative error code is returned,
2052 * otherwise 0 or 1 will be returned in info.error. 0 Indicates that
2053 * the scan had to be stopped because the parent does not completely
2056 info
.object
= object
;
2057 info
.backing_object
= backing_object
;
2062 vm_page_rb_tree_RB_SCAN(&backing_object
->rb_memq
, NULL
,
2063 vm_object_backing_scan_callback
,
2065 } while (info
.error
< 0);
2071 * The caller must hold the object.
2074 vm_object_backing_scan_callback(vm_page_t p
, void *data
)
2076 struct rb_vm_page_scan_info
*info
= data
;
2077 vm_object_t backing_object
;
2080 vm_pindex_t new_pindex
;
2081 vm_pindex_t backing_offset_index
;
2085 new_pindex
= pindex
- info
->backing_offset_index
;
2087 object
= info
->object
;
2088 backing_object
= info
->backing_object
;
2089 backing_offset_index
= info
->backing_offset_index
;
2091 if (op
& OBSC_TEST_ALL_SHADOWED
) {
2095 * Ignore pages outside the parent object's range
2096 * and outside the parent object's mapping of the
2099 * note that we do not busy the backing object's
2102 if (pindex
< backing_offset_index
||
2103 new_pindex
>= object
->size
2109 * See if the parent has the page or if the parent's
2110 * object pager has the page. If the parent has the
2111 * page but the page is not valid, the parent's
2112 * object pager must have the page.
2114 * If this fails, the parent does not completely shadow
2115 * the object and we might as well give up now.
2117 pp
= vm_page_lookup(object
, new_pindex
);
2118 if ((pp
== NULL
|| pp
->valid
== 0) &&
2119 !vm_pager_has_page(object
, new_pindex
)
2121 info
->error
= 0; /* problemo */
2122 return(-1); /* stop the scan */
2127 * Check for busy page. Note that we may have lost (p) when we
2128 * possibly blocked above.
2130 if (op
& (OBSC_COLLAPSE_WAIT
| OBSC_COLLAPSE_NOWAIT
)) {
2133 if (vm_page_busy_try(p
, TRUE
)) {
2134 if (op
& OBSC_COLLAPSE_NOWAIT
) {
2138 * If we slept, anything could have
2139 * happened. Ask that the scan be restarted.
2141 * Since the object is marked dead, the
2142 * backing offset should not have changed.
2144 vm_page_sleep_busy(p
, TRUE
, "vmocol");
2151 * If (p) is no longer valid restart the scan.
2153 if (p
->object
!= backing_object
|| p
->pindex
!= pindex
) {
2154 kprintf("vm_object_backing_scan: Warning: page "
2155 "%p ripped out from under us\n", p
);
2161 if (op
& OBSC_COLLAPSE_NOWAIT
) {
2162 if (p
->valid
== 0 ||
2164 (p
->flags
& PG_NEED_COMMIT
)) {
2169 /* XXX what if p->valid == 0 , hold_count, etc? */
2173 p
->object
== backing_object
,
2174 ("vm_object_qcollapse(): object mismatch")
2178 * Destroy any associated swap
2180 if (backing_object
->type
== OBJT_SWAP
)
2181 swap_pager_freespace(backing_object
, p
->pindex
, 1);
2184 p
->pindex
< backing_offset_index
||
2185 new_pindex
>= object
->size
2188 * Page is out of the parent object's range, we
2189 * can simply destroy it.
2191 vm_page_protect(p
, VM_PROT_NONE
);
2196 pp
= vm_page_lookup(object
, new_pindex
);
2197 if (pp
!= NULL
|| vm_pager_has_page(object
, new_pindex
)) {
2199 * page already exists in parent OR swap exists
2200 * for this location in the parent. Destroy
2201 * the original page from the backing object.
2203 * Leave the parent's page alone
2205 vm_page_protect(p
, VM_PROT_NONE
);
2211 * Page does not exist in parent, rename the
2212 * page from the backing object to the main object.
2214 * If the page was mapped to a process, it can remain
2215 * mapped through the rename.
2217 if ((p
->queue
- p
->pc
) == PQ_CACHE
)
2218 vm_page_deactivate(p
);
2220 vm_page_rename(p
, object
, new_pindex
);
2222 /* page automatically made dirty by rename */
2228 * This version of collapse allows the operation to occur earlier and
2229 * when paging_in_progress is true for an object... This is not a complete
2230 * operation, but should plug 99.9% of the rest of the leaks.
2232 * The caller must hold the object and backing_object and both must be
2235 * (only called from vm_object_collapse)
2238 vm_object_qcollapse(vm_object_t object
, vm_object_t backing_object
)
2240 if (backing_object
->ref_count
== 1) {
2241 atomic_add_int(&backing_object
->ref_count
, 2);
2242 #if defined(DEBUG_LOCKS)
2243 debugvm_object_add(backing_object
, "qcollapse", 1, 2);
2245 vm_object_backing_scan(object
, backing_object
,
2246 OBSC_COLLAPSE_NOWAIT
);
2247 atomic_add_int(&backing_object
->ref_count
, -2);
2248 #if defined(DEBUG_LOCKS)
2249 debugvm_object_add(backing_object
, "qcollapse", 2, -2);
2255 * Collapse an object with the object backing it. Pages in the backing
2256 * object are moved into the parent, and the backing object is deallocated.
2257 * Any conflict is resolved in favor of the parent's existing pages.
2259 * object must be held and chain-locked on call.
2261 * The caller must have an extra ref on object to prevent a race from
2262 * destroying it during the collapse.
2265 vm_object_collapse(vm_object_t object
, struct vm_object_dealloc_list
**dlistp
)
2267 struct vm_object_dealloc_list
*dlist
= NULL
;
2268 vm_object_t backing_object
;
2271 * Only one thread is attempting a collapse at any given moment.
2272 * There are few restrictions for (object) that callers of this
2273 * function check so reentrancy is likely.
2275 KKASSERT(object
!= NULL
);
2276 vm_object_assert_held(object
);
2277 KKASSERT(object
->chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
));
2284 * We can only collapse a DEFAULT/SWAP object with a
2285 * DEFAULT/SWAP object.
2287 if (object
->type
!= OBJT_DEFAULT
&& object
->type
!= OBJT_SWAP
) {
2288 backing_object
= NULL
;
2292 backing_object
= object
->backing_object
;
2293 if (backing_object
== NULL
)
2295 if (backing_object
->type
!= OBJT_DEFAULT
&&
2296 backing_object
->type
!= OBJT_SWAP
) {
2297 backing_object
= NULL
;
2302 * Hold (token lock) the backing_object and retest conditions.
2304 vm_object_hold(backing_object
);
2305 if (backing_object
!= object
->backing_object
||
2306 (backing_object
->type
!= OBJT_DEFAULT
&&
2307 backing_object
->type
!= OBJT_SWAP
)) {
2308 vm_object_drop(backing_object
);
2313 * Chain-lock the backing object too because if we
2314 * successfully merge its pages into the top object we
2315 * will collapse backing_object->backing_object as the
2316 * new backing_object. Re-check that it is still our
2319 vm_object_chain_acquire(backing_object
, 0);
2320 if (backing_object
!= object
->backing_object
) {
2321 vm_object_chain_release(backing_object
);
2322 vm_object_drop(backing_object
);
2327 * We check the backing object first, because it is most
2328 * likely not collapsable.
2330 if (backing_object
->handle
!= NULL
||
2331 (backing_object
->type
!= OBJT_DEFAULT
&&
2332 backing_object
->type
!= OBJT_SWAP
) ||
2333 (backing_object
->flags
& OBJ_DEAD
) ||
2334 object
->handle
!= NULL
||
2335 (object
->type
!= OBJT_DEFAULT
&&
2336 object
->type
!= OBJT_SWAP
) ||
2337 (object
->flags
& OBJ_DEAD
)) {
2342 * If paging is in progress we can't do a normal collapse.
2344 if (object
->paging_in_progress
!= 0 ||
2345 backing_object
->paging_in_progress
!= 0
2347 vm_object_qcollapse(object
, backing_object
);
2352 * We know that we can either collapse the backing object (if
2353 * the parent is the only reference to it) or (perhaps) have
2354 * the parent bypass the object if the parent happens to shadow
2355 * all the resident pages in the entire backing object.
2357 * This is ignoring pager-backed pages such as swap pages.
2358 * vm_object_backing_scan fails the shadowing test in this
2361 if (backing_object
->ref_count
== 1) {
2363 * If there is exactly one reference to the backing
2364 * object, we can collapse it into the parent.
2366 KKASSERT(object
->backing_object
== backing_object
);
2367 vm_object_backing_scan(object
, backing_object
,
2368 OBSC_COLLAPSE_WAIT
);
2371 * Move the pager from backing_object to object.
2373 if (backing_object
->type
== OBJT_SWAP
) {
2374 vm_object_pip_add(backing_object
, 1);
2377 * scrap the paging_offset junk and do a
2378 * discrete copy. This also removes major
2379 * assumptions about how the swap-pager
2380 * works from where it doesn't belong. The
2381 * new swapper is able to optimize the
2382 * destroy-source case.
2384 vm_object_pip_add(object
, 1);
2385 swap_pager_copy(backing_object
, object
,
2386 OFF_TO_IDX(object
->backing_object_offset
),
2388 vm_object_pip_wakeup(object
);
2389 vm_object_pip_wakeup(backing_object
);
2393 * Object now shadows whatever backing_object did.
2394 * Remove object from backing_object's shadow_list.
2396 * Removing object from backing_objects shadow list
2397 * requires releasing object, which we will do below.
2399 KKASSERT(object
->backing_object
== backing_object
);
2400 if (object
->flags
& OBJ_ONSHADOW
) {
2401 LIST_REMOVE(object
, shadow_list
);
2402 backing_object
->shadow_count
--;
2403 atomic_add_int(&backing_object
->generation
, 1);
2404 vm_object_clear_flag(object
, OBJ_ONSHADOW
);
2408 * backing_object->backing_object moves from within
2409 * backing_object to within object.
2411 * OBJT_VNODE bbobj's should have empty shadow lists.
2413 while ((bbobj
= backing_object
->backing_object
) != NULL
) {
2414 if (bbobj
->type
== OBJT_VNODE
)
2415 vm_object_hold_shared(bbobj
);
2417 vm_object_hold(bbobj
);
2418 if (bbobj
== backing_object
->backing_object
)
2420 vm_object_drop(bbobj
);
2424 * We are removing backing_object from bbobj's
2425 * shadow list and adding object to bbobj's shadow
2426 * list, so the ref_count on bbobj is unchanged.
2429 if (backing_object
->flags
& OBJ_ONSHADOW
) {
2430 /* not locked exclusively if vnode */
2431 KKASSERT(bbobj
->type
!= OBJT_VNODE
);
2432 LIST_REMOVE(backing_object
,
2434 bbobj
->shadow_count
--;
2435 atomic_add_int(&bbobj
->generation
, 1);
2436 vm_object_clear_flag(backing_object
,
2439 backing_object
->backing_object
= NULL
;
2441 object
->backing_object
= bbobj
;
2443 if (bbobj
->type
!= OBJT_VNODE
) {
2444 LIST_INSERT_HEAD(&bbobj
->shadow_head
,
2445 object
, shadow_list
);
2446 bbobj
->shadow_count
++;
2447 atomic_add_int(&bbobj
->generation
, 1);
2448 vm_object_set_flag(object
,
2453 object
->backing_object_offset
+=
2454 backing_object
->backing_object_offset
;
2456 vm_object_drop(bbobj
);
2459 * Discard the old backing_object. Nothing should be
2460 * able to ref it, other than a vm_map_split(),
2461 * and vm_map_split() will stall on our chain lock.
2462 * And we control the parent so it shouldn't be
2463 * possible for it to go away either.
2465 * Since the backing object has no pages, no pager
2466 * left, and no object references within it, all
2467 * that is necessary is to dispose of it.
2469 KASSERT(backing_object
->ref_count
== 1,
2470 ("backing_object %p was somehow "
2471 "re-referenced during collapse!",
2473 KASSERT(RB_EMPTY(&backing_object
->rb_memq
),
2474 ("backing_object %p somehow has left "
2475 "over pages during collapse!",
2479 * The object can be destroyed.
2481 * XXX just fall through and dodealloc instead
2482 * of forcing destruction?
2484 atomic_add_int(&backing_object
->ref_count
, -1);
2485 #if defined(DEBUG_LOCKS)
2486 debugvm_object_add(backing_object
, "collapse", 1, -1);
2488 if ((backing_object
->flags
& OBJ_DEAD
) == 0)
2489 vm_object_terminate(backing_object
);
2494 * If we do not entirely shadow the backing object,
2495 * there is nothing we can do so we give up.
2497 if (vm_object_backing_scan(object
, backing_object
,
2498 OBSC_TEST_ALL_SHADOWED
) == 0) {
2503 * bbobj is backing_object->backing_object. Since
2504 * object completely shadows backing_object we can
2505 * bypass it and become backed by bbobj instead.
2507 * The shadow list for vnode backing objects is not
2508 * used and a shared hold is allowed.
2510 while ((bbobj
= backing_object
->backing_object
) != NULL
) {
2511 if (bbobj
->type
== OBJT_VNODE
)
2512 vm_object_hold_shared(bbobj
);
2514 vm_object_hold(bbobj
);
2515 if (bbobj
== backing_object
->backing_object
)
2517 vm_object_drop(bbobj
);
2521 * Make object shadow bbobj instead of backing_object.
2522 * Remove object from backing_object's shadow list.
2524 * Deallocating backing_object will not remove
2525 * it, since its reference count is at least 2.
2527 * Removing object from backing_object's shadow
2528 * list requires releasing a ref, which we do
2529 * below by setting dodealloc to 1.
2531 KKASSERT(object
->backing_object
== backing_object
);
2532 if (object
->flags
& OBJ_ONSHADOW
) {
2533 LIST_REMOVE(object
, shadow_list
);
2534 backing_object
->shadow_count
--;
2535 atomic_add_int(&backing_object
->generation
, 1);
2536 vm_object_clear_flag(object
, OBJ_ONSHADOW
);
2540 * Add a ref to bbobj, bbobj now shadows object.
2542 * NOTE: backing_object->backing_object still points
2543 * to bbobj. That relationship remains intact
2544 * because backing_object has > 1 ref, so
2545 * someone else is pointing to it (hence why
2546 * we can't collapse it into object and can
2547 * only handle the all-shadowed bypass case).
2550 if (bbobj
->type
!= OBJT_VNODE
) {
2551 vm_object_chain_wait(bbobj
, 0);
2552 vm_object_reference_locked(bbobj
);
2553 LIST_INSERT_HEAD(&bbobj
->shadow_head
,
2554 object
, shadow_list
);
2555 bbobj
->shadow_count
++;
2556 atomic_add_int(&bbobj
->generation
, 1);
2557 vm_object_set_flag(object
,
2560 vm_object_reference_quick(bbobj
);
2562 object
->backing_object_offset
+=
2563 backing_object
->backing_object_offset
;
2564 object
->backing_object
= bbobj
;
2565 vm_object_drop(bbobj
);
2567 object
->backing_object
= NULL
;
2571 * Drop the reference count on backing_object. To
2572 * handle ref_count races properly we can't assume
2573 * that the ref_count is still at least 2 so we
2574 * have to actually call vm_object_deallocate()
2575 * (after clearing the chainlock).
2582 * Ok, we want to loop on the new object->bbobj association,
2583 * possibly collapsing it further. However if dodealloc is
2584 * non-zero we have to deallocate the backing_object which
2585 * itself can potentially undergo a collapse, creating a
2586 * recursion depth issue with the LWKT token subsystem.
2588 * In the case where we must deallocate the backing_object
2589 * it is possible now that the backing_object has a single
2590 * shadow count on some other object (not represented here
2591 * as yet), since it no longer shadows us. Thus when we
2592 * call vm_object_deallocate() it may attempt to collapse
2593 * itself into its remaining parent.
2596 struct vm_object_dealloc_list
*dtmp
;
2598 vm_object_chain_release(backing_object
);
2599 vm_object_unlock(backing_object
);
2600 /* backing_object remains held */
2603 * Auto-deallocation list for caller convenience.
2608 dtmp
= kmalloc(sizeof(*dtmp
), M_TEMP
, M_WAITOK
);
2609 dtmp
->object
= backing_object
;
2610 dtmp
->next
= *dlistp
;
2613 vm_object_chain_release(backing_object
);
2614 vm_object_drop(backing_object
);
2616 /* backing_object = NULL; not needed */
2621 * Clean up any left over backing_object
2623 if (backing_object
) {
2624 vm_object_chain_release(backing_object
);
2625 vm_object_drop(backing_object
);
2629 * Clean up any auto-deallocation list. This is a convenience
2630 * for top-level callers so they don't have to pass &dlist.
2631 * Do not clean up any caller-passed dlistp, the caller will
2635 vm_object_deallocate_list(&dlist
);
2640 * vm_object_collapse() may collect additional objects in need of
2641 * deallocation. This routine deallocates these objects. The
2642 * deallocation itself can trigger additional collapses (which the
2643 * deallocate function takes care of). This procedure is used to
2644 * reduce procedural recursion since these vm_object shadow chains
2645 * can become quite long.
2648 vm_object_deallocate_list(struct vm_object_dealloc_list
**dlistp
)
2650 struct vm_object_dealloc_list
*dlist
;
2652 while ((dlist
= *dlistp
) != NULL
) {
2653 *dlistp
= dlist
->next
;
2654 vm_object_lock(dlist
->object
);
2655 vm_object_deallocate_locked(dlist
->object
);
2656 vm_object_drop(dlist
->object
);
2657 kfree(dlist
, M_TEMP
);
2662 * Removes all physical pages in the specified object range from the
2663 * object's list of pages.
2667 static int vm_object_page_remove_callback(vm_page_t p
, void *data
);
2670 vm_object_page_remove(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
,
2671 boolean_t clean_only
)
2673 struct rb_vm_page_scan_info info
;
2677 * Degenerate cases and assertions
2679 vm_object_hold(object
);
2680 if (object
== NULL
||
2681 (object
->resident_page_count
== 0 && object
->swblock_count
== 0)) {
2682 vm_object_drop(object
);
2685 KASSERT(object
->type
!= OBJT_PHYS
,
2686 ("attempt to remove pages from a physical object"));
2689 * Indicate that paging is occuring on the object
2691 vm_object_pip_add(object
, 1);
2694 * Figure out the actual removal range and whether we are removing
2695 * the entire contents of the object or not. If removing the entire
2696 * contents, be sure to get all pages, even those that might be
2697 * beyond the end of the object.
2699 info
.object
= object
;
2700 info
.start_pindex
= start
;
2702 info
.end_pindex
= (vm_pindex_t
)-1;
2704 info
.end_pindex
= end
- 1;
2705 info
.limit
= clean_only
;
2707 all
= (start
== 0 && info
.end_pindex
>= object
->size
- 1);
2710 * Loop until we are sure we have gotten them all.
2714 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
2715 vm_object_page_remove_callback
, &info
);
2716 } while (info
.error
);
2719 * Remove any related swap if throwing away pages, or for
2720 * non-swap objects (the swap is a clean copy in that case).
2722 if (object
->type
!= OBJT_SWAP
|| clean_only
== FALSE
) {
2724 swap_pager_freespace_all(object
);
2726 swap_pager_freespace(object
, info
.start_pindex
,
2727 info
.end_pindex
- info
.start_pindex
+ 1);
2733 vm_object_pip_wakeup(object
);
2734 vm_object_drop(object
);
2738 * The caller must hold the object.
2740 * NOTE: User yields are allowed when removing more than one page, but not
2741 * allowed if only removing one page (the path for single page removals
2742 * might hold a spinlock).
2745 vm_object_page_remove_callback(vm_page_t p
, void *data
)
2747 struct rb_vm_page_scan_info
*info
= data
;
2749 if (info
->object
!= p
->object
||
2750 p
->pindex
< info
->start_pindex
||
2751 p
->pindex
> info
->end_pindex
) {
2752 kprintf("vm_object_page_remove_callbackA: obj/pg race %p/%p\n",
2756 if (vm_page_busy_try(p
, TRUE
)) {
2757 vm_page_sleep_busy(p
, TRUE
, "vmopar");
2761 if (info
->object
!= p
->object
) {
2762 /* this should never happen */
2763 kprintf("vm_object_page_remove_callbackB: obj/pg race %p/%p\n",
2770 * Wired pages cannot be destroyed, but they can be invalidated
2771 * and we do so if clean_only (limit) is not set.
2773 * WARNING! The page may be wired due to being part of a buffer
2774 * cache buffer, and the buffer might be marked B_CACHE.
2775 * This is fine as part of a truncation but VFSs must be
2776 * sure to fix the buffer up when re-extending the file.
2778 * NOTE! PG_NEED_COMMIT is ignored.
2780 if (p
->wire_count
!= 0) {
2781 vm_page_protect(p
, VM_PROT_NONE
);
2782 if (info
->limit
== 0)
2789 * limit is our clean_only flag. If set and the page is dirty or
2790 * requires a commit, do not free it. If set and the page is being
2791 * held by someone, do not free it.
2793 if (info
->limit
&& p
->valid
) {
2794 vm_page_test_dirty(p
);
2795 if ((p
->valid
& p
->dirty
) || (p
->flags
& PG_NEED_COMMIT
)) {
2804 vm_page_protect(p
, VM_PROT_NONE
);
2808 * Must be at end to avoid SMP races, caller holds object token
2811 if ((++info
->count
& 63) == 0)
2818 * Try to extend prev_object into an adjoining region of virtual
2819 * memory, return TRUE on success.
2821 * The caller does not need to hold (prev_object) but must have a stable
2822 * pointer to it (typically by holding the vm_map locked).
2824 * This function only works for anonymous memory objects which either
2825 * have (a) one reference or (b) we are extending the object's size.
2826 * Otherwise the related VM pages we want to use for the object might
2827 * be in use by another mapping.
2830 vm_object_coalesce(vm_object_t prev_object
, vm_pindex_t prev_pindex
,
2831 vm_size_t prev_size
, vm_size_t next_size
)
2833 vm_pindex_t next_pindex
;
2835 if (prev_object
== NULL
)
2838 vm_object_hold(prev_object
);
2840 if (prev_object
->type
!= OBJT_DEFAULT
&&
2841 prev_object
->type
!= OBJT_SWAP
) {
2842 vm_object_drop(prev_object
);
2847 * Try to collapse the object first
2849 vm_object_chain_acquire(prev_object
, 0);
2850 vm_object_collapse(prev_object
, NULL
);
2853 * We can't coalesce if we shadow another object (figuring out the
2854 * relationships become too complex).
2856 if (prev_object
->backing_object
!= NULL
) {
2857 vm_object_chain_release(prev_object
);
2858 vm_object_drop(prev_object
);
2862 prev_size
>>= PAGE_SHIFT
;
2863 next_size
>>= PAGE_SHIFT
;
2864 next_pindex
= prev_pindex
+ prev_size
;
2867 * We can't if the object has more than one ref count unless we
2868 * are extending it into newly minted space.
2870 if (prev_object
->ref_count
> 1 &&
2871 prev_object
->size
!= next_pindex
) {
2872 vm_object_chain_release(prev_object
);
2873 vm_object_drop(prev_object
);
2878 * Remove any pages that may still be in the object from a previous
2881 if (next_pindex
< prev_object
->size
) {
2882 vm_object_page_remove(prev_object
,
2884 next_pindex
+ next_size
, FALSE
);
2885 if (prev_object
->type
== OBJT_SWAP
)
2886 swap_pager_freespace(prev_object
,
2887 next_pindex
, next_size
);
2891 * Extend the object if necessary.
2893 if (next_pindex
+ next_size
> prev_object
->size
)
2894 prev_object
->size
= next_pindex
+ next_size
;
2895 vm_object_chain_release(prev_object
);
2896 vm_object_drop(prev_object
);
2902 * Make the object writable and flag is being possibly dirty.
2904 * The object might not be held (or might be held but held shared),
2905 * the related vnode is probably not held either. Object and vnode are
2906 * stable by virtue of the vm_page busied by the caller preventing
2909 * If the related mount is flagged MNTK_THR_SYNC we need to call
2910 * vsetobjdirty(). Filesystems using this option usually shortcut
2911 * synchronization by only scanning the syncer list.
2914 vm_object_set_writeable_dirty(vm_object_t object
)
2918 /*vm_object_assert_held(object);*/
2920 * Avoid contention in vm fault path by checking the state before
2921 * issuing an atomic op on it.
2923 if ((object
->flags
& (OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
)) !=
2924 (OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
)) {
2925 vm_object_set_flag(object
, OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
);
2927 if (object
->type
== OBJT_VNODE
&&
2928 (vp
= (struct vnode
*)object
->handle
) != NULL
) {
2929 if ((vp
->v_flag
& VOBJDIRTY
) == 0) {
2931 (vp
->v_mount
->mnt_kern_flag
& MNTK_THR_SYNC
)) {
2933 * New style THR_SYNC places vnodes on the
2934 * syncer list more deterministically.
2939 * Old style scan would not necessarily place
2940 * a vnode on the syncer list when possibly
2941 * modified via mmap.
2943 vsetflags(vp
, VOBJDIRTY
);
2949 #include "opt_ddb.h"
2951 #include <sys/cons.h>
2953 #include <ddb/ddb.h>
2955 static int _vm_object_in_map (vm_map_t map
, vm_object_t object
,
2956 vm_map_entry_t entry
);
2957 static int vm_object_in_map (vm_object_t object
);
2960 * The caller must hold the object.
2963 _vm_object_in_map(vm_map_t map
, vm_object_t object
, vm_map_entry_t entry
)
2966 vm_map_entry_t tmpe
;
2967 vm_object_t obj
, nobj
;
2973 tmpe
= map
->header
.next
;
2974 entcount
= map
->nentries
;
2975 while (entcount
-- && (tmpe
!= &map
->header
)) {
2976 if( _vm_object_in_map(map
, object
, tmpe
)) {
2983 switch(entry
->maptype
) {
2984 case VM_MAPTYPE_SUBMAP
:
2985 tmpm
= entry
->object
.sub_map
;
2986 tmpe
= tmpm
->header
.next
;
2987 entcount
= tmpm
->nentries
;
2988 while (entcount
-- && tmpe
!= &tmpm
->header
) {
2989 if( _vm_object_in_map(tmpm
, object
, tmpe
)) {
2995 case VM_MAPTYPE_NORMAL
:
2996 case VM_MAPTYPE_VPAGETABLE
:
2997 obj
= entry
->object
.vm_object
;
2999 if (obj
== object
) {
3000 if (obj
!= entry
->object
.vm_object
)
3001 vm_object_drop(obj
);
3004 while ((nobj
= obj
->backing_object
) != NULL
) {
3005 vm_object_hold(nobj
);
3006 if (nobj
== obj
->backing_object
)
3008 vm_object_drop(nobj
);
3010 if (obj
!= entry
->object
.vm_object
) {
3012 vm_object_lock_swap();
3013 vm_object_drop(obj
);
3024 static int vm_object_in_map_callback(struct proc
*p
, void *data
);
3026 struct vm_object_in_map_info
{
3035 vm_object_in_map(vm_object_t object
)
3037 struct vm_object_in_map_info info
;
3040 info
.object
= object
;
3042 allproc_scan(vm_object_in_map_callback
, &info
, 0);
3045 if( _vm_object_in_map(&kernel_map
, object
, 0))
3047 if( _vm_object_in_map(&pager_map
, object
, 0))
3049 if( _vm_object_in_map(&buffer_map
, object
, 0))
3058 vm_object_in_map_callback(struct proc
*p
, void *data
)
3060 struct vm_object_in_map_info
*info
= data
;
3063 if (_vm_object_in_map(&p
->p_vmspace
->vm_map
, info
->object
, 0)) {
3071 DB_SHOW_COMMAND(vmochk
, vm_object_check
)
3073 struct vm_object_hash
*hash
;
3078 * make sure that internal objs are in a map somewhere
3079 * and none have zero ref counts.
3081 for (n
= 0; n
< VMOBJ_HSIZE
; ++n
) {
3082 hash
= &vm_object_hash
[n
];
3083 for (object
= TAILQ_FIRST(&hash
->list
);
3085 object
= TAILQ_NEXT(object
, object_list
)) {
3086 if (object
->type
== OBJT_MARKER
)
3088 if (object
->handle
!= NULL
||
3089 (object
->type
!= OBJT_DEFAULT
&&
3090 object
->type
!= OBJT_SWAP
)) {
3093 if (object
->ref_count
== 0) {
3094 db_printf("vmochk: internal obj has "
3095 "zero ref count: %ld\n",
3096 (long)object
->size
);
3098 if (vm_object_in_map(object
))
3100 db_printf("vmochk: internal obj is not in a map: "
3101 "ref: %d, size: %lu: 0x%lx, "
3102 "backing_object: %p\n",
3103 object
->ref_count
, (u_long
)object
->size
,
3104 (u_long
)object
->size
,
3105 (void *)object
->backing_object
);
3113 DB_SHOW_COMMAND(object
, vm_object_print_static
)
3115 /* XXX convert args. */
3116 vm_object_t object
= (vm_object_t
)addr
;
3117 boolean_t full
= have_addr
;
3121 /* XXX count is an (unused) arg. Avoid shadowing it. */
3122 #define count was_count
3130 "Object %p: type=%d, size=0x%lx, res=%ld, ref=%d, flags=0x%x\n",
3131 object
, (int)object
->type
, (u_long
)object
->size
,
3132 object
->resident_page_count
, object
->ref_count
, object
->flags
);
3134 * XXX no %qd in kernel. Truncate object->backing_object_offset.
3136 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n",
3137 object
->shadow_count
,
3138 object
->backing_object
? object
->backing_object
->ref_count
: 0,
3139 object
->backing_object
, (long)object
->backing_object_offset
);
3146 RB_FOREACH(p
, vm_page_rb_tree
, &object
->rb_memq
) {
3148 db_iprintf("memory:=");
3149 else if (count
== 6) {
3157 db_printf("(off=0x%lx,page=0x%lx)",
3158 (u_long
) p
->pindex
, (u_long
) VM_PAGE_TO_PHYS(p
));
3169 * XXX need this non-static entry for calling from vm_map_print.
3174 vm_object_print(/* db_expr_t */ long addr
,
3175 boolean_t have_addr
,
3176 /* db_expr_t */ long count
,
3179 vm_object_print_static(addr
, have_addr
, count
, modif
);
3185 DB_SHOW_COMMAND(vmopag
, vm_object_print_pages
)
3187 struct vm_object_hash
*hash
;
3193 for (n
= 0; n
< VMOBJ_HSIZE
; ++n
) {
3194 hash
= &vm_object_hash
[n
];
3195 for (object
= TAILQ_FIRST(&hash
->list
);
3197 object
= TAILQ_NEXT(object
, object_list
)) {
3198 vm_pindex_t idx
, fidx
;
3200 vm_paddr_t pa
= -1, padiff
;
3204 if (object
->type
== OBJT_MARKER
)
3206 db_printf("new object: %p\n", (void *)object
);
3216 osize
= object
->size
;
3219 for (idx
= 0; idx
< osize
; idx
++) {
3220 m
= vm_page_lookup(object
, idx
);
3223 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3224 (long)fidx
, rcount
, (long)pa
);
3238 (VM_PAGE_TO_PHYS(m
) == pa
+ rcount
* PAGE_SIZE
)) {
3243 padiff
= pa
+ rcount
* PAGE_SIZE
- VM_PAGE_TO_PHYS(m
);
3244 padiff
>>= PAGE_SHIFT
;
3245 padiff
&= PQ_L2_MASK
;
3247 pa
= VM_PAGE_TO_PHYS(m
) - rcount
* PAGE_SIZE
;
3251 db_printf(" index(%ld)run(%d)pa(0x%lx)",
3252 (long)fidx
, rcount
, (long)pa
);
3253 db_printf("pd(%ld)\n", (long)padiff
);
3263 pa
= VM_PAGE_TO_PHYS(m
);
3267 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3268 (long)fidx
, rcount
, (long)pa
);