FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_object.c
1 /*-
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * The Mach Operating System project at Carnegie-Mellon University.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
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.
19 *
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
30 * SUCH DAMAGE.
31 *
32 * from: @(#)vm_object.c 8.5 (Berkeley) 3/22/94
33 *
34 *
35 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
36 * All rights reserved.
37 *
38 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
39 *
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.
45 *
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.
49 *
50 * Carnegie Mellon requests users of this software to return to
51 *
52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
53 * School of Computer Science
54 * Carnegie Mellon University
55 * Pittsburgh PA 15213-3890
56 *
57 * any improvements or extensions that they make and grant Carnegie the
58 * rights to redistribute these changes.
59 */
60
61 /*
62 * Virtual memory object module.
63 */
64
65 #include <sys/cdefs.h>
66 __FBSDID("$FreeBSD: releng/10.1/sys/vm/vm_object.c 270920 2014-09-01 07:58:15Z kib $");
67
68 #include "opt_vm.h"
69
70 #include <sys/param.h>
71 #include <sys/systm.h>
72 #include <sys/lock.h>
73 #include <sys/mman.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/rwlock.h>
82 #include <sys/vnode.h>
83 #include <sys/vmmeter.h>
84 #include <sys/sx.h>
85
86 #include <vm/vm.h>
87 #include <vm/vm_param.h>
88 #include <vm/pmap.h>
89 #include <vm/vm_map.h>
90 #include <vm/vm_object.h>
91 #include <vm/vm_page.h>
92 #include <vm/vm_pageout.h>
93 #include <vm/vm_pager.h>
94 #include <vm/swap_pager.h>
95 #include <vm/vm_kern.h>
96 #include <vm/vm_extern.h>
97 #include <vm/vm_radix.h>
98 #include <vm/vm_reserv.h>
99 #include <vm/uma.h>
100
101 static int old_msync;
102 SYSCTL_INT(_vm, OID_AUTO, old_msync, CTLFLAG_RW, &old_msync, 0,
103 "Use old (insecure) msync behavior");
104
105 static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p,
106 int pagerflags, int flags, boolean_t *clearobjflags,
107 boolean_t *eio);
108 static boolean_t vm_object_page_remove_write(vm_page_t p, int flags,
109 boolean_t *clearobjflags);
110 static void vm_object_qcollapse(vm_object_t object);
111 static void vm_object_vndeallocate(vm_object_t object);
112
113 /*
114 * Virtual memory objects maintain the actual data
115 * associated with allocated virtual memory. A given
116 * page of memory exists within exactly one object.
117 *
118 * An object is only deallocated when all "references"
119 * are given up. Only one "reference" to a given
120 * region of an object should be writeable.
121 *
122 * Associated with each object is a list of all resident
123 * memory pages belonging to that object; this list is
124 * maintained by the "vm_page" module, and locked by the object's
125 * lock.
126 *
127 * Each object also records a "pager" routine which is
128 * used to retrieve (and store) pages to the proper backing
129 * storage. In addition, objects may be backed by other
130 * objects from which they were virtual-copied.
131 *
132 * The only items within the object structure which are
133 * modified after time of creation are:
134 * reference count locked by object's lock
135 * pager routine locked by object's lock
136 *
137 */
138
139 struct object_q vm_object_list;
140 struct mtx vm_object_list_mtx; /* lock for object list and count */
141
142 struct vm_object kernel_object_store;
143 struct vm_object kmem_object_store;
144
145 static SYSCTL_NODE(_vm_stats, OID_AUTO, object, CTLFLAG_RD, 0,
146 "VM object stats");
147
148 static long object_collapses;
149 SYSCTL_LONG(_vm_stats_object, OID_AUTO, collapses, CTLFLAG_RD,
150 &object_collapses, 0, "VM object collapses");
151
152 static long object_bypasses;
153 SYSCTL_LONG(_vm_stats_object, OID_AUTO, bypasses, CTLFLAG_RD,
154 &object_bypasses, 0, "VM object bypasses");
155
156 static uma_zone_t obj_zone;
157
158 static int vm_object_zinit(void *mem, int size, int flags);
159
160 #ifdef INVARIANTS
161 static void vm_object_zdtor(void *mem, int size, void *arg);
162
163 static void
164 vm_object_zdtor(void *mem, int size, void *arg)
165 {
166 vm_object_t object;
167
168 object = (vm_object_t)mem;
169 KASSERT(TAILQ_EMPTY(&object->memq),
170 ("object %p has resident pages in its memq", object));
171 KASSERT(vm_radix_is_empty(&object->rtree),
172 ("object %p has resident pages in its trie", object));
173 #if VM_NRESERVLEVEL > 0
174 KASSERT(LIST_EMPTY(&object->rvq),
175 ("object %p has reservations",
176 object));
177 #endif
178 KASSERT(vm_object_cache_is_empty(object),
179 ("object %p has cached pages",
180 object));
181 KASSERT(object->paging_in_progress == 0,
182 ("object %p paging_in_progress = %d",
183 object, object->paging_in_progress));
184 KASSERT(object->resident_page_count == 0,
185 ("object %p resident_page_count = %d",
186 object, object->resident_page_count));
187 KASSERT(object->shadow_count == 0,
188 ("object %p shadow_count = %d",
189 object, object->shadow_count));
190 }
191 #endif
192
193 static int
194 vm_object_zinit(void *mem, int size, int flags)
195 {
196 vm_object_t object;
197
198 object = (vm_object_t)mem;
199 bzero(&object->lock, sizeof(object->lock));
200 rw_init_flags(&object->lock, "vm object", RW_DUPOK);
201
202 /* These are true for any object that has been freed */
203 object->rtree.rt_root = 0;
204 object->rtree.rt_flags = 0;
205 object->paging_in_progress = 0;
206 object->resident_page_count = 0;
207 object->shadow_count = 0;
208 object->cache.rt_root = 0;
209 object->cache.rt_flags = 0;
210 return (0);
211 }
212
213 static void
214 _vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object)
215 {
216
217 TAILQ_INIT(&object->memq);
218 LIST_INIT(&object->shadow_head);
219
220 object->type = type;
221 switch (type) {
222 case OBJT_DEAD:
223 panic("_vm_object_allocate: can't create OBJT_DEAD");
224 case OBJT_DEFAULT:
225 case OBJT_SWAP:
226 object->flags = OBJ_ONEMAPPING;
227 break;
228 case OBJT_DEVICE:
229 case OBJT_SG:
230 object->flags = OBJ_FICTITIOUS | OBJ_UNMANAGED;
231 break;
232 case OBJT_MGTDEVICE:
233 object->flags = OBJ_FICTITIOUS;
234 break;
235 case OBJT_PHYS:
236 object->flags = OBJ_UNMANAGED;
237 break;
238 case OBJT_VNODE:
239 object->flags = 0;
240 break;
241 default:
242 panic("_vm_object_allocate: type %d is undefined", type);
243 }
244 object->size = size;
245 object->generation = 1;
246 object->ref_count = 1;
247 object->memattr = VM_MEMATTR_DEFAULT;
248 object->cred = NULL;
249 object->charge = 0;
250 object->handle = NULL;
251 object->backing_object = NULL;
252 object->backing_object_offset = (vm_ooffset_t) 0;
253 #if VM_NRESERVLEVEL > 0
254 LIST_INIT(&object->rvq);
255 #endif
256
257 mtx_lock(&vm_object_list_mtx);
258 TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
259 mtx_unlock(&vm_object_list_mtx);
260 }
261
262 /*
263 * vm_object_init:
264 *
265 * Initialize the VM objects module.
266 */
267 void
268 vm_object_init(void)
269 {
270 TAILQ_INIT(&vm_object_list);
271 mtx_init(&vm_object_list_mtx, "vm object_list", NULL, MTX_DEF);
272
273 rw_init(&kernel_object->lock, "kernel vm object");
274 _vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
275 kernel_object);
276 #if VM_NRESERVLEVEL > 0
277 kernel_object->flags |= OBJ_COLORED;
278 kernel_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
279 #endif
280
281 rw_init(&kmem_object->lock, "kmem vm object");
282 _vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
283 kmem_object);
284 #if VM_NRESERVLEVEL > 0
285 kmem_object->flags |= OBJ_COLORED;
286 kmem_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
287 #endif
288
289 /*
290 * The lock portion of struct vm_object must be type stable due
291 * to vm_pageout_fallback_object_lock locking a vm object
292 * without holding any references to it.
293 */
294 obj_zone = uma_zcreate("VM OBJECT", sizeof (struct vm_object), NULL,
295 #ifdef INVARIANTS
296 vm_object_zdtor,
297 #else
298 NULL,
299 #endif
300 vm_object_zinit, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
301
302 vm_radix_init();
303 }
304
305 void
306 vm_object_clear_flag(vm_object_t object, u_short bits)
307 {
308
309 VM_OBJECT_ASSERT_WLOCKED(object);
310 object->flags &= ~bits;
311 }
312
313 /*
314 * Sets the default memory attribute for the specified object. Pages
315 * that are allocated to this object are by default assigned this memory
316 * attribute.
317 *
318 * Presently, this function must be called before any pages are allocated
319 * to the object. In the future, this requirement may be relaxed for
320 * "default" and "swap" objects.
321 */
322 int
323 vm_object_set_memattr(vm_object_t object, vm_memattr_t memattr)
324 {
325
326 VM_OBJECT_ASSERT_WLOCKED(object);
327 switch (object->type) {
328 case OBJT_DEFAULT:
329 case OBJT_DEVICE:
330 case OBJT_MGTDEVICE:
331 case OBJT_PHYS:
332 case OBJT_SG:
333 case OBJT_SWAP:
334 case OBJT_VNODE:
335 if (!TAILQ_EMPTY(&object->memq))
336 return (KERN_FAILURE);
337 break;
338 case OBJT_DEAD:
339 return (KERN_INVALID_ARGUMENT);
340 default:
341 panic("vm_object_set_memattr: object %p is of undefined type",
342 object);
343 }
344 object->memattr = memattr;
345 return (KERN_SUCCESS);
346 }
347
348 void
349 vm_object_pip_add(vm_object_t object, short i)
350 {
351
352 VM_OBJECT_ASSERT_WLOCKED(object);
353 object->paging_in_progress += i;
354 }
355
356 void
357 vm_object_pip_subtract(vm_object_t object, short i)
358 {
359
360 VM_OBJECT_ASSERT_WLOCKED(object);
361 object->paging_in_progress -= i;
362 }
363
364 void
365 vm_object_pip_wakeup(vm_object_t object)
366 {
367
368 VM_OBJECT_ASSERT_WLOCKED(object);
369 object->paging_in_progress--;
370 if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
371 vm_object_clear_flag(object, OBJ_PIPWNT);
372 wakeup(object);
373 }
374 }
375
376 void
377 vm_object_pip_wakeupn(vm_object_t object, short i)
378 {
379
380 VM_OBJECT_ASSERT_WLOCKED(object);
381 if (i)
382 object->paging_in_progress -= i;
383 if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
384 vm_object_clear_flag(object, OBJ_PIPWNT);
385 wakeup(object);
386 }
387 }
388
389 void
390 vm_object_pip_wait(vm_object_t object, char *waitid)
391 {
392
393 VM_OBJECT_ASSERT_WLOCKED(object);
394 while (object->paging_in_progress) {
395 object->flags |= OBJ_PIPWNT;
396 VM_OBJECT_SLEEP(object, object, PVM, waitid, 0);
397 }
398 }
399
400 /*
401 * vm_object_allocate:
402 *
403 * Returns a new object with the given size.
404 */
405 vm_object_t
406 vm_object_allocate(objtype_t type, vm_pindex_t size)
407 {
408 vm_object_t object;
409
410 object = (vm_object_t)uma_zalloc(obj_zone, M_WAITOK);
411 _vm_object_allocate(type, size, object);
412 return (object);
413 }
414
415
416 /*
417 * vm_object_reference:
418 *
419 * Gets another reference to the given object. Note: OBJ_DEAD
420 * objects can be referenced during final cleaning.
421 */
422 void
423 vm_object_reference(vm_object_t object)
424 {
425 if (object == NULL)
426 return;
427 VM_OBJECT_WLOCK(object);
428 vm_object_reference_locked(object);
429 VM_OBJECT_WUNLOCK(object);
430 }
431
432 /*
433 * vm_object_reference_locked:
434 *
435 * Gets another reference to the given object.
436 *
437 * The object must be locked.
438 */
439 void
440 vm_object_reference_locked(vm_object_t object)
441 {
442 struct vnode *vp;
443
444 VM_OBJECT_ASSERT_WLOCKED(object);
445 object->ref_count++;
446 if (object->type == OBJT_VNODE) {
447 vp = object->handle;
448 vref(vp);
449 }
450 }
451
452 /*
453 * Handle deallocating an object of type OBJT_VNODE.
454 */
455 static void
456 vm_object_vndeallocate(vm_object_t object)
457 {
458 struct vnode *vp = (struct vnode *) object->handle;
459
460 VM_OBJECT_ASSERT_WLOCKED(object);
461 KASSERT(object->type == OBJT_VNODE,
462 ("vm_object_vndeallocate: not a vnode object"));
463 KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
464 #ifdef INVARIANTS
465 if (object->ref_count == 0) {
466 vprint("vm_object_vndeallocate", vp);
467 panic("vm_object_vndeallocate: bad object reference count");
468 }
469 #endif
470
471 if (object->ref_count > 1) {
472 object->ref_count--;
473 VM_OBJECT_WUNLOCK(object);
474 /* vrele may need the vnode lock. */
475 vrele(vp);
476 } else {
477 vhold(vp);
478 VM_OBJECT_WUNLOCK(object);
479 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
480 vdrop(vp);
481 VM_OBJECT_WLOCK(object);
482 object->ref_count--;
483 if (object->type == OBJT_DEAD) {
484 VM_OBJECT_WUNLOCK(object);
485 VOP_UNLOCK(vp, 0);
486 } else {
487 if (object->ref_count == 0)
488 VOP_UNSET_TEXT(vp);
489 VM_OBJECT_WUNLOCK(object);
490 vput(vp);
491 }
492 }
493 }
494
495 /*
496 * vm_object_deallocate:
497 *
498 * Release a reference to the specified object,
499 * gained either through a vm_object_allocate
500 * or a vm_object_reference call. When all references
501 * are gone, storage associated with this object
502 * may be relinquished.
503 *
504 * No object may be locked.
505 */
506 void
507 vm_object_deallocate(vm_object_t object)
508 {
509 vm_object_t temp;
510 struct vnode *vp;
511
512 while (object != NULL) {
513 VM_OBJECT_WLOCK(object);
514 if (object->type == OBJT_VNODE) {
515 vm_object_vndeallocate(object);
516 return;
517 }
518
519 KASSERT(object->ref_count != 0,
520 ("vm_object_deallocate: object deallocated too many times: %d", object->type));
521
522 /*
523 * If the reference count goes to 0 we start calling
524 * vm_object_terminate() on the object chain.
525 * A ref count of 1 may be a special case depending on the
526 * shadow count being 0 or 1.
527 */
528 object->ref_count--;
529 if (object->ref_count > 1) {
530 VM_OBJECT_WUNLOCK(object);
531 return;
532 } else if (object->ref_count == 1) {
533 if (object->type == OBJT_SWAP &&
534 (object->flags & OBJ_TMPFS) != 0) {
535 vp = object->un_pager.swp.swp_tmpfs;
536 vhold(vp);
537 VM_OBJECT_WUNLOCK(object);
538 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
539 VM_OBJECT_WLOCK(object);
540 if (object->type == OBJT_DEAD ||
541 object->ref_count != 1) {
542 VM_OBJECT_WUNLOCK(object);
543 VOP_UNLOCK(vp, 0);
544 vdrop(vp);
545 return;
546 }
547 if ((object->flags & OBJ_TMPFS) != 0)
548 VOP_UNSET_TEXT(vp);
549 VOP_UNLOCK(vp, 0);
550 vdrop(vp);
551 }
552 if (object->shadow_count == 0 &&
553 object->handle == NULL &&
554 (object->type == OBJT_DEFAULT ||
555 (object->type == OBJT_SWAP &&
556 (object->flags & OBJ_TMPFS_NODE) == 0))) {
557 vm_object_set_flag(object, OBJ_ONEMAPPING);
558 } else if ((object->shadow_count == 1) &&
559 (object->handle == NULL) &&
560 (object->type == OBJT_DEFAULT ||
561 object->type == OBJT_SWAP)) {
562 vm_object_t robject;
563
564 robject = LIST_FIRST(&object->shadow_head);
565 KASSERT(robject != NULL,
566 ("vm_object_deallocate: ref_count: %d, shadow_count: %d",
567 object->ref_count,
568 object->shadow_count));
569 KASSERT((robject->flags & OBJ_TMPFS_NODE) == 0,
570 ("shadowed tmpfs v_object %p", object));
571 if (!VM_OBJECT_TRYWLOCK(robject)) {
572 /*
573 * Avoid a potential deadlock.
574 */
575 object->ref_count++;
576 VM_OBJECT_WUNLOCK(object);
577 /*
578 * More likely than not the thread
579 * holding robject's lock has lower
580 * priority than the current thread.
581 * Let the lower priority thread run.
582 */
583 pause("vmo_de", 1);
584 continue;
585 }
586 /*
587 * Collapse object into its shadow unless its
588 * shadow is dead. In that case, object will
589 * be deallocated by the thread that is
590 * deallocating its shadow.
591 */
592 if ((robject->flags & OBJ_DEAD) == 0 &&
593 (robject->handle == NULL) &&
594 (robject->type == OBJT_DEFAULT ||
595 robject->type == OBJT_SWAP)) {
596
597 robject->ref_count++;
598 retry:
599 if (robject->paging_in_progress) {
600 VM_OBJECT_WUNLOCK(object);
601 vm_object_pip_wait(robject,
602 "objde1");
603 temp = robject->backing_object;
604 if (object == temp) {
605 VM_OBJECT_WLOCK(object);
606 goto retry;
607 }
608 } else if (object->paging_in_progress) {
609 VM_OBJECT_WUNLOCK(robject);
610 object->flags |= OBJ_PIPWNT;
611 VM_OBJECT_SLEEP(object, object,
612 PDROP | PVM, "objde2", 0);
613 VM_OBJECT_WLOCK(robject);
614 temp = robject->backing_object;
615 if (object == temp) {
616 VM_OBJECT_WLOCK(object);
617 goto retry;
618 }
619 } else
620 VM_OBJECT_WUNLOCK(object);
621
622 if (robject->ref_count == 1) {
623 robject->ref_count--;
624 object = robject;
625 goto doterm;
626 }
627 object = robject;
628 vm_object_collapse(object);
629 VM_OBJECT_WUNLOCK(object);
630 continue;
631 }
632 VM_OBJECT_WUNLOCK(robject);
633 }
634 VM_OBJECT_WUNLOCK(object);
635 return;
636 }
637 doterm:
638 temp = object->backing_object;
639 if (temp != NULL) {
640 KASSERT((object->flags & OBJ_TMPFS_NODE) == 0,
641 ("shadowed tmpfs v_object 2 %p", object));
642 VM_OBJECT_WLOCK(temp);
643 LIST_REMOVE(object, shadow_list);
644 temp->shadow_count--;
645 VM_OBJECT_WUNLOCK(temp);
646 object->backing_object = NULL;
647 }
648 /*
649 * Don't double-terminate, we could be in a termination
650 * recursion due to the terminate having to sync data
651 * to disk.
652 */
653 if ((object->flags & OBJ_DEAD) == 0)
654 vm_object_terminate(object);
655 else
656 VM_OBJECT_WUNLOCK(object);
657 object = temp;
658 }
659 }
660
661 /*
662 * vm_object_destroy removes the object from the global object list
663 * and frees the space for the object.
664 */
665 void
666 vm_object_destroy(vm_object_t object)
667 {
668
669 /*
670 * Remove the object from the global object list.
671 */
672 mtx_lock(&vm_object_list_mtx);
673 TAILQ_REMOVE(&vm_object_list, object, object_list);
674 mtx_unlock(&vm_object_list_mtx);
675
676 /*
677 * Release the allocation charge.
678 */
679 if (object->cred != NULL) {
680 KASSERT(object->type == OBJT_DEFAULT ||
681 object->type == OBJT_SWAP,
682 ("vm_object_terminate: non-swap obj %p has cred",
683 object));
684 swap_release_by_cred(object->charge, object->cred);
685 object->charge = 0;
686 crfree(object->cred);
687 object->cred = NULL;
688 }
689
690 /*
691 * Free the space for the object.
692 */
693 uma_zfree(obj_zone, object);
694 }
695
696 /*
697 * vm_object_terminate actually destroys the specified object, freeing
698 * up all previously used resources.
699 *
700 * The object must be locked.
701 * This routine may block.
702 */
703 void
704 vm_object_terminate(vm_object_t object)
705 {
706 vm_page_t p, p_next;
707
708 VM_OBJECT_ASSERT_WLOCKED(object);
709
710 /*
711 * Make sure no one uses us.
712 */
713 vm_object_set_flag(object, OBJ_DEAD);
714
715 /*
716 * wait for the pageout daemon to be done with the object
717 */
718 vm_object_pip_wait(object, "objtrm");
719
720 KASSERT(!object->paging_in_progress,
721 ("vm_object_terminate: pageout in progress"));
722
723 /*
724 * Clean and free the pages, as appropriate. All references to the
725 * object are gone, so we don't need to lock it.
726 */
727 if (object->type == OBJT_VNODE) {
728 struct vnode *vp = (struct vnode *)object->handle;
729
730 /*
731 * Clean pages and flush buffers.
732 */
733 vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
734 VM_OBJECT_WUNLOCK(object);
735
736 vinvalbuf(vp, V_SAVE, 0, 0);
737
738 VM_OBJECT_WLOCK(object);
739 }
740
741 KASSERT(object->ref_count == 0,
742 ("vm_object_terminate: object with references, ref_count=%d",
743 object->ref_count));
744
745 /*
746 * Free any remaining pageable pages. This also removes them from the
747 * paging queues. However, don't free wired pages, just remove them
748 * from the object. Rather than incrementally removing each page from
749 * the object, the page and object are reset to any empty state.
750 */
751 TAILQ_FOREACH_SAFE(p, &object->memq, listq, p_next) {
752 vm_page_assert_unbusied(p);
753 vm_page_lock(p);
754 /*
755 * Optimize the page's removal from the object by resetting
756 * its "object" field. Specifically, if the page is not
757 * wired, then the effect of this assignment is that
758 * vm_page_free()'s call to vm_page_remove() will return
759 * immediately without modifying the page or the object.
760 */
761 p->object = NULL;
762 if (p->wire_count == 0) {
763 vm_page_free(p);
764 PCPU_INC(cnt.v_pfree);
765 }
766 vm_page_unlock(p);
767 }
768 /*
769 * If the object contained any pages, then reset it to an empty state.
770 * None of the object's fields, including "resident_page_count", were
771 * modified by the preceding loop.
772 */
773 if (object->resident_page_count != 0) {
774 vm_radix_reclaim_allnodes(&object->rtree);
775 TAILQ_INIT(&object->memq);
776 object->resident_page_count = 0;
777 if (object->type == OBJT_VNODE)
778 vdrop(object->handle);
779 }
780
781 #if VM_NRESERVLEVEL > 0
782 if (__predict_false(!LIST_EMPTY(&object->rvq)))
783 vm_reserv_break_all(object);
784 #endif
785 if (__predict_false(!vm_object_cache_is_empty(object)))
786 vm_page_cache_free(object, 0, 0);
787
788 /*
789 * Let the pager know object is dead.
790 */
791 vm_pager_deallocate(object);
792 VM_OBJECT_WUNLOCK(object);
793
794 vm_object_destroy(object);
795 }
796
797 /*
798 * Make the page read-only so that we can clear the object flags. However, if
799 * this is a nosync mmap then the object is likely to stay dirty so do not
800 * mess with the page and do not clear the object flags. Returns TRUE if the
801 * page should be flushed, and FALSE otherwise.
802 */
803 static boolean_t
804 vm_object_page_remove_write(vm_page_t p, int flags, boolean_t *clearobjflags)
805 {
806
807 /*
808 * If we have been asked to skip nosync pages and this is a
809 * nosync page, skip it. Note that the object flags were not
810 * cleared in this case so we do not have to set them.
811 */
812 if ((flags & OBJPC_NOSYNC) != 0 && (p->oflags & VPO_NOSYNC) != 0) {
813 *clearobjflags = FALSE;
814 return (FALSE);
815 } else {
816 pmap_remove_write(p);
817 return (p->dirty != 0);
818 }
819 }
820
821 /*
822 * vm_object_page_clean
823 *
824 * Clean all dirty pages in the specified range of object. Leaves page
825 * on whatever queue it is currently on. If NOSYNC is set then do not
826 * write out pages with VPO_NOSYNC set (originally comes from MAP_NOSYNC),
827 * leaving the object dirty.
828 *
829 * When stuffing pages asynchronously, allow clustering. XXX we need a
830 * synchronous clustering mode implementation.
831 *
832 * Odd semantics: if start == end, we clean everything.
833 *
834 * The object must be locked.
835 *
836 * Returns FALSE if some page from the range was not written, as
837 * reported by the pager, and TRUE otherwise.
838 */
839 boolean_t
840 vm_object_page_clean(vm_object_t object, vm_ooffset_t start, vm_ooffset_t end,
841 int flags)
842 {
843 vm_page_t np, p;
844 vm_pindex_t pi, tend, tstart;
845 int curgeneration, n, pagerflags;
846 boolean_t clearobjflags, eio, res;
847
848 VM_OBJECT_ASSERT_WLOCKED(object);
849
850 /*
851 * The OBJ_MIGHTBEDIRTY flag is only set for OBJT_VNODE
852 * objects. The check below prevents the function from
853 * operating on non-vnode objects.
854 */
855 if ((object->flags & OBJ_MIGHTBEDIRTY) == 0 ||
856 object->resident_page_count == 0)
857 return (TRUE);
858
859 pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) != 0 ?
860 VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK;
861 pagerflags |= (flags & OBJPC_INVAL) != 0 ? VM_PAGER_PUT_INVAL : 0;
862
863 tstart = OFF_TO_IDX(start);
864 tend = (end == 0) ? object->size : OFF_TO_IDX(end + PAGE_MASK);
865 clearobjflags = tstart == 0 && tend >= object->size;
866 res = TRUE;
867
868 rescan:
869 curgeneration = object->generation;
870
871 for (p = vm_page_find_least(object, tstart); p != NULL; p = np) {
872 pi = p->pindex;
873 if (pi >= tend)
874 break;
875 np = TAILQ_NEXT(p, listq);
876 if (p->valid == 0)
877 continue;
878 if (vm_page_sleep_if_busy(p, "vpcwai")) {
879 if (object->generation != curgeneration) {
880 if ((flags & OBJPC_SYNC) != 0)
881 goto rescan;
882 else
883 clearobjflags = FALSE;
884 }
885 np = vm_page_find_least(object, pi);
886 continue;
887 }
888 if (!vm_object_page_remove_write(p, flags, &clearobjflags))
889 continue;
890
891 n = vm_object_page_collect_flush(object, p, pagerflags,
892 flags, &clearobjflags, &eio);
893 if (eio) {
894 res = FALSE;
895 clearobjflags = FALSE;
896 }
897 if (object->generation != curgeneration) {
898 if ((flags & OBJPC_SYNC) != 0)
899 goto rescan;
900 else
901 clearobjflags = FALSE;
902 }
903
904 /*
905 * If the VOP_PUTPAGES() did a truncated write, so
906 * that even the first page of the run is not fully
907 * written, vm_pageout_flush() returns 0 as the run
908 * length. Since the condition that caused truncated
909 * write may be permanent, e.g. exhausted free space,
910 * accepting n == 0 would cause an infinite loop.
911 *
912 * Forwarding the iterator leaves the unwritten page
913 * behind, but there is not much we can do there if
914 * filesystem refuses to write it.
915 */
916 if (n == 0) {
917 n = 1;
918 clearobjflags = FALSE;
919 }
920 np = vm_page_find_least(object, pi + n);
921 }
922 #if 0
923 VOP_FSYNC(vp, (pagerflags & VM_PAGER_PUT_SYNC) ? MNT_WAIT : 0);
924 #endif
925
926 if (clearobjflags)
927 vm_object_clear_flag(object, OBJ_MIGHTBEDIRTY);
928 return (res);
929 }
930
931 static int
932 vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags,
933 int flags, boolean_t *clearobjflags, boolean_t *eio)
934 {
935 vm_page_t ma[vm_pageout_page_count], p_first, tp;
936 int count, i, mreq, runlen;
937
938 vm_page_lock_assert(p, MA_NOTOWNED);
939 VM_OBJECT_ASSERT_WLOCKED(object);
940
941 count = 1;
942 mreq = 0;
943
944 for (tp = p; count < vm_pageout_page_count; count++) {
945 tp = vm_page_next(tp);
946 if (tp == NULL || vm_page_busied(tp))
947 break;
948 if (!vm_object_page_remove_write(tp, flags, clearobjflags))
949 break;
950 }
951
952 for (p_first = p; count < vm_pageout_page_count; count++) {
953 tp = vm_page_prev(p_first);
954 if (tp == NULL || vm_page_busied(tp))
955 break;
956 if (!vm_object_page_remove_write(tp, flags, clearobjflags))
957 break;
958 p_first = tp;
959 mreq++;
960 }
961
962 for (tp = p_first, i = 0; i < count; tp = TAILQ_NEXT(tp, listq), i++)
963 ma[i] = tp;
964
965 vm_pageout_flush(ma, count, pagerflags, mreq, &runlen, eio);
966 return (runlen);
967 }
968
969 /*
970 * Note that there is absolutely no sense in writing out
971 * anonymous objects, so we track down the vnode object
972 * to write out.
973 * We invalidate (remove) all pages from the address space
974 * for semantic correctness.
975 *
976 * If the backing object is a device object with unmanaged pages, then any
977 * mappings to the specified range of pages must be removed before this
978 * function is called.
979 *
980 * Note: certain anonymous maps, such as MAP_NOSYNC maps,
981 * may start out with a NULL object.
982 */
983 boolean_t
984 vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
985 boolean_t syncio, boolean_t invalidate)
986 {
987 vm_object_t backing_object;
988 struct vnode *vp;
989 struct mount *mp;
990 int error, flags, fsync_after;
991 boolean_t res;
992
993 if (object == NULL)
994 return (TRUE);
995 res = TRUE;
996 error = 0;
997 VM_OBJECT_WLOCK(object);
998 while ((backing_object = object->backing_object) != NULL) {
999 VM_OBJECT_WLOCK(backing_object);
1000 offset += object->backing_object_offset;
1001 VM_OBJECT_WUNLOCK(object);
1002 object = backing_object;
1003 if (object->size < OFF_TO_IDX(offset + size))
1004 size = IDX_TO_OFF(object->size) - offset;
1005 }
1006 /*
1007 * Flush pages if writing is allowed, invalidate them
1008 * if invalidation requested. Pages undergoing I/O
1009 * will be ignored by vm_object_page_remove().
1010 *
1011 * We cannot lock the vnode and then wait for paging
1012 * to complete without deadlocking against vm_fault.
1013 * Instead we simply call vm_object_page_remove() and
1014 * allow it to block internally on a page-by-page
1015 * basis when it encounters pages undergoing async
1016 * I/O.
1017 */
1018 if (object->type == OBJT_VNODE &&
1019 (object->flags & OBJ_MIGHTBEDIRTY) != 0) {
1020 vp = object->handle;
1021 VM_OBJECT_WUNLOCK(object);
1022 (void) vn_start_write(vp, &mp, V_WAIT);
1023 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
1024 if (syncio && !invalidate && offset == 0 &&
1025 OFF_TO_IDX(size) == object->size) {
1026 /*
1027 * If syncing the whole mapping of the file,
1028 * it is faster to schedule all the writes in
1029 * async mode, also allowing the clustering,
1030 * and then wait for i/o to complete.
1031 */
1032 flags = 0;
1033 fsync_after = TRUE;
1034 } else {
1035 flags = (syncio || invalidate) ? OBJPC_SYNC : 0;
1036 flags |= invalidate ? (OBJPC_SYNC | OBJPC_INVAL) : 0;
1037 fsync_after = FALSE;
1038 }
1039 VM_OBJECT_WLOCK(object);
1040 res = vm_object_page_clean(object, offset, offset + size,
1041 flags);
1042 VM_OBJECT_WUNLOCK(object);
1043 if (fsync_after)
1044 error = VOP_FSYNC(vp, MNT_WAIT, curthread);
1045 VOP_UNLOCK(vp, 0);
1046 vn_finished_write(mp);
1047 if (error != 0)
1048 res = FALSE;
1049 VM_OBJECT_WLOCK(object);
1050 }
1051 if ((object->type == OBJT_VNODE ||
1052 object->type == OBJT_DEVICE) && invalidate) {
1053 if (object->type == OBJT_DEVICE)
1054 /*
1055 * The option OBJPR_NOTMAPPED must be passed here
1056 * because vm_object_page_remove() cannot remove
1057 * unmanaged mappings.
1058 */
1059 flags = OBJPR_NOTMAPPED;
1060 else if (old_msync)
1061 flags = OBJPR_NOTWIRED;
1062 else
1063 flags = OBJPR_CLEANONLY | OBJPR_NOTWIRED;
1064 vm_object_page_remove(object, OFF_TO_IDX(offset),
1065 OFF_TO_IDX(offset + size + PAGE_MASK), flags);
1066 }
1067 VM_OBJECT_WUNLOCK(object);
1068 return (res);
1069 }
1070
1071 /*
1072 * vm_object_madvise:
1073 *
1074 * Implements the madvise function at the object/page level.
1075 *
1076 * MADV_WILLNEED (any object)
1077 *
1078 * Activate the specified pages if they are resident.
1079 *
1080 * MADV_DONTNEED (any object)
1081 *
1082 * Deactivate the specified pages if they are resident.
1083 *
1084 * MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects,
1085 * OBJ_ONEMAPPING only)
1086 *
1087 * Deactivate and clean the specified pages if they are
1088 * resident. This permits the process to reuse the pages
1089 * without faulting or the kernel to reclaim the pages
1090 * without I/O.
1091 */
1092 void
1093 vm_object_madvise(vm_object_t object, vm_pindex_t pindex, vm_pindex_t end,
1094 int advise)
1095 {
1096 vm_pindex_t tpindex;
1097 vm_object_t backing_object, tobject;
1098 vm_page_t m;
1099
1100 if (object == NULL)
1101 return;
1102 VM_OBJECT_WLOCK(object);
1103 /*
1104 * Locate and adjust resident pages
1105 */
1106 for (; pindex < end; pindex += 1) {
1107 relookup:
1108 tobject = object;
1109 tpindex = pindex;
1110 shadowlookup:
1111 /*
1112 * MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
1113 * and those pages must be OBJ_ONEMAPPING.
1114 */
1115 if (advise == MADV_FREE) {
1116 if ((tobject->type != OBJT_DEFAULT &&
1117 tobject->type != OBJT_SWAP) ||
1118 (tobject->flags & OBJ_ONEMAPPING) == 0) {
1119 goto unlock_tobject;
1120 }
1121 } else if ((tobject->flags & OBJ_UNMANAGED) != 0)
1122 goto unlock_tobject;
1123 m = vm_page_lookup(tobject, tpindex);
1124 if (m == NULL && advise == MADV_WILLNEED) {
1125 /*
1126 * If the page is cached, reactivate it.
1127 */
1128 m = vm_page_alloc(tobject, tpindex, VM_ALLOC_IFCACHED |
1129 VM_ALLOC_NOBUSY);
1130 }
1131 if (m == NULL) {
1132 /*
1133 * There may be swap even if there is no backing page
1134 */
1135 if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
1136 swap_pager_freespace(tobject, tpindex, 1);
1137 /*
1138 * next object
1139 */
1140 backing_object = tobject->backing_object;
1141 if (backing_object == NULL)
1142 goto unlock_tobject;
1143 VM_OBJECT_WLOCK(backing_object);
1144 tpindex += OFF_TO_IDX(tobject->backing_object_offset);
1145 if (tobject != object)
1146 VM_OBJECT_WUNLOCK(tobject);
1147 tobject = backing_object;
1148 goto shadowlookup;
1149 } else if (m->valid != VM_PAGE_BITS_ALL)
1150 goto unlock_tobject;
1151 /*
1152 * If the page is not in a normal state, skip it.
1153 */
1154 vm_page_lock(m);
1155 if (m->hold_count != 0 || m->wire_count != 0) {
1156 vm_page_unlock(m);
1157 goto unlock_tobject;
1158 }
1159 KASSERT((m->flags & PG_FICTITIOUS) == 0,
1160 ("vm_object_madvise: page %p is fictitious", m));
1161 KASSERT((m->oflags & VPO_UNMANAGED) == 0,
1162 ("vm_object_madvise: page %p is not managed", m));
1163 if (vm_page_busied(m)) {
1164 if (advise == MADV_WILLNEED) {
1165 /*
1166 * Reference the page before unlocking and
1167 * sleeping so that the page daemon is less
1168 * likely to reclaim it.
1169 */
1170 vm_page_aflag_set(m, PGA_REFERENCED);
1171 }
1172 if (object != tobject)
1173 VM_OBJECT_WUNLOCK(object);
1174 VM_OBJECT_WUNLOCK(tobject);
1175 vm_page_busy_sleep(m, "madvpo");
1176 VM_OBJECT_WLOCK(object);
1177 goto relookup;
1178 }
1179 if (advise == MADV_WILLNEED) {
1180 vm_page_activate(m);
1181 } else {
1182 vm_page_advise(m, advise);
1183 }
1184 vm_page_unlock(m);
1185 if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
1186 swap_pager_freespace(tobject, tpindex, 1);
1187 unlock_tobject:
1188 if (tobject != object)
1189 VM_OBJECT_WUNLOCK(tobject);
1190 }
1191 VM_OBJECT_WUNLOCK(object);
1192 }
1193
1194 /*
1195 * vm_object_shadow:
1196 *
1197 * Create a new object which is backed by the
1198 * specified existing object range. The source
1199 * object reference is deallocated.
1200 *
1201 * The new object and offset into that object
1202 * are returned in the source parameters.
1203 */
1204 void
1205 vm_object_shadow(
1206 vm_object_t *object, /* IN/OUT */
1207 vm_ooffset_t *offset, /* IN/OUT */
1208 vm_size_t length)
1209 {
1210 vm_object_t source;
1211 vm_object_t result;
1212
1213 source = *object;
1214
1215 /*
1216 * Don't create the new object if the old object isn't shared.
1217 */
1218 if (source != NULL) {
1219 VM_OBJECT_WLOCK(source);
1220 if (source->ref_count == 1 &&
1221 source->handle == NULL &&
1222 (source->type == OBJT_DEFAULT ||
1223 source->type == OBJT_SWAP)) {
1224 VM_OBJECT_WUNLOCK(source);
1225 return;
1226 }
1227 VM_OBJECT_WUNLOCK(source);
1228 }
1229
1230 /*
1231 * Allocate a new object with the given length.
1232 */
1233 result = vm_object_allocate(OBJT_DEFAULT, atop(length));
1234
1235 /*
1236 * The new object shadows the source object, adding a reference to it.
1237 * Our caller changes his reference to point to the new object,
1238 * removing a reference to the source object. Net result: no change
1239 * of reference count.
1240 *
1241 * Try to optimize the result object's page color when shadowing
1242 * in order to maintain page coloring consistency in the combined
1243 * shadowed object.
1244 */
1245 result->backing_object = source;
1246 /*
1247 * Store the offset into the source object, and fix up the offset into
1248 * the new object.
1249 */
1250 result->backing_object_offset = *offset;
1251 if (source != NULL) {
1252 VM_OBJECT_WLOCK(source);
1253 LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list);
1254 source->shadow_count++;
1255 #if VM_NRESERVLEVEL > 0
1256 result->flags |= source->flags & OBJ_COLORED;
1257 result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) &
1258 ((1 << (VM_NFREEORDER - 1)) - 1);
1259 #endif
1260 VM_OBJECT_WUNLOCK(source);
1261 }
1262
1263
1264 /*
1265 * Return the new things
1266 */
1267 *offset = 0;
1268 *object = result;
1269 }
1270
1271 /*
1272 * vm_object_split:
1273 *
1274 * Split the pages in a map entry into a new object. This affords
1275 * easier removal of unused pages, and keeps object inheritance from
1276 * being a negative impact on memory usage.
1277 */
1278 void
1279 vm_object_split(vm_map_entry_t entry)
1280 {
1281 vm_page_t m, m_next;
1282 vm_object_t orig_object, new_object, source;
1283 vm_pindex_t idx, offidxstart;
1284 vm_size_t size;
1285
1286 orig_object = entry->object.vm_object;
1287 if (orig_object->type != OBJT_DEFAULT && orig_object->type != OBJT_SWAP)
1288 return;
1289 if (orig_object->ref_count <= 1)
1290 return;
1291 VM_OBJECT_WUNLOCK(orig_object);
1292
1293 offidxstart = OFF_TO_IDX(entry->offset);
1294 size = atop(entry->end - entry->start);
1295
1296 /*
1297 * If swap_pager_copy() is later called, it will convert new_object
1298 * into a swap object.
1299 */
1300 new_object = vm_object_allocate(OBJT_DEFAULT, size);
1301
1302 /*
1303 * At this point, the new object is still private, so the order in
1304 * which the original and new objects are locked does not matter.
1305 */
1306 VM_OBJECT_WLOCK(new_object);
1307 VM_OBJECT_WLOCK(orig_object);
1308 source = orig_object->backing_object;
1309 if (source != NULL) {
1310 VM_OBJECT_WLOCK(source);
1311 if ((source->flags & OBJ_DEAD) != 0) {
1312 VM_OBJECT_WUNLOCK(source);
1313 VM_OBJECT_WUNLOCK(orig_object);
1314 VM_OBJECT_WUNLOCK(new_object);
1315 vm_object_deallocate(new_object);
1316 VM_OBJECT_WLOCK(orig_object);
1317 return;
1318 }
1319 LIST_INSERT_HEAD(&source->shadow_head,
1320 new_object, shadow_list);
1321 source->shadow_count++;
1322 vm_object_reference_locked(source); /* for new_object */
1323 vm_object_clear_flag(source, OBJ_ONEMAPPING);
1324 VM_OBJECT_WUNLOCK(source);
1325 new_object->backing_object_offset =
1326 orig_object->backing_object_offset + entry->offset;
1327 new_object->backing_object = source;
1328 }
1329 if (orig_object->cred != NULL) {
1330 new_object->cred = orig_object->cred;
1331 crhold(orig_object->cred);
1332 new_object->charge = ptoa(size);
1333 KASSERT(orig_object->charge >= ptoa(size),
1334 ("orig_object->charge < 0"));
1335 orig_object->charge -= ptoa(size);
1336 }
1337 retry:
1338 m = vm_page_find_least(orig_object, offidxstart);
1339 for (; m != NULL && (idx = m->pindex - offidxstart) < size;
1340 m = m_next) {
1341 m_next = TAILQ_NEXT(m, listq);
1342
1343 /*
1344 * We must wait for pending I/O to complete before we can
1345 * rename the page.
1346 *
1347 * We do not have to VM_PROT_NONE the page as mappings should
1348 * not be changed by this operation.
1349 */
1350 if (vm_page_busied(m)) {
1351 VM_OBJECT_WUNLOCK(new_object);
1352 vm_page_lock(m);
1353 VM_OBJECT_WUNLOCK(orig_object);
1354 vm_page_busy_sleep(m, "spltwt");
1355 VM_OBJECT_WLOCK(orig_object);
1356 VM_OBJECT_WLOCK(new_object);
1357 goto retry;
1358 }
1359
1360 /* vm_page_rename() will handle dirty and cache. */
1361 if (vm_page_rename(m, new_object, idx)) {
1362 VM_OBJECT_WUNLOCK(new_object);
1363 VM_OBJECT_WUNLOCK(orig_object);
1364 VM_WAIT;
1365 VM_OBJECT_WLOCK(orig_object);
1366 VM_OBJECT_WLOCK(new_object);
1367 goto retry;
1368 }
1369 #if VM_NRESERVLEVEL > 0
1370 /*
1371 * If some of the reservation's allocated pages remain with
1372 * the original object, then transferring the reservation to
1373 * the new object is neither particularly beneficial nor
1374 * particularly harmful as compared to leaving the reservation
1375 * with the original object. If, however, all of the
1376 * reservation's allocated pages are transferred to the new
1377 * object, then transferring the reservation is typically
1378 * beneficial. Determining which of these two cases applies
1379 * would be more costly than unconditionally renaming the
1380 * reservation.
1381 */
1382 vm_reserv_rename(m, new_object, orig_object, offidxstart);
1383 #endif
1384 if (orig_object->type == OBJT_SWAP)
1385 vm_page_xbusy(m);
1386 }
1387 if (orig_object->type == OBJT_SWAP) {
1388 /*
1389 * swap_pager_copy() can sleep, in which case the orig_object's
1390 * and new_object's locks are released and reacquired.
1391 */
1392 swap_pager_copy(orig_object, new_object, offidxstart, 0);
1393 TAILQ_FOREACH(m, &new_object->memq, listq)
1394 vm_page_xunbusy(m);
1395
1396 /*
1397 * Transfer any cached pages from orig_object to new_object.
1398 * If swap_pager_copy() found swapped out pages within the
1399 * specified range of orig_object, then it changed
1400 * new_object's type to OBJT_SWAP when it transferred those
1401 * pages to new_object. Otherwise, new_object's type
1402 * should still be OBJT_DEFAULT and orig_object should not
1403 * contain any cached pages within the specified range.
1404 */
1405 if (__predict_false(!vm_object_cache_is_empty(orig_object)))
1406 vm_page_cache_transfer(orig_object, offidxstart,
1407 new_object);
1408 }
1409 VM_OBJECT_WUNLOCK(orig_object);
1410 VM_OBJECT_WUNLOCK(new_object);
1411 entry->object.vm_object = new_object;
1412 entry->offset = 0LL;
1413 vm_object_deallocate(orig_object);
1414 VM_OBJECT_WLOCK(new_object);
1415 }
1416
1417 #define OBSC_TEST_ALL_SHADOWED 0x0001
1418 #define OBSC_COLLAPSE_NOWAIT 0x0002
1419 #define OBSC_COLLAPSE_WAIT 0x0004
1420
1421 static int
1422 vm_object_backing_scan(vm_object_t object, int op)
1423 {
1424 int r = 1;
1425 vm_page_t p;
1426 vm_object_t backing_object;
1427 vm_pindex_t backing_offset_index;
1428
1429 VM_OBJECT_ASSERT_WLOCKED(object);
1430 VM_OBJECT_ASSERT_WLOCKED(object->backing_object);
1431
1432 backing_object = object->backing_object;
1433 backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
1434
1435 /*
1436 * Initial conditions
1437 */
1438 if (op & OBSC_TEST_ALL_SHADOWED) {
1439 /*
1440 * We do not want to have to test for the existence of cache
1441 * or swap pages in the backing object. XXX but with the
1442 * new swapper this would be pretty easy to do.
1443 *
1444 * XXX what about anonymous MAP_SHARED memory that hasn't
1445 * been ZFOD faulted yet? If we do not test for this, the
1446 * shadow test may succeed! XXX
1447 */
1448 if (backing_object->type != OBJT_DEFAULT) {
1449 return (0);
1450 }
1451 }
1452 if (op & OBSC_COLLAPSE_WAIT) {
1453 vm_object_set_flag(backing_object, OBJ_DEAD);
1454 }
1455
1456 /*
1457 * Our scan
1458 */
1459 p = TAILQ_FIRST(&backing_object->memq);
1460 while (p) {
1461 vm_page_t next = TAILQ_NEXT(p, listq);
1462 vm_pindex_t new_pindex = p->pindex - backing_offset_index;
1463
1464 if (op & OBSC_TEST_ALL_SHADOWED) {
1465 vm_page_t pp;
1466
1467 /*
1468 * Ignore pages outside the parent object's range
1469 * and outside the parent object's mapping of the
1470 * backing object.
1471 *
1472 * note that we do not busy the backing object's
1473 * page.
1474 */
1475 if (
1476 p->pindex < backing_offset_index ||
1477 new_pindex >= object->size
1478 ) {
1479 p = next;
1480 continue;
1481 }
1482
1483 /*
1484 * See if the parent has the page or if the parent's
1485 * object pager has the page. If the parent has the
1486 * page but the page is not valid, the parent's
1487 * object pager must have the page.
1488 *
1489 * If this fails, the parent does not completely shadow
1490 * the object and we might as well give up now.
1491 */
1492
1493 pp = vm_page_lookup(object, new_pindex);
1494 if (
1495 (pp == NULL || pp->valid == 0) &&
1496 !vm_pager_has_page(object, new_pindex, NULL, NULL)
1497 ) {
1498 r = 0;
1499 break;
1500 }
1501 }
1502
1503 /*
1504 * Check for busy page
1505 */
1506 if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
1507 vm_page_t pp;
1508
1509 if (op & OBSC_COLLAPSE_NOWAIT) {
1510 if (!p->valid || vm_page_busied(p)) {
1511 p = next;
1512 continue;
1513 }
1514 } else if (op & OBSC_COLLAPSE_WAIT) {
1515 if (vm_page_busied(p)) {
1516 VM_OBJECT_WUNLOCK(object);
1517 vm_page_lock(p);
1518 VM_OBJECT_WUNLOCK(backing_object);
1519 vm_page_busy_sleep(p, "vmocol");
1520 VM_OBJECT_WLOCK(object);
1521 VM_OBJECT_WLOCK(backing_object);
1522 /*
1523 * If we slept, anything could have
1524 * happened. Since the object is
1525 * marked dead, the backing offset
1526 * should not have changed so we
1527 * just restart our scan.
1528 */
1529 p = TAILQ_FIRST(&backing_object->memq);
1530 continue;
1531 }
1532 }
1533
1534 KASSERT(
1535 p->object == backing_object,
1536 ("vm_object_backing_scan: object mismatch")
1537 );
1538
1539 if (
1540 p->pindex < backing_offset_index ||
1541 new_pindex >= object->size
1542 ) {
1543 if (backing_object->type == OBJT_SWAP)
1544 swap_pager_freespace(backing_object,
1545 p->pindex, 1);
1546
1547 /*
1548 * Page is out of the parent object's range, we
1549 * can simply destroy it.
1550 */
1551 vm_page_lock(p);
1552 KASSERT(!pmap_page_is_mapped(p),
1553 ("freeing mapped page %p", p));
1554 if (p->wire_count == 0)
1555 vm_page_free(p);
1556 else
1557 vm_page_remove(p);
1558 vm_page_unlock(p);
1559 p = next;
1560 continue;
1561 }
1562
1563 pp = vm_page_lookup(object, new_pindex);
1564 if (
1565 (op & OBSC_COLLAPSE_NOWAIT) != 0 &&
1566 (pp != NULL && pp->valid == 0)
1567 ) {
1568 if (backing_object->type == OBJT_SWAP)
1569 swap_pager_freespace(backing_object,
1570 p->pindex, 1);
1571
1572 /*
1573 * The page in the parent is not (yet) valid.
1574 * We don't know anything about the state of
1575 * the original page. It might be mapped,
1576 * so we must avoid the next if here.
1577 *
1578 * This is due to a race in vm_fault() where
1579 * we must unbusy the original (backing_obj)
1580 * page before we can (re)lock the parent.
1581 * Hence we can get here.
1582 */
1583 p = next;
1584 continue;
1585 }
1586 if (
1587 pp != NULL ||
1588 vm_pager_has_page(object, new_pindex, NULL, NULL)
1589 ) {
1590 if (backing_object->type == OBJT_SWAP)
1591 swap_pager_freespace(backing_object,
1592 p->pindex, 1);
1593
1594 /*
1595 * page already exists in parent OR swap exists
1596 * for this location in the parent. Destroy
1597 * the original page from the backing object.
1598 *
1599 * Leave the parent's page alone
1600 */
1601 vm_page_lock(p);
1602 KASSERT(!pmap_page_is_mapped(p),
1603 ("freeing mapped page %p", p));
1604 if (p->wire_count == 0)
1605 vm_page_free(p);
1606 else
1607 vm_page_remove(p);
1608 vm_page_unlock(p);
1609 p = next;
1610 continue;
1611 }
1612
1613 /*
1614 * Page does not exist in parent, rename the
1615 * page from the backing object to the main object.
1616 *
1617 * If the page was mapped to a process, it can remain
1618 * mapped through the rename.
1619 * vm_page_rename() will handle dirty and cache.
1620 */
1621 if (vm_page_rename(p, object, new_pindex)) {
1622 if (op & OBSC_COLLAPSE_NOWAIT) {
1623 p = next;
1624 continue;
1625 }
1626 VM_OBJECT_WLOCK(backing_object);
1627 VM_OBJECT_WUNLOCK(object);
1628 VM_WAIT;
1629 VM_OBJECT_WLOCK(object);
1630 VM_OBJECT_WLOCK(backing_object);
1631 p = TAILQ_FIRST(&backing_object->memq);
1632 continue;
1633 }
1634
1635 /* Use the old pindex to free the right page. */
1636 if (backing_object->type == OBJT_SWAP)
1637 swap_pager_freespace(backing_object,
1638 new_pindex + backing_offset_index, 1);
1639
1640 #if VM_NRESERVLEVEL > 0
1641 /*
1642 * Rename the reservation.
1643 */
1644 vm_reserv_rename(p, object, backing_object,
1645 backing_offset_index);
1646 #endif
1647 }
1648 p = next;
1649 }
1650 return (r);
1651 }
1652
1653
1654 /*
1655 * this version of collapse allows the operation to occur earlier and
1656 * when paging_in_progress is true for an object... This is not a complete
1657 * operation, but should plug 99.9% of the rest of the leaks.
1658 */
1659 static void
1660 vm_object_qcollapse(vm_object_t object)
1661 {
1662 vm_object_t backing_object = object->backing_object;
1663
1664 VM_OBJECT_ASSERT_WLOCKED(object);
1665 VM_OBJECT_ASSERT_WLOCKED(backing_object);
1666
1667 if (backing_object->ref_count != 1)
1668 return;
1669
1670 vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT);
1671 }
1672
1673 /*
1674 * vm_object_collapse:
1675 *
1676 * Collapse an object with the object backing it.
1677 * Pages in the backing object are moved into the
1678 * parent, and the backing object is deallocated.
1679 */
1680 void
1681 vm_object_collapse(vm_object_t object)
1682 {
1683 VM_OBJECT_ASSERT_WLOCKED(object);
1684
1685 while (TRUE) {
1686 vm_object_t backing_object;
1687
1688 /*
1689 * Verify that the conditions are right for collapse:
1690 *
1691 * The object exists and the backing object exists.
1692 */
1693 if ((backing_object = object->backing_object) == NULL)
1694 break;
1695
1696 /*
1697 * we check the backing object first, because it is most likely
1698 * not collapsable.
1699 */
1700 VM_OBJECT_WLOCK(backing_object);
1701 if (backing_object->handle != NULL ||
1702 (backing_object->type != OBJT_DEFAULT &&
1703 backing_object->type != OBJT_SWAP) ||
1704 (backing_object->flags & OBJ_DEAD) ||
1705 object->handle != NULL ||
1706 (object->type != OBJT_DEFAULT &&
1707 object->type != OBJT_SWAP) ||
1708 (object->flags & OBJ_DEAD)) {
1709 VM_OBJECT_WUNLOCK(backing_object);
1710 break;
1711 }
1712
1713 if (
1714 object->paging_in_progress != 0 ||
1715 backing_object->paging_in_progress != 0
1716 ) {
1717 vm_object_qcollapse(object);
1718 VM_OBJECT_WUNLOCK(backing_object);
1719 break;
1720 }
1721 /*
1722 * We know that we can either collapse the backing object (if
1723 * the parent is the only reference to it) or (perhaps) have
1724 * the parent bypass the object if the parent happens to shadow
1725 * all the resident pages in the entire backing object.
1726 *
1727 * This is ignoring pager-backed pages such as swap pages.
1728 * vm_object_backing_scan fails the shadowing test in this
1729 * case.
1730 */
1731 if (backing_object->ref_count == 1) {
1732 /*
1733 * If there is exactly one reference to the backing
1734 * object, we can collapse it into the parent.
1735 */
1736 vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT);
1737
1738 #if VM_NRESERVLEVEL > 0
1739 /*
1740 * Break any reservations from backing_object.
1741 */
1742 if (__predict_false(!LIST_EMPTY(&backing_object->rvq)))
1743 vm_reserv_break_all(backing_object);
1744 #endif
1745
1746 /*
1747 * Move the pager from backing_object to object.
1748 */
1749 if (backing_object->type == OBJT_SWAP) {
1750 /*
1751 * swap_pager_copy() can sleep, in which case
1752 * the backing_object's and object's locks are
1753 * released and reacquired.
1754 * Since swap_pager_copy() is being asked to
1755 * destroy the source, it will change the
1756 * backing_object's type to OBJT_DEFAULT.
1757 */
1758 swap_pager_copy(
1759 backing_object,
1760 object,
1761 OFF_TO_IDX(object->backing_object_offset), TRUE);
1762
1763 /*
1764 * Free any cached pages from backing_object.
1765 */
1766 if (__predict_false(
1767 !vm_object_cache_is_empty(backing_object)))
1768 vm_page_cache_free(backing_object, 0, 0);
1769 }
1770 /*
1771 * Object now shadows whatever backing_object did.
1772 * Note that the reference to
1773 * backing_object->backing_object moves from within
1774 * backing_object to within object.
1775 */
1776 LIST_REMOVE(object, shadow_list);
1777 backing_object->shadow_count--;
1778 if (backing_object->backing_object) {
1779 VM_OBJECT_WLOCK(backing_object->backing_object);
1780 LIST_REMOVE(backing_object, shadow_list);
1781 LIST_INSERT_HEAD(
1782 &backing_object->backing_object->shadow_head,
1783 object, shadow_list);
1784 /*
1785 * The shadow_count has not changed.
1786 */
1787 VM_OBJECT_WUNLOCK(backing_object->backing_object);
1788 }
1789 object->backing_object = backing_object->backing_object;
1790 object->backing_object_offset +=
1791 backing_object->backing_object_offset;
1792
1793 /*
1794 * Discard backing_object.
1795 *
1796 * Since the backing object has no pages, no pager left,
1797 * and no object references within it, all that is
1798 * necessary is to dispose of it.
1799 */
1800 KASSERT(backing_object->ref_count == 1, (
1801 "backing_object %p was somehow re-referenced during collapse!",
1802 backing_object));
1803 VM_OBJECT_WUNLOCK(backing_object);
1804 vm_object_destroy(backing_object);
1805
1806 object_collapses++;
1807 } else {
1808 vm_object_t new_backing_object;
1809
1810 /*
1811 * If we do not entirely shadow the backing object,
1812 * there is nothing we can do so we give up.
1813 */
1814 if (object->resident_page_count != object->size &&
1815 vm_object_backing_scan(object,
1816 OBSC_TEST_ALL_SHADOWED) == 0) {
1817 VM_OBJECT_WUNLOCK(backing_object);
1818 break;
1819 }
1820
1821 /*
1822 * Make the parent shadow the next object in the
1823 * chain. Deallocating backing_object will not remove
1824 * it, since its reference count is at least 2.
1825 */
1826 LIST_REMOVE(object, shadow_list);
1827 backing_object->shadow_count--;
1828
1829 new_backing_object = backing_object->backing_object;
1830 if ((object->backing_object = new_backing_object) != NULL) {
1831 VM_OBJECT_WLOCK(new_backing_object);
1832 LIST_INSERT_HEAD(
1833 &new_backing_object->shadow_head,
1834 object,
1835 shadow_list
1836 );
1837 new_backing_object->shadow_count++;
1838 vm_object_reference_locked(new_backing_object);
1839 VM_OBJECT_WUNLOCK(new_backing_object);
1840 object->backing_object_offset +=
1841 backing_object->backing_object_offset;
1842 }
1843
1844 /*
1845 * Drop the reference count on backing_object. Since
1846 * its ref_count was at least 2, it will not vanish.
1847 */
1848 backing_object->ref_count--;
1849 VM_OBJECT_WUNLOCK(backing_object);
1850 object_bypasses++;
1851 }
1852
1853 /*
1854 * Try again with this object's new backing object.
1855 */
1856 }
1857 }
1858
1859 /*
1860 * vm_object_page_remove:
1861 *
1862 * For the given object, either frees or invalidates each of the
1863 * specified pages. In general, a page is freed. However, if a page is
1864 * wired for any reason other than the existence of a managed, wired
1865 * mapping, then it may be invalidated but not removed from the object.
1866 * Pages are specified by the given range ["start", "end") and the option
1867 * OBJPR_CLEANONLY. As a special case, if "end" is zero, then the range
1868 * extends from "start" to the end of the object. If the option
1869 * OBJPR_CLEANONLY is specified, then only the non-dirty pages within the
1870 * specified range are affected. If the option OBJPR_NOTMAPPED is
1871 * specified, then the pages within the specified range must have no
1872 * mappings. Otherwise, if this option is not specified, any mappings to
1873 * the specified pages are removed before the pages are freed or
1874 * invalidated.
1875 *
1876 * In general, this operation should only be performed on objects that
1877 * contain managed pages. There are, however, two exceptions. First, it
1878 * is performed on the kernel and kmem objects by vm_map_entry_delete().
1879 * Second, it is used by msync(..., MS_INVALIDATE) to invalidate device-
1880 * backed pages. In both of these cases, the option OBJPR_CLEANONLY must
1881 * not be specified and the option OBJPR_NOTMAPPED must be specified.
1882 *
1883 * The object must be locked.
1884 */
1885 void
1886 vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
1887 int options)
1888 {
1889 vm_page_t p, next;
1890 int wirings;
1891
1892 VM_OBJECT_ASSERT_WLOCKED(object);
1893 KASSERT((object->flags & OBJ_UNMANAGED) == 0 ||
1894 (options & (OBJPR_CLEANONLY | OBJPR_NOTMAPPED)) == OBJPR_NOTMAPPED,
1895 ("vm_object_page_remove: illegal options for object %p", object));
1896 if (object->resident_page_count == 0)
1897 goto skipmemq;
1898 vm_object_pip_add(object, 1);
1899 again:
1900 p = vm_page_find_least(object, start);
1901
1902 /*
1903 * Here, the variable "p" is either (1) the page with the least pindex
1904 * greater than or equal to the parameter "start" or (2) NULL.
1905 */
1906 for (; p != NULL && (p->pindex < end || end == 0); p = next) {
1907 next = TAILQ_NEXT(p, listq);
1908
1909 /*
1910 * If the page is wired for any reason besides the existence
1911 * of managed, wired mappings, then it cannot be freed. For
1912 * example, fictitious pages, which represent device memory,
1913 * are inherently wired and cannot be freed. They can,
1914 * however, be invalidated if the option OBJPR_CLEANONLY is
1915 * not specified.
1916 */
1917 vm_page_lock(p);
1918 if (vm_page_xbusied(p)) {
1919 VM_OBJECT_WUNLOCK(object);
1920 vm_page_busy_sleep(p, "vmopax");
1921 VM_OBJECT_WLOCK(object);
1922 goto again;
1923 }
1924 if ((wirings = p->wire_count) != 0 &&
1925 (wirings = pmap_page_wired_mappings(p)) != p->wire_count) {
1926 if ((options & (OBJPR_NOTWIRED | OBJPR_NOTMAPPED)) ==
1927 0) {
1928 pmap_remove_all(p);
1929 /* Account for removal of wired mappings. */
1930 if (wirings != 0)
1931 p->wire_count -= wirings;
1932 }
1933 if ((options & OBJPR_CLEANONLY) == 0) {
1934 p->valid = 0;
1935 vm_page_undirty(p);
1936 }
1937 goto next;
1938 }
1939 if (vm_page_busied(p)) {
1940 VM_OBJECT_WUNLOCK(object);
1941 vm_page_busy_sleep(p, "vmopar");
1942 VM_OBJECT_WLOCK(object);
1943 goto again;
1944 }
1945 KASSERT((p->flags & PG_FICTITIOUS) == 0,
1946 ("vm_object_page_remove: page %p is fictitious", p));
1947 if ((options & OBJPR_CLEANONLY) != 0 && p->valid != 0) {
1948 if ((options & OBJPR_NOTMAPPED) == 0)
1949 pmap_remove_write(p);
1950 if (p->dirty)
1951 goto next;
1952 }
1953 if ((options & OBJPR_NOTMAPPED) == 0) {
1954 if ((options & OBJPR_NOTWIRED) != 0 && wirings != 0)
1955 goto next;
1956 pmap_remove_all(p);
1957 /* Account for removal of wired mappings. */
1958 if (wirings != 0) {
1959 KASSERT(p->wire_count == wirings,
1960 ("inconsistent wire count %d %d %p",
1961 p->wire_count, wirings, p));
1962 p->wire_count = 0;
1963 atomic_subtract_int(&cnt.v_wire_count, 1);
1964 }
1965 }
1966 vm_page_free(p);
1967 next:
1968 vm_page_unlock(p);
1969 }
1970 vm_object_pip_wakeup(object);
1971 skipmemq:
1972 if (__predict_false(!vm_object_cache_is_empty(object)))
1973 vm_page_cache_free(object, start, end);
1974 }
1975
1976 /*
1977 * vm_object_page_cache:
1978 *
1979 * For the given object, attempt to move the specified clean
1980 * pages to the cache queue. If a page is wired for any reason,
1981 * then it will not be changed. Pages are specified by the given
1982 * range ["start", "end"). As a special case, if "end" is zero,
1983 * then the range extends from "start" to the end of the object.
1984 * Any mappings to the specified pages are removed before the
1985 * pages are moved to the cache queue.
1986 *
1987 * This operation should only be performed on objects that
1988 * contain non-fictitious, managed pages.
1989 *
1990 * The object must be locked.
1991 */
1992 void
1993 vm_object_page_cache(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
1994 {
1995 struct mtx *mtx, *new_mtx;
1996 vm_page_t p, next;
1997
1998 VM_OBJECT_ASSERT_WLOCKED(object);
1999 KASSERT((object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0,
2000 ("vm_object_page_cache: illegal object %p", object));
2001 if (object->resident_page_count == 0)
2002 return;
2003 p = vm_page_find_least(object, start);
2004
2005 /*
2006 * Here, the variable "p" is either (1) the page with the least pindex
2007 * greater than or equal to the parameter "start" or (2) NULL.
2008 */
2009 mtx = NULL;
2010 for (; p != NULL && (p->pindex < end || end == 0); p = next) {
2011 next = TAILQ_NEXT(p, listq);
2012
2013 /*
2014 * Avoid releasing and reacquiring the same page lock.
2015 */
2016 new_mtx = vm_page_lockptr(p);
2017 if (mtx != new_mtx) {
2018 if (mtx != NULL)
2019 mtx_unlock(mtx);
2020 mtx = new_mtx;
2021 mtx_lock(mtx);
2022 }
2023 vm_page_try_to_cache(p);
2024 }
2025 if (mtx != NULL)
2026 mtx_unlock(mtx);
2027 }
2028
2029 /*
2030 * Populate the specified range of the object with valid pages. Returns
2031 * TRUE if the range is successfully populated and FALSE otherwise.
2032 *
2033 * Note: This function should be optimized to pass a larger array of
2034 * pages to vm_pager_get_pages() before it is applied to a non-
2035 * OBJT_DEVICE object.
2036 *
2037 * The object must be locked.
2038 */
2039 boolean_t
2040 vm_object_populate(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
2041 {
2042 vm_page_t m, ma[1];
2043 vm_pindex_t pindex;
2044 int rv;
2045
2046 VM_OBJECT_ASSERT_WLOCKED(object);
2047 for (pindex = start; pindex < end; pindex++) {
2048 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
2049 if (m->valid != VM_PAGE_BITS_ALL) {
2050 ma[0] = m;
2051 rv = vm_pager_get_pages(object, ma, 1, 0);
2052 m = vm_page_lookup(object, pindex);
2053 if (m == NULL)
2054 break;
2055 if (rv != VM_PAGER_OK) {
2056 vm_page_lock(m);
2057 vm_page_free(m);
2058 vm_page_unlock(m);
2059 break;
2060 }
2061 }
2062 /*
2063 * Keep "m" busy because a subsequent iteration may unlock
2064 * the object.
2065 */
2066 }
2067 if (pindex > start) {
2068 m = vm_page_lookup(object, start);
2069 while (m != NULL && m->pindex < pindex) {
2070 vm_page_xunbusy(m);
2071 m = TAILQ_NEXT(m, listq);
2072 }
2073 }
2074 return (pindex == end);
2075 }
2076
2077 /*
2078 * Routine: vm_object_coalesce
2079 * Function: Coalesces two objects backing up adjoining
2080 * regions of memory into a single object.
2081 *
2082 * returns TRUE if objects were combined.
2083 *
2084 * NOTE: Only works at the moment if the second object is NULL -
2085 * if it's not, which object do we lock first?
2086 *
2087 * Parameters:
2088 * prev_object First object to coalesce
2089 * prev_offset Offset into prev_object
2090 * prev_size Size of reference to prev_object
2091 * next_size Size of reference to the second object
2092 * reserved Indicator that extension region has
2093 * swap accounted for
2094 *
2095 * Conditions:
2096 * The object must *not* be locked.
2097 */
2098 boolean_t
2099 vm_object_coalesce(vm_object_t prev_object, vm_ooffset_t prev_offset,
2100 vm_size_t prev_size, vm_size_t next_size, boolean_t reserved)
2101 {
2102 vm_pindex_t next_pindex;
2103
2104 if (prev_object == NULL)
2105 return (TRUE);
2106 VM_OBJECT_WLOCK(prev_object);
2107 if ((prev_object->type != OBJT_DEFAULT &&
2108 prev_object->type != OBJT_SWAP) ||
2109 (prev_object->flags & OBJ_TMPFS_NODE) != 0) {
2110 VM_OBJECT_WUNLOCK(prev_object);
2111 return (FALSE);
2112 }
2113
2114 /*
2115 * Try to collapse the object first
2116 */
2117 vm_object_collapse(prev_object);
2118
2119 /*
2120 * Can't coalesce if: . more than one reference . paged out . shadows
2121 * another object . has a copy elsewhere (any of which mean that the
2122 * pages not mapped to prev_entry may be in use anyway)
2123 */
2124 if (prev_object->backing_object != NULL) {
2125 VM_OBJECT_WUNLOCK(prev_object);
2126 return (FALSE);
2127 }
2128
2129 prev_size >>= PAGE_SHIFT;
2130 next_size >>= PAGE_SHIFT;
2131 next_pindex = OFF_TO_IDX(prev_offset) + prev_size;
2132
2133 if ((prev_object->ref_count > 1) &&
2134 (prev_object->size != next_pindex)) {
2135 VM_OBJECT_WUNLOCK(prev_object);
2136 return (FALSE);
2137 }
2138
2139 /*
2140 * Account for the charge.
2141 */
2142 if (prev_object->cred != NULL) {
2143
2144 /*
2145 * If prev_object was charged, then this mapping,
2146 * althought not charged now, may become writable
2147 * later. Non-NULL cred in the object would prevent
2148 * swap reservation during enabling of the write
2149 * access, so reserve swap now. Failed reservation
2150 * cause allocation of the separate object for the map
2151 * entry, and swap reservation for this entry is
2152 * managed in appropriate time.
2153 */
2154 if (!reserved && !swap_reserve_by_cred(ptoa(next_size),
2155 prev_object->cred)) {
2156 return (FALSE);
2157 }
2158 prev_object->charge += ptoa(next_size);
2159 }
2160
2161 /*
2162 * Remove any pages that may still be in the object from a previous
2163 * deallocation.
2164 */
2165 if (next_pindex < prev_object->size) {
2166 vm_object_page_remove(prev_object, next_pindex, next_pindex +
2167 next_size, 0);
2168 if (prev_object->type == OBJT_SWAP)
2169 swap_pager_freespace(prev_object,
2170 next_pindex, next_size);
2171 #if 0
2172 if (prev_object->cred != NULL) {
2173 KASSERT(prev_object->charge >=
2174 ptoa(prev_object->size - next_pindex),
2175 ("object %p overcharged 1 %jx %jx", prev_object,
2176 (uintmax_t)next_pindex, (uintmax_t)next_size));
2177 prev_object->charge -= ptoa(prev_object->size -
2178 next_pindex);
2179 }
2180 #endif
2181 }
2182
2183 /*
2184 * Extend the object if necessary.
2185 */
2186 if (next_pindex + next_size > prev_object->size)
2187 prev_object->size = next_pindex + next_size;
2188
2189 VM_OBJECT_WUNLOCK(prev_object);
2190 return (TRUE);
2191 }
2192
2193 void
2194 vm_object_set_writeable_dirty(vm_object_t object)
2195 {
2196
2197 VM_OBJECT_ASSERT_WLOCKED(object);
2198 if (object->type != OBJT_VNODE)
2199 return;
2200 object->generation++;
2201 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0)
2202 return;
2203 vm_object_set_flag(object, OBJ_MIGHTBEDIRTY);
2204 }
2205
2206 /*
2207 * vm_object_unwire:
2208 *
2209 * For each page offset within the specified range of the given object,
2210 * find the highest-level page in the shadow chain and unwire it. A page
2211 * must exist at every page offset, and the highest-level page must be
2212 * wired.
2213 */
2214 void
2215 vm_object_unwire(vm_object_t object, vm_ooffset_t offset, vm_size_t length,
2216 uint8_t queue)
2217 {
2218 vm_object_t tobject;
2219 vm_page_t m, tm;
2220 vm_pindex_t end_pindex, pindex, tpindex;
2221 int depth, locked_depth;
2222
2223 KASSERT((offset & PAGE_MASK) == 0,
2224 ("vm_object_unwire: offset is not page aligned"));
2225 KASSERT((length & PAGE_MASK) == 0,
2226 ("vm_object_unwire: length is not a multiple of PAGE_SIZE"));
2227 /* The wired count of a fictitious page never changes. */
2228 if ((object->flags & OBJ_FICTITIOUS) != 0)
2229 return;
2230 pindex = OFF_TO_IDX(offset);
2231 end_pindex = pindex + atop(length);
2232 locked_depth = 1;
2233 VM_OBJECT_RLOCK(object);
2234 m = vm_page_find_least(object, pindex);
2235 while (pindex < end_pindex) {
2236 if (m == NULL || pindex < m->pindex) {
2237 /*
2238 * The first object in the shadow chain doesn't
2239 * contain a page at the current index. Therefore,
2240 * the page must exist in a backing object.
2241 */
2242 tobject = object;
2243 tpindex = pindex;
2244 depth = 0;
2245 do {
2246 tpindex +=
2247 OFF_TO_IDX(tobject->backing_object_offset);
2248 tobject = tobject->backing_object;
2249 KASSERT(tobject != NULL,
2250 ("vm_object_unwire: missing page"));
2251 if ((tobject->flags & OBJ_FICTITIOUS) != 0)
2252 goto next_page;
2253 depth++;
2254 if (depth == locked_depth) {
2255 locked_depth++;
2256 VM_OBJECT_RLOCK(tobject);
2257 }
2258 } while ((tm = vm_page_lookup(tobject, tpindex)) ==
2259 NULL);
2260 } else {
2261 tm = m;
2262 m = TAILQ_NEXT(m, listq);
2263 }
2264 vm_page_lock(tm);
2265 vm_page_unwire(tm, queue);
2266 vm_page_unlock(tm);
2267 next_page:
2268 pindex++;
2269 }
2270 /* Release the accumulated object locks. */
2271 for (depth = 0; depth < locked_depth; depth++) {
2272 tobject = object->backing_object;
2273 VM_OBJECT_RUNLOCK(object);
2274 object = tobject;
2275 }
2276 }
2277
2278 #include "opt_ddb.h"
2279 #ifdef DDB
2280 #include <sys/kernel.h>
2281
2282 #include <sys/cons.h>
2283
2284 #include <ddb/ddb.h>
2285
2286 static int
2287 _vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry)
2288 {
2289 vm_map_t tmpm;
2290 vm_map_entry_t tmpe;
2291 vm_object_t obj;
2292 int entcount;
2293
2294 if (map == 0)
2295 return 0;
2296
2297 if (entry == 0) {
2298 tmpe = map->header.next;
2299 entcount = map->nentries;
2300 while (entcount-- && (tmpe != &map->header)) {
2301 if (_vm_object_in_map(map, object, tmpe)) {
2302 return 1;
2303 }
2304 tmpe = tmpe->next;
2305 }
2306 } else if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) {
2307 tmpm = entry->object.sub_map;
2308 tmpe = tmpm->header.next;
2309 entcount = tmpm->nentries;
2310 while (entcount-- && tmpe != &tmpm->header) {
2311 if (_vm_object_in_map(tmpm, object, tmpe)) {
2312 return 1;
2313 }
2314 tmpe = tmpe->next;
2315 }
2316 } else if ((obj = entry->object.vm_object) != NULL) {
2317 for (; obj; obj = obj->backing_object)
2318 if (obj == object) {
2319 return 1;
2320 }
2321 }
2322 return 0;
2323 }
2324
2325 static int
2326 vm_object_in_map(vm_object_t object)
2327 {
2328 struct proc *p;
2329
2330 /* sx_slock(&allproc_lock); */
2331 FOREACH_PROC_IN_SYSTEM(p) {
2332 if (!p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */)
2333 continue;
2334 if (_vm_object_in_map(&p->p_vmspace->vm_map, object, 0)) {
2335 /* sx_sunlock(&allproc_lock); */
2336 return 1;
2337 }
2338 }
2339 /* sx_sunlock(&allproc_lock); */
2340 if (_vm_object_in_map(kernel_map, object, 0))
2341 return 1;
2342 return 0;
2343 }
2344
2345 DB_SHOW_COMMAND(vmochk, vm_object_check)
2346 {
2347 vm_object_t object;
2348
2349 /*
2350 * make sure that internal objs are in a map somewhere
2351 * and none have zero ref counts.
2352 */
2353 TAILQ_FOREACH(object, &vm_object_list, object_list) {
2354 if (object->handle == NULL &&
2355 (object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) {
2356 if (object->ref_count == 0) {
2357 db_printf("vmochk: internal obj has zero ref count: %ld\n",
2358 (long)object->size);
2359 }
2360 if (!vm_object_in_map(object)) {
2361 db_printf(
2362 "vmochk: internal obj is not in a map: "
2363 "ref: %d, size: %lu: 0x%lx, backing_object: %p\n",
2364 object->ref_count, (u_long)object->size,
2365 (u_long)object->size,
2366 (void *)object->backing_object);
2367 }
2368 }
2369 }
2370 }
2371
2372 /*
2373 * vm_object_print: [ debug ]
2374 */
2375 DB_SHOW_COMMAND(object, vm_object_print_static)
2376 {
2377 /* XXX convert args. */
2378 vm_object_t object = (vm_object_t)addr;
2379 boolean_t full = have_addr;
2380
2381 vm_page_t p;
2382
2383 /* XXX count is an (unused) arg. Avoid shadowing it. */
2384 #define count was_count
2385
2386 int count;
2387
2388 if (object == NULL)
2389 return;
2390
2391 db_iprintf(
2392 "Object %p: type=%d, size=0x%jx, res=%d, ref=%d, flags=0x%x ruid %d charge %jx\n",
2393 object, (int)object->type, (uintmax_t)object->size,
2394 object->resident_page_count, object->ref_count, object->flags,
2395 object->cred ? object->cred->cr_ruid : -1, (uintmax_t)object->charge);
2396 db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%jx\n",
2397 object->shadow_count,
2398 object->backing_object ? object->backing_object->ref_count : 0,
2399 object->backing_object, (uintmax_t)object->backing_object_offset);
2400
2401 if (!full)
2402 return;
2403
2404 db_indent += 2;
2405 count = 0;
2406 TAILQ_FOREACH(p, &object->memq, listq) {
2407 if (count == 0)
2408 db_iprintf("memory:=");
2409 else if (count == 6) {
2410 db_printf("\n");
2411 db_iprintf(" ...");
2412 count = 0;
2413 } else
2414 db_printf(",");
2415 count++;
2416
2417 db_printf("(off=0x%jx,page=0x%jx)",
2418 (uintmax_t)p->pindex, (uintmax_t)VM_PAGE_TO_PHYS(p));
2419 }
2420 if (count != 0)
2421 db_printf("\n");
2422 db_indent -= 2;
2423 }
2424
2425 /* XXX. */
2426 #undef count
2427
2428 /* XXX need this non-static entry for calling from vm_map_print. */
2429 void
2430 vm_object_print(
2431 /* db_expr_t */ long addr,
2432 boolean_t have_addr,
2433 /* db_expr_t */ long count,
2434 char *modif)
2435 {
2436 vm_object_print_static(addr, have_addr, count, modif);
2437 }
2438
2439 DB_SHOW_COMMAND(vmopag, vm_object_print_pages)
2440 {
2441 vm_object_t object;
2442 vm_pindex_t fidx;
2443 vm_paddr_t pa;
2444 vm_page_t m, prev_m;
2445 int rcount, nl, c;
2446
2447 nl = 0;
2448 TAILQ_FOREACH(object, &vm_object_list, object_list) {
2449 db_printf("new object: %p\n", (void *)object);
2450 if (nl > 18) {
2451 c = cngetc();
2452 if (c != ' ')
2453 return;
2454 nl = 0;
2455 }
2456 nl++;
2457 rcount = 0;
2458 fidx = 0;
2459 pa = -1;
2460 TAILQ_FOREACH(m, &object->memq, listq) {
2461 if (m->pindex > 128)
2462 break;
2463 if ((prev_m = TAILQ_PREV(m, pglist, listq)) != NULL &&
2464 prev_m->pindex + 1 != m->pindex) {
2465 if (rcount) {
2466 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
2467 (long)fidx, rcount, (long)pa);
2468 if (nl > 18) {
2469 c = cngetc();
2470 if (c != ' ')
2471 return;
2472 nl = 0;
2473 }
2474 nl++;
2475 rcount = 0;
2476 }
2477 }
2478 if (rcount &&
2479 (VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
2480 ++rcount;
2481 continue;
2482 }
2483 if (rcount) {
2484 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
2485 (long)fidx, rcount, (long)pa);
2486 if (nl > 18) {
2487 c = cngetc();
2488 if (c != ' ')
2489 return;
2490 nl = 0;
2491 }
2492 nl++;
2493 }
2494 fidx = m->pindex;
2495 pa = VM_PAGE_TO_PHYS(m);
2496 rcount = 1;
2497 }
2498 if (rcount) {
2499 db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
2500 (long)fidx, rcount, (long)pa);
2501 if (nl > 18) {
2502 c = cngetc();
2503 if (c != ' ')
2504 return;
2505 nl = 0;
2506 }
2507 nl++;
2508 }
2509 }
2510 }
2511 #endif /* DDB */
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