2 * Copyright (c) 1991, 1993
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 * 4. 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.
62 * Virtual memory object module.
65 #include <sys/cdefs.h>
66 __FBSDID("$FreeBSD$");
70 #include <sys/param.h>
71 #include <sys/systm.h>
74 #include <sys/mount.h>
75 #include <sys/kernel.h>
76 #include <sys/sysctl.h>
77 #include <sys/mutex.h>
78 #include <sys/proc.h> /* for curproc, pageproc */
79 #include <sys/socket.h>
80 #include <sys/resourcevar.h>
81 #include <sys/vnode.h>
82 #include <sys/vmmeter.h>
86 #include <vm/vm_param.h>
88 #include <vm/vm_map.h>
89 #include <vm/vm_object.h>
90 #include <vm/vm_page.h>
91 #include <vm/vm_pageout.h>
92 #include <vm/vm_pager.h>
93 #include <vm/swap_pager.h>
94 #include <vm/vm_kern.h>
95 #include <vm/vm_extern.h>
96 #include <vm/vm_reserv.h>
100 SYSCTL_INT(_vm, OID_AUTO, old_msync, CTLFLAG_RW, &old_msync, 0,
101 "Use old (insecure) msync behavior");
103 static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p,
104 int pagerflags, int flags, boolean_t *clearobjflags,
106 static boolean_t vm_object_page_remove_write(vm_page_t p, int flags,
107 boolean_t *clearobjflags);
108 static void vm_object_qcollapse(vm_object_t object);
109 static void vm_object_vndeallocate(vm_object_t object);
112 * Virtual memory objects maintain the actual data
113 * associated with allocated virtual memory. A given
114 * page of memory exists within exactly one object.
116 * An object is only deallocated when all "references"
117 * are given up. Only one "reference" to a given
118 * region of an object should be writeable.
120 * Associated with each object is a list of all resident
121 * memory pages belonging to that object; this list is
122 * maintained by the "vm_page" module, and locked by the object's
125 * Each object also records a "pager" routine which is
126 * used to retrieve (and store) pages to the proper backing
127 * storage. In addition, objects may be backed by other
128 * objects from which they were virtual-copied.
130 * The only items within the object structure which are
131 * modified after time of creation are:
132 * reference count locked by object's lock
133 * pager routine locked by object's lock
137 struct object_q vm_object_list;
138 struct mtx vm_object_list_mtx; /* lock for object list and count */
140 struct vm_object kernel_object_store;
141 struct vm_object kmem_object_store;
143 static SYSCTL_NODE(_vm_stats, OID_AUTO, object, CTLFLAG_RD, 0,
146 static long object_collapses;
147 SYSCTL_LONG(_vm_stats_object, OID_AUTO, collapses, CTLFLAG_RD,
148 &object_collapses, 0, "VM object collapses");
150 static long object_bypasses;
151 SYSCTL_LONG(_vm_stats_object, OID_AUTO, bypasses, CTLFLAG_RD,
152 &object_bypasses, 0, "VM object bypasses");
154 static uma_zone_t obj_zone;
156 static int vm_object_zinit(void *mem, int size, int flags);
159 static void vm_object_zdtor(void *mem, int size, void *arg);
162 vm_object_zdtor(void *mem, int size, void *arg)
166 object = (vm_object_t)mem;
167 KASSERT(TAILQ_EMPTY(&object->memq),
168 ("object %p has resident pages",
170 #if VM_NRESERVLEVEL > 0
171 KASSERT(LIST_EMPTY(&object->rvq),
172 ("object %p has reservations",
175 KASSERT(object->cache == NULL,
176 ("object %p has cached pages",
178 KASSERT(object->paging_in_progress == 0,
179 ("object %p paging_in_progress = %d",
180 object, object->paging_in_progress));
181 KASSERT(object->resident_page_count == 0,
182 ("object %p resident_page_count = %d",
183 object, object->resident_page_count));
184 KASSERT(object->shadow_count == 0,
185 ("object %p shadow_count = %d",
186 object, object->shadow_count));
191 vm_object_zinit(void *mem, int size, int flags)
195 object = (vm_object_t)mem;
196 bzero(&object->mtx, sizeof(object->mtx));
197 VM_OBJECT_LOCK_INIT(object, "standard object");
199 /* These are true for any object that has been freed */
200 object->paging_in_progress = 0;
201 object->resident_page_count = 0;
202 object->shadow_count = 0;
207 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object)
210 TAILQ_INIT(&object->memq);
211 LIST_INIT(&object->shadow_head);
217 panic("_vm_object_allocate: can't create OBJT_DEAD");
220 object->flags = OBJ_ONEMAPPING;
224 object->flags = OBJ_FICTITIOUS | OBJ_UNMANAGED;
227 object->flags = OBJ_FICTITIOUS;
230 object->flags = OBJ_UNMANAGED;
236 panic("_vm_object_allocate: type %d is undefined", type);
239 object->generation = 1;
240 object->ref_count = 1;
241 object->memattr = VM_MEMATTR_DEFAULT;
244 object->pg_color = 0;
245 object->handle = NULL;
246 object->backing_object = NULL;
247 object->backing_object_offset = (vm_ooffset_t) 0;
248 #if VM_NRESERVLEVEL > 0
249 LIST_INIT(&object->rvq);
251 object->cache = NULL;
253 mtx_lock(&vm_object_list_mtx);
254 TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
255 mtx_unlock(&vm_object_list_mtx);
261 * Initialize the VM objects module.
266 TAILQ_INIT(&vm_object_list);
267 mtx_init(&vm_object_list_mtx, "vm object_list", NULL, MTX_DEF);
269 VM_OBJECT_LOCK_INIT(kernel_object, "kernel object");
270 _vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
272 #if VM_NRESERVLEVEL > 0
273 kernel_object->flags |= OBJ_COLORED;
274 kernel_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
277 VM_OBJECT_LOCK_INIT(kmem_object, "kmem object");
278 _vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
280 #if VM_NRESERVLEVEL > 0
281 kmem_object->flags |= OBJ_COLORED;
282 kmem_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
286 * The lock portion of struct vm_object must be type stable due
287 * to vm_pageout_fallback_object_lock locking a vm object
288 * without holding any references to it.
290 obj_zone = uma_zcreate("VM OBJECT", sizeof (struct vm_object), NULL,
296 vm_object_zinit, NULL, UMA_ALIGN_PTR, UMA_ZONE_VM|UMA_ZONE_NOFREE);
300 vm_object_clear_flag(vm_object_t object, u_short bits)
303 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
304 object->flags &= ~bits;
308 * Sets the default memory attribute for the specified object. Pages
309 * that are allocated to this object are by default assigned this memory
312 * Presently, this function must be called before any pages are allocated
313 * to the object. In the future, this requirement may be relaxed for
314 * "default" and "swap" objects.
317 vm_object_set_memattr(vm_object_t object, vm_memattr_t memattr)
320 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
321 switch (object->type) {
329 if (!TAILQ_EMPTY(&object->memq))
330 return (KERN_FAILURE);
333 return (KERN_INVALID_ARGUMENT);
335 panic("vm_object_set_memattr: object %p is of undefined type",
338 object->memattr = memattr;
339 return (KERN_SUCCESS);
343 vm_object_pip_add(vm_object_t object, short i)
346 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
347 object->paging_in_progress += i;
351 vm_object_pip_subtract(vm_object_t object, short i)
354 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
355 object->paging_in_progress -= i;
359 vm_object_pip_wakeup(vm_object_t object)
362 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
363 object->paging_in_progress--;
364 if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
365 vm_object_clear_flag(object, OBJ_PIPWNT);
371 vm_object_pip_wakeupn(vm_object_t object, short i)
374 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
376 object->paging_in_progress -= i;
377 if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
378 vm_object_clear_flag(object, OBJ_PIPWNT);
384 vm_object_pip_wait(vm_object_t object, char *waitid)
387 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
388 while (object->paging_in_progress) {
389 object->flags |= OBJ_PIPWNT;
390 VM_OBJECT_SLEEP(object, object, PVM, waitid, 0);
395 * vm_object_allocate:
397 * Returns a new object with the given size.
400 vm_object_allocate(objtype_t type, vm_pindex_t size)
404 object = (vm_object_t)uma_zalloc(obj_zone, M_WAITOK);
405 _vm_object_allocate(type, size, object);
411 * vm_object_reference:
413 * Gets another reference to the given object. Note: OBJ_DEAD
414 * objects can be referenced during final cleaning.
417 vm_object_reference(vm_object_t object)
421 VM_OBJECT_LOCK(object);
422 vm_object_reference_locked(object);
423 VM_OBJECT_UNLOCK(object);
427 * vm_object_reference_locked:
429 * Gets another reference to the given object.
431 * The object must be locked.
434 vm_object_reference_locked(vm_object_t object)
438 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
440 if (object->type == OBJT_VNODE) {
447 * Handle deallocating an object of type OBJT_VNODE.
450 vm_object_vndeallocate(vm_object_t object)
452 struct vnode *vp = (struct vnode *) object->handle;
454 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
455 KASSERT(object->type == OBJT_VNODE,
456 ("vm_object_vndeallocate: not a vnode object"));
457 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
459 if (object->ref_count == 0) {
460 vprint("vm_object_vndeallocate", vp);
461 panic("vm_object_vndeallocate: bad object reference count");
465 if (object->ref_count > 1) {
467 VM_OBJECT_UNLOCK(object);
468 /* vrele may need the vnode lock. */
472 VM_OBJECT_UNLOCK(object);
473 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
475 VM_OBJECT_LOCK(object);
477 if (object->type == OBJT_DEAD) {
478 VM_OBJECT_UNLOCK(object);
481 if (object->ref_count == 0)
483 VM_OBJECT_UNLOCK(object);
490 * vm_object_deallocate:
492 * Release a reference to the specified object,
493 * gained either through a vm_object_allocate
494 * or a vm_object_reference call. When all references
495 * are gone, storage associated with this object
496 * may be relinquished.
498 * No object may be locked.
501 vm_object_deallocate(vm_object_t object)
505 while (object != NULL) {
506 VM_OBJECT_LOCK(object);
507 if (object->type == OBJT_VNODE) {
508 vm_object_vndeallocate(object);
512 KASSERT(object->ref_count != 0,
513 ("vm_object_deallocate: object deallocated too many times: %d", object->type));
516 * If the reference count goes to 0 we start calling
517 * vm_object_terminate() on the object chain.
518 * A ref count of 1 may be a special case depending on the
519 * shadow count being 0 or 1.
522 if (object->ref_count > 1) {
523 VM_OBJECT_UNLOCK(object);
525 } else if (object->ref_count == 1) {
526 if (object->shadow_count == 0 &&
527 object->handle == NULL &&
528 (object->type == OBJT_DEFAULT ||
529 object->type == OBJT_SWAP)) {
530 vm_object_set_flag(object, OBJ_ONEMAPPING);
531 } else if ((object->shadow_count == 1) &&
532 (object->handle == NULL) &&
533 (object->type == OBJT_DEFAULT ||
534 object->type == OBJT_SWAP)) {
537 robject = LIST_FIRST(&object->shadow_head);
538 KASSERT(robject != NULL,
539 ("vm_object_deallocate: ref_count: %d, shadow_count: %d",
541 object->shadow_count));
542 if (!VM_OBJECT_TRYLOCK(robject)) {
544 * Avoid a potential deadlock.
547 VM_OBJECT_UNLOCK(object);
549 * More likely than not the thread
550 * holding robject's lock has lower
551 * priority than the current thread.
552 * Let the lower priority thread run.
558 * Collapse object into its shadow unless its
559 * shadow is dead. In that case, object will
560 * be deallocated by the thread that is
561 * deallocating its shadow.
563 if ((robject->flags & OBJ_DEAD) == 0 &&
564 (robject->handle == NULL) &&
565 (robject->type == OBJT_DEFAULT ||
566 robject->type == OBJT_SWAP)) {
568 robject->ref_count++;
570 if (robject->paging_in_progress) {
571 VM_OBJECT_UNLOCK(object);
572 vm_object_pip_wait(robject,
574 temp = robject->backing_object;
575 if (object == temp) {
576 VM_OBJECT_LOCK(object);
579 } else if (object->paging_in_progress) {
580 VM_OBJECT_UNLOCK(robject);
581 object->flags |= OBJ_PIPWNT;
582 VM_OBJECT_SLEEP(object, object,
583 PDROP | PVM, "objde2", 0);
584 VM_OBJECT_LOCK(robject);
585 temp = robject->backing_object;
586 if (object == temp) {
587 VM_OBJECT_LOCK(object);
591 VM_OBJECT_UNLOCK(object);
593 if (robject->ref_count == 1) {
594 robject->ref_count--;
599 vm_object_collapse(object);
600 VM_OBJECT_UNLOCK(object);
603 VM_OBJECT_UNLOCK(robject);
605 VM_OBJECT_UNLOCK(object);
609 temp = object->backing_object;
611 VM_OBJECT_LOCK(temp);
612 LIST_REMOVE(object, shadow_list);
613 temp->shadow_count--;
614 VM_OBJECT_UNLOCK(temp);
615 object->backing_object = NULL;
618 * Don't double-terminate, we could be in a termination
619 * recursion due to the terminate having to sync data
622 if ((object->flags & OBJ_DEAD) == 0)
623 vm_object_terminate(object);
625 VM_OBJECT_UNLOCK(object);
631 * vm_object_destroy removes the object from the global object list
632 * and frees the space for the object.
635 vm_object_destroy(vm_object_t object)
639 * Remove the object from the global object list.
641 mtx_lock(&vm_object_list_mtx);
642 TAILQ_REMOVE(&vm_object_list, object, object_list);
643 mtx_unlock(&vm_object_list_mtx);
646 * Release the allocation charge.
648 if (object->cred != NULL) {
649 KASSERT(object->type == OBJT_DEFAULT ||
650 object->type == OBJT_SWAP,
651 ("vm_object_terminate: non-swap obj %p has cred",
653 swap_release_by_cred(object->charge, object->cred);
655 crfree(object->cred);
660 * Free the space for the object.
662 uma_zfree(obj_zone, object);
666 * vm_object_terminate actually destroys the specified object, freeing
667 * up all previously used resources.
669 * The object must be locked.
670 * This routine may block.
673 vm_object_terminate(vm_object_t object)
677 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
680 * Make sure no one uses us.
682 vm_object_set_flag(object, OBJ_DEAD);
685 * wait for the pageout daemon to be done with the object
687 vm_object_pip_wait(object, "objtrm");
689 KASSERT(!object->paging_in_progress,
690 ("vm_object_terminate: pageout in progress"));
693 * Clean and free the pages, as appropriate. All references to the
694 * object are gone, so we don't need to lock it.
696 if (object->type == OBJT_VNODE) {
697 struct vnode *vp = (struct vnode *)object->handle;
700 * Clean pages and flush buffers.
702 vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
703 VM_OBJECT_UNLOCK(object);
705 vinvalbuf(vp, V_SAVE, 0, 0);
707 VM_OBJECT_LOCK(object);
710 KASSERT(object->ref_count == 0,
711 ("vm_object_terminate: object with references, ref_count=%d",
715 * Free any remaining pageable pages. This also removes them from the
716 * paging queues. However, don't free wired pages, just remove them
717 * from the object. Rather than incrementally removing each page from
718 * the object, the page and object are reset to any empty state.
720 TAILQ_FOREACH_SAFE(p, &object->memq, listq, p_next) {
721 KASSERT(!p->busy && (p->oflags & VPO_BUSY) == 0,
722 ("vm_object_terminate: freeing busy page %p", p));
725 * Optimize the page's removal from the object by resetting
726 * its "object" field. Specifically, if the page is not
727 * wired, then the effect of this assignment is that
728 * vm_page_free()'s call to vm_page_remove() will return
729 * immediately without modifying the page or the object.
732 if (p->wire_count == 0) {
734 PCPU_INC(cnt.v_pfree);
739 * If the object contained any pages, then reset it to an empty state.
740 * None of the object's fields, including "resident_page_count", were
741 * modified by the preceding loop.
743 if (object->resident_page_count != 0) {
745 TAILQ_INIT(&object->memq);
746 object->resident_page_count = 0;
747 if (object->type == OBJT_VNODE)
748 vdrop(object->handle);
751 #if VM_NRESERVLEVEL > 0
752 if (__predict_false(!LIST_EMPTY(&object->rvq)))
753 vm_reserv_break_all(object);
755 if (__predict_false(object->cache != NULL))
756 vm_page_cache_free(object, 0, 0);
759 * Let the pager know object is dead.
761 vm_pager_deallocate(object);
762 VM_OBJECT_UNLOCK(object);
764 vm_object_destroy(object);
768 * Make the page read-only so that we can clear the object flags. However, if
769 * this is a nosync mmap then the object is likely to stay dirty so do not
770 * mess with the page and do not clear the object flags. Returns TRUE if the
771 * page should be flushed, and FALSE otherwise.
774 vm_object_page_remove_write(vm_page_t p, int flags, boolean_t *clearobjflags)
778 * If we have been asked to skip nosync pages and this is a
779 * nosync page, skip it. Note that the object flags were not
780 * cleared in this case so we do not have to set them.
782 if ((flags & OBJPC_NOSYNC) != 0 && (p->oflags & VPO_NOSYNC) != 0) {
783 *clearobjflags = FALSE;
786 pmap_remove_write(p);
787 return (p->dirty != 0);
792 * vm_object_page_clean
794 * Clean all dirty pages in the specified range of object. Leaves page
795 * on whatever queue it is currently on. If NOSYNC is set then do not
796 * write out pages with VPO_NOSYNC set (originally comes from MAP_NOSYNC),
797 * leaving the object dirty.
799 * When stuffing pages asynchronously, allow clustering. XXX we need a
800 * synchronous clustering mode implementation.
802 * Odd semantics: if start == end, we clean everything.
804 * The object must be locked.
806 * Returns FALSE if some page from the range was not written, as
807 * reported by the pager, and TRUE otherwise.
810 vm_object_page_clean(vm_object_t object, vm_ooffset_t start, vm_ooffset_t end,
814 vm_pindex_t pi, tend, tstart;
815 int curgeneration, n, pagerflags;
816 boolean_t clearobjflags, eio, res;
818 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
819 KASSERT(object->type == OBJT_VNODE, ("Not a vnode object"));
820 if ((object->flags & OBJ_MIGHTBEDIRTY) == 0 ||
821 object->resident_page_count == 0)
824 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) != 0 ?
825 VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK;
826 pagerflags |= (flags & OBJPC_INVAL) != 0 ? VM_PAGER_PUT_INVAL : 0;
828 tstart = OFF_TO_IDX(start);
829 tend = (end == 0) ? object->size : OFF_TO_IDX(end + PAGE_MASK);
830 clearobjflags = tstart == 0 && tend >= object->size;
834 curgeneration = object->generation;
836 for (p = vm_page_find_least(object, tstart); p != NULL; p = np) {
840 np = TAILQ_NEXT(p, listq);
843 if (vm_page_sleep_if_busy(p, TRUE, "vpcwai")) {
844 if (object->generation != curgeneration) {
845 if ((flags & OBJPC_SYNC) != 0)
848 clearobjflags = FALSE;
850 np = vm_page_find_least(object, pi);
853 if (!vm_object_page_remove_write(p, flags, &clearobjflags))
856 n = vm_object_page_collect_flush(object, p, pagerflags,
857 flags, &clearobjflags, &eio);
860 clearobjflags = FALSE;
862 if (object->generation != curgeneration) {
863 if ((flags & OBJPC_SYNC) != 0)
866 clearobjflags = FALSE;
870 * If the VOP_PUTPAGES() did a truncated write, so
871 * that even the first page of the run is not fully
872 * written, vm_pageout_flush() returns 0 as the run
873 * length. Since the condition that caused truncated
874 * write may be permanent, e.g. exhausted free space,
875 * accepting n == 0 would cause an infinite loop.
877 * Forwarding the iterator leaves the unwritten page
878 * behind, but there is not much we can do there if
879 * filesystem refuses to write it.
883 clearobjflags = FALSE;
885 np = vm_page_find_least(object, pi + n);
888 VOP_FSYNC(vp, (pagerflags & VM_PAGER_PUT_SYNC) ? MNT_WAIT : 0);
892 vm_object_clear_flag(object, OBJ_MIGHTBEDIRTY);
897 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags,
898 int flags, boolean_t *clearobjflags, boolean_t *eio)
900 vm_page_t ma[vm_pageout_page_count], p_first, tp;
901 int count, i, mreq, runlen;
903 vm_page_lock_assert(p, MA_NOTOWNED);
904 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
909 for (tp = p; count < vm_pageout_page_count; count++) {
910 tp = vm_page_next(tp);
911 if (tp == NULL || tp->busy != 0 || (tp->oflags & VPO_BUSY) != 0)
913 if (!vm_object_page_remove_write(tp, flags, clearobjflags))
917 for (p_first = p; count < vm_pageout_page_count; count++) {
918 tp = vm_page_prev(p_first);
919 if (tp == NULL || tp->busy != 0 || (tp->oflags & VPO_BUSY) != 0)
921 if (!vm_object_page_remove_write(tp, flags, clearobjflags))
927 for (tp = p_first, i = 0; i < count; tp = TAILQ_NEXT(tp, listq), i++)
930 vm_pageout_flush(ma, count, pagerflags, mreq, &runlen, eio);
935 * Note that there is absolutely no sense in writing out
936 * anonymous objects, so we track down the vnode object
938 * We invalidate (remove) all pages from the address space
939 * for semantic correctness.
941 * If the backing object is a device object with unmanaged pages, then any
942 * mappings to the specified range of pages must be removed before this
943 * function is called.
945 * Note: certain anonymous maps, such as MAP_NOSYNC maps,
946 * may start out with a NULL object.
949 vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
950 boolean_t syncio, boolean_t invalidate)
952 vm_object_t backing_object;
955 int error, flags, fsync_after;
962 VM_OBJECT_LOCK(object);
963 while ((backing_object = object->backing_object) != NULL) {
964 VM_OBJECT_LOCK(backing_object);
965 offset += object->backing_object_offset;
966 VM_OBJECT_UNLOCK(object);
967 object = backing_object;
968 if (object->size < OFF_TO_IDX(offset + size))
969 size = IDX_TO_OFF(object->size) - offset;
972 * Flush pages if writing is allowed, invalidate them
973 * if invalidation requested. Pages undergoing I/O
974 * will be ignored by vm_object_page_remove().
976 * We cannot lock the vnode and then wait for paging
977 * to complete without deadlocking against vm_fault.
978 * Instead we simply call vm_object_page_remove() and
979 * allow it to block internally on a page-by-page
980 * basis when it encounters pages undergoing async
983 if (object->type == OBJT_VNODE &&
984 (object->flags & OBJ_MIGHTBEDIRTY) != 0) {
986 VM_OBJECT_UNLOCK(object);
987 (void) vn_start_write(vp, &mp, V_WAIT);
988 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
989 if (syncio && !invalidate && offset == 0 &&
990 OFF_TO_IDX(size) == object->size) {
992 * If syncing the whole mapping of the file,
993 * it is faster to schedule all the writes in
994 * async mode, also allowing the clustering,
995 * and then wait for i/o to complete.
1000 flags = (syncio || invalidate) ? OBJPC_SYNC : 0;
1001 flags |= invalidate ? (OBJPC_SYNC | OBJPC_INVAL) : 0;
1002 fsync_after = FALSE;
1004 VM_OBJECT_LOCK(object);
1005 res = vm_object_page_clean(object, offset, offset + size,
1007 VM_OBJECT_UNLOCK(object);
1009 error = VOP_FSYNC(vp, MNT_WAIT, curthread);
1011 vn_finished_write(mp);
1014 VM_OBJECT_LOCK(object);
1016 if ((object->type == OBJT_VNODE ||
1017 object->type == OBJT_DEVICE) && invalidate) {
1018 if (object->type == OBJT_DEVICE)
1020 * The option OBJPR_NOTMAPPED must be passed here
1021 * because vm_object_page_remove() cannot remove
1022 * unmanaged mappings.
1024 flags = OBJPR_NOTMAPPED;
1028 flags = OBJPR_CLEANONLY;
1029 vm_object_page_remove(object, OFF_TO_IDX(offset),
1030 OFF_TO_IDX(offset + size + PAGE_MASK), flags);
1032 VM_OBJECT_UNLOCK(object);
1037 * vm_object_madvise:
1039 * Implements the madvise function at the object/page level.
1041 * MADV_WILLNEED (any object)
1043 * Activate the specified pages if they are resident.
1045 * MADV_DONTNEED (any object)
1047 * Deactivate the specified pages if they are resident.
1049 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects,
1050 * OBJ_ONEMAPPING only)
1052 * Deactivate and clean the specified pages if they are
1053 * resident. This permits the process to reuse the pages
1054 * without faulting or the kernel to reclaim the pages
1058 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, vm_pindex_t end,
1061 vm_pindex_t tpindex;
1062 vm_object_t backing_object, tobject;
1067 VM_OBJECT_LOCK(object);
1069 * Locate and adjust resident pages
1071 for (; pindex < end; pindex += 1) {
1077 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
1078 * and those pages must be OBJ_ONEMAPPING.
1080 if (advise == MADV_FREE) {
1081 if ((tobject->type != OBJT_DEFAULT &&
1082 tobject->type != OBJT_SWAP) ||
1083 (tobject->flags & OBJ_ONEMAPPING) == 0) {
1084 goto unlock_tobject;
1086 } else if ((tobject->flags & OBJ_UNMANAGED) != 0)
1087 goto unlock_tobject;
1088 m = vm_page_lookup(tobject, tpindex);
1089 if (m == NULL && advise == MADV_WILLNEED) {
1091 * If the page is cached, reactivate it.
1093 m = vm_page_alloc(tobject, tpindex, VM_ALLOC_IFCACHED |
1098 * There may be swap even if there is no backing page
1100 if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
1101 swap_pager_freespace(tobject, tpindex, 1);
1105 backing_object = tobject->backing_object;
1106 if (backing_object == NULL)
1107 goto unlock_tobject;
1108 VM_OBJECT_LOCK(backing_object);
1109 tpindex += OFF_TO_IDX(tobject->backing_object_offset);
1110 if (tobject != object)
1111 VM_OBJECT_UNLOCK(tobject);
1112 tobject = backing_object;
1114 } else if (m->valid != VM_PAGE_BITS_ALL)
1115 goto unlock_tobject;
1117 * If the page is not in a normal state, skip it.
1120 if (m->hold_count != 0 || m->wire_count != 0) {
1122 goto unlock_tobject;
1124 KASSERT((m->flags & PG_FICTITIOUS) == 0,
1125 ("vm_object_madvise: page %p is fictitious", m));
1126 KASSERT((m->oflags & VPO_UNMANAGED) == 0,
1127 ("vm_object_madvise: page %p is not managed", m));
1128 if ((m->oflags & VPO_BUSY) || m->busy) {
1129 if (advise == MADV_WILLNEED) {
1131 * Reference the page before unlocking and
1132 * sleeping so that the page daemon is less
1133 * likely to reclaim it.
1135 vm_page_aflag_set(m, PGA_REFERENCED);
1138 if (object != tobject)
1139 VM_OBJECT_UNLOCK(object);
1140 m->oflags |= VPO_WANTED;
1141 VM_OBJECT_SLEEP(tobject, m, PDROP | PVM, "madvpo", 0);
1142 VM_OBJECT_LOCK(object);
1145 if (advise == MADV_WILLNEED) {
1146 vm_page_activate(m);
1147 } else if (advise == MADV_DONTNEED) {
1148 vm_page_dontneed(m);
1149 } else if (advise == MADV_FREE) {
1151 * Mark the page clean. This will allow the page
1152 * to be freed up by the system. However, such pages
1153 * are often reused quickly by malloc()/free()
1154 * so we do not do anything that would cause
1155 * a page fault if we can help it.
1157 * Specifically, we do not try to actually free
1158 * the page now nor do we try to put it in the
1159 * cache (which would cause a page fault on reuse).
1161 * But we do make the page is freeable as we
1162 * can without actually taking the step of unmapping
1165 pmap_clear_modify(m);
1168 vm_page_dontneed(m);
1171 if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
1172 swap_pager_freespace(tobject, tpindex, 1);
1174 if (tobject != object)
1175 VM_OBJECT_UNLOCK(tobject);
1177 VM_OBJECT_UNLOCK(object);
1183 * Create a new object which is backed by the
1184 * specified existing object range. The source
1185 * object reference is deallocated.
1187 * The new object and offset into that object
1188 * are returned in the source parameters.
1192 vm_object_t *object, /* IN/OUT */
1193 vm_ooffset_t *offset, /* IN/OUT */
1202 * Don't create the new object if the old object isn't shared.
1204 if (source != NULL) {
1205 VM_OBJECT_LOCK(source);
1206 if (source->ref_count == 1 &&
1207 source->handle == NULL &&
1208 (source->type == OBJT_DEFAULT ||
1209 source->type == OBJT_SWAP)) {
1210 VM_OBJECT_UNLOCK(source);
1213 VM_OBJECT_UNLOCK(source);
1217 * Allocate a new object with the given length.
1219 result = vm_object_allocate(OBJT_DEFAULT, atop(length));
1222 * The new object shadows the source object, adding a reference to it.
1223 * Our caller changes his reference to point to the new object,
1224 * removing a reference to the source object. Net result: no change
1225 * of reference count.
1227 * Try to optimize the result object's page color when shadowing
1228 * in order to maintain page coloring consistency in the combined
1231 result->backing_object = source;
1233 * Store the offset into the source object, and fix up the offset into
1236 result->backing_object_offset = *offset;
1237 if (source != NULL) {
1238 VM_OBJECT_LOCK(source);
1239 LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list);
1240 source->shadow_count++;
1241 #if VM_NRESERVLEVEL > 0
1242 result->flags |= source->flags & OBJ_COLORED;
1243 result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) &
1244 ((1 << (VM_NFREEORDER - 1)) - 1);
1246 VM_OBJECT_UNLOCK(source);
1251 * Return the new things
1260 * Split the pages in a map entry into a new object. This affords
1261 * easier removal of unused pages, and keeps object inheritance from
1262 * being a negative impact on memory usage.
1265 vm_object_split(vm_map_entry_t entry)
1267 vm_page_t m, m_next;
1268 vm_object_t orig_object, new_object, source;
1269 vm_pindex_t idx, offidxstart;
1272 orig_object = entry->object.vm_object;
1273 if (orig_object->type != OBJT_DEFAULT && orig_object->type != OBJT_SWAP)
1275 if (orig_object->ref_count <= 1)
1277 VM_OBJECT_UNLOCK(orig_object);
1279 offidxstart = OFF_TO_IDX(entry->offset);
1280 size = atop(entry->end - entry->start);
1283 * If swap_pager_copy() is later called, it will convert new_object
1284 * into a swap object.
1286 new_object = vm_object_allocate(OBJT_DEFAULT, size);
1289 * At this point, the new object is still private, so the order in
1290 * which the original and new objects are locked does not matter.
1292 VM_OBJECT_LOCK(new_object);
1293 VM_OBJECT_LOCK(orig_object);
1294 source = orig_object->backing_object;
1295 if (source != NULL) {
1296 VM_OBJECT_LOCK(source);
1297 if ((source->flags & OBJ_DEAD) != 0) {
1298 VM_OBJECT_UNLOCK(source);
1299 VM_OBJECT_UNLOCK(orig_object);
1300 VM_OBJECT_UNLOCK(new_object);
1301 vm_object_deallocate(new_object);
1302 VM_OBJECT_LOCK(orig_object);
1305 LIST_INSERT_HEAD(&source->shadow_head,
1306 new_object, shadow_list);
1307 source->shadow_count++;
1308 vm_object_reference_locked(source); /* for new_object */
1309 vm_object_clear_flag(source, OBJ_ONEMAPPING);
1310 VM_OBJECT_UNLOCK(source);
1311 new_object->backing_object_offset =
1312 orig_object->backing_object_offset + entry->offset;
1313 new_object->backing_object = source;
1315 if (orig_object->cred != NULL) {
1316 new_object->cred = orig_object->cred;
1317 crhold(orig_object->cred);
1318 new_object->charge = ptoa(size);
1319 KASSERT(orig_object->charge >= ptoa(size),
1320 ("orig_object->charge < 0"));
1321 orig_object->charge -= ptoa(size);
1324 m = vm_page_find_least(orig_object, offidxstart);
1325 for (; m != NULL && (idx = m->pindex - offidxstart) < size;
1327 m_next = TAILQ_NEXT(m, listq);
1330 * We must wait for pending I/O to complete before we can
1333 * We do not have to VM_PROT_NONE the page as mappings should
1334 * not be changed by this operation.
1336 if ((m->oflags & VPO_BUSY) || m->busy) {
1337 VM_OBJECT_UNLOCK(new_object);
1338 m->oflags |= VPO_WANTED;
1339 VM_OBJECT_SLEEP(orig_object, m, PVM, "spltwt", 0);
1340 VM_OBJECT_LOCK(new_object);
1343 #if VM_NRESERVLEVEL > 0
1345 * If some of the reservation's allocated pages remain with
1346 * the original object, then transferring the reservation to
1347 * the new object is neither particularly beneficial nor
1348 * particularly harmful as compared to leaving the reservation
1349 * with the original object. If, however, all of the
1350 * reservation's allocated pages are transferred to the new
1351 * object, then transferring the reservation is typically
1352 * beneficial. Determining which of these two cases applies
1353 * would be more costly than unconditionally renaming the
1356 vm_reserv_rename(m, new_object, orig_object, offidxstart);
1359 vm_page_rename(m, new_object, idx);
1361 /* page automatically made dirty by rename and cache handled */
1364 if (orig_object->type == OBJT_SWAP) {
1366 * swap_pager_copy() can sleep, in which case the orig_object's
1367 * and new_object's locks are released and reacquired.
1369 swap_pager_copy(orig_object, new_object, offidxstart, 0);
1372 * Transfer any cached pages from orig_object to new_object.
1373 * If swap_pager_copy() found swapped out pages within the
1374 * specified range of orig_object, then it changed
1375 * new_object's type to OBJT_SWAP when it transferred those
1376 * pages to new_object. Otherwise, new_object's type
1377 * should still be OBJT_DEFAULT and orig_object should not
1378 * contain any cached pages within the specified range.
1380 if (__predict_false(orig_object->cache != NULL))
1381 vm_page_cache_transfer(orig_object, offidxstart,
1384 VM_OBJECT_UNLOCK(orig_object);
1385 TAILQ_FOREACH(m, &new_object->memq, listq)
1387 VM_OBJECT_UNLOCK(new_object);
1388 entry->object.vm_object = new_object;
1389 entry->offset = 0LL;
1390 vm_object_deallocate(orig_object);
1391 VM_OBJECT_LOCK(new_object);
1394 #define OBSC_TEST_ALL_SHADOWED 0x0001
1395 #define OBSC_COLLAPSE_NOWAIT 0x0002
1396 #define OBSC_COLLAPSE_WAIT 0x0004
1399 vm_object_backing_scan(vm_object_t object, int op)
1403 vm_object_t backing_object;
1404 vm_pindex_t backing_offset_index;
1406 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1407 VM_OBJECT_LOCK_ASSERT(object->backing_object, MA_OWNED);
1409 backing_object = object->backing_object;
1410 backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
1413 * Initial conditions
1415 if (op & OBSC_TEST_ALL_SHADOWED) {
1417 * We do not want to have to test for the existence of cache
1418 * or swap pages in the backing object. XXX but with the
1419 * new swapper this would be pretty easy to do.
1421 * XXX what about anonymous MAP_SHARED memory that hasn't
1422 * been ZFOD faulted yet? If we do not test for this, the
1423 * shadow test may succeed! XXX
1425 if (backing_object->type != OBJT_DEFAULT) {
1429 if (op & OBSC_COLLAPSE_WAIT) {
1430 vm_object_set_flag(backing_object, OBJ_DEAD);
1436 p = TAILQ_FIRST(&backing_object->memq);
1438 vm_page_t next = TAILQ_NEXT(p, listq);
1439 vm_pindex_t new_pindex = p->pindex - backing_offset_index;
1441 if (op & OBSC_TEST_ALL_SHADOWED) {
1445 * Ignore pages outside the parent object's range
1446 * and outside the parent object's mapping of the
1449 * note that we do not busy the backing object's
1453 p->pindex < backing_offset_index ||
1454 new_pindex >= object->size
1461 * See if the parent has the page or if the parent's
1462 * object pager has the page. If the parent has the
1463 * page but the page is not valid, the parent's
1464 * object pager must have the page.
1466 * If this fails, the parent does not completely shadow
1467 * the object and we might as well give up now.
1470 pp = vm_page_lookup(object, new_pindex);
1472 (pp == NULL || pp->valid == 0) &&
1473 !vm_pager_has_page(object, new_pindex, NULL, NULL)
1481 * Check for busy page
1483 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
1486 if (op & OBSC_COLLAPSE_NOWAIT) {
1487 if ((p->oflags & VPO_BUSY) ||
1493 } else if (op & OBSC_COLLAPSE_WAIT) {
1494 if ((p->oflags & VPO_BUSY) || p->busy) {
1495 VM_OBJECT_UNLOCK(object);
1496 p->oflags |= VPO_WANTED;
1497 VM_OBJECT_SLEEP(backing_object, p,
1498 PDROP | PVM, "vmocol", 0);
1499 VM_OBJECT_LOCK(object);
1500 VM_OBJECT_LOCK(backing_object);
1502 * If we slept, anything could have
1503 * happened. Since the object is
1504 * marked dead, the backing offset
1505 * should not have changed so we
1506 * just restart our scan.
1508 p = TAILQ_FIRST(&backing_object->memq);
1514 p->object == backing_object,
1515 ("vm_object_backing_scan: object mismatch")
1519 * Destroy any associated swap
1521 if (backing_object->type == OBJT_SWAP) {
1522 swap_pager_freespace(
1530 p->pindex < backing_offset_index ||
1531 new_pindex >= object->size
1534 * Page is out of the parent object's range, we
1535 * can simply destroy it.
1538 KASSERT(!pmap_page_is_mapped(p),
1539 ("freeing mapped page %p", p));
1540 if (p->wire_count == 0)
1549 pp = vm_page_lookup(object, new_pindex);
1551 (op & OBSC_COLLAPSE_NOWAIT) != 0 &&
1552 (pp != NULL && pp->valid == 0)
1555 * The page in the parent is not (yet) valid.
1556 * We don't know anything about the state of
1557 * the original page. It might be mapped,
1558 * so we must avoid the next if here.
1560 * This is due to a race in vm_fault() where
1561 * we must unbusy the original (backing_obj)
1562 * page before we can (re)lock the parent.
1563 * Hence we can get here.
1570 vm_pager_has_page(object, new_pindex, NULL, NULL)
1573 * page already exists in parent OR swap exists
1574 * for this location in the parent. Destroy
1575 * the original page from the backing object.
1577 * Leave the parent's page alone
1580 KASSERT(!pmap_page_is_mapped(p),
1581 ("freeing mapped page %p", p));
1582 if (p->wire_count == 0)
1591 #if VM_NRESERVLEVEL > 0
1593 * Rename the reservation.
1595 vm_reserv_rename(p, object, backing_object,
1596 backing_offset_index);
1600 * Page does not exist in parent, rename the
1601 * page from the backing object to the main object.
1603 * If the page was mapped to a process, it can remain
1604 * mapped through the rename.
1607 vm_page_rename(p, object, new_pindex);
1609 /* page automatically made dirty by rename */
1618 * this version of collapse allows the operation to occur earlier and
1619 * when paging_in_progress is true for an object... This is not a complete
1620 * operation, but should plug 99.9% of the rest of the leaks.
1623 vm_object_qcollapse(vm_object_t object)
1625 vm_object_t backing_object = object->backing_object;
1627 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1628 VM_OBJECT_LOCK_ASSERT(backing_object, MA_OWNED);
1630 if (backing_object->ref_count != 1)
1633 vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT);
1637 * vm_object_collapse:
1639 * Collapse an object with the object backing it.
1640 * Pages in the backing object are moved into the
1641 * parent, and the backing object is deallocated.
1644 vm_object_collapse(vm_object_t object)
1646 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1649 vm_object_t backing_object;
1652 * Verify that the conditions are right for collapse:
1654 * The object exists and the backing object exists.
1656 if ((backing_object = object->backing_object) == NULL)
1660 * we check the backing object first, because it is most likely
1663 VM_OBJECT_LOCK(backing_object);
1664 if (backing_object->handle != NULL ||
1665 (backing_object->type != OBJT_DEFAULT &&
1666 backing_object->type != OBJT_SWAP) ||
1667 (backing_object->flags & OBJ_DEAD) ||
1668 object->handle != NULL ||
1669 (object->type != OBJT_DEFAULT &&
1670 object->type != OBJT_SWAP) ||
1671 (object->flags & OBJ_DEAD)) {
1672 VM_OBJECT_UNLOCK(backing_object);
1677 object->paging_in_progress != 0 ||
1678 backing_object->paging_in_progress != 0
1680 vm_object_qcollapse(object);
1681 VM_OBJECT_UNLOCK(backing_object);
1685 * We know that we can either collapse the backing object (if
1686 * the parent is the only reference to it) or (perhaps) have
1687 * the parent bypass the object if the parent happens to shadow
1688 * all the resident pages in the entire backing object.
1690 * This is ignoring pager-backed pages such as swap pages.
1691 * vm_object_backing_scan fails the shadowing test in this
1694 if (backing_object->ref_count == 1) {
1696 * If there is exactly one reference to the backing
1697 * object, we can collapse it into the parent.
1699 vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT);
1701 #if VM_NRESERVLEVEL > 0
1703 * Break any reservations from backing_object.
1705 if (__predict_false(!LIST_EMPTY(&backing_object->rvq)))
1706 vm_reserv_break_all(backing_object);
1710 * Move the pager from backing_object to object.
1712 if (backing_object->type == OBJT_SWAP) {
1714 * swap_pager_copy() can sleep, in which case
1715 * the backing_object's and object's locks are
1716 * released and reacquired.
1717 * Since swap_pager_copy() is being asked to
1718 * destroy the source, it will change the
1719 * backing_object's type to OBJT_DEFAULT.
1724 OFF_TO_IDX(object->backing_object_offset), TRUE);
1727 * Free any cached pages from backing_object.
1729 if (__predict_false(backing_object->cache != NULL))
1730 vm_page_cache_free(backing_object, 0, 0);
1733 * Object now shadows whatever backing_object did.
1734 * Note that the reference to
1735 * backing_object->backing_object moves from within
1736 * backing_object to within object.
1738 LIST_REMOVE(object, shadow_list);
1739 backing_object->shadow_count--;
1740 if (backing_object->backing_object) {
1741 VM_OBJECT_LOCK(backing_object->backing_object);
1742 LIST_REMOVE(backing_object, shadow_list);
1744 &backing_object->backing_object->shadow_head,
1745 object, shadow_list);
1747 * The shadow_count has not changed.
1749 VM_OBJECT_UNLOCK(backing_object->backing_object);
1751 object->backing_object = backing_object->backing_object;
1752 object->backing_object_offset +=
1753 backing_object->backing_object_offset;
1756 * Discard backing_object.
1758 * Since the backing object has no pages, no pager left,
1759 * and no object references within it, all that is
1760 * necessary is to dispose of it.
1762 KASSERT(backing_object->ref_count == 1, (
1763 "backing_object %p was somehow re-referenced during collapse!",
1765 VM_OBJECT_UNLOCK(backing_object);
1766 vm_object_destroy(backing_object);
1770 vm_object_t new_backing_object;
1773 * If we do not entirely shadow the backing object,
1774 * there is nothing we can do so we give up.
1776 if (object->resident_page_count != object->size &&
1777 vm_object_backing_scan(object,
1778 OBSC_TEST_ALL_SHADOWED) == 0) {
1779 VM_OBJECT_UNLOCK(backing_object);
1784 * Make the parent shadow the next object in the
1785 * chain. Deallocating backing_object will not remove
1786 * it, since its reference count is at least 2.
1788 LIST_REMOVE(object, shadow_list);
1789 backing_object->shadow_count--;
1791 new_backing_object = backing_object->backing_object;
1792 if ((object->backing_object = new_backing_object) != NULL) {
1793 VM_OBJECT_LOCK(new_backing_object);
1795 &new_backing_object->shadow_head,
1799 new_backing_object->shadow_count++;
1800 vm_object_reference_locked(new_backing_object);
1801 VM_OBJECT_UNLOCK(new_backing_object);
1802 object->backing_object_offset +=
1803 backing_object->backing_object_offset;
1807 * Drop the reference count on backing_object. Since
1808 * its ref_count was at least 2, it will not vanish.
1810 backing_object->ref_count--;
1811 VM_OBJECT_UNLOCK(backing_object);
1816 * Try again with this object's new backing object.
1822 * vm_object_page_remove:
1824 * For the given object, either frees or invalidates each of the
1825 * specified pages. In general, a page is freed. However, if a page is
1826 * wired for any reason other than the existence of a managed, wired
1827 * mapping, then it may be invalidated but not removed from the object.
1828 * Pages are specified by the given range ["start", "end") and the option
1829 * OBJPR_CLEANONLY. As a special case, if "end" is zero, then the range
1830 * extends from "start" to the end of the object. If the option
1831 * OBJPR_CLEANONLY is specified, then only the non-dirty pages within the
1832 * specified range are affected. If the option OBJPR_NOTMAPPED is
1833 * specified, then the pages within the specified range must have no
1834 * mappings. Otherwise, if this option is not specified, any mappings to
1835 * the specified pages are removed before the pages are freed or
1838 * In general, this operation should only be performed on objects that
1839 * contain managed pages. There are, however, two exceptions. First, it
1840 * is performed on the kernel and kmem objects by vm_map_entry_delete().
1841 * Second, it is used by msync(..., MS_INVALIDATE) to invalidate device-
1842 * backed pages. In both of these cases, the option OBJPR_CLEANONLY must
1843 * not be specified and the option OBJPR_NOTMAPPED must be specified.
1845 * The object must be locked.
1848 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
1854 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1855 KASSERT((object->flags & OBJ_UNMANAGED) == 0 ||
1856 (options & (OBJPR_CLEANONLY | OBJPR_NOTMAPPED)) == OBJPR_NOTMAPPED,
1857 ("vm_object_page_remove: illegal options for object %p", object));
1858 if (object->resident_page_count == 0)
1860 vm_object_pip_add(object, 1);
1862 p = vm_page_find_least(object, start);
1865 * Here, the variable "p" is either (1) the page with the least pindex
1866 * greater than or equal to the parameter "start" or (2) NULL.
1868 for (; p != NULL && (p->pindex < end || end == 0); p = next) {
1869 next = TAILQ_NEXT(p, listq);
1872 * If the page is wired for any reason besides the existence
1873 * of managed, wired mappings, then it cannot be freed. For
1874 * example, fictitious pages, which represent device memory,
1875 * are inherently wired and cannot be freed. They can,
1876 * however, be invalidated if the option OBJPR_CLEANONLY is
1880 if ((wirings = p->wire_count) != 0 &&
1881 (wirings = pmap_page_wired_mappings(p)) != p->wire_count) {
1882 if ((options & OBJPR_NOTMAPPED) == 0) {
1884 /* Account for removal of wired mappings. */
1886 p->wire_count -= wirings;
1888 if ((options & OBJPR_CLEANONLY) == 0) {
1895 if (vm_page_sleep_if_busy(p, TRUE, "vmopar"))
1897 KASSERT((p->flags & PG_FICTITIOUS) == 0,
1898 ("vm_object_page_remove: page %p is fictitious", p));
1899 if ((options & OBJPR_CLEANONLY) != 0 && p->valid != 0) {
1900 if ((options & OBJPR_NOTMAPPED) == 0)
1901 pmap_remove_write(p);
1907 if ((options & OBJPR_NOTMAPPED) == 0) {
1909 /* Account for removal of wired mappings. */
1911 KASSERT(p->wire_count == wirings,
1912 ("inconsistent wire count %d %d %p",
1913 p->wire_count, wirings, p));
1915 atomic_subtract_int(&cnt.v_wire_count, 1);
1921 vm_object_pip_wakeup(object);
1923 if (__predict_false(object->cache != NULL))
1924 vm_page_cache_free(object, start, end);
1928 * vm_object_page_cache:
1930 * For the given object, attempt to move the specified clean
1931 * pages to the cache queue. If a page is wired for any reason,
1932 * then it will not be changed. Pages are specified by the given
1933 * range ["start", "end"). As a special case, if "end" is zero,
1934 * then the range extends from "start" to the end of the object.
1935 * Any mappings to the specified pages are removed before the
1936 * pages are moved to the cache queue.
1938 * This operation should only be performed on objects that
1939 * contain non-fictitious, managed pages.
1941 * The object must be locked.
1944 vm_object_page_cache(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
1946 struct mtx *mtx, *new_mtx;
1949 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1950 KASSERT((object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0,
1951 ("vm_object_page_cache: illegal object %p", object));
1952 if (object->resident_page_count == 0)
1954 p = vm_page_find_least(object, start);
1957 * Here, the variable "p" is either (1) the page with the least pindex
1958 * greater than or equal to the parameter "start" or (2) NULL.
1961 for (; p != NULL && (p->pindex < end || end == 0); p = next) {
1962 next = TAILQ_NEXT(p, listq);
1965 * Avoid releasing and reacquiring the same page lock.
1967 new_mtx = vm_page_lockptr(p);
1968 if (mtx != new_mtx) {
1974 vm_page_try_to_cache(p);
1981 * Populate the specified range of the object with valid pages. Returns
1982 * TRUE if the range is successfully populated and FALSE otherwise.
1984 * Note: This function should be optimized to pass a larger array of
1985 * pages to vm_pager_get_pages() before it is applied to a non-
1986 * OBJT_DEVICE object.
1988 * The object must be locked.
1991 vm_object_populate(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
1997 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1998 for (pindex = start; pindex < end; pindex++) {
1999 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL |
2001 if (m->valid != VM_PAGE_BITS_ALL) {
2003 rv = vm_pager_get_pages(object, ma, 1, 0);
2004 m = vm_page_lookup(object, pindex);
2007 if (rv != VM_PAGER_OK) {
2015 * Keep "m" busy because a subsequent iteration may unlock
2019 if (pindex > start) {
2020 m = vm_page_lookup(object, start);
2021 while (m != NULL && m->pindex < pindex) {
2023 m = TAILQ_NEXT(m, listq);
2026 return (pindex == end);
2030 * Routine: vm_object_coalesce
2031 * Function: Coalesces two objects backing up adjoining
2032 * regions of memory into a single object.
2034 * returns TRUE if objects were combined.
2036 * NOTE: Only works at the moment if the second object is NULL -
2037 * if it's not, which object do we lock first?
2040 * prev_object First object to coalesce
2041 * prev_offset Offset into prev_object
2042 * prev_size Size of reference to prev_object
2043 * next_size Size of reference to the second object
2044 * reserved Indicator that extension region has
2045 * swap accounted for
2048 * The object must *not* be locked.
2051 vm_object_coalesce(vm_object_t prev_object, vm_ooffset_t prev_offset,
2052 vm_size_t prev_size, vm_size_t next_size, boolean_t reserved)
2054 vm_pindex_t next_pindex;
2056 if (prev_object == NULL)
2058 VM_OBJECT_LOCK(prev_object);
2059 if (prev_object->type != OBJT_DEFAULT &&
2060 prev_object->type != OBJT_SWAP) {
2061 VM_OBJECT_UNLOCK(prev_object);
2066 * Try to collapse the object first
2068 vm_object_collapse(prev_object);
2071 * Can't coalesce if: . more than one reference . paged out . shadows
2072 * another object . has a copy elsewhere (any of which mean that the
2073 * pages not mapped to prev_entry may be in use anyway)
2075 if (prev_object->backing_object != NULL) {
2076 VM_OBJECT_UNLOCK(prev_object);
2080 prev_size >>= PAGE_SHIFT;
2081 next_size >>= PAGE_SHIFT;
2082 next_pindex = OFF_TO_IDX(prev_offset) + prev_size;
2084 if ((prev_object->ref_count > 1) &&
2085 (prev_object->size != next_pindex)) {
2086 VM_OBJECT_UNLOCK(prev_object);
2091 * Account for the charge.
2093 if (prev_object->cred != NULL) {
2096 * If prev_object was charged, then this mapping,
2097 * althought not charged now, may become writable
2098 * later. Non-NULL cred in the object would prevent
2099 * swap reservation during enabling of the write
2100 * access, so reserve swap now. Failed reservation
2101 * cause allocation of the separate object for the map
2102 * entry, and swap reservation for this entry is
2103 * managed in appropriate time.
2105 if (!reserved && !swap_reserve_by_cred(ptoa(next_size),
2106 prev_object->cred)) {
2109 prev_object->charge += ptoa(next_size);
2113 * Remove any pages that may still be in the object from a previous
2116 if (next_pindex < prev_object->size) {
2117 vm_object_page_remove(prev_object, next_pindex, next_pindex +
2119 if (prev_object->type == OBJT_SWAP)
2120 swap_pager_freespace(prev_object,
2121 next_pindex, next_size);
2123 if (prev_object->cred != NULL) {
2124 KASSERT(prev_object->charge >=
2125 ptoa(prev_object->size - next_pindex),
2126 ("object %p overcharged 1 %jx %jx", prev_object,
2127 (uintmax_t)next_pindex, (uintmax_t)next_size));
2128 prev_object->charge -= ptoa(prev_object->size -
2135 * Extend the object if necessary.
2137 if (next_pindex + next_size > prev_object->size)
2138 prev_object->size = next_pindex + next_size;
2140 VM_OBJECT_UNLOCK(prev_object);
2145 vm_object_set_writeable_dirty(vm_object_t object)
2148 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
2149 if (object->type != OBJT_VNODE)
2151 object->generation++;
2152 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0)
2154 vm_object_set_flag(object, OBJ_MIGHTBEDIRTY);
2157 #include "opt_ddb.h"
2159 #include <sys/kernel.h>
2161 #include <sys/cons.h>
2163 #include <ddb/ddb.h>
2166 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry)
2169 vm_map_entry_t tmpe;
2177 tmpe = map->header.next;
2178 entcount = map->nentries;
2179 while (entcount-- && (tmpe != &map->header)) {
2180 if (_vm_object_in_map(map, object, tmpe)) {
2185 } else if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) {
2186 tmpm = entry->object.sub_map;
2187 tmpe = tmpm->header.next;
2188 entcount = tmpm->nentries;
2189 while (entcount-- && tmpe != &tmpm->header) {
2190 if (_vm_object_in_map(tmpm, object, tmpe)) {
2195 } else if ((obj = entry->object.vm_object) != NULL) {
2196 for (; obj; obj = obj->backing_object)
2197 if (obj == object) {
2205 vm_object_in_map(vm_object_t object)
2209 /* sx_slock(&allproc_lock); */
2210 FOREACH_PROC_IN_SYSTEM(p) {
2211 if (!p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */)
2213 if (_vm_object_in_map(&p->p_vmspace->vm_map, object, 0)) {
2214 /* sx_sunlock(&allproc_lock); */
2218 /* sx_sunlock(&allproc_lock); */
2219 if (_vm_object_in_map(kernel_map, object, 0))
2221 if (_vm_object_in_map(kmem_map, object, 0))
2223 if (_vm_object_in_map(pager_map, object, 0))
2225 if (_vm_object_in_map(buffer_map, object, 0))
2230 DB_SHOW_COMMAND(vmochk, vm_object_check)
2235 * make sure that internal objs are in a map somewhere
2236 * and none have zero ref counts.
2238 TAILQ_FOREACH(object, &vm_object_list, object_list) {
2239 if (object->handle == NULL &&
2240 (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) {
2241 if (object->ref_count == 0) {
2242 db_printf("vmochk: internal obj has zero ref count: %ld\n",
2243 (long)object->size);
2245 if (!vm_object_in_map(object)) {
2247 "vmochk: internal obj is not in a map: "
2248 "ref: %d, size: %lu: 0x%lx, backing_object: %p\n",
2249 object->ref_count, (u_long)object->size,
2250 (u_long)object->size,
2251 (void *)object->backing_object);
2258 * vm_object_print: [ debug ]
2260 DB_SHOW_COMMAND(object, vm_object_print_static)
2262 /* XXX convert args. */
2263 vm_object_t object = (vm_object_t)addr;
2264 boolean_t full = have_addr;
2268 /* XXX count is an (unused) arg. Avoid shadowing it. */
2269 #define count was_count
2277 "Object %p: type=%d, size=0x%jx, res=%d, ref=%d, flags=0x%x ruid %d charge %jx\n",
2278 object, (int)object->type, (uintmax_t)object->size,
2279 object->resident_page_count, object->ref_count, object->flags,
2280 object->cred ? object->cred->cr_ruid : -1, (uintmax_t)object->charge);
2281 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%jx\n",
2282 object->shadow_count,
2283 object->backing_object ? object->backing_object->ref_count : 0,
2284 object->backing_object, (uintmax_t)object->backing_object_offset);
2291 TAILQ_FOREACH(p, &object->memq, listq) {
2293 db_iprintf("memory:=");
2294 else if (count == 6) {
2302 db_printf("(off=0x%jx,page=0x%jx)",
2303 (uintmax_t)p->pindex, (uintmax_t)VM_PAGE_TO_PHYS(p));
2313 /* XXX need this non-static entry for calling from vm_map_print. */
2316 /* db_expr_t */ long addr,
2317 boolean_t have_addr,
2318 /* db_expr_t */ long count,
2321 vm_object_print_static(addr, have_addr, count, modif);
2324 DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
2329 vm_page_t m, prev_m;
2333 TAILQ_FOREACH(object, &vm_object_list, object_list) {
2334 db_printf("new object: %p\n", (void *)object);
2345 TAILQ_FOREACH(m, &object->memq, listq) {
2346 if (m->pindex > 128)
2348 if ((prev_m = TAILQ_PREV(m, pglist, listq)) != NULL &&
2349 prev_m->pindex + 1 != m->pindex) {
2351 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
2352 (long)fidx, rcount, (long)pa);
2364 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
2369 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
2370 (long)fidx, rcount, (long)pa);
2380 pa = VM_PAGE_TO_PHYS(m);
2384 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
2385 (long)fidx, rcount, (long)pa);