2 * Copyright (c) 1991, 1993, 2013
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * The Mach Operating System project at Carnegie-Mellon University.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * from: @(#)vm_object.c 8.5 (Berkeley) 3/22/94
35 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
36 * All rights reserved.
38 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
40 * Permission to use, copy, modify and distribute this software and
41 * its documentation is hereby granted, provided that both the copyright
42 * notice and this permission notice appear in all copies of the
43 * software, derivative works or modified versions, and any portions
44 * thereof, and that both notices appear in supporting documentation.
46 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
47 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
48 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
50 * Carnegie Mellon requests users of this software to return to
52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
53 * School of Computer Science
54 * Carnegie Mellon University
55 * Pittsburgh PA 15213-3890
57 * any improvements or extensions that they make and grant Carnegie the
58 * rights to redistribute these changes.
60 * $FreeBSD: src/sys/vm/vm_object.c,v 1.171.2.8 2003/05/26 19:17:56 alc Exp $
64 * Virtual memory object module.
67 #include <sys/param.h>
68 #include <sys/systm.h>
69 #include <sys/proc.h> /* for curproc, pageproc */
70 #include <sys/thread.h>
71 #include <sys/vnode.h>
72 #include <sys/vmmeter.h>
74 #include <sys/mount.h>
75 #include <sys/kernel.h>
76 #include <sys/sysctl.h>
77 #include <sys/refcount.h>
80 #include <vm/vm_param.h>
82 #include <vm/vm_map.h>
83 #include <vm/vm_object.h>
84 #include <vm/vm_page.h>
85 #include <vm/vm_pageout.h>
86 #include <vm/vm_pager.h>
87 #include <vm/swap_pager.h>
88 #include <vm/vm_kern.h>
89 #include <vm/vm_extern.h>
90 #include <vm/vm_zone.h>
92 #include <vm/vm_page2.h>
94 #include <machine/specialreg.h>
96 #define EASY_SCAN_FACTOR 8
98 static void vm_object_qcollapse(vm_object_t object
,
99 vm_object_t backing_object
);
100 static void vm_object_page_collect_flush(vm_object_t object
, vm_page_t p
,
102 static void vm_object_lock_init(vm_object_t
);
106 * Virtual memory objects maintain the actual data
107 * associated with allocated virtual memory. A given
108 * page of memory exists within exactly one object.
110 * An object is only deallocated when all "references"
111 * are given up. Only one "reference" to a given
112 * region of an object should be writeable.
114 * Associated with each object is a list of all resident
115 * memory pages belonging to that object; this list is
116 * maintained by the "vm_page" module, and locked by the object's
119 * Each object also records a "pager" routine which is
120 * used to retrieve (and store) pages to the proper backing
121 * storage. In addition, objects may be backed by other
122 * objects from which they were virtual-copied.
124 * The only items within the object structure which are
125 * modified after time of creation are:
126 * reference count locked by object's lock
127 * pager routine locked by object's lock
131 struct vm_object kernel_object
;
133 static long vm_object_count
;
135 static long object_collapses
;
136 static long object_bypasses
;
137 static vm_zone_t obj_zone
;
138 static struct vm_zone obj_zone_store
;
139 #define VM_OBJECTS_INIT 256
140 static struct vm_object vm_objects_init
[VM_OBJECTS_INIT
];
142 struct object_q vm_object_lists
[VMOBJ_HSIZE
];
143 struct lwkt_token vmobj_tokens
[VMOBJ_HSIZE
];
145 #if defined(DEBUG_LOCKS)
147 #define vm_object_vndeallocate(obj, vpp) \
148 debugvm_object_vndeallocate(obj, vpp, __FILE__, __LINE__)
151 * Debug helper to track hold/drop/ref/deallocate calls.
154 debugvm_object_add(vm_object_t obj
, char *file
, int line
, int addrem
)
158 i
= atomic_fetchadd_int(&obj
->debug_index
, 1);
159 i
= i
& (VMOBJ_DEBUG_ARRAY_SIZE
- 1);
160 ksnprintf(obj
->debug_hold_thrs
[i
],
161 sizeof(obj
->debug_hold_thrs
[i
]),
163 (addrem
== -1 ? '-' : (addrem
== 1 ? '+' : '=')),
164 (curthread
->td_proc
? curthread
->td_proc
->p_pid
: -1),
167 obj
->debug_hold_file
[i
] = file
;
168 obj
->debug_hold_line
[i
] = line
;
170 /* Uncomment for debugging obj refs/derefs in reproducable cases */
171 if (strcmp(curthread
->td_comm
, "sshd") == 0) {
172 kprintf("%d %p refs=%d ar=%d file: %s/%d\n",
173 (curthread
->td_proc
? curthread
->td_proc
->p_pid
: -1),
174 obj
, obj
->ref_count
, addrem
, file
, line
);
182 * Misc low level routines
185 vm_object_lock_init(vm_object_t obj
)
187 #if defined(DEBUG_LOCKS)
190 obj
->debug_index
= 0;
191 for (i
= 0; i
< VMOBJ_DEBUG_ARRAY_SIZE
; i
++) {
192 obj
->debug_hold_thrs
[i
][0] = 0;
193 obj
->debug_hold_file
[i
] = NULL
;
194 obj
->debug_hold_line
[i
] = 0;
200 vm_object_lock_swap(void)
206 vm_object_lock(vm_object_t obj
)
208 lwkt_gettoken(&obj
->token
);
212 * Returns TRUE on sucesss
215 vm_object_lock_try(vm_object_t obj
)
217 return(lwkt_trytoken(&obj
->token
));
221 vm_object_lock_shared(vm_object_t obj
)
223 lwkt_gettoken_shared(&obj
->token
);
227 vm_object_unlock(vm_object_t obj
)
229 lwkt_reltoken(&obj
->token
);
233 vm_object_upgrade(vm_object_t obj
)
235 lwkt_reltoken(&obj
->token
);
236 lwkt_gettoken(&obj
->token
);
240 vm_object_downgrade(vm_object_t obj
)
242 lwkt_reltoken(&obj
->token
);
243 lwkt_gettoken_shared(&obj
->token
);
247 vm_object_assert_held(vm_object_t obj
)
249 ASSERT_LWKT_TOKEN_HELD(&obj
->token
);
255 globaldata_t gd
= mycpu
;
258 pg_color
= (int)(intptr_t)gd
->gd_curthread
>> 10;
259 pg_color
+= gd
->gd_quick_color
;
260 gd
->gd_quick_color
+= PQ_PRIME2
;
266 VMOBJDEBUG(vm_object_hold
)(vm_object_t obj VMOBJDBARGS
)
268 KKASSERT(obj
!= NULL
);
271 * Object must be held (object allocation is stable due to callers
272 * context, typically already holding the token on a parent object)
273 * prior to potentially blocking on the lock, otherwise the object
274 * can get ripped away from us.
276 refcount_acquire(&obj
->hold_count
);
279 #if defined(DEBUG_LOCKS)
280 debugvm_object_add(obj
, file
, line
, 1);
285 VMOBJDEBUG(vm_object_hold_try
)(vm_object_t obj VMOBJDBARGS
)
287 KKASSERT(obj
!= NULL
);
290 * Object must be held (object allocation is stable due to callers
291 * context, typically already holding the token on a parent object)
292 * prior to potentially blocking on the lock, otherwise the object
293 * can get ripped away from us.
295 refcount_acquire(&obj
->hold_count
);
296 if (vm_object_lock_try(obj
) == 0) {
297 if (refcount_release(&obj
->hold_count
)) {
298 if (obj
->ref_count
== 0 && (obj
->flags
& OBJ_DEAD
))
299 zfree(obj_zone
, obj
);
304 #if defined(DEBUG_LOCKS)
305 debugvm_object_add(obj
, file
, line
, 1);
311 VMOBJDEBUG(vm_object_hold_shared
)(vm_object_t obj VMOBJDBARGS
)
313 KKASSERT(obj
!= NULL
);
316 * Object must be held (object allocation is stable due to callers
317 * context, typically already holding the token on a parent object)
318 * prior to potentially blocking on the lock, otherwise the object
319 * can get ripped away from us.
321 refcount_acquire(&obj
->hold_count
);
322 vm_object_lock_shared(obj
);
324 #if defined(DEBUG_LOCKS)
325 debugvm_object_add(obj
, file
, line
, 1);
330 * Drop the token and hold_count on the object.
332 * WARNING! Token might be shared.
335 VMOBJDEBUG(vm_object_drop
)(vm_object_t obj VMOBJDBARGS
)
341 * No new holders should be possible once we drop hold_count 1->0 as
342 * there is no longer any way to reference the object.
344 KKASSERT(obj
->hold_count
> 0);
345 if (refcount_release(&obj
->hold_count
)) {
346 #if defined(DEBUG_LOCKS)
347 debugvm_object_add(obj
, file
, line
, -1);
350 if (obj
->ref_count
== 0 && (obj
->flags
& OBJ_DEAD
)) {
351 vm_object_unlock(obj
);
352 zfree(obj_zone
, obj
);
354 vm_object_unlock(obj
);
357 #if defined(DEBUG_LOCKS)
358 debugvm_object_add(obj
, file
, line
, -1);
360 vm_object_unlock(obj
);
365 * Initialize a freshly allocated object, returning a held object.
367 * Used only by vm_object_allocate() and zinitna().
372 _vm_object_allocate(objtype_t type
, vm_pindex_t size
, vm_object_t object
)
376 RB_INIT(&object
->rb_memq
);
377 LIST_INIT(&object
->shadow_head
);
378 lwkt_token_init(&object
->token
, "vmobj");
382 object
->ref_count
= 1;
383 object
->memattr
= VM_MEMATTR_DEFAULT
;
384 object
->hold_count
= 0;
386 if ((object
->type
== OBJT_DEFAULT
) || (object
->type
== OBJT_SWAP
))
387 vm_object_set_flag(object
, OBJ_ONEMAPPING
);
388 object
->paging_in_progress
= 0;
389 object
->resident_page_count
= 0;
390 object
->agg_pv_list_count
= 0;
391 object
->shadow_count
= 0;
392 /* cpu localization twist */
393 object
->pg_color
= vm_quickcolor();
394 object
->handle
= NULL
;
395 object
->backing_object
= NULL
;
396 object
->backing_object_offset
= (vm_ooffset_t
)0;
398 object
->generation
++;
399 object
->swblock_count
= 0;
400 RB_INIT(&object
->swblock_root
);
401 vm_object_lock_init(object
);
402 pmap_object_init(object
);
404 vm_object_hold(object
);
406 n
= VMOBJ_HASH(object
);
407 atomic_add_long(&vm_object_count
, 1);
408 lwkt_gettoken(&vmobj_tokens
[n
]);
409 TAILQ_INSERT_TAIL(&vm_object_lists
[n
], object
, object_list
);
410 lwkt_reltoken(&vmobj_tokens
[n
]);
414 * Initialize the VM objects module.
416 * Called from the low level boot code only.
423 for (i
= 0; i
< VMOBJ_HSIZE
; ++i
) {
424 TAILQ_INIT(&vm_object_lists
[i
]);
425 lwkt_token_init(&vmobj_tokens
[i
], "vmobjlst");
428 _vm_object_allocate(OBJT_DEFAULT
, OFF_TO_IDX(KvaEnd
),
430 vm_object_drop(&kernel_object
);
432 obj_zone
= &obj_zone_store
;
433 zbootinit(obj_zone
, "VM OBJECT", sizeof (struct vm_object
),
434 vm_objects_init
, VM_OBJECTS_INIT
);
438 vm_object_init2(void)
440 zinitna(obj_zone
, NULL
, NULL
, 0, 0, ZONE_PANICFAIL
, 1);
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 result
= (vm_object_t
) zalloc(obj_zone
);
455 _vm_object_allocate(type
, size
, result
);
456 vm_object_drop(result
);
462 * This version returns a held object, allowing further atomic initialization
466 vm_object_allocate_hold(objtype_t type
, vm_pindex_t size
)
470 result
= (vm_object_t
) zalloc(obj_zone
);
472 _vm_object_allocate(type
, size
, result
);
478 * Add an additional reference to a vm_object. The object must already be
479 * held. The original non-lock version is no longer supported. The object
480 * must NOT be chain locked by anyone at the time the reference is added.
482 * Referencing a chain-locked object can blow up the fairly sensitive
483 * ref_count and shadow_count tests in the deallocator. Most callers
484 * will call vm_object_chain_wait() prior to calling
485 * vm_object_reference_locked() to avoid the case.
487 * The object must be held, but may be held shared if desired (hence why
488 * we use an atomic op).
491 VMOBJDEBUG(vm_object_reference_locked
)(vm_object_t object VMOBJDBARGS
)
493 KKASSERT(object
!= NULL
);
494 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
495 KKASSERT((object
->chainlk
& (CHAINLK_EXCL
| CHAINLK_MASK
)) == 0);
496 atomic_add_int(&object
->ref_count
, 1);
497 if (object
->type
== OBJT_VNODE
) {
498 vref(object
->handle
);
499 /* XXX what if the vnode is being destroyed? */
501 #if defined(DEBUG_LOCKS)
502 debugvm_object_add(object
, file
, line
, 1);
507 * This version is only allowed for vnode objects.
510 VMOBJDEBUG(vm_object_reference_quick
)(vm_object_t object VMOBJDBARGS
)
512 KKASSERT(object
->type
== OBJT_VNODE
);
513 atomic_add_int(&object
->ref_count
, 1);
514 vref(object
->handle
);
515 #if defined(DEBUG_LOCKS)
516 debugvm_object_add(object
, file
, line
, 1);
521 * Object OBJ_CHAINLOCK lock handling.
523 * The caller can chain-lock backing objects recursively and then
524 * use vm_object_chain_release_all() to undo the whole chain.
526 * Chain locks are used to prevent collapses and are only applicable
527 * to OBJT_DEFAULT and OBJT_SWAP objects. Chain locking operations
528 * on other object types are ignored. This is also important because
529 * it allows e.g. the vnode underlying a memory mapping to take concurrent
532 * The object must usually be held on entry, though intermediate
533 * objects need not be held on release. The object must be held exclusively,
534 * NOT shared. Note that the prefault path checks the shared state and
535 * avoids using the chain functions.
538 vm_object_chain_wait(vm_object_t object
, int shared
)
540 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
542 uint32_t chainlk
= object
->chainlk
;
546 if (chainlk
& (CHAINLK_EXCL
| CHAINLK_EXCLREQ
)) {
547 tsleep_interlock(object
, 0);
548 if (atomic_cmpset_int(&object
->chainlk
,
550 chainlk
| CHAINLK_WAIT
)) {
551 tsleep(object
, PINTERLOCKED
,
560 if (chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
)) {
561 tsleep_interlock(object
, 0);
562 if (atomic_cmpset_int(&object
->chainlk
,
564 chainlk
| CHAINLK_WAIT
))
566 tsleep(object
, PINTERLOCKED
,
571 if (atomic_cmpset_int(&object
->chainlk
,
573 chainlk
& ~CHAINLK_WAIT
))
575 if (chainlk
& CHAINLK_WAIT
)
587 vm_object_chain_acquire(vm_object_t object
, int shared
)
589 if (object
->type
!= OBJT_DEFAULT
&& object
->type
!= OBJT_SWAP
)
591 if (vm_shared_fault
== 0)
595 uint32_t chainlk
= object
->chainlk
;
599 if (chainlk
& (CHAINLK_EXCL
| CHAINLK_EXCLREQ
)) {
600 tsleep_interlock(object
, 0);
601 if (atomic_cmpset_int(&object
->chainlk
,
603 chainlk
| CHAINLK_WAIT
)) {
604 tsleep(object
, PINTERLOCKED
,
608 } else if (atomic_cmpset_int(&object
->chainlk
,
609 chainlk
, chainlk
+ 1)) {
614 if (chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
)) {
615 tsleep_interlock(object
, 0);
616 if (atomic_cmpset_int(&object
->chainlk
,
621 tsleep(object
, PINTERLOCKED
,
626 if (atomic_cmpset_int(&object
->chainlk
,
628 (chainlk
| CHAINLK_EXCL
) &
631 if (chainlk
& CHAINLK_WAIT
)
643 vm_object_chain_release(vm_object_t object
)
645 /*ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));*/
646 if (object
->type
!= OBJT_DEFAULT
&& object
->type
!= OBJT_SWAP
)
648 KKASSERT(object
->chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
));
650 uint32_t chainlk
= object
->chainlk
;
653 if (chainlk
& CHAINLK_MASK
) {
654 if ((chainlk
& CHAINLK_MASK
) == 1 &&
655 atomic_cmpset_int(&object
->chainlk
,
657 (chainlk
- 1) & ~CHAINLK_WAIT
)) {
658 if (chainlk
& CHAINLK_WAIT
)
662 if ((chainlk
& CHAINLK_MASK
) > 1 &&
663 atomic_cmpset_int(&object
->chainlk
,
664 chainlk
, chainlk
- 1)) {
669 KKASSERT(chainlk
& CHAINLK_EXCL
);
670 if (atomic_cmpset_int(&object
->chainlk
,
672 chainlk
& ~(CHAINLK_EXCL
|
674 if (chainlk
& CHAINLK_WAIT
)
683 * Release the chain from first_object through and including stopobj.
684 * The caller is typically holding the first and last object locked
685 * (shared or exclusive) to prevent destruction races.
687 * We release stopobj first as an optimization as this object is most
688 * likely to be shared across multiple processes.
691 vm_object_chain_release_all(vm_object_t first_object
, vm_object_t stopobj
)
693 vm_object_t backing_object
;
696 vm_object_chain_release(stopobj
);
697 object
= first_object
;
699 while (object
!= stopobj
) {
701 backing_object
= object
->backing_object
;
702 vm_object_chain_release(object
);
703 object
= backing_object
;
708 * Dereference an object and its underlying vnode. The object may be
709 * held shared. On return the object will remain held.
711 * This function may return a vnode in *vpp which the caller must release
712 * after the caller drops its own lock. If vpp is NULL, we assume that
713 * the caller was holding an exclusive lock on the object and we vrele()
717 VMOBJDEBUG(vm_object_vndeallocate
)(vm_object_t object
, struct vnode
**vpp
720 struct vnode
*vp
= (struct vnode
*) object
->handle
;
722 KASSERT(object
->type
== OBJT_VNODE
,
723 ("vm_object_vndeallocate: not a vnode object"));
724 KASSERT(vp
!= NULL
, ("vm_object_vndeallocate: missing vp"));
725 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
727 if (object
->ref_count
== 0) {
728 vprint("vm_object_vndeallocate", vp
);
729 panic("vm_object_vndeallocate: bad object reference count");
733 int count
= object
->ref_count
;
736 vm_object_upgrade(object
);
737 if (atomic_cmpset_int(&object
->ref_count
, count
, 0)) {
738 vclrflags(vp
, VTEXT
);
742 if (atomic_cmpset_int(&object
->ref_count
,
749 #if defined(DEBUG_LOCKS)
750 debugvm_object_add(object
, file
, line
, -1);
754 * vrele or return the vp to vrele. We can only safely vrele(vp)
755 * if the object was locked exclusively. But there are two races
758 * We had to upgrade the object above to safely clear VTEXT
759 * but the alternative path where the shared lock is retained
760 * can STILL race to 0 in other paths and cause our own vrele()
761 * to terminate the vnode. We can't allow that if the VM object
762 * is still locked shared.
771 * Release a reference to the specified object, gained either through a
772 * vm_object_allocate or a vm_object_reference call. When all references
773 * are gone, storage associated with this object may be relinquished.
775 * The caller does not have to hold the object locked but must have control
776 * over the reference in question in order to guarantee that the object
777 * does not get ripped out from under us.
779 * XXX Currently all deallocations require an exclusive lock.
782 VMOBJDEBUG(vm_object_deallocate
)(vm_object_t object VMOBJDBARGS
)
791 count
= object
->ref_count
;
795 * If decrementing the count enters into special handling
796 * territory (0, 1, or 2) we have to do it the hard way.
797 * Fortunate though, objects with only a few refs like this
798 * are not likely to be heavily contended anyway.
800 * For vnode objects we only care about 1->0 transitions.
802 if (count
<= 3 || (object
->type
== OBJT_VNODE
&& count
<= 1)) {
803 #if defined(DEBUG_LOCKS)
804 debugvm_object_add(object
, file
, line
, 0);
806 vm_object_hold(object
);
807 vm_object_deallocate_locked(object
);
808 vm_object_drop(object
);
813 * Try to decrement ref_count without acquiring a hold on
814 * the object. This is particularly important for the exec*()
815 * and exit*() code paths because the program binary may
816 * have a great deal of sharing and an exclusive lock will
817 * crowbar performance in those circumstances.
819 if (object
->type
== OBJT_VNODE
) {
820 vp
= (struct vnode
*)object
->handle
;
821 if (atomic_cmpset_int(&object
->ref_count
,
823 #if defined(DEBUG_LOCKS)
824 debugvm_object_add(object
, file
, line
, -1);
832 if (atomic_cmpset_int(&object
->ref_count
,
834 #if defined(DEBUG_LOCKS)
835 debugvm_object_add(object
, file
, line
, -1);
846 VMOBJDEBUG(vm_object_deallocate_locked
)(vm_object_t object VMOBJDBARGS
)
848 struct vm_object_dealloc_list
*dlist
= NULL
;
849 struct vm_object_dealloc_list
*dtmp
;
854 * We may chain deallocate object, but additional objects may
855 * collect on the dlist which also have to be deallocated. We
856 * must avoid a recursion, vm_object chains can get deep.
860 while (object
!= NULL
) {
862 * vnode case, caller either locked the object exclusively
863 * or this is a recursion with must_drop != 0 and the vnode
864 * object will be locked shared.
866 * If locked shared we have to drop the object before we can
867 * call vrele() or risk a shared/exclusive livelock.
869 if (object
->type
== OBJT_VNODE
) {
870 ASSERT_LWKT_TOKEN_HELD(&object
->token
);
872 struct vnode
*tmp_vp
;
874 vm_object_vndeallocate(object
, &tmp_vp
);
875 vm_object_drop(object
);
880 vm_object_vndeallocate(object
, NULL
);
884 ASSERT_LWKT_TOKEN_HELD_EXCL(&object
->token
);
887 * Normal case (object is locked exclusively)
889 if (object
->ref_count
== 0) {
890 panic("vm_object_deallocate: object deallocated "
891 "too many times: %d", object
->type
);
893 if (object
->ref_count
> 2) {
894 atomic_add_int(&object
->ref_count
, -1);
895 #if defined(DEBUG_LOCKS)
896 debugvm_object_add(object
, file
, line
, -1);
902 * Here on ref_count of one or two, which are special cases for
905 * Nominal ref_count > 1 case if the second ref is not from
908 * (ONEMAPPING only applies to DEFAULT AND SWAP objects)
910 if (object
->ref_count
== 2 && object
->shadow_count
== 0) {
911 if (object
->type
== OBJT_DEFAULT
||
912 object
->type
== OBJT_SWAP
) {
913 vm_object_set_flag(object
, OBJ_ONEMAPPING
);
915 atomic_add_int(&object
->ref_count
, -1);
916 #if defined(DEBUG_LOCKS)
917 debugvm_object_add(object
, file
, line
, -1);
923 * If the second ref is from a shadow we chain along it
924 * upwards if object's handle is exhausted.
926 * We have to decrement object->ref_count before potentially
927 * collapsing the first shadow object or the collapse code
928 * will not be able to handle the degenerate case to remove
929 * object. However, if we do it too early the object can
930 * get ripped out from under us.
932 if (object
->ref_count
== 2 && object
->shadow_count
== 1 &&
933 object
->handle
== NULL
&& (object
->type
== OBJT_DEFAULT
||
934 object
->type
== OBJT_SWAP
)) {
935 temp
= LIST_FIRST(&object
->shadow_head
);
936 KKASSERT(temp
!= NULL
);
937 vm_object_hold(temp
);
940 * Wait for any paging to complete so the collapse
941 * doesn't (or isn't likely to) qcollapse. pip
942 * waiting must occur before we acquire the
946 temp
->paging_in_progress
||
947 object
->paging_in_progress
949 vm_object_pip_wait(temp
, "objde1");
950 vm_object_pip_wait(object
, "objde2");
954 * If the parent is locked we have to give up, as
955 * otherwise we would be acquiring locks in the
956 * wrong order and potentially deadlock.
958 if (temp
->chainlk
& (CHAINLK_EXCL
| CHAINLK_MASK
)) {
959 vm_object_drop(temp
);
962 vm_object_chain_acquire(temp
, 0);
965 * Recheck/retry after the hold and the paging
966 * wait, both of which can block us.
968 if (object
->ref_count
!= 2 ||
969 object
->shadow_count
!= 1 ||
971 LIST_FIRST(&object
->shadow_head
) != temp
||
972 (object
->type
!= OBJT_DEFAULT
&&
973 object
->type
!= OBJT_SWAP
)) {
974 vm_object_chain_release(temp
);
975 vm_object_drop(temp
);
980 * We can safely drop object's ref_count now.
982 KKASSERT(object
->ref_count
== 2);
983 atomic_add_int(&object
->ref_count
, -1);
984 #if defined(DEBUG_LOCKS)
985 debugvm_object_add(object
, file
, line
, -1);
989 * If our single parent is not collapseable just
990 * decrement ref_count (2->1) and stop.
992 if (temp
->handle
|| (temp
->type
!= OBJT_DEFAULT
&&
993 temp
->type
!= OBJT_SWAP
)) {
994 vm_object_chain_release(temp
);
995 vm_object_drop(temp
);
1000 * At this point we have already dropped object's
1001 * ref_count so it is possible for a race to
1002 * deallocate obj out from under us. Any collapse
1003 * will re-check the situation. We must not block
1004 * until we are able to collapse.
1006 * Bump temp's ref_count to avoid an unwanted
1007 * degenerate recursion (can't call
1008 * vm_object_reference_locked() because it asserts
1009 * that CHAINLOCK is not set).
1011 atomic_add_int(&temp
->ref_count
, 1);
1012 KKASSERT(temp
->ref_count
> 1);
1015 * Collapse temp, then deallocate the extra ref
1018 vm_object_collapse(temp
, &dlist
);
1019 vm_object_chain_release(temp
);
1021 vm_object_lock_swap();
1022 vm_object_drop(object
);
1030 * Drop the ref and handle termination on the 1->0 transition.
1031 * We may have blocked above so we have to recheck.
1034 KKASSERT(object
->ref_count
!= 0);
1035 if (object
->ref_count
>= 2) {
1036 atomic_add_int(&object
->ref_count
, -1);
1037 #if defined(DEBUG_LOCKS)
1038 debugvm_object_add(object
, file
, line
, -1);
1042 KKASSERT(object
->ref_count
== 1);
1045 * 1->0 transition. Chain through the backing_object.
1046 * Maintain the ref until we've located the backing object,
1049 while ((temp
= object
->backing_object
) != NULL
) {
1050 if (temp
->type
== OBJT_VNODE
)
1051 vm_object_hold_shared(temp
);
1053 vm_object_hold(temp
);
1054 if (temp
== object
->backing_object
)
1056 vm_object_drop(temp
);
1060 * 1->0 transition verified, retry if ref_count is no longer
1061 * 1. Otherwise disconnect the backing_object (temp) and
1064 if (object
->ref_count
!= 1) {
1065 vm_object_drop(temp
);
1070 * It shouldn't be possible for the object to be chain locked
1071 * if we're removing the last ref on it.
1073 * Removing object from temp's shadow list requires dropping
1074 * temp, which we will do on loop.
1076 * NOTE! vnodes do not use the shadow list, but still have
1077 * the backing_object reference.
1079 KKASSERT((object
->chainlk
& (CHAINLK_EXCL
|CHAINLK_MASK
)) == 0);
1082 if (object
->flags
& OBJ_ONSHADOW
) {
1083 LIST_REMOVE(object
, shadow_list
);
1084 temp
->shadow_count
--;
1086 vm_object_clear_flag(object
, OBJ_ONSHADOW
);
1088 object
->backing_object
= NULL
;
1091 atomic_add_int(&object
->ref_count
, -1);
1092 if ((object
->flags
& OBJ_DEAD
) == 0)
1093 vm_object_terminate(object
);
1094 if (must_drop
&& temp
)
1095 vm_object_lock_swap();
1097 vm_object_drop(object
);
1102 if (must_drop
&& object
)
1103 vm_object_drop(object
);
1106 * Additional tail recursion on dlist. Avoid a recursion. Objects
1107 * on the dlist have a hold count but are not locked.
1109 if ((dtmp
= dlist
) != NULL
) {
1111 object
= dtmp
->object
;
1112 kfree(dtmp
, M_TEMP
);
1114 vm_object_lock(object
); /* already held, add lock */
1115 must_drop
= 1; /* and we're responsible for it */
1121 * Destroy the specified object, freeing up related resources.
1123 * The object must have zero references.
1125 * The object must held. The caller is responsible for dropping the object
1126 * after terminate returns. Terminate does NOT drop the object.
1128 static int vm_object_terminate_callback(vm_page_t p
, void *data
);
1131 vm_object_terminate(vm_object_t object
)
1133 struct rb_vm_page_scan_info info
;
1137 * Make sure no one uses us. Once we set OBJ_DEAD we should be
1138 * able to safely block.
1140 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
1141 KKASSERT((object
->flags
& OBJ_DEAD
) == 0);
1142 vm_object_set_flag(object
, OBJ_DEAD
);
1145 * Wait for the pageout daemon to be done with the object
1147 vm_object_pip_wait(object
, "objtrm1");
1149 KASSERT(!object
->paging_in_progress
,
1150 ("vm_object_terminate: pageout in progress"));
1153 * Clean and free the pages, as appropriate. All references to the
1154 * object are gone, so we don't need to lock it.
1156 if (object
->type
== OBJT_VNODE
) {
1160 * Clean pages and flush buffers.
1162 * NOTE! TMPFS buffer flushes do not typically flush the
1163 * actual page to swap as this would be highly
1164 * inefficient, and normal filesystems usually wrap
1165 * page flushes with buffer cache buffers.
1167 * To deal with this we have to call vinvalbuf() both
1168 * before and after the vm_object_page_clean().
1170 vp
= (struct vnode
*) object
->handle
;
1171 vinvalbuf(vp
, V_SAVE
, 0, 0);
1172 vm_object_page_clean(object
, 0, 0, OBJPC_SYNC
);
1173 vinvalbuf(vp
, V_SAVE
, 0, 0);
1177 * Wait for any I/O to complete, after which there had better not
1178 * be any references left on the object.
1180 vm_object_pip_wait(object
, "objtrm2");
1182 if (object
->ref_count
!= 0) {
1183 panic("vm_object_terminate: object with references, "
1184 "ref_count=%d", object
->ref_count
);
1188 * Cleanup any shared pmaps associated with this object.
1190 pmap_object_free(object
);
1193 * Now free any remaining pages. For internal objects, this also
1194 * removes them from paging queues. Don't free wired pages, just
1195 * remove them from the object.
1198 info
.object
= object
;
1199 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, NULL
,
1200 vm_object_terminate_callback
, &info
);
1203 * Let the pager know object is dead.
1205 vm_pager_deallocate(object
);
1208 * Wait for the object hold count to hit 1, clean out pages as
1209 * we go. vmobj_token interlocks any race conditions that might
1210 * pick the object up from the vm_object_list after we have cleared
1214 if (RB_ROOT(&object
->rb_memq
) == NULL
)
1216 kprintf("vm_object_terminate: Warning, object %p "
1217 "still has %d pages\n",
1218 object
, object
->resident_page_count
);
1219 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, NULL
,
1220 vm_object_terminate_callback
, &info
);
1224 * There had better not be any pages left
1226 KKASSERT(object
->resident_page_count
== 0);
1229 * Remove the object from the global object list.
1231 n
= VMOBJ_HASH(object
);
1232 lwkt_gettoken(&vmobj_tokens
[n
]);
1233 TAILQ_REMOVE(&vm_object_lists
[n
], object
, object_list
);
1234 lwkt_reltoken(&vmobj_tokens
[n
]);
1235 atomic_add_long(&vm_object_count
, -1);
1237 if (object
->ref_count
!= 0) {
1238 panic("vm_object_terminate2: object with references, "
1239 "ref_count=%d", object
->ref_count
);
1243 * NOTE: The object hold_count is at least 1, so we cannot zfree()
1244 * the object here. See vm_object_drop().
1249 * The caller must hold the object.
1252 vm_object_terminate_callback(vm_page_t p
, void *data
)
1254 struct rb_vm_page_scan_info
*info
= data
;
1257 if ((++info
->count
& 63) == 0)
1260 if (object
!= info
->object
) {
1261 kprintf("vm_object_terminate_callback: obj/pg race %p/%p\n",
1265 vm_page_busy_wait(p
, TRUE
, "vmpgtrm");
1266 if (object
!= p
->object
) {
1267 kprintf("vm_object_terminate: Warning: Encountered "
1268 "busied page %p on queue %d\n", p
, p
->queue
);
1270 } else if (p
->wire_count
== 0) {
1272 * NOTE: p->dirty and PG_NEED_COMMIT are ignored.
1275 mycpu
->gd_cnt
.v_pfree
++;
1277 if (p
->queue
!= PQ_NONE
)
1278 kprintf("vm_object_terminate: Warning: Encountered "
1279 "wired page %p on queue %d\n", p
, p
->queue
);
1287 * Clean all dirty pages in the specified range of object. Leaves page
1288 * on whatever queue it is currently on. If NOSYNC is set then do not
1289 * write out pages with PG_NOSYNC set (originally comes from MAP_NOSYNC),
1290 * leaving the object dirty.
1292 * When stuffing pages asynchronously, allow clustering. XXX we need a
1293 * synchronous clustering mode implementation.
1295 * Odd semantics: if start == end, we clean everything.
1297 * The object must be locked? XXX
1299 static int vm_object_page_clean_pass1(struct vm_page
*p
, void *data
);
1300 static int vm_object_page_clean_pass2(struct vm_page
*p
, void *data
);
1303 vm_object_page_clean(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
,
1306 struct rb_vm_page_scan_info info
;
1312 vm_object_hold(object
);
1313 if (object
->type
!= OBJT_VNODE
||
1314 (object
->flags
& OBJ_MIGHTBEDIRTY
) == 0) {
1315 vm_object_drop(object
);
1319 pagerflags
= (flags
& (OBJPC_SYNC
| OBJPC_INVAL
)) ?
1320 VM_PAGER_PUT_SYNC
: VM_PAGER_CLUSTER_OK
;
1321 pagerflags
|= (flags
& OBJPC_INVAL
) ? VM_PAGER_PUT_INVAL
: 0;
1323 vp
= object
->handle
;
1326 * Interlock other major object operations. This allows us to
1327 * temporarily clear OBJ_WRITEABLE and OBJ_MIGHTBEDIRTY.
1329 vm_object_set_flag(object
, OBJ_CLEANING
);
1332 * Handle 'entire object' case
1334 info
.start_pindex
= start
;
1336 info
.end_pindex
= object
->size
- 1;
1338 info
.end_pindex
= end
- 1;
1340 wholescan
= (start
== 0 && info
.end_pindex
== object
->size
- 1);
1342 info
.pagerflags
= pagerflags
;
1343 info
.object
= object
;
1346 * If cleaning the entire object do a pass to mark the pages read-only.
1347 * If everything worked out ok, clear OBJ_WRITEABLE and
1353 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
1354 vm_object_page_clean_pass1
, &info
);
1355 if (info
.error
== 0) {
1356 vm_object_clear_flag(object
,
1357 OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
);
1358 if (object
->type
== OBJT_VNODE
&&
1359 (vp
= (struct vnode
*)object
->handle
) != NULL
) {
1361 * Use new-style interface to clear VISDIRTY
1362 * because the vnode is not necessarily removed
1363 * from the syncer list(s) as often as it was
1364 * under the old interface, which can leave
1365 * the vnode on the syncer list after reclaim.
1373 * Do a pass to clean all the dirty pages we find.
1378 generation
= object
->generation
;
1379 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
1380 vm_object_page_clean_pass2
, &info
);
1381 } while (info
.error
|| generation
!= object
->generation
);
1383 vm_object_clear_flag(object
, OBJ_CLEANING
);
1384 vm_object_drop(object
);
1388 * The caller must hold the object.
1392 vm_object_page_clean_pass1(struct vm_page
*p
, void *data
)
1394 struct rb_vm_page_scan_info
*info
= data
;
1396 if ((++info
->count
& 63) == 0)
1398 if (p
->object
!= info
->object
||
1399 p
->pindex
< info
->start_pindex
||
1400 p
->pindex
> info
->end_pindex
) {
1401 kprintf("vm_object_page_clean_pass1: obj/pg race %p/%p\n",
1405 vm_page_flag_set(p
, PG_CLEANCHK
);
1406 if ((info
->limit
& OBJPC_NOSYNC
) && (p
->flags
& PG_NOSYNC
)) {
1408 } else if (vm_page_busy_try(p
, FALSE
) == 0) {
1409 if (p
->object
== info
->object
)
1410 vm_page_protect(p
, VM_PROT_READ
);
1419 * The caller must hold the object
1423 vm_object_page_clean_pass2(struct vm_page
*p
, void *data
)
1425 struct rb_vm_page_scan_info
*info
= data
;
1428 if (p
->object
!= info
->object
||
1429 p
->pindex
< info
->start_pindex
||
1430 p
->pindex
> info
->end_pindex
) {
1431 kprintf("vm_object_page_clean_pass2: obj/pg race %p/%p\n",
1437 * Do not mess with pages that were inserted after we started
1438 * the cleaning pass.
1440 if ((p
->flags
& PG_CLEANCHK
) == 0)
1443 generation
= info
->object
->generation
;
1444 vm_page_busy_wait(p
, TRUE
, "vpcwai");
1446 if (p
->object
!= info
->object
||
1447 p
->pindex
< info
->start_pindex
||
1448 p
->pindex
> info
->end_pindex
||
1449 info
->object
->generation
!= generation
) {
1456 * Before wasting time traversing the pmaps, check for trivial
1457 * cases where the page cannot be dirty.
1459 if (p
->valid
== 0 || (p
->queue
- p
->pc
) == PQ_CACHE
) {
1460 KKASSERT((p
->dirty
& p
->valid
) == 0 &&
1461 (p
->flags
& PG_NEED_COMMIT
) == 0);
1467 * Check whether the page is dirty or not. The page has been set
1468 * to be read-only so the check will not race a user dirtying the
1471 vm_page_test_dirty(p
);
1472 if ((p
->dirty
& p
->valid
) == 0 && (p
->flags
& PG_NEED_COMMIT
) == 0) {
1473 vm_page_flag_clear(p
, PG_CLEANCHK
);
1479 * If we have been asked to skip nosync pages and this is a
1480 * nosync page, skip it. Note that the object flags were
1481 * not cleared in this case (because pass1 will have returned an
1482 * error), so we do not have to set them.
1484 if ((info
->limit
& OBJPC_NOSYNC
) && (p
->flags
& PG_NOSYNC
)) {
1485 vm_page_flag_clear(p
, PG_CLEANCHK
);
1491 * Flush as many pages as we can. PG_CLEANCHK will be cleared on
1492 * the pages that get successfully flushed. Set info->error if
1493 * we raced an object modification.
1495 vm_object_page_collect_flush(info
->object
, p
, info
->pagerflags
);
1496 /* vm_wait_nominal(); this can deadlock the system in syncer/pageout */
1498 if ((++info
->count
& 63) == 0)
1505 * Collect the specified page and nearby pages and flush them out.
1506 * The number of pages flushed is returned. The passed page is busied
1507 * by the caller and we are responsible for its disposition.
1509 * The caller must hold the object.
1512 vm_object_page_collect_flush(vm_object_t object
, vm_page_t p
, int pagerflags
)
1520 vm_page_t ma
[BLIST_MAX_ALLOC
];
1522 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
1525 page_base
= pi
% BLIST_MAX_ALLOC
;
1533 tp
= vm_page_lookup_busy_try(object
, pi
- page_base
+ ib
,
1539 if ((pagerflags
& VM_PAGER_IGNORE_CLEANCHK
) == 0 &&
1540 (tp
->flags
& PG_CLEANCHK
) == 0) {
1544 if ((tp
->queue
- tp
->pc
) == PQ_CACHE
) {
1545 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1549 vm_page_test_dirty(tp
);
1550 if ((tp
->dirty
& tp
->valid
) == 0 &&
1551 (tp
->flags
& PG_NEED_COMMIT
) == 0) {
1552 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1561 while (is
< BLIST_MAX_ALLOC
&&
1562 pi
- page_base
+ is
< object
->size
) {
1565 tp
= vm_page_lookup_busy_try(object
, pi
- page_base
+ is
,
1571 if ((pagerflags
& VM_PAGER_IGNORE_CLEANCHK
) == 0 &&
1572 (tp
->flags
& PG_CLEANCHK
) == 0) {
1576 if ((tp
->queue
- tp
->pc
) == PQ_CACHE
) {
1577 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1581 vm_page_test_dirty(tp
);
1582 if ((tp
->dirty
& tp
->valid
) == 0 &&
1583 (tp
->flags
& PG_NEED_COMMIT
) == 0) {
1584 vm_page_flag_clear(tp
, PG_CLEANCHK
);
1593 * All pages in the ma[] array are busied now
1595 for (i
= ib
; i
< is
; ++i
) {
1596 vm_page_flag_clear(ma
[i
], PG_CLEANCHK
);
1597 vm_page_hold(ma
[i
]); /* XXX need this any more? */
1599 vm_pageout_flush(&ma
[ib
], is
- ib
, pagerflags
);
1600 for (i
= ib
; i
< is
; ++i
) /* XXX need this any more? */
1601 vm_page_unhold(ma
[i
]);
1605 * Same as vm_object_pmap_copy, except range checking really
1606 * works, and is meant for small sections of an object.
1608 * This code protects resident pages by making them read-only
1609 * and is typically called on a fork or split when a page
1610 * is converted to copy-on-write.
1612 * NOTE: If the page is already at VM_PROT_NONE, calling
1613 * vm_page_protect will have no effect.
1616 vm_object_pmap_copy_1(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
)
1621 if (object
== NULL
|| (object
->flags
& OBJ_WRITEABLE
) == 0)
1624 vm_object_hold(object
);
1625 for (idx
= start
; idx
< end
; idx
++) {
1626 p
= vm_page_lookup(object
, idx
);
1629 vm_page_protect(p
, VM_PROT_READ
);
1631 vm_object_drop(object
);
1635 * Removes all physical pages in the specified object range from all
1638 * The object must *not* be locked.
1641 static int vm_object_pmap_remove_callback(vm_page_t p
, void *data
);
1644 vm_object_pmap_remove(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
)
1646 struct rb_vm_page_scan_info info
;
1650 info
.start_pindex
= start
;
1651 info
.end_pindex
= end
- 1;
1653 info
.object
= object
;
1655 vm_object_hold(object
);
1656 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
1657 vm_object_pmap_remove_callback
, &info
);
1658 if (start
== 0 && end
== object
->size
)
1659 vm_object_clear_flag(object
, OBJ_WRITEABLE
);
1660 vm_object_drop(object
);
1664 * The caller must hold the object
1667 vm_object_pmap_remove_callback(vm_page_t p
, void *data
)
1669 struct rb_vm_page_scan_info
*info
= data
;
1671 if ((++info
->count
& 63) == 0)
1674 if (info
->object
!= p
->object
||
1675 p
->pindex
< info
->start_pindex
||
1676 p
->pindex
> info
->end_pindex
) {
1677 kprintf("vm_object_pmap_remove_callback: obj/pg race %p/%p\n",
1682 vm_page_protect(p
, VM_PROT_NONE
);
1688 * Implements the madvise function at the object/page level.
1690 * MADV_WILLNEED (any object)
1692 * Activate the specified pages if they are resident.
1694 * MADV_DONTNEED (any object)
1696 * Deactivate the specified pages if they are resident.
1698 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects, OBJ_ONEMAPPING only)
1700 * Deactivate and clean the specified pages if they are
1701 * resident. This permits the process to reuse the pages
1702 * without faulting or the kernel to reclaim the pages
1708 vm_object_madvise(vm_object_t object
, vm_pindex_t pindex
, int count
, int advise
)
1710 vm_pindex_t end
, tpindex
;
1711 vm_object_t tobject
;
1719 end
= pindex
+ count
;
1721 vm_object_hold(object
);
1725 * Locate and adjust resident pages
1727 for (; pindex
< end
; pindex
+= 1) {
1729 if (tobject
!= object
)
1730 vm_object_drop(tobject
);
1735 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
1736 * and those pages must be OBJ_ONEMAPPING.
1738 if (advise
== MADV_FREE
) {
1739 if ((tobject
->type
!= OBJT_DEFAULT
&&
1740 tobject
->type
!= OBJT_SWAP
) ||
1741 (tobject
->flags
& OBJ_ONEMAPPING
) == 0) {
1746 m
= vm_page_lookup_busy_try(tobject
, tpindex
, TRUE
, &error
);
1749 vm_page_sleep_busy(m
, TRUE
, "madvpo");
1754 * There may be swap even if there is no backing page
1756 if (advise
== MADV_FREE
&& tobject
->type
== OBJT_SWAP
)
1757 swap_pager_freespace(tobject
, tpindex
, 1);
1762 while ((xobj
= tobject
->backing_object
) != NULL
) {
1763 KKASSERT(xobj
!= object
);
1764 vm_object_hold(xobj
);
1765 if (xobj
== tobject
->backing_object
)
1767 vm_object_drop(xobj
);
1771 tpindex
+= OFF_TO_IDX(tobject
->backing_object_offset
);
1772 if (tobject
!= object
) {
1773 vm_object_lock_swap();
1774 vm_object_drop(tobject
);
1781 * If the page is not in a normal active state, we skip it.
1782 * If the page is not managed there are no page queues to
1783 * mess with. Things can break if we mess with pages in
1784 * any of the below states.
1786 if (m
->wire_count
||
1787 (m
->flags
& (PG_UNMANAGED
| PG_NEED_COMMIT
)) ||
1788 m
->valid
!= VM_PAGE_BITS_ALL
1795 * Theoretically once a page is known not to be busy, an
1796 * interrupt cannot come along and rip it out from under us.
1799 if (advise
== MADV_WILLNEED
) {
1800 vm_page_activate(m
);
1801 } else if (advise
== MADV_DONTNEED
) {
1802 vm_page_dontneed(m
);
1803 } else if (advise
== MADV_FREE
) {
1805 * Mark the page clean. This will allow the page
1806 * to be freed up by the system. However, such pages
1807 * are often reused quickly by malloc()/free()
1808 * so we do not do anything that would cause
1809 * a page fault if we can help it.
1811 * Specifically, we do not try to actually free
1812 * the page now nor do we try to put it in the
1813 * cache (which would cause a page fault on reuse).
1815 * But we do make the page is freeable as we
1816 * can without actually taking the step of unmapping
1819 pmap_clear_modify(m
);
1822 vm_page_dontneed(m
);
1823 if (tobject
->type
== OBJT_SWAP
)
1824 swap_pager_freespace(tobject
, tpindex
, 1);
1828 if (tobject
!= object
)
1829 vm_object_drop(tobject
);
1830 vm_object_drop(object
);
1834 * Create a new object which is backed by the specified existing object
1835 * range. Replace the pointer and offset that was pointing at the existing
1836 * object with the pointer/offset for the new object.
1838 * If addref is non-zero the returned object is given an additional reference.
1839 * This mechanic exists to avoid the situation where refs might be 1 and
1840 * race against a collapse when the caller intends to bump it. So the
1841 * caller cannot add the ref after the fact. Used when the caller is
1842 * duplicating a vm_map_entry.
1844 * No other requirements.
1847 vm_object_shadow(vm_object_t
*objectp
, vm_ooffset_t
*offset
, vm_size_t length
,
1857 * Don't create the new object if the old object isn't shared.
1858 * We have to chain wait before adding the reference to avoid
1859 * racing a collapse or deallocation.
1861 * Clear OBJ_ONEMAPPING flag when shadowing.
1863 * The caller owns a ref on source via *objectp which we are going
1864 * to replace. This ref is inherited by the backing_object assignment.
1865 * from nobject and does not need to be incremented here.
1867 * However, we add a temporary extra reference to the original source
1868 * prior to holding nobject in case we block, to avoid races where
1869 * someone else might believe that the source can be collapsed.
1873 if (source
->type
!= OBJT_VNODE
) {
1875 vm_object_hold(source
);
1876 vm_object_chain_wait(source
, 0);
1877 if (source
->ref_count
== 1 &&
1878 source
->handle
== NULL
&&
1879 (source
->type
== OBJT_DEFAULT
||
1880 source
->type
== OBJT_SWAP
)) {
1882 vm_object_reference_locked(source
);
1883 vm_object_clear_flag(source
,
1886 vm_object_drop(source
);
1889 vm_object_reference_locked(source
);
1890 vm_object_clear_flag(source
, OBJ_ONEMAPPING
);
1892 vm_object_reference_quick(source
);
1893 vm_object_clear_flag(source
, OBJ_ONEMAPPING
);
1898 * Allocate a new object with the given length. The new object
1899 * is returned referenced but we may have to add another one.
1900 * If we are adding a second reference we must clear OBJ_ONEMAPPING.
1901 * (typically because the caller is about to clone a vm_map_entry).
1903 * The source object currently has an extra reference to prevent
1904 * collapses into it while we mess with its shadow list, which
1905 * we will remove later in this routine.
1907 * The target object may require a second reference if asked for one
1910 result
= vm_object_allocate(OBJT_DEFAULT
, length
);
1912 panic("vm_object_shadow: no object for shadowing");
1913 vm_object_hold(result
);
1915 vm_object_reference_locked(result
);
1916 vm_object_clear_flag(result
, OBJ_ONEMAPPING
);
1920 * The new object shadows the source object. Chain wait before
1921 * adjusting shadow_count or the shadow list to avoid races.
1923 * Try to optimize the result object's page color when shadowing
1924 * in order to maintain page coloring consistency in the combined
1927 * The backing_object reference to source requires adding a ref to
1928 * source. We simply inherit the ref from the original *objectp
1929 * (which we are replacing) so no additional refs need to be added.
1930 * (we must still clean up the extra ref we had to prevent collapse
1933 * SHADOWING IS NOT APPLICABLE TO OBJT_VNODE OBJECTS
1935 KKASSERT(result
->backing_object
== NULL
);
1936 result
->backing_object
= source
;
1938 if (useshadowlist
) {
1939 vm_object_chain_wait(source
, 0);
1940 LIST_INSERT_HEAD(&source
->shadow_head
,
1941 result
, shadow_list
);
1942 source
->shadow_count
++;
1943 source
->generation
++;
1944 vm_object_set_flag(result
, OBJ_ONSHADOW
);
1946 /* cpu localization twist */
1947 result
->pg_color
= vm_quickcolor();
1951 * Adjust the return storage. Drop the ref on source before
1954 result
->backing_object_offset
= *offset
;
1955 vm_object_drop(result
);
1958 if (useshadowlist
) {
1959 vm_object_deallocate_locked(source
);
1960 vm_object_drop(source
);
1962 vm_object_deallocate(source
);
1967 * Return the new things
1972 #define OBSC_TEST_ALL_SHADOWED 0x0001
1973 #define OBSC_COLLAPSE_NOWAIT 0x0002
1974 #define OBSC_COLLAPSE_WAIT 0x0004
1976 static int vm_object_backing_scan_callback(vm_page_t p
, void *data
);
1979 * The caller must hold the object.
1982 vm_object_backing_scan(vm_object_t object
, vm_object_t backing_object
, int op
)
1984 struct rb_vm_page_scan_info info
;
1987 vm_object_assert_held(object
);
1988 vm_object_assert_held(backing_object
);
1990 KKASSERT(backing_object
== object
->backing_object
);
1991 info
.backing_offset_index
= OFF_TO_IDX(object
->backing_object_offset
);
1994 * Initial conditions
1996 if (op
& OBSC_TEST_ALL_SHADOWED
) {
1998 * We do not want to have to test for the existence of
1999 * swap pages in the backing object. XXX but with the
2000 * new swapper this would be pretty easy to do.
2002 * XXX what about anonymous MAP_SHARED memory that hasn't
2003 * been ZFOD faulted yet? If we do not test for this, the
2004 * shadow test may succeed! XXX
2006 if (backing_object
->type
!= OBJT_DEFAULT
)
2009 if (op
& OBSC_COLLAPSE_WAIT
) {
2010 KKASSERT((backing_object
->flags
& OBJ_DEAD
) == 0);
2011 vm_object_set_flag(backing_object
, OBJ_DEAD
);
2013 n
= VMOBJ_HASH(backing_object
);
2014 lwkt_gettoken(&vmobj_tokens
[n
]);
2015 TAILQ_REMOVE(&vm_object_lists
[n
], backing_object
, object_list
);
2016 lwkt_reltoken(&vmobj_tokens
[n
]);
2017 atomic_add_long(&vm_object_count
, -1);
2021 * Our scan. We have to retry if a negative error code is returned,
2022 * otherwise 0 or 1 will be returned in info.error. 0 Indicates that
2023 * the scan had to be stopped because the parent does not completely
2026 info
.object
= object
;
2027 info
.backing_object
= backing_object
;
2032 vm_page_rb_tree_RB_SCAN(&backing_object
->rb_memq
, NULL
,
2033 vm_object_backing_scan_callback
,
2035 } while (info
.error
< 0);
2041 * The caller must hold the object.
2044 vm_object_backing_scan_callback(vm_page_t p
, void *data
)
2046 struct rb_vm_page_scan_info
*info
= data
;
2047 vm_object_t backing_object
;
2050 vm_pindex_t new_pindex
;
2051 vm_pindex_t backing_offset_index
;
2055 new_pindex
= pindex
- info
->backing_offset_index
;
2057 object
= info
->object
;
2058 backing_object
= info
->backing_object
;
2059 backing_offset_index
= info
->backing_offset_index
;
2061 if (op
& OBSC_TEST_ALL_SHADOWED
) {
2065 * Ignore pages outside the parent object's range
2066 * and outside the parent object's mapping of the
2069 * note that we do not busy the backing object's
2072 if (pindex
< backing_offset_index
||
2073 new_pindex
>= object
->size
2079 * See if the parent has the page or if the parent's
2080 * object pager has the page. If the parent has the
2081 * page but the page is not valid, the parent's
2082 * object pager must have the page.
2084 * If this fails, the parent does not completely shadow
2085 * the object and we might as well give up now.
2087 pp
= vm_page_lookup(object
, new_pindex
);
2088 if ((pp
== NULL
|| pp
->valid
== 0) &&
2089 !vm_pager_has_page(object
, new_pindex
)
2091 info
->error
= 0; /* problemo */
2092 return(-1); /* stop the scan */
2097 * Check for busy page. Note that we may have lost (p) when we
2098 * possibly blocked above.
2100 if (op
& (OBSC_COLLAPSE_WAIT
| OBSC_COLLAPSE_NOWAIT
)) {
2103 if (vm_page_busy_try(p
, TRUE
)) {
2104 if (op
& OBSC_COLLAPSE_NOWAIT
) {
2108 * If we slept, anything could have
2109 * happened. Ask that the scan be restarted.
2111 * Since the object is marked dead, the
2112 * backing offset should not have changed.
2114 vm_page_sleep_busy(p
, TRUE
, "vmocol");
2121 * If (p) is no longer valid restart the scan.
2123 if (p
->object
!= backing_object
|| p
->pindex
!= pindex
) {
2124 kprintf("vm_object_backing_scan: Warning: page "
2125 "%p ripped out from under us\n", p
);
2131 if (op
& OBSC_COLLAPSE_NOWAIT
) {
2132 if (p
->valid
== 0 ||
2134 (p
->flags
& PG_NEED_COMMIT
)) {
2139 /* XXX what if p->valid == 0 , hold_count, etc? */
2143 p
->object
== backing_object
,
2144 ("vm_object_qcollapse(): object mismatch")
2148 * Destroy any associated swap
2150 if (backing_object
->type
== OBJT_SWAP
)
2151 swap_pager_freespace(backing_object
, p
->pindex
, 1);
2154 p
->pindex
< backing_offset_index
||
2155 new_pindex
>= object
->size
2158 * Page is out of the parent object's range, we
2159 * can simply destroy it.
2161 vm_page_protect(p
, VM_PROT_NONE
);
2166 pp
= vm_page_lookup(object
, new_pindex
);
2167 if (pp
!= NULL
|| vm_pager_has_page(object
, new_pindex
)) {
2169 * page already exists in parent OR swap exists
2170 * for this location in the parent. Destroy
2171 * the original page from the backing object.
2173 * Leave the parent's page alone
2175 vm_page_protect(p
, VM_PROT_NONE
);
2181 * Page does not exist in parent, rename the
2182 * page from the backing object to the main object.
2184 * If the page was mapped to a process, it can remain
2185 * mapped through the rename.
2187 if ((p
->queue
- p
->pc
) == PQ_CACHE
)
2188 vm_page_deactivate(p
);
2190 vm_page_rename(p
, object
, new_pindex
);
2192 /* page automatically made dirty by rename */
2198 * This version of collapse allows the operation to occur earlier and
2199 * when paging_in_progress is true for an object... This is not a complete
2200 * operation, but should plug 99.9% of the rest of the leaks.
2202 * The caller must hold the object and backing_object and both must be
2205 * (only called from vm_object_collapse)
2208 vm_object_qcollapse(vm_object_t object
, vm_object_t backing_object
)
2210 if (backing_object
->ref_count
== 1) {
2211 atomic_add_int(&backing_object
->ref_count
, 2);
2212 #if defined(DEBUG_LOCKS)
2213 debugvm_object_add(backing_object
, "qcollapse", 1, 2);
2215 vm_object_backing_scan(object
, backing_object
,
2216 OBSC_COLLAPSE_NOWAIT
);
2217 atomic_add_int(&backing_object
->ref_count
, -2);
2218 #if defined(DEBUG_LOCKS)
2219 debugvm_object_add(backing_object
, "qcollapse", 2, -2);
2225 * Collapse an object with the object backing it. Pages in the backing
2226 * object are moved into the parent, and the backing object is deallocated.
2227 * Any conflict is resolved in favor of the parent's existing pages.
2229 * object must be held and chain-locked on call.
2231 * The caller must have an extra ref on object to prevent a race from
2232 * destroying it during the collapse.
2235 vm_object_collapse(vm_object_t object
, struct vm_object_dealloc_list
**dlistp
)
2237 struct vm_object_dealloc_list
*dlist
= NULL
;
2238 vm_object_t backing_object
;
2241 * Only one thread is attempting a collapse at any given moment.
2242 * There are few restrictions for (object) that callers of this
2243 * function check so reentrancy is likely.
2245 KKASSERT(object
!= NULL
);
2246 vm_object_assert_held(object
);
2247 KKASSERT(object
->chainlk
& (CHAINLK_MASK
| CHAINLK_EXCL
));
2254 * We can only collapse a DEFAULT/SWAP object with a
2255 * DEFAULT/SWAP object.
2257 if (object
->type
!= OBJT_DEFAULT
&& object
->type
!= OBJT_SWAP
) {
2258 backing_object
= NULL
;
2262 backing_object
= object
->backing_object
;
2263 if (backing_object
== NULL
)
2265 if (backing_object
->type
!= OBJT_DEFAULT
&&
2266 backing_object
->type
!= OBJT_SWAP
) {
2267 backing_object
= NULL
;
2272 * Hold the backing_object and check for races
2274 vm_object_hold(backing_object
);
2275 if (backing_object
!= object
->backing_object
||
2276 (backing_object
->type
!= OBJT_DEFAULT
&&
2277 backing_object
->type
!= OBJT_SWAP
)) {
2278 vm_object_drop(backing_object
);
2283 * Chain-lock the backing object too because if we
2284 * successfully merge its pages into the top object we
2285 * will collapse backing_object->backing_object as the
2286 * new backing_object. Re-check that it is still our
2289 vm_object_chain_acquire(backing_object
, 0);
2290 if (backing_object
!= object
->backing_object
) {
2291 vm_object_chain_release(backing_object
);
2292 vm_object_drop(backing_object
);
2297 * we check the backing object first, because it is most likely
2300 if (backing_object
->handle
!= NULL
||
2301 (backing_object
->type
!= OBJT_DEFAULT
&&
2302 backing_object
->type
!= OBJT_SWAP
) ||
2303 (backing_object
->flags
& OBJ_DEAD
) ||
2304 object
->handle
!= NULL
||
2305 (object
->type
!= OBJT_DEFAULT
&&
2306 object
->type
!= OBJT_SWAP
) ||
2307 (object
->flags
& OBJ_DEAD
)) {
2312 * If paging is in progress we can't do a normal collapse.
2315 object
->paging_in_progress
!= 0 ||
2316 backing_object
->paging_in_progress
!= 0
2318 vm_object_qcollapse(object
, backing_object
);
2323 * We know that we can either collapse the backing object (if
2324 * the parent is the only reference to it) or (perhaps) have
2325 * the parent bypass the object if the parent happens to shadow
2326 * all the resident pages in the entire backing object.
2328 * This is ignoring pager-backed pages such as swap pages.
2329 * vm_object_backing_scan fails the shadowing test in this
2332 if (backing_object
->ref_count
== 1) {
2334 * If there is exactly one reference to the backing
2335 * object, we can collapse it into the parent.
2337 KKASSERT(object
->backing_object
== backing_object
);
2338 vm_object_backing_scan(object
, backing_object
,
2339 OBSC_COLLAPSE_WAIT
);
2342 * Move the pager from backing_object to object.
2344 if (backing_object
->type
== OBJT_SWAP
) {
2345 vm_object_pip_add(backing_object
, 1);
2348 * scrap the paging_offset junk and do a
2349 * discrete copy. This also removes major
2350 * assumptions about how the swap-pager
2351 * works from where it doesn't belong. The
2352 * new swapper is able to optimize the
2353 * destroy-source case.
2355 vm_object_pip_add(object
, 1);
2356 swap_pager_copy(backing_object
, object
,
2357 OFF_TO_IDX(object
->backing_object_offset
),
2359 vm_object_pip_wakeup(object
);
2360 vm_object_pip_wakeup(backing_object
);
2364 * Object now shadows whatever backing_object did.
2365 * Remove object from backing_object's shadow_list.
2367 * Removing object from backing_objects shadow list
2368 * requires releasing object, which we will do below.
2370 KKASSERT(object
->backing_object
== backing_object
);
2371 if (object
->flags
& OBJ_ONSHADOW
) {
2372 LIST_REMOVE(object
, shadow_list
);
2373 backing_object
->shadow_count
--;
2374 backing_object
->generation
++;
2375 vm_object_clear_flag(object
, OBJ_ONSHADOW
);
2379 * backing_object->backing_object moves from within
2380 * backing_object to within object.
2382 * OBJT_VNODE bbobj's should have empty shadow lists.
2384 while ((bbobj
= backing_object
->backing_object
) != NULL
) {
2385 if (bbobj
->type
== OBJT_VNODE
)
2386 vm_object_hold_shared(bbobj
);
2388 vm_object_hold(bbobj
);
2389 if (bbobj
== backing_object
->backing_object
)
2391 vm_object_drop(bbobj
);
2395 * We are removing backing_object from bbobj's
2396 * shadow list and adding object to bbobj's shadow
2397 * list, so the ref_count on bbobj is unchanged.
2400 if (backing_object
->flags
& OBJ_ONSHADOW
) {
2401 /* not locked exclusively if vnode */
2402 KKASSERT(bbobj
->type
!= OBJT_VNODE
);
2403 LIST_REMOVE(backing_object
,
2405 bbobj
->shadow_count
--;
2406 bbobj
->generation
++;
2407 vm_object_clear_flag(backing_object
,
2410 backing_object
->backing_object
= NULL
;
2412 object
->backing_object
= bbobj
;
2414 if (bbobj
->type
!= OBJT_VNODE
) {
2415 LIST_INSERT_HEAD(&bbobj
->shadow_head
,
2416 object
, shadow_list
);
2417 bbobj
->shadow_count
++;
2418 bbobj
->generation
++;
2419 vm_object_set_flag(object
,
2424 object
->backing_object_offset
+=
2425 backing_object
->backing_object_offset
;
2427 vm_object_drop(bbobj
);
2430 * Discard the old backing_object. Nothing should be
2431 * able to ref it, other than a vm_map_split(),
2432 * and vm_map_split() will stall on our chain lock.
2433 * And we control the parent so it shouldn't be
2434 * possible for it to go away either.
2436 * Since the backing object has no pages, no pager
2437 * left, and no object references within it, all
2438 * that is necessary is to dispose of it.
2440 KASSERT(backing_object
->ref_count
== 1,
2441 ("backing_object %p was somehow "
2442 "re-referenced during collapse!",
2444 KASSERT(RB_EMPTY(&backing_object
->rb_memq
),
2445 ("backing_object %p somehow has left "
2446 "over pages during collapse!",
2450 * The object can be destroyed.
2452 * XXX just fall through and dodealloc instead
2453 * of forcing destruction?
2455 atomic_add_int(&backing_object
->ref_count
, -1);
2456 #if defined(DEBUG_LOCKS)
2457 debugvm_object_add(backing_object
, "collapse", 1, -1);
2459 if ((backing_object
->flags
& OBJ_DEAD
) == 0)
2460 vm_object_terminate(backing_object
);
2465 * If we do not entirely shadow the backing object,
2466 * there is nothing we can do so we give up.
2468 if (vm_object_backing_scan(object
, backing_object
,
2469 OBSC_TEST_ALL_SHADOWED
) == 0) {
2474 * bbobj is backing_object->backing_object. Since
2475 * object completely shadows backing_object we can
2476 * bypass it and become backed by bbobj instead.
2478 * The shadow list for vnode backing objects is not
2479 * used and a shared hold is allowed.
2481 while ((bbobj
= backing_object
->backing_object
) != NULL
) {
2482 if (bbobj
->type
== OBJT_VNODE
)
2483 vm_object_hold_shared(bbobj
);
2485 vm_object_hold(bbobj
);
2486 if (bbobj
== backing_object
->backing_object
)
2488 vm_object_drop(bbobj
);
2492 * Make object shadow bbobj instead of backing_object.
2493 * Remove object from backing_object's shadow list.
2495 * Deallocating backing_object will not remove
2496 * it, since its reference count is at least 2.
2498 * Removing object from backing_object's shadow
2499 * list requires releasing a ref, which we do
2500 * below by setting dodealloc to 1.
2502 KKASSERT(object
->backing_object
== backing_object
);
2503 if (object
->flags
& OBJ_ONSHADOW
) {
2504 LIST_REMOVE(object
, shadow_list
);
2505 backing_object
->shadow_count
--;
2506 backing_object
->generation
++;
2507 vm_object_clear_flag(object
, OBJ_ONSHADOW
);
2511 * Add a ref to bbobj, bbobj now shadows object.
2513 * NOTE: backing_object->backing_object still points
2514 * to bbobj. That relationship remains intact
2515 * because backing_object has > 1 ref, so
2516 * someone else is pointing to it (hence why
2517 * we can't collapse it into object and can
2518 * only handle the all-shadowed bypass case).
2521 if (bbobj
->type
!= OBJT_VNODE
) {
2522 vm_object_chain_wait(bbobj
, 0);
2523 vm_object_reference_locked(bbobj
);
2524 LIST_INSERT_HEAD(&bbobj
->shadow_head
,
2525 object
, shadow_list
);
2526 bbobj
->shadow_count
++;
2527 bbobj
->generation
++;
2528 vm_object_set_flag(object
,
2531 vm_object_reference_quick(bbobj
);
2533 object
->backing_object_offset
+=
2534 backing_object
->backing_object_offset
;
2535 object
->backing_object
= bbobj
;
2536 vm_object_drop(bbobj
);
2538 object
->backing_object
= NULL
;
2542 * Drop the reference count on backing_object. To
2543 * handle ref_count races properly we can't assume
2544 * that the ref_count is still at least 2 so we
2545 * have to actually call vm_object_deallocate()
2546 * (after clearing the chainlock).
2553 * Ok, we want to loop on the new object->bbobj association,
2554 * possibly collapsing it further. However if dodealloc is
2555 * non-zero we have to deallocate the backing_object which
2556 * itself can potentially undergo a collapse, creating a
2557 * recursion depth issue with the LWKT token subsystem.
2559 * In the case where we must deallocate the backing_object
2560 * it is possible now that the backing_object has a single
2561 * shadow count on some other object (not represented here
2562 * as yet), since it no longer shadows us. Thus when we
2563 * call vm_object_deallocate() it may attempt to collapse
2564 * itself into its remaining parent.
2567 struct vm_object_dealloc_list
*dtmp
;
2569 vm_object_chain_release(backing_object
);
2570 vm_object_unlock(backing_object
);
2571 /* backing_object remains held */
2574 * Auto-deallocation list for caller convenience.
2579 dtmp
= kmalloc(sizeof(*dtmp
), M_TEMP
, M_WAITOK
);
2580 dtmp
->object
= backing_object
;
2581 dtmp
->next
= *dlistp
;
2584 vm_object_chain_release(backing_object
);
2585 vm_object_drop(backing_object
);
2587 /* backing_object = NULL; not needed */
2592 * Clean up any left over backing_object
2594 if (backing_object
) {
2595 vm_object_chain_release(backing_object
);
2596 vm_object_drop(backing_object
);
2600 * Clean up any auto-deallocation list. This is a convenience
2601 * for top-level callers so they don't have to pass &dlist.
2602 * Do not clean up any caller-passed dlistp, the caller will
2606 vm_object_deallocate_list(&dlist
);
2611 * vm_object_collapse() may collect additional objects in need of
2612 * deallocation. This routine deallocates these objects. The
2613 * deallocation itself can trigger additional collapses (which the
2614 * deallocate function takes care of). This procedure is used to
2615 * reduce procedural recursion since these vm_object shadow chains
2616 * can become quite long.
2619 vm_object_deallocate_list(struct vm_object_dealloc_list
**dlistp
)
2621 struct vm_object_dealloc_list
*dlist
;
2623 while ((dlist
= *dlistp
) != NULL
) {
2624 *dlistp
= dlist
->next
;
2625 vm_object_lock(dlist
->object
);
2626 vm_object_deallocate_locked(dlist
->object
);
2627 vm_object_drop(dlist
->object
);
2628 kfree(dlist
, M_TEMP
);
2633 * Removes all physical pages in the specified object range from the
2634 * object's list of pages.
2638 static int vm_object_page_remove_callback(vm_page_t p
, void *data
);
2641 vm_object_page_remove(vm_object_t object
, vm_pindex_t start
, vm_pindex_t end
,
2642 boolean_t clean_only
)
2644 struct rb_vm_page_scan_info info
;
2648 * Degenerate cases and assertions
2650 vm_object_hold(object
);
2651 if (object
== NULL
||
2652 (object
->resident_page_count
== 0 && object
->swblock_count
== 0)) {
2653 vm_object_drop(object
);
2656 KASSERT(object
->type
!= OBJT_PHYS
,
2657 ("attempt to remove pages from a physical object"));
2660 * Indicate that paging is occuring on the object
2662 vm_object_pip_add(object
, 1);
2665 * Figure out the actual removal range and whether we are removing
2666 * the entire contents of the object or not. If removing the entire
2667 * contents, be sure to get all pages, even those that might be
2668 * beyond the end of the object.
2670 info
.object
= object
;
2671 info
.start_pindex
= start
;
2673 info
.end_pindex
= (vm_pindex_t
)-1;
2675 info
.end_pindex
= end
- 1;
2676 info
.limit
= clean_only
;
2678 all
= (start
== 0 && info
.end_pindex
>= object
->size
- 1);
2681 * Loop until we are sure we have gotten them all.
2685 vm_page_rb_tree_RB_SCAN(&object
->rb_memq
, rb_vm_page_scancmp
,
2686 vm_object_page_remove_callback
, &info
);
2687 } while (info
.error
);
2690 * Remove any related swap if throwing away pages, or for
2691 * non-swap objects (the swap is a clean copy in that case).
2693 if (object
->type
!= OBJT_SWAP
|| clean_only
== FALSE
) {
2695 swap_pager_freespace_all(object
);
2697 swap_pager_freespace(object
, info
.start_pindex
,
2698 info
.end_pindex
- info
.start_pindex
+ 1);
2704 vm_object_pip_wakeup(object
);
2705 vm_object_drop(object
);
2709 * The caller must hold the object.
2711 * NOTE: User yields are allowed when removing more than one page, but not
2712 * allowed if only removing one page (the path for single page removals
2713 * might hold a spinlock).
2716 vm_object_page_remove_callback(vm_page_t p
, void *data
)
2718 struct rb_vm_page_scan_info
*info
= data
;
2720 if ((++info
->count
& 63) == 0)
2723 if (info
->object
!= p
->object
||
2724 p
->pindex
< info
->start_pindex
||
2725 p
->pindex
> info
->end_pindex
) {
2726 kprintf("vm_object_page_remove_callbackA: obj/pg race %p/%p\n",
2730 if (vm_page_busy_try(p
, TRUE
)) {
2731 vm_page_sleep_busy(p
, TRUE
, "vmopar");
2735 if (info
->object
!= p
->object
) {
2736 /* this should never happen */
2737 kprintf("vm_object_page_remove_callbackB: obj/pg race %p/%p\n",
2744 * Wired pages cannot be destroyed, but they can be invalidated
2745 * and we do so if clean_only (limit) is not set.
2747 * WARNING! The page may be wired due to being part of a buffer
2748 * cache buffer, and the buffer might be marked B_CACHE.
2749 * This is fine as part of a truncation but VFSs must be
2750 * sure to fix the buffer up when re-extending the file.
2752 * NOTE! PG_NEED_COMMIT is ignored.
2754 if (p
->wire_count
!= 0) {
2755 vm_page_protect(p
, VM_PROT_NONE
);
2756 if (info
->limit
== 0)
2763 * limit is our clean_only flag. If set and the page is dirty or
2764 * requires a commit, do not free it. If set and the page is being
2765 * held by someone, do not free it.
2767 if (info
->limit
&& p
->valid
) {
2768 vm_page_test_dirty(p
);
2769 if ((p
->valid
& p
->dirty
) || (p
->flags
& PG_NEED_COMMIT
)) {
2778 vm_page_protect(p
, VM_PROT_NONE
);
2785 * Coalesces two objects backing up adjoining regions of memory into a
2788 * returns TRUE if objects were combined.
2790 * NOTE: Only works at the moment if the second object is NULL -
2791 * if it's not, which object do we lock first?
2794 * prev_object First object to coalesce
2795 * prev_offset Offset into prev_object
2796 * next_object Second object into coalesce
2797 * next_offset Offset into next_object
2799 * prev_size Size of reference to prev_object
2800 * next_size Size of reference to next_object
2802 * The caller does not need to hold (prev_object) but must have a stable
2803 * pointer to it (typically by holding the vm_map locked).
2806 vm_object_coalesce(vm_object_t prev_object
, vm_pindex_t prev_pindex
,
2807 vm_size_t prev_size
, vm_size_t next_size
)
2809 vm_pindex_t next_pindex
;
2811 if (prev_object
== NULL
)
2814 vm_object_hold(prev_object
);
2816 if (prev_object
->type
!= OBJT_DEFAULT
&&
2817 prev_object
->type
!= OBJT_SWAP
) {
2818 vm_object_drop(prev_object
);
2823 * Try to collapse the object first
2825 vm_object_chain_acquire(prev_object
, 0);
2826 vm_object_collapse(prev_object
, NULL
);
2829 * Can't coalesce if: . more than one reference . paged out . shadows
2830 * another object . has a copy elsewhere (any of which mean that the
2831 * pages not mapped to prev_entry may be in use anyway)
2834 if (prev_object
->backing_object
!= NULL
) {
2835 vm_object_chain_release(prev_object
);
2836 vm_object_drop(prev_object
);
2840 prev_size
>>= PAGE_SHIFT
;
2841 next_size
>>= PAGE_SHIFT
;
2842 next_pindex
= prev_pindex
+ prev_size
;
2844 if ((prev_object
->ref_count
> 1) &&
2845 (prev_object
->size
!= next_pindex
)) {
2846 vm_object_chain_release(prev_object
);
2847 vm_object_drop(prev_object
);
2852 * Remove any pages that may still be in the object from a previous
2855 if (next_pindex
< prev_object
->size
) {
2856 vm_object_page_remove(prev_object
,
2858 next_pindex
+ next_size
, FALSE
);
2859 if (prev_object
->type
== OBJT_SWAP
)
2860 swap_pager_freespace(prev_object
,
2861 next_pindex
, next_size
);
2865 * Extend the object if necessary.
2867 if (next_pindex
+ next_size
> prev_object
->size
)
2868 prev_object
->size
= next_pindex
+ next_size
;
2870 vm_object_chain_release(prev_object
);
2871 vm_object_drop(prev_object
);
2876 * Make the object writable and flag is being possibly dirty.
2878 * The object might not be held (or might be held but held shared),
2879 * the related vnode is probably not held either. Object and vnode are
2880 * stable by virtue of the vm_page busied by the caller preventing
2883 * If the related mount is flagged MNTK_THR_SYNC we need to call
2884 * vsetobjdirty(). Filesystems using this option usually shortcut
2885 * synchronization by only scanning the syncer list.
2888 vm_object_set_writeable_dirty(vm_object_t object
)
2892 /*vm_object_assert_held(object);*/
2894 * Avoid contention in vm fault path by checking the state before
2895 * issuing an atomic op on it.
2897 if ((object
->flags
& (OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
)) !=
2898 (OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
)) {
2899 vm_object_set_flag(object
, OBJ_WRITEABLE
|OBJ_MIGHTBEDIRTY
);
2901 if (object
->type
== OBJT_VNODE
&&
2902 (vp
= (struct vnode
*)object
->handle
) != NULL
) {
2903 if ((vp
->v_flag
& VOBJDIRTY
) == 0) {
2905 (vp
->v_mount
->mnt_kern_flag
& MNTK_THR_SYNC
)) {
2907 * New style THR_SYNC places vnodes on the
2908 * syncer list more deterministically.
2913 * Old style scan would not necessarily place
2914 * a vnode on the syncer list when possibly
2915 * modified via mmap.
2917 vsetflags(vp
, VOBJDIRTY
);
2923 #include "opt_ddb.h"
2925 #include <sys/kernel.h>
2927 #include <sys/cons.h>
2929 #include <ddb/ddb.h>
2931 static int _vm_object_in_map (vm_map_t map
, vm_object_t object
,
2932 vm_map_entry_t entry
);
2933 static int vm_object_in_map (vm_object_t object
);
2936 * The caller must hold the object.
2939 _vm_object_in_map(vm_map_t map
, vm_object_t object
, vm_map_entry_t entry
)
2942 vm_map_entry_t tmpe
;
2943 vm_object_t obj
, nobj
;
2949 tmpe
= map
->header
.next
;
2950 entcount
= map
->nentries
;
2951 while (entcount
-- && (tmpe
!= &map
->header
)) {
2952 if( _vm_object_in_map(map
, object
, tmpe
)) {
2959 switch(entry
->maptype
) {
2960 case VM_MAPTYPE_SUBMAP
:
2961 tmpm
= entry
->object
.sub_map
;
2962 tmpe
= tmpm
->header
.next
;
2963 entcount
= tmpm
->nentries
;
2964 while (entcount
-- && tmpe
!= &tmpm
->header
) {
2965 if( _vm_object_in_map(tmpm
, object
, tmpe
)) {
2971 case VM_MAPTYPE_NORMAL
:
2972 case VM_MAPTYPE_VPAGETABLE
:
2973 obj
= entry
->object
.vm_object
;
2975 if (obj
== object
) {
2976 if (obj
!= entry
->object
.vm_object
)
2977 vm_object_drop(obj
);
2980 while ((nobj
= obj
->backing_object
) != NULL
) {
2981 vm_object_hold(nobj
);
2982 if (nobj
== obj
->backing_object
)
2984 vm_object_drop(nobj
);
2986 if (obj
!= entry
->object
.vm_object
) {
2988 vm_object_lock_swap();
2989 vm_object_drop(obj
);
3000 static int vm_object_in_map_callback(struct proc
*p
, void *data
);
3002 struct vm_object_in_map_info
{
3011 vm_object_in_map(vm_object_t object
)
3013 struct vm_object_in_map_info info
;
3016 info
.object
= object
;
3018 allproc_scan(vm_object_in_map_callback
, &info
);
3021 if( _vm_object_in_map(&kernel_map
, object
, 0))
3023 if( _vm_object_in_map(&pager_map
, object
, 0))
3025 if( _vm_object_in_map(&buffer_map
, object
, 0))
3034 vm_object_in_map_callback(struct proc
*p
, void *data
)
3036 struct vm_object_in_map_info
*info
= data
;
3039 if (_vm_object_in_map(&p
->p_vmspace
->vm_map
, info
->object
, 0)) {
3047 DB_SHOW_COMMAND(vmochk
, vm_object_check
)
3053 * make sure that internal objs are in a map somewhere
3054 * and none have zero ref counts.
3056 for (n
= 0; n
< VMOBJ_HSIZE
; ++n
) {
3057 for (object
= TAILQ_FIRST(&vm_object_lists
[n
]);
3059 object
= TAILQ_NEXT(object
, object_list
)) {
3060 if (object
->type
== OBJT_MARKER
)
3062 if (object
->handle
!= NULL
||
3063 (object
->type
!= OBJT_DEFAULT
&&
3064 object
->type
!= OBJT_SWAP
)) {
3067 if (object
->ref_count
== 0) {
3068 db_printf("vmochk: internal obj has "
3069 "zero ref count: %ld\n",
3070 (long)object
->size
);
3072 if (vm_object_in_map(object
))
3074 db_printf("vmochk: internal obj is not in a map: "
3075 "ref: %d, size: %lu: 0x%lx, "
3076 "backing_object: %p\n",
3077 object
->ref_count
, (u_long
)object
->size
,
3078 (u_long
)object
->size
,
3079 (void *)object
->backing_object
);
3087 DB_SHOW_COMMAND(object
, vm_object_print_static
)
3089 /* XXX convert args. */
3090 vm_object_t object
= (vm_object_t
)addr
;
3091 boolean_t full
= have_addr
;
3095 /* XXX count is an (unused) arg. Avoid shadowing it. */
3096 #define count was_count
3104 "Object %p: type=%d, size=0x%lx, res=%d, ref=%d, flags=0x%x\n",
3105 object
, (int)object
->type
, (u_long
)object
->size
,
3106 object
->resident_page_count
, object
->ref_count
, object
->flags
);
3108 * XXX no %qd in kernel. Truncate object->backing_object_offset.
3110 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%lx\n",
3111 object
->shadow_count
,
3112 object
->backing_object
? object
->backing_object
->ref_count
: 0,
3113 object
->backing_object
, (long)object
->backing_object_offset
);
3120 RB_FOREACH(p
, vm_page_rb_tree
, &object
->rb_memq
) {
3122 db_iprintf("memory:=");
3123 else if (count
== 6) {
3131 db_printf("(off=0x%lx,page=0x%lx)",
3132 (u_long
) p
->pindex
, (u_long
) VM_PAGE_TO_PHYS(p
));
3143 * XXX need this non-static entry for calling from vm_map_print.
3148 vm_object_print(/* db_expr_t */ long addr
,
3149 boolean_t have_addr
,
3150 /* db_expr_t */ long count
,
3153 vm_object_print_static(addr
, have_addr
, count
, modif
);
3159 DB_SHOW_COMMAND(vmopag
, vm_object_print_pages
)
3166 for (n
= 0; n
< VMOBJ_HSIZE
; ++n
) {
3167 for (object
= TAILQ_FIRST(&vm_object_lists
[n
]);
3169 object
= TAILQ_NEXT(object
, object_list
)) {
3170 vm_pindex_t idx
, fidx
;
3172 vm_paddr_t pa
= -1, padiff
;
3176 if (object
->type
== OBJT_MARKER
)
3178 db_printf("new object: %p\n", (void *)object
);
3188 osize
= object
->size
;
3191 for (idx
= 0; idx
< osize
; idx
++) {
3192 m
= vm_page_lookup(object
, idx
);
3195 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3196 (long)fidx
, rcount
, (long)pa
);
3210 (VM_PAGE_TO_PHYS(m
) == pa
+ rcount
* PAGE_SIZE
)) {
3215 padiff
= pa
+ rcount
* PAGE_SIZE
- VM_PAGE_TO_PHYS(m
);
3216 padiff
>>= PAGE_SHIFT
;
3217 padiff
&= PQ_L2_MASK
;
3219 pa
= VM_PAGE_TO_PHYS(m
) - rcount
* PAGE_SIZE
;
3223 db_printf(" index(%ld)run(%d)pa(0x%lx)",
3224 (long)fidx
, rcount
, (long)pa
);
3225 db_printf("pd(%ld)\n", (long)padiff
);
3235 pa
= VM_PAGE_TO_PHYS(m
);
3239 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
3240 (long)fidx
, rcount
, (long)pa
);