FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_page.c
1 /*-
2 * Copyright (c) 1991 Regents of the University of California.
3 * All rights reserved.
4 * Copyright (c) 1998 Matthew Dillon. All Rights Reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * The Mach Operating System project at Carnegie-Mellon University.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * from: @(#)vm_page.c 7.4 (Berkeley) 5/7/91
34 */
35
36 /*-
37 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
38 * All rights reserved.
39 *
40 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
41 *
42 * Permission to use, copy, modify and distribute this software and
43 * its documentation is hereby granted, provided that both the copyright
44 * notice and this permission notice appear in all copies of the
45 * software, derivative works or modified versions, and any portions
46 * thereof, and that both notices appear in supporting documentation.
47 *
48 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
49 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
50 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
51 *
52 * Carnegie Mellon requests users of this software to return to
53 *
54 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
55 * School of Computer Science
56 * Carnegie Mellon University
57 * Pittsburgh PA 15213-3890
58 *
59 * any improvements or extensions that they make and grant Carnegie the
60 * rights to redistribute these changes.
61 */
62
63 /*
64 * GENERAL RULES ON VM_PAGE MANIPULATION
65 *
66 * - a pageq mutex is required when adding or removing a page from a
67 * page queue (vm_page_queue[]), regardless of other mutexes or the
68 * busy state of a page.
69 *
70 * - a hash chain mutex is required when associating or disassociating
71 * a page from the VM PAGE CACHE hash table (vm_page_buckets),
72 * regardless of other mutexes or the busy state of a page.
73 *
74 * - either a hash chain mutex OR a busied page is required in order
75 * to modify the page flags. A hash chain mutex must be obtained in
76 * order to busy a page. A page's flags cannot be modified by a
77 * hash chain mutex if the page is marked busy.
78 *
79 * - The object memq mutex is held when inserting or removing
80 * pages from an object (vm_page_insert() or vm_page_remove()). This
81 * is different from the object's main mutex.
82 *
83 * Generally speaking, you have to be aware of side effects when running
84 * vm_page ops. A vm_page_lookup() will return with the hash chain
85 * locked, whether it was able to lookup the page or not. vm_page_free(),
86 * vm_page_cache(), vm_page_activate(), and a number of other routines
87 * will release the hash chain mutex for you. Intermediate manipulation
88 * routines such as vm_page_flag_set() expect the hash chain to be held
89 * on entry and the hash chain will remain held on return.
90 *
91 * pageq scanning can only occur with the pageq in question locked.
92 * We have a known bottleneck with the active queue, but the cache
93 * and free queues are actually arrays already.
94 */
95
96 /*
97 * Resident memory management module.
98 */
99
100 #include <sys/cdefs.h>
101 __FBSDID("$FreeBSD: releng/8.3/sys/vm/vm_page.c 227422 2011-11-10 17:04:33Z alc $");
102
103 #include "opt_vm.h"
104
105 #include <sys/param.h>
106 #include <sys/systm.h>
107 #include <sys/lock.h>
108 #include <sys/kernel.h>
109 #include <sys/limits.h>
110 #include <sys/malloc.h>
111 #include <sys/msgbuf.h>
112 #include <sys/mutex.h>
113 #include <sys/proc.h>
114 #include <sys/sysctl.h>
115 #include <sys/vmmeter.h>
116 #include <sys/vnode.h>
117
118 #include <vm/vm.h>
119 #include <vm/vm_param.h>
120 #include <vm/vm_kern.h>
121 #include <vm/vm_object.h>
122 #include <vm/vm_page.h>
123 #include <vm/vm_pageout.h>
124 #include <vm/vm_pager.h>
125 #include <vm/vm_phys.h>
126 #include <vm/vm_reserv.h>
127 #include <vm/vm_extern.h>
128 #include <vm/uma.h>
129 #include <vm/uma_int.h>
130
131 #include <machine/md_var.h>
132
133 /*
134 * Associated with page of user-allocatable memory is a
135 * page structure.
136 */
137
138 struct vpgqueues vm_page_queues[PQ_COUNT];
139 struct mtx vm_page_queue_mtx;
140 struct mtx vm_page_queue_free_mtx;
141
142 vm_page_t vm_page_array = 0;
143 int vm_page_array_size = 0;
144 long first_page = 0;
145 int vm_page_zero_count = 0;
146
147 static int boot_pages = UMA_BOOT_PAGES;
148 TUNABLE_INT("vm.boot_pages", &boot_pages);
149 SYSCTL_INT(_vm, OID_AUTO, boot_pages, CTLFLAG_RD, &boot_pages, 0,
150 "number of pages allocated for bootstrapping the VM system");
151
152 static void vm_page_enqueue(int queue, vm_page_t m);
153
154 /* Make sure that u_long is at least 64 bits when PAGE_SIZE is 32K. */
155 #if PAGE_SIZE == 32768
156 #ifdef CTASSERT
157 CTASSERT(sizeof(u_long) >= 8);
158 #endif
159 #endif
160
161 /*
162 * vm_set_page_size:
163 *
164 * Sets the page size, perhaps based upon the memory
165 * size. Must be called before any use of page-size
166 * dependent functions.
167 */
168 void
169 vm_set_page_size(void)
170 {
171 if (cnt.v_page_size == 0)
172 cnt.v_page_size = PAGE_SIZE;
173 if (((cnt.v_page_size - 1) & cnt.v_page_size) != 0)
174 panic("vm_set_page_size: page size not a power of two");
175 }
176
177 /*
178 * vm_page_blacklist_lookup:
179 *
180 * See if a physical address in this page has been listed
181 * in the blacklist tunable. Entries in the tunable are
182 * separated by spaces or commas. If an invalid integer is
183 * encountered then the rest of the string is skipped.
184 */
185 static int
186 vm_page_blacklist_lookup(char *list, vm_paddr_t pa)
187 {
188 vm_paddr_t bad;
189 char *cp, *pos;
190
191 for (pos = list; *pos != '\0'; pos = cp) {
192 bad = strtoq(pos, &cp, 0);
193 if (*cp != '\0') {
194 if (*cp == ' ' || *cp == ',') {
195 cp++;
196 if (cp == pos)
197 continue;
198 } else
199 break;
200 }
201 if (pa == trunc_page(bad))
202 return (1);
203 }
204 return (0);
205 }
206
207 /*
208 * vm_page_startup:
209 *
210 * Initializes the resident memory module.
211 *
212 * Allocates memory for the page cells, and
213 * for the object/offset-to-page hash table headers.
214 * Each page cell is initialized and placed on the free list.
215 */
216 vm_offset_t
217 vm_page_startup(vm_offset_t vaddr)
218 {
219 vm_offset_t mapped;
220 vm_paddr_t page_range;
221 vm_paddr_t new_end;
222 int i;
223 vm_paddr_t pa;
224 vm_paddr_t last_pa;
225 char *list;
226
227 /* the biggest memory array is the second group of pages */
228 vm_paddr_t end;
229 vm_paddr_t biggestsize;
230 vm_paddr_t low_water, high_water;
231 int biggestone;
232
233 biggestsize = 0;
234 biggestone = 0;
235 vaddr = round_page(vaddr);
236
237 for (i = 0; phys_avail[i + 1]; i += 2) {
238 phys_avail[i] = round_page(phys_avail[i]);
239 phys_avail[i + 1] = trunc_page(phys_avail[i + 1]);
240 }
241
242 low_water = phys_avail[0];
243 high_water = phys_avail[1];
244
245 for (i = 0; phys_avail[i + 1]; i += 2) {
246 vm_paddr_t size = phys_avail[i + 1] - phys_avail[i];
247
248 if (size > biggestsize) {
249 biggestone = i;
250 biggestsize = size;
251 }
252 if (phys_avail[i] < low_water)
253 low_water = phys_avail[i];
254 if (phys_avail[i + 1] > high_water)
255 high_water = phys_avail[i + 1];
256 }
257
258 #ifdef XEN
259 low_water = 0;
260 #endif
261
262 end = phys_avail[biggestone+1];
263
264 /*
265 * Initialize the locks.
266 */
267 mtx_init(&vm_page_queue_mtx, "vm page queue mutex", NULL, MTX_DEF |
268 MTX_RECURSE);
269 mtx_init(&vm_page_queue_free_mtx, "vm page queue free mutex", NULL,
270 MTX_DEF);
271
272 /*
273 * Initialize the queue headers for the hold queue, the active queue,
274 * and the inactive queue.
275 */
276 for (i = 0; i < PQ_COUNT; i++)
277 TAILQ_INIT(&vm_page_queues[i].pl);
278 vm_page_queues[PQ_INACTIVE].cnt = &cnt.v_inactive_count;
279 vm_page_queues[PQ_ACTIVE].cnt = &cnt.v_active_count;
280 vm_page_queues[PQ_HOLD].cnt = &cnt.v_active_count;
281
282 /*
283 * Allocate memory for use when boot strapping the kernel memory
284 * allocator.
285 */
286 new_end = end - (boot_pages * UMA_SLAB_SIZE);
287 new_end = trunc_page(new_end);
288 mapped = pmap_map(&vaddr, new_end, end,
289 VM_PROT_READ | VM_PROT_WRITE);
290 bzero((void *)mapped, end - new_end);
291 uma_startup((void *)mapped, boot_pages);
292
293 #if defined(__amd64__) || defined(__i386__) || defined(__arm__) || \
294 defined(__mips__)
295 /*
296 * Allocate a bitmap to indicate that a random physical page
297 * needs to be included in a minidump.
298 *
299 * The amd64 port needs this to indicate which direct map pages
300 * need to be dumped, via calls to dump_add_page()/dump_drop_page().
301 *
302 * However, i386 still needs this workspace internally within the
303 * minidump code. In theory, they are not needed on i386, but are
304 * included should the sf_buf code decide to use them.
305 */
306 last_pa = 0;
307 for (i = 0; dump_avail[i + 1] != 0; i += 2)
308 if (dump_avail[i + 1] > last_pa)
309 last_pa = dump_avail[i + 1];
310 page_range = last_pa / PAGE_SIZE;
311 vm_page_dump_size = round_page(roundup2(page_range, NBBY) / NBBY);
312 new_end -= vm_page_dump_size;
313 vm_page_dump = (void *)(uintptr_t)pmap_map(&vaddr, new_end,
314 new_end + vm_page_dump_size, VM_PROT_READ | VM_PROT_WRITE);
315 bzero((void *)vm_page_dump, vm_page_dump_size);
316 #endif
317 #ifdef __amd64__
318 /*
319 * Request that the physical pages underlying the message buffer be
320 * included in a crash dump. Since the message buffer is accessed
321 * through the direct map, they are not automatically included.
322 */
323 pa = DMAP_TO_PHYS((vm_offset_t)msgbufp->msg_ptr);
324 last_pa = pa + round_page(msgbufsize);
325 while (pa < last_pa) {
326 dump_add_page(pa);
327 pa += PAGE_SIZE;
328 }
329 #endif
330 /*
331 * Compute the number of pages of memory that will be available for
332 * use (taking into account the overhead of a page structure per
333 * page).
334 */
335 first_page = low_water / PAGE_SIZE;
336 #ifdef VM_PHYSSEG_SPARSE
337 page_range = 0;
338 for (i = 0; phys_avail[i + 1] != 0; i += 2)
339 page_range += atop(phys_avail[i + 1] - phys_avail[i]);
340 #elif defined(VM_PHYSSEG_DENSE)
341 page_range = high_water / PAGE_SIZE - first_page;
342 #else
343 #error "Either VM_PHYSSEG_DENSE or VM_PHYSSEG_SPARSE must be defined."
344 #endif
345 end = new_end;
346
347 /*
348 * Reserve an unmapped guard page to trap access to vm_page_array[-1].
349 */
350 vaddr += PAGE_SIZE;
351
352 /*
353 * Initialize the mem entry structures now, and put them in the free
354 * queue.
355 */
356 new_end = trunc_page(end - page_range * sizeof(struct vm_page));
357 mapped = pmap_map(&vaddr, new_end, end,
358 VM_PROT_READ | VM_PROT_WRITE);
359 vm_page_array = (vm_page_t) mapped;
360 #if VM_NRESERVLEVEL > 0
361 /*
362 * Allocate memory for the reservation management system's data
363 * structures.
364 */
365 new_end = vm_reserv_startup(&vaddr, new_end, high_water);
366 #endif
367 #ifdef __amd64__
368 /*
369 * pmap_map on amd64 comes out of the direct-map, not kvm like i386,
370 * so the pages must be tracked for a crashdump to include this data.
371 * This includes the vm_page_array and the early UMA bootstrap pages.
372 */
373 for (pa = new_end; pa < phys_avail[biggestone + 1]; pa += PAGE_SIZE)
374 dump_add_page(pa);
375 #endif
376 phys_avail[biggestone + 1] = new_end;
377
378 /*
379 * Clear all of the page structures
380 */
381 bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page));
382 for (i = 0; i < page_range; i++)
383 vm_page_array[i].order = VM_NFREEORDER;
384 vm_page_array_size = page_range;
385
386 /*
387 * Initialize the physical memory allocator.
388 */
389 vm_phys_init();
390
391 /*
392 * Add every available physical page that is not blacklisted to
393 * the free lists.
394 */
395 cnt.v_page_count = 0;
396 cnt.v_free_count = 0;
397 list = getenv("vm.blacklist");
398 for (i = 0; phys_avail[i + 1] != 0; i += 2) {
399 pa = phys_avail[i];
400 last_pa = phys_avail[i + 1];
401 while (pa < last_pa) {
402 if (list != NULL &&
403 vm_page_blacklist_lookup(list, pa))
404 printf("Skipping page with pa 0x%jx\n",
405 (uintmax_t)pa);
406 else
407 vm_phys_add_page(pa);
408 pa += PAGE_SIZE;
409 }
410 }
411 freeenv(list);
412 #if VM_NRESERVLEVEL > 0
413 /*
414 * Initialize the reservation management system.
415 */
416 vm_reserv_init();
417 #endif
418 return (vaddr);
419 }
420
421 void
422 vm_page_flag_set(vm_page_t m, unsigned short bits)
423 {
424
425 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
426 m->flags |= bits;
427 }
428
429 void
430 vm_page_flag_clear(vm_page_t m, unsigned short bits)
431 {
432
433 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
434 m->flags &= ~bits;
435 }
436
437 void
438 vm_page_busy(vm_page_t m)
439 {
440
441 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
442 KASSERT((m->oflags & VPO_BUSY) == 0,
443 ("vm_page_busy: page already busy!!!"));
444 m->oflags |= VPO_BUSY;
445 }
446
447 /*
448 * vm_page_flash:
449 *
450 * wakeup anyone waiting for the page.
451 */
452 void
453 vm_page_flash(vm_page_t m)
454 {
455
456 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
457 if (m->oflags & VPO_WANTED) {
458 m->oflags &= ~VPO_WANTED;
459 wakeup(m);
460 }
461 }
462
463 /*
464 * vm_page_wakeup:
465 *
466 * clear the VPO_BUSY flag and wakeup anyone waiting for the
467 * page.
468 *
469 */
470 void
471 vm_page_wakeup(vm_page_t m)
472 {
473
474 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
475 KASSERT(m->oflags & VPO_BUSY, ("vm_page_wakeup: page not busy!!!"));
476 m->oflags &= ~VPO_BUSY;
477 vm_page_flash(m);
478 }
479
480 void
481 vm_page_io_start(vm_page_t m)
482 {
483
484 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
485 m->busy++;
486 }
487
488 void
489 vm_page_io_finish(vm_page_t m)
490 {
491
492 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
493 m->busy--;
494 if (m->busy == 0)
495 vm_page_flash(m);
496 }
497
498 /*
499 * Keep page from being freed by the page daemon
500 * much of the same effect as wiring, except much lower
501 * overhead and should be used only for *very* temporary
502 * holding ("wiring").
503 */
504 void
505 vm_page_hold(vm_page_t mem)
506 {
507
508 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
509 mem->hold_count++;
510 }
511
512 void
513 vm_page_unhold(vm_page_t mem)
514 {
515
516 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
517 --mem->hold_count;
518 KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!"));
519 if (mem->hold_count == 0 && VM_PAGE_INQUEUE2(mem, PQ_HOLD))
520 vm_page_free_toq(mem);
521 }
522
523 /*
524 * vm_page_free:
525 *
526 * Free a page.
527 */
528 void
529 vm_page_free(vm_page_t m)
530 {
531
532 m->flags &= ~PG_ZERO;
533 vm_page_free_toq(m);
534 }
535
536 /*
537 * vm_page_free_zero:
538 *
539 * Free a page to the zerod-pages queue
540 */
541 void
542 vm_page_free_zero(vm_page_t m)
543 {
544
545 m->flags |= PG_ZERO;
546 vm_page_free_toq(m);
547 }
548
549 /*
550 * vm_page_sleep:
551 *
552 * Sleep and release the page queues lock.
553 *
554 * The object containing the given page must be locked.
555 */
556 void
557 vm_page_sleep(vm_page_t m, const char *msg)
558 {
559
560 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
561 if (!mtx_owned(&vm_page_queue_mtx))
562 vm_page_lock_queues();
563 vm_page_flag_set(m, PG_REFERENCED);
564 vm_page_unlock_queues();
565
566 /*
567 * It's possible that while we sleep, the page will get
568 * unbusied and freed. If we are holding the object
569 * lock, we will assume we hold a reference to the object
570 * such that even if m->object changes, we can re-lock
571 * it.
572 */
573 m->oflags |= VPO_WANTED;
574 msleep(m, VM_OBJECT_MTX(m->object), PVM, msg, 0);
575 }
576
577 /*
578 * vm_page_dirty:
579 *
580 * make page all dirty
581 */
582 void
583 vm_page_dirty(vm_page_t m)
584 {
585
586 KASSERT((m->flags & PG_CACHED) == 0,
587 ("vm_page_dirty: page in cache!"));
588 KASSERT(!VM_PAGE_IS_FREE(m),
589 ("vm_page_dirty: page is free!"));
590 KASSERT(m->valid == VM_PAGE_BITS_ALL,
591 ("vm_page_dirty: page is invalid!"));
592 m->dirty = VM_PAGE_BITS_ALL;
593 }
594
595 /*
596 * vm_page_splay:
597 *
598 * Implements Sleator and Tarjan's top-down splay algorithm. Returns
599 * the vm_page containing the given pindex. If, however, that
600 * pindex is not found in the vm_object, returns a vm_page that is
601 * adjacent to the pindex, coming before or after it.
602 */
603 vm_page_t
604 vm_page_splay(vm_pindex_t pindex, vm_page_t root)
605 {
606 struct vm_page dummy;
607 vm_page_t lefttreemax, righttreemin, y;
608
609 if (root == NULL)
610 return (root);
611 lefttreemax = righttreemin = &dummy;
612 for (;; root = y) {
613 if (pindex < root->pindex) {
614 if ((y = root->left) == NULL)
615 break;
616 if (pindex < y->pindex) {
617 /* Rotate right. */
618 root->left = y->right;
619 y->right = root;
620 root = y;
621 if ((y = root->left) == NULL)
622 break;
623 }
624 /* Link into the new root's right tree. */
625 righttreemin->left = root;
626 righttreemin = root;
627 } else if (pindex > root->pindex) {
628 if ((y = root->right) == NULL)
629 break;
630 if (pindex > y->pindex) {
631 /* Rotate left. */
632 root->right = y->left;
633 y->left = root;
634 root = y;
635 if ((y = root->right) == NULL)
636 break;
637 }
638 /* Link into the new root's left tree. */
639 lefttreemax->right = root;
640 lefttreemax = root;
641 } else
642 break;
643 }
644 /* Assemble the new root. */
645 lefttreemax->right = root->left;
646 righttreemin->left = root->right;
647 root->left = dummy.right;
648 root->right = dummy.left;
649 return (root);
650 }
651
652 /*
653 * vm_page_insert: [ internal use only ]
654 *
655 * Inserts the given mem entry into the object and object list.
656 *
657 * The pagetables are not updated but will presumably fault the page
658 * in if necessary, or if a kernel page the caller will at some point
659 * enter the page into the kernel's pmap. We are not allowed to block
660 * here so we *can't* do this anyway.
661 *
662 * The object and page must be locked.
663 * This routine may not block.
664 */
665 void
666 vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex)
667 {
668 vm_page_t root;
669
670 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
671 if (m->object != NULL)
672 panic("vm_page_insert: page already inserted");
673
674 /*
675 * Record the object/offset pair in this page
676 */
677 m->object = object;
678 m->pindex = pindex;
679
680 /*
681 * Now link into the object's ordered list of backed pages.
682 */
683 root = object->root;
684 if (root == NULL) {
685 m->left = NULL;
686 m->right = NULL;
687 TAILQ_INSERT_TAIL(&object->memq, m, listq);
688 } else {
689 root = vm_page_splay(pindex, root);
690 if (pindex < root->pindex) {
691 m->left = root->left;
692 m->right = root;
693 root->left = NULL;
694 TAILQ_INSERT_BEFORE(root, m, listq);
695 } else if (pindex == root->pindex)
696 panic("vm_page_insert: offset already allocated");
697 else {
698 m->right = root->right;
699 m->left = root;
700 root->right = NULL;
701 TAILQ_INSERT_AFTER(&object->memq, root, m, listq);
702 }
703 }
704 object->root = m;
705
706 /*
707 * show that the object has one more resident page.
708 */
709 object->resident_page_count++;
710 /*
711 * Hold the vnode until the last page is released.
712 */
713 if (object->resident_page_count == 1 && object->type == OBJT_VNODE)
714 vhold((struct vnode *)object->handle);
715
716 /*
717 * Since we are inserting a new and possibly dirty page,
718 * update the object's OBJ_MIGHTBEDIRTY flag.
719 */
720 if (m->flags & PG_WRITEABLE)
721 vm_object_set_writeable_dirty(object);
722 }
723
724 /*
725 * vm_page_remove:
726 * NOTE: used by device pager as well -wfj
727 *
728 * Removes the given mem entry from the object/offset-page
729 * table and the object page list, but do not invalidate/terminate
730 * the backing store.
731 *
732 * The object and page must be locked.
733 * The underlying pmap entry (if any) is NOT removed here.
734 * This routine may not block.
735 */
736 void
737 vm_page_remove(vm_page_t m)
738 {
739 vm_object_t object;
740 vm_page_t next, prev, root;
741
742 if ((object = m->object) == NULL)
743 return;
744 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
745 if (m->oflags & VPO_BUSY) {
746 m->oflags &= ~VPO_BUSY;
747 vm_page_flash(m);
748 }
749 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
750
751 /*
752 * Now remove from the object's list of backed pages.
753 */
754 if ((next = TAILQ_NEXT(m, listq)) != NULL && next->left == m) {
755 /*
756 * Since the page's successor in the list is also its parent
757 * in the tree, its right subtree must be empty.
758 */
759 next->left = m->left;
760 KASSERT(m->right == NULL,
761 ("vm_page_remove: page %p has right child", m));
762 } else if ((prev = TAILQ_PREV(m, pglist, listq)) != NULL &&
763 prev->right == m) {
764 /*
765 * Since the page's predecessor in the list is also its parent
766 * in the tree, its left subtree must be empty.
767 */
768 KASSERT(m->left == NULL,
769 ("vm_page_remove: page %p has left child", m));
770 prev->right = m->right;
771 } else {
772 if (m != object->root)
773 vm_page_splay(m->pindex, object->root);
774 if (m->left == NULL)
775 root = m->right;
776 else if (m->right == NULL)
777 root = m->left;
778 else {
779 /*
780 * Move the page's successor to the root, because
781 * pages are usually removed in ascending order.
782 */
783 if (m->right != next)
784 vm_page_splay(m->pindex, m->right);
785 next->left = m->left;
786 root = next;
787 }
788 object->root = root;
789 }
790 TAILQ_REMOVE(&object->memq, m, listq);
791
792 /*
793 * And show that the object has one fewer resident page.
794 */
795 object->resident_page_count--;
796 /*
797 * The vnode may now be recycled.
798 */
799 if (object->resident_page_count == 0 && object->type == OBJT_VNODE)
800 vdrop((struct vnode *)object->handle);
801
802 m->object = NULL;
803 }
804
805 /*
806 * vm_page_lookup:
807 *
808 * Returns the page associated with the object/offset
809 * pair specified; if none is found, NULL is returned.
810 *
811 * The object must be locked.
812 * This routine may not block.
813 * This is a critical path routine
814 */
815 vm_page_t
816 vm_page_lookup(vm_object_t object, vm_pindex_t pindex)
817 {
818 vm_page_t m;
819
820 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
821 if ((m = object->root) != NULL && m->pindex != pindex) {
822 m = vm_page_splay(pindex, m);
823 if ((object->root = m)->pindex != pindex)
824 m = NULL;
825 }
826 return (m);
827 }
828
829 /*
830 * vm_page_find_least:
831 *
832 * Returns the page associated with the object with least pindex
833 * greater than or equal to the parameter pindex, or NULL.
834 *
835 * The object must be locked.
836 * The routine may not block.
837 */
838 vm_page_t
839 vm_page_find_least(vm_object_t object, vm_pindex_t pindex)
840 {
841 vm_page_t m;
842
843 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
844 if ((m = TAILQ_FIRST(&object->memq)) != NULL) {
845 if (m->pindex < pindex) {
846 m = vm_page_splay(pindex, object->root);
847 if ((object->root = m)->pindex < pindex)
848 m = TAILQ_NEXT(m, listq);
849 }
850 }
851 return (m);
852 }
853
854 /*
855 * Returns the given page's successor (by pindex) within the object if it is
856 * resident; if none is found, NULL is returned.
857 *
858 * The object must be locked.
859 */
860 vm_page_t
861 vm_page_next(vm_page_t m)
862 {
863 vm_page_t next;
864
865 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
866 if ((next = TAILQ_NEXT(m, listq)) != NULL &&
867 next->pindex != m->pindex + 1)
868 next = NULL;
869 return (next);
870 }
871
872 /*
873 * Returns the given page's predecessor (by pindex) within the object if it is
874 * resident; if none is found, NULL is returned.
875 *
876 * The object must be locked.
877 */
878 vm_page_t
879 vm_page_prev(vm_page_t m)
880 {
881 vm_page_t prev;
882
883 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
884 if ((prev = TAILQ_PREV(m, pglist, listq)) != NULL &&
885 prev->pindex != m->pindex - 1)
886 prev = NULL;
887 return (prev);
888 }
889
890 /*
891 * vm_page_rename:
892 *
893 * Move the given memory entry from its
894 * current object to the specified target object/offset.
895 *
896 * The object must be locked.
897 * This routine may not block.
898 *
899 * Note: swap associated with the page must be invalidated by the move. We
900 * have to do this for several reasons: (1) we aren't freeing the
901 * page, (2) we are dirtying the page, (3) the VM system is probably
902 * moving the page from object A to B, and will then later move
903 * the backing store from A to B and we can't have a conflict.
904 *
905 * Note: we *always* dirty the page. It is necessary both for the
906 * fact that we moved it, and because we may be invalidating
907 * swap. If the page is on the cache, we have to deactivate it
908 * or vm_page_dirty() will panic. Dirty pages are not allowed
909 * on the cache.
910 */
911 void
912 vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex)
913 {
914
915 vm_page_remove(m);
916 vm_page_insert(m, new_object, new_pindex);
917 vm_page_dirty(m);
918 }
919
920 /*
921 * Convert all of the given object's cached pages that have a
922 * pindex within the given range into free pages. If the value
923 * zero is given for "end", then the range's upper bound is
924 * infinity. If the given object is backed by a vnode and it
925 * transitions from having one or more cached pages to none, the
926 * vnode's hold count is reduced.
927 */
928 void
929 vm_page_cache_free(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
930 {
931 vm_page_t m, m_next;
932 boolean_t empty;
933
934 mtx_lock(&vm_page_queue_free_mtx);
935 if (__predict_false(object->cache == NULL)) {
936 mtx_unlock(&vm_page_queue_free_mtx);
937 return;
938 }
939 m = object->cache = vm_page_splay(start, object->cache);
940 if (m->pindex < start) {
941 if (m->right == NULL)
942 m = NULL;
943 else {
944 m_next = vm_page_splay(start, m->right);
945 m_next->left = m;
946 m->right = NULL;
947 m = object->cache = m_next;
948 }
949 }
950
951 /*
952 * At this point, "m" is either (1) a reference to the page
953 * with the least pindex that is greater than or equal to
954 * "start" or (2) NULL.
955 */
956 for (; m != NULL && (m->pindex < end || end == 0); m = m_next) {
957 /*
958 * Find "m"'s successor and remove "m" from the
959 * object's cache.
960 */
961 if (m->right == NULL) {
962 object->cache = m->left;
963 m_next = NULL;
964 } else {
965 m_next = vm_page_splay(start, m->right);
966 m_next->left = m->left;
967 object->cache = m_next;
968 }
969 /* Convert "m" to a free page. */
970 m->object = NULL;
971 m->valid = 0;
972 /* Clear PG_CACHED and set PG_FREE. */
973 m->flags ^= PG_CACHED | PG_FREE;
974 KASSERT((m->flags & (PG_CACHED | PG_FREE)) == PG_FREE,
975 ("vm_page_cache_free: page %p has inconsistent flags", m));
976 cnt.v_cache_count--;
977 cnt.v_free_count++;
978 }
979 empty = object->cache == NULL;
980 mtx_unlock(&vm_page_queue_free_mtx);
981 if (object->type == OBJT_VNODE && empty)
982 vdrop(object->handle);
983 }
984
985 /*
986 * Returns the cached page that is associated with the given
987 * object and offset. If, however, none exists, returns NULL.
988 *
989 * The free page queue must be locked.
990 */
991 static inline vm_page_t
992 vm_page_cache_lookup(vm_object_t object, vm_pindex_t pindex)
993 {
994 vm_page_t m;
995
996 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
997 if ((m = object->cache) != NULL && m->pindex != pindex) {
998 m = vm_page_splay(pindex, m);
999 if ((object->cache = m)->pindex != pindex)
1000 m = NULL;
1001 }
1002 return (m);
1003 }
1004
1005 /*
1006 * Remove the given cached page from its containing object's
1007 * collection of cached pages.
1008 *
1009 * The free page queue must be locked.
1010 */
1011 void
1012 vm_page_cache_remove(vm_page_t m)
1013 {
1014 vm_object_t object;
1015 vm_page_t root;
1016
1017 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
1018 KASSERT((m->flags & PG_CACHED) != 0,
1019 ("vm_page_cache_remove: page %p is not cached", m));
1020 object = m->object;
1021 if (m != object->cache) {
1022 root = vm_page_splay(m->pindex, object->cache);
1023 KASSERT(root == m,
1024 ("vm_page_cache_remove: page %p is not cached in object %p",
1025 m, object));
1026 }
1027 if (m->left == NULL)
1028 root = m->right;
1029 else if (m->right == NULL)
1030 root = m->left;
1031 else {
1032 root = vm_page_splay(m->pindex, m->left);
1033 root->right = m->right;
1034 }
1035 object->cache = root;
1036 m->object = NULL;
1037 cnt.v_cache_count--;
1038 }
1039
1040 /*
1041 * Transfer all of the cached pages with offset greater than or
1042 * equal to 'offidxstart' from the original object's cache to the
1043 * new object's cache. However, any cached pages with offset
1044 * greater than or equal to the new object's size are kept in the
1045 * original object. Initially, the new object's cache must be
1046 * empty. Offset 'offidxstart' in the original object must
1047 * correspond to offset zero in the new object.
1048 *
1049 * The new object must be locked.
1050 */
1051 void
1052 vm_page_cache_transfer(vm_object_t orig_object, vm_pindex_t offidxstart,
1053 vm_object_t new_object)
1054 {
1055 vm_page_t m, m_next;
1056
1057 /*
1058 * Insertion into an object's collection of cached pages
1059 * requires the object to be locked. In contrast, removal does
1060 * not.
1061 */
1062 VM_OBJECT_LOCK_ASSERT(new_object, MA_OWNED);
1063 KASSERT(new_object->cache == NULL,
1064 ("vm_page_cache_transfer: object %p has cached pages",
1065 new_object));
1066 mtx_lock(&vm_page_queue_free_mtx);
1067 if ((m = orig_object->cache) != NULL) {
1068 /*
1069 * Transfer all of the pages with offset greater than or
1070 * equal to 'offidxstart' from the original object's
1071 * cache to the new object's cache.
1072 */
1073 m = vm_page_splay(offidxstart, m);
1074 if (m->pindex < offidxstart) {
1075 orig_object->cache = m;
1076 new_object->cache = m->right;
1077 m->right = NULL;
1078 } else {
1079 orig_object->cache = m->left;
1080 new_object->cache = m;
1081 m->left = NULL;
1082 }
1083 while ((m = new_object->cache) != NULL) {
1084 if ((m->pindex - offidxstart) >= new_object->size) {
1085 /*
1086 * Return all of the cached pages with
1087 * offset greater than or equal to the
1088 * new object's size to the original
1089 * object's cache.
1090 */
1091 new_object->cache = m->left;
1092 m->left = orig_object->cache;
1093 orig_object->cache = m;
1094 break;
1095 }
1096 m_next = vm_page_splay(m->pindex, m->right);
1097 /* Update the page's object and offset. */
1098 m->object = new_object;
1099 m->pindex -= offidxstart;
1100 if (m_next == NULL)
1101 break;
1102 m->right = NULL;
1103 m_next->left = m;
1104 new_object->cache = m_next;
1105 }
1106 KASSERT(new_object->cache == NULL ||
1107 new_object->type == OBJT_SWAP,
1108 ("vm_page_cache_transfer: object %p's type is incompatible"
1109 " with cached pages", new_object));
1110 }
1111 mtx_unlock(&vm_page_queue_free_mtx);
1112 }
1113
1114 /*
1115 * vm_page_alloc:
1116 *
1117 * Allocate and return a memory cell associated
1118 * with this VM object/offset pair.
1119 *
1120 * The caller must always specify an allocation class.
1121 *
1122 * allocation classes:
1123 * VM_ALLOC_NORMAL normal process request
1124 * VM_ALLOC_SYSTEM system *really* needs a page
1125 * VM_ALLOC_INTERRUPT interrupt time request
1126 *
1127 * optional allocation flags:
1128 * VM_ALLOC_ZERO prefer a zeroed page
1129 * VM_ALLOC_WIRED wire the allocated page
1130 * VM_ALLOC_NOOBJ page is not associated with a vm object
1131 * VM_ALLOC_NOBUSY do not set the page busy
1132 * VM_ALLOC_IFCACHED return page only if it is cached
1133 * VM_ALLOC_IFNOTCACHED return NULL, do not reactivate if the page
1134 * is cached
1135 *
1136 * This routine may not sleep.
1137 */
1138 vm_page_t
1139 vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req)
1140 {
1141 struct vnode *vp = NULL;
1142 vm_object_t m_object;
1143 vm_page_t m;
1144 int flags, page_req;
1145
1146 if ((req & VM_ALLOC_NOOBJ) == 0) {
1147 KASSERT(object != NULL,
1148 ("vm_page_alloc: NULL object."));
1149 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1150 }
1151
1152 page_req = req & VM_ALLOC_CLASS_MASK;
1153
1154 /*
1155 * The pager is allowed to eat deeper into the free page list.
1156 */
1157 if ((curproc == pageproc) && (page_req != VM_ALLOC_INTERRUPT))
1158 page_req = VM_ALLOC_SYSTEM;
1159
1160 mtx_lock(&vm_page_queue_free_mtx);
1161 if (cnt.v_free_count + cnt.v_cache_count > cnt.v_free_reserved ||
1162 (page_req == VM_ALLOC_SYSTEM &&
1163 cnt.v_free_count + cnt.v_cache_count > cnt.v_interrupt_free_min) ||
1164 (page_req == VM_ALLOC_INTERRUPT &&
1165 cnt.v_free_count + cnt.v_cache_count > 0)) {
1166 /*
1167 * Allocate from the free queue if the number of free pages
1168 * exceeds the minimum for the request class.
1169 */
1170 if (object != NULL &&
1171 (m = vm_page_cache_lookup(object, pindex)) != NULL) {
1172 if ((req & VM_ALLOC_IFNOTCACHED) != 0) {
1173 mtx_unlock(&vm_page_queue_free_mtx);
1174 return (NULL);
1175 }
1176 if (vm_phys_unfree_page(m))
1177 vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m, 0);
1178 #if VM_NRESERVLEVEL > 0
1179 else if (!vm_reserv_reactivate_page(m))
1180 #else
1181 else
1182 #endif
1183 panic("vm_page_alloc: cache page %p is missing"
1184 " from the free queue", m);
1185 } else if ((req & VM_ALLOC_IFCACHED) != 0) {
1186 mtx_unlock(&vm_page_queue_free_mtx);
1187 return (NULL);
1188 #if VM_NRESERVLEVEL > 0
1189 } else if (object == NULL || object->type == OBJT_DEVICE ||
1190 object->type == OBJT_SG ||
1191 (object->flags & OBJ_COLORED) == 0 ||
1192 (m = vm_reserv_alloc_page(object, pindex)) == NULL) {
1193 #else
1194 } else {
1195 #endif
1196 m = vm_phys_alloc_pages(object != NULL ?
1197 VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRECT, 0);
1198 #if VM_NRESERVLEVEL > 0
1199 if (m == NULL && vm_reserv_reclaim_inactive()) {
1200 m = vm_phys_alloc_pages(object != NULL ?
1201 VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRECT,
1202 0);
1203 }
1204 #endif
1205 }
1206 } else {
1207 /*
1208 * Not allocatable, give up.
1209 */
1210 mtx_unlock(&vm_page_queue_free_mtx);
1211 atomic_add_int(&vm_pageout_deficit, 1);
1212 pagedaemon_wakeup();
1213 return (NULL);
1214 }
1215
1216 /*
1217 * At this point we had better have found a good page.
1218 */
1219
1220 KASSERT(m != NULL, ("vm_page_alloc: missing page"));
1221 KASSERT(m->queue == PQ_NONE,
1222 ("vm_page_alloc: page %p has unexpected queue %d", m, m->queue));
1223 KASSERT(m->wire_count == 0, ("vm_page_alloc: page %p is wired", m));
1224 KASSERT(m->hold_count == 0, ("vm_page_alloc: page %p is held", m));
1225 KASSERT(m->busy == 0, ("vm_page_alloc: page %p is busy", m));
1226 KASSERT(m->dirty == 0, ("vm_page_alloc: page %p is dirty", m));
1227 KASSERT(pmap_page_get_memattr(m) == VM_MEMATTR_DEFAULT,
1228 ("vm_page_alloc: page %p has unexpected memattr %d", m,
1229 pmap_page_get_memattr(m)));
1230 if ((m->flags & PG_CACHED) != 0) {
1231 KASSERT(m->valid != 0,
1232 ("vm_page_alloc: cached page %p is invalid", m));
1233 if (m->object == object && m->pindex == pindex)
1234 cnt.v_reactivated++;
1235 else
1236 m->valid = 0;
1237 m_object = m->object;
1238 vm_page_cache_remove(m);
1239 if (m_object->type == OBJT_VNODE && m_object->cache == NULL)
1240 vp = m_object->handle;
1241 } else {
1242 KASSERT(VM_PAGE_IS_FREE(m),
1243 ("vm_page_alloc: page %p is not free", m));
1244 KASSERT(m->valid == 0,
1245 ("vm_page_alloc: free page %p is valid", m));
1246 cnt.v_free_count--;
1247 }
1248
1249 /*
1250 * Initialize structure. Only the PG_ZERO flag is inherited.
1251 */
1252 flags = 0;
1253 if (m->flags & PG_ZERO) {
1254 vm_page_zero_count--;
1255 if (req & VM_ALLOC_ZERO)
1256 flags = PG_ZERO;
1257 }
1258 if (object == NULL || object->type == OBJT_PHYS)
1259 flags |= PG_UNMANAGED;
1260 m->flags = flags;
1261 if (req & (VM_ALLOC_NOBUSY | VM_ALLOC_NOOBJ))
1262 m->oflags = 0;
1263 else
1264 m->oflags = VPO_BUSY;
1265 if (req & VM_ALLOC_WIRED) {
1266 atomic_add_int(&cnt.v_wire_count, 1);
1267 m->wire_count = 1;
1268 }
1269 m->act_count = 0;
1270 mtx_unlock(&vm_page_queue_free_mtx);
1271
1272 if (object != NULL) {
1273 /* Ignore device objects; the pager sets "memattr" for them. */
1274 if (object->memattr != VM_MEMATTR_DEFAULT &&
1275 object->type != OBJT_DEVICE && object->type != OBJT_SG)
1276 pmap_page_set_memattr(m, object->memattr);
1277 vm_page_insert(m, object, pindex);
1278 } else
1279 m->pindex = pindex;
1280
1281 /*
1282 * The following call to vdrop() must come after the above call
1283 * to vm_page_insert() in case both affect the same object and
1284 * vnode. Otherwise, the affected vnode's hold count could
1285 * temporarily become zero.
1286 */
1287 if (vp != NULL)
1288 vdrop(vp);
1289
1290 /*
1291 * Don't wakeup too often - wakeup the pageout daemon when
1292 * we would be nearly out of memory.
1293 */
1294 if (vm_paging_needed())
1295 pagedaemon_wakeup();
1296
1297 return (m);
1298 }
1299
1300 /*
1301 * Initialize a page that has been freshly dequeued from a freelist.
1302 * The caller has to drop the vnode returned, if it is not NULL.
1303 *
1304 * To be called with vm_page_queue_free_mtx held.
1305 */
1306 struct vnode *
1307 vm_page_alloc_init(vm_page_t m)
1308 {
1309 struct vnode *drop;
1310 vm_object_t m_object;
1311
1312 KASSERT(m->queue == PQ_NONE,
1313 ("vm_page_alloc_init: page %p has unexpected queue %d",
1314 m, m->queue));
1315 KASSERT(m->wire_count == 0,
1316 ("vm_page_alloc_init: page %p is wired", m));
1317 KASSERT(m->hold_count == 0,
1318 ("vm_page_alloc_init: page %p is held", m));
1319 KASSERT(m->busy == 0,
1320 ("vm_page_alloc_init: page %p is busy", m));
1321 KASSERT(m->dirty == 0,
1322 ("vm_page_alloc_init: page %p is dirty", m));
1323 KASSERT(pmap_page_get_memattr(m) == VM_MEMATTR_DEFAULT,
1324 ("vm_page_alloc_init: page %p has unexpected memattr %d",
1325 m, pmap_page_get_memattr(m)));
1326 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
1327 drop = NULL;
1328 if ((m->flags & PG_CACHED) != 0) {
1329 m->valid = 0;
1330 m_object = m->object;
1331 vm_page_cache_remove(m);
1332 if (m_object->type == OBJT_VNODE &&
1333 m_object->cache == NULL)
1334 drop = m_object->handle;
1335 } else {
1336 KASSERT(VM_PAGE_IS_FREE(m),
1337 ("vm_page_alloc_init: page %p is not free", m));
1338 KASSERT(m->valid == 0,
1339 ("vm_page_alloc_init: free page %p is valid", m));
1340 cnt.v_free_count--;
1341 }
1342 if (m->flags & PG_ZERO)
1343 vm_page_zero_count--;
1344 /* Don't clear the PG_ZERO flag; we'll need it later. */
1345 m->flags = PG_UNMANAGED | (m->flags & PG_ZERO);
1346 m->oflags = 0;
1347 /* Unmanaged pages don't use "act_count". */
1348 return (drop);
1349 }
1350
1351 /*
1352 * vm_page_alloc_freelist:
1353 *
1354 * Allocate a page from the specified freelist.
1355 * Only the ALLOC_CLASS values in req are honored, other request flags
1356 * are ignored.
1357 */
1358 vm_page_t
1359 vm_page_alloc_freelist(int flind, int req)
1360 {
1361 struct vnode *drop;
1362 vm_page_t m;
1363 int page_req;
1364
1365 m = NULL;
1366 page_req = req & VM_ALLOC_CLASS_MASK;
1367 mtx_lock(&vm_page_queue_free_mtx);
1368 /*
1369 * Do not allocate reserved pages unless the req has asked for it.
1370 */
1371 if (cnt.v_free_count + cnt.v_cache_count > cnt.v_free_reserved ||
1372 (page_req == VM_ALLOC_SYSTEM &&
1373 cnt.v_free_count + cnt.v_cache_count > cnt.v_interrupt_free_min) ||
1374 (page_req == VM_ALLOC_INTERRUPT &&
1375 cnt.v_free_count + cnt.v_cache_count > 0)) {
1376 m = vm_phys_alloc_freelist_pages(flind, VM_FREEPOOL_DIRECT, 0);
1377 }
1378 if (m == NULL) {
1379 mtx_unlock(&vm_page_queue_free_mtx);
1380 return (NULL);
1381 }
1382 drop = vm_page_alloc_init(m);
1383 mtx_unlock(&vm_page_queue_free_mtx);
1384 if (drop)
1385 vdrop(drop);
1386 return (m);
1387 }
1388
1389 /*
1390 * vm_wait: (also see VM_WAIT macro)
1391 *
1392 * Block until free pages are available for allocation
1393 * - Called in various places before memory allocations.
1394 */
1395 void
1396 vm_wait(void)
1397 {
1398
1399 mtx_lock(&vm_page_queue_free_mtx);
1400 if (curproc == pageproc) {
1401 vm_pageout_pages_needed = 1;
1402 msleep(&vm_pageout_pages_needed, &vm_page_queue_free_mtx,
1403 PDROP | PSWP, "VMWait", 0);
1404 } else {
1405 if (!vm_pages_needed) {
1406 vm_pages_needed = 1;
1407 wakeup(&vm_pages_needed);
1408 }
1409 msleep(&cnt.v_free_count, &vm_page_queue_free_mtx, PDROP | PVM,
1410 "vmwait", 0);
1411 }
1412 }
1413
1414 /*
1415 * vm_waitpfault: (also see VM_WAITPFAULT macro)
1416 *
1417 * Block until free pages are available for allocation
1418 * - Called only in vm_fault so that processes page faulting
1419 * can be easily tracked.
1420 * - Sleeps at a lower priority than vm_wait() so that vm_wait()ing
1421 * processes will be able to grab memory first. Do not change
1422 * this balance without careful testing first.
1423 */
1424 void
1425 vm_waitpfault(void)
1426 {
1427
1428 mtx_lock(&vm_page_queue_free_mtx);
1429 if (!vm_pages_needed) {
1430 vm_pages_needed = 1;
1431 wakeup(&vm_pages_needed);
1432 }
1433 msleep(&cnt.v_free_count, &vm_page_queue_free_mtx, PDROP | PUSER,
1434 "pfault", 0);
1435 }
1436
1437 /*
1438 * vm_page_requeue:
1439 *
1440 * If the given page is contained within a page queue, move it to the tail
1441 * of that queue.
1442 *
1443 * The page queues must be locked.
1444 */
1445 void
1446 vm_page_requeue(vm_page_t m)
1447 {
1448 int queue = VM_PAGE_GETQUEUE(m);
1449 struct vpgqueues *vpq;
1450
1451 if (queue != PQ_NONE) {
1452 vpq = &vm_page_queues[queue];
1453 TAILQ_REMOVE(&vpq->pl, m, pageq);
1454 TAILQ_INSERT_TAIL(&vpq->pl, m, pageq);
1455 }
1456 }
1457
1458 /*
1459 * vm_pageq_remove:
1460 *
1461 * Remove a page from its queue.
1462 *
1463 * The queue containing the given page must be locked.
1464 * This routine may not block.
1465 */
1466 void
1467 vm_pageq_remove(vm_page_t m)
1468 {
1469 int queue = VM_PAGE_GETQUEUE(m);
1470 struct vpgqueues *pq;
1471
1472 if (queue != PQ_NONE) {
1473 VM_PAGE_SETQUEUE2(m, PQ_NONE);
1474 pq = &vm_page_queues[queue];
1475 TAILQ_REMOVE(&pq->pl, m, pageq);
1476 (*pq->cnt)--;
1477 }
1478 }
1479
1480 /*
1481 * vm_page_enqueue:
1482 *
1483 * Add the given page to the specified queue.
1484 *
1485 * The page queues must be locked.
1486 */
1487 static void
1488 vm_page_enqueue(int queue, vm_page_t m)
1489 {
1490 struct vpgqueues *vpq;
1491
1492 vpq = &vm_page_queues[queue];
1493 VM_PAGE_SETQUEUE2(m, queue);
1494 TAILQ_INSERT_TAIL(&vpq->pl, m, pageq);
1495 ++*vpq->cnt;
1496 }
1497
1498 /*
1499 * vm_page_activate:
1500 *
1501 * Put the specified page on the active list (if appropriate).
1502 * Ensure that act_count is at least ACT_INIT but do not otherwise
1503 * mess with it.
1504 *
1505 * The page queues must be locked.
1506 * This routine may not block.
1507 */
1508 void
1509 vm_page_activate(vm_page_t m)
1510 {
1511
1512 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
1513 if (VM_PAGE_GETKNOWNQUEUE2(m) != PQ_ACTIVE) {
1514 vm_pageq_remove(m);
1515 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) {
1516 if (m->act_count < ACT_INIT)
1517 m->act_count = ACT_INIT;
1518 vm_page_enqueue(PQ_ACTIVE, m);
1519 }
1520 } else {
1521 if (m->act_count < ACT_INIT)
1522 m->act_count = ACT_INIT;
1523 }
1524 }
1525
1526 /*
1527 * vm_page_free_wakeup:
1528 *
1529 * Helper routine for vm_page_free_toq() and vm_page_cache(). This
1530 * routine is called when a page has been added to the cache or free
1531 * queues.
1532 *
1533 * The page queues must be locked.
1534 * This routine may not block.
1535 */
1536 static inline void
1537 vm_page_free_wakeup(void)
1538 {
1539
1540 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
1541 /*
1542 * if pageout daemon needs pages, then tell it that there are
1543 * some free.
1544 */
1545 if (vm_pageout_pages_needed &&
1546 cnt.v_cache_count + cnt.v_free_count >= cnt.v_pageout_free_min) {
1547 wakeup(&vm_pageout_pages_needed);
1548 vm_pageout_pages_needed = 0;
1549 }
1550 /*
1551 * wakeup processes that are waiting on memory if we hit a
1552 * high water mark. And wakeup scheduler process if we have
1553 * lots of memory. this process will swapin processes.
1554 */
1555 if (vm_pages_needed && !vm_page_count_min()) {
1556 vm_pages_needed = 0;
1557 wakeup(&cnt.v_free_count);
1558 }
1559 }
1560
1561 /*
1562 * vm_page_free_toq:
1563 *
1564 * Returns the given page to the free list,
1565 * disassociating it with any VM object.
1566 *
1567 * Object and page must be locked prior to entry.
1568 * This routine may not block.
1569 */
1570
1571 void
1572 vm_page_free_toq(vm_page_t m)
1573 {
1574
1575 if (VM_PAGE_GETQUEUE(m) != PQ_NONE)
1576 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
1577 KASSERT(!pmap_page_is_mapped(m),
1578 ("vm_page_free_toq: freeing mapped page %p", m));
1579 PCPU_INC(cnt.v_tfree);
1580
1581 if (m->busy || VM_PAGE_IS_FREE(m)) {
1582 printf(
1583 "vm_page_free: pindex(%lu), busy(%d), VPO_BUSY(%d), hold(%d)\n",
1584 (u_long)m->pindex, m->busy, (m->oflags & VPO_BUSY) ? 1 : 0,
1585 m->hold_count);
1586 if (VM_PAGE_IS_FREE(m))
1587 panic("vm_page_free: freeing free page");
1588 else
1589 panic("vm_page_free: freeing busy page");
1590 }
1591
1592 /*
1593 * unqueue, then remove page. Note that we cannot destroy
1594 * the page here because we do not want to call the pager's
1595 * callback routine until after we've put the page on the
1596 * appropriate free queue.
1597 */
1598 vm_pageq_remove(m);
1599 vm_page_remove(m);
1600
1601 /*
1602 * If fictitious remove object association and
1603 * return, otherwise delay object association removal.
1604 */
1605 if ((m->flags & PG_FICTITIOUS) != 0) {
1606 return;
1607 }
1608
1609 m->valid = 0;
1610 vm_page_undirty(m);
1611
1612 if (m->wire_count != 0) {
1613 if (m->wire_count > 1) {
1614 panic("vm_page_free: invalid wire count (%d), pindex: 0x%lx",
1615 m->wire_count, (long)m->pindex);
1616 }
1617 panic("vm_page_free: freeing wired page");
1618 }
1619 if (m->hold_count != 0) {
1620 m->flags &= ~PG_ZERO;
1621 vm_page_enqueue(PQ_HOLD, m);
1622 } else {
1623 /*
1624 * Restore the default memory attribute to the page.
1625 */
1626 if (pmap_page_get_memattr(m) != VM_MEMATTR_DEFAULT)
1627 pmap_page_set_memattr(m, VM_MEMATTR_DEFAULT);
1628
1629 /*
1630 * Insert the page into the physical memory allocator's
1631 * cache/free page queues.
1632 */
1633 mtx_lock(&vm_page_queue_free_mtx);
1634 m->flags |= PG_FREE;
1635 cnt.v_free_count++;
1636 #if VM_NRESERVLEVEL > 0
1637 if (!vm_reserv_free_page(m))
1638 #else
1639 if (TRUE)
1640 #endif
1641 vm_phys_free_pages(m, 0);
1642 if ((m->flags & PG_ZERO) != 0)
1643 ++vm_page_zero_count;
1644 else
1645 vm_page_zero_idle_wakeup();
1646 vm_page_free_wakeup();
1647 mtx_unlock(&vm_page_queue_free_mtx);
1648 }
1649 }
1650
1651 /*
1652 * vm_page_wire:
1653 *
1654 * Mark this page as wired down by yet
1655 * another map, removing it from paging queues
1656 * as necessary.
1657 *
1658 * The page queues must be locked.
1659 * This routine may not block.
1660 */
1661 void
1662 vm_page_wire(vm_page_t m)
1663 {
1664
1665 /*
1666 * Only bump the wire statistics if the page is not already wired,
1667 * and only unqueue the page if it is on some queue (if it is unmanaged
1668 * it is already off the queues).
1669 */
1670 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
1671 if (m->flags & PG_FICTITIOUS)
1672 return;
1673 if (m->wire_count == 0) {
1674 if ((m->flags & PG_UNMANAGED) == 0)
1675 vm_pageq_remove(m);
1676 atomic_add_int(&cnt.v_wire_count, 1);
1677 }
1678 m->wire_count++;
1679 KASSERT(m->wire_count != 0, ("vm_page_wire: wire_count overflow m=%p", m));
1680 }
1681
1682 /*
1683 * vm_page_unwire:
1684 *
1685 * Release one wiring of this page, potentially
1686 * enabling it to be paged again.
1687 *
1688 * Many pages placed on the inactive queue should actually go
1689 * into the cache, but it is difficult to figure out which. What
1690 * we do instead, if the inactive target is well met, is to put
1691 * clean pages at the head of the inactive queue instead of the tail.
1692 * This will cause them to be moved to the cache more quickly and
1693 * if not actively re-referenced, freed more quickly. If we just
1694 * stick these pages at the end of the inactive queue, heavy filesystem
1695 * meta-data accesses can cause an unnecessary paging load on memory bound
1696 * processes. This optimization causes one-time-use metadata to be
1697 * reused more quickly.
1698 *
1699 * BUT, if we are in a low-memory situation we have no choice but to
1700 * put clean pages on the cache queue.
1701 *
1702 * A number of routines use vm_page_unwire() to guarantee that the page
1703 * will go into either the inactive or active queues, and will NEVER
1704 * be placed in the cache - for example, just after dirtying a page.
1705 * dirty pages in the cache are not allowed.
1706 *
1707 * The page queues must be locked.
1708 * This routine may not block.
1709 */
1710 void
1711 vm_page_unwire(vm_page_t m, int activate)
1712 {
1713
1714 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
1715 if (m->flags & PG_FICTITIOUS)
1716 return;
1717 if (m->wire_count > 0) {
1718 m->wire_count--;
1719 if (m->wire_count == 0) {
1720 atomic_subtract_int(&cnt.v_wire_count, 1);
1721 if (m->flags & PG_UNMANAGED) {
1722 ;
1723 } else if (activate)
1724 vm_page_enqueue(PQ_ACTIVE, m);
1725 else {
1726 vm_page_flag_clear(m, PG_WINATCFLS);
1727 vm_page_enqueue(PQ_INACTIVE, m);
1728 }
1729 }
1730 } else {
1731 panic("vm_page_unwire: invalid wire count: %d", m->wire_count);
1732 }
1733 }
1734
1735
1736 /*
1737 * Move the specified page to the inactive queue. If the page has
1738 * any associated swap, the swap is deallocated.
1739 *
1740 * Normally athead is 0 resulting in LRU operation. athead is set
1741 * to 1 if we want this page to be 'as if it were placed in the cache',
1742 * except without unmapping it from the process address space.
1743 *
1744 * This routine may not block.
1745 */
1746 static inline void
1747 _vm_page_deactivate(vm_page_t m, int athead)
1748 {
1749
1750 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
1751
1752 /*
1753 * Ignore if already inactive.
1754 */
1755 if (VM_PAGE_INQUEUE2(m, PQ_INACTIVE))
1756 return;
1757 if (m->wire_count == 0 && (m->flags & PG_UNMANAGED) == 0) {
1758 vm_page_flag_clear(m, PG_WINATCFLS);
1759 vm_pageq_remove(m);
1760 if (athead)
1761 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
1762 else
1763 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
1764 VM_PAGE_SETQUEUE2(m, PQ_INACTIVE);
1765 cnt.v_inactive_count++;
1766 }
1767 }
1768
1769 void
1770 vm_page_deactivate(vm_page_t m)
1771 {
1772 _vm_page_deactivate(m, 0);
1773 }
1774
1775 /*
1776 * vm_page_try_to_cache:
1777 *
1778 * Returns 0 on failure, 1 on success
1779 */
1780 int
1781 vm_page_try_to_cache(vm_page_t m)
1782 {
1783
1784 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
1785 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
1786 if (m->dirty || m->hold_count || m->busy || m->wire_count ||
1787 (m->oflags & VPO_BUSY) || (m->flags & PG_UNMANAGED)) {
1788 return (0);
1789 }
1790 pmap_remove_all(m);
1791 if (m->dirty)
1792 return (0);
1793 vm_page_cache(m);
1794 return (1);
1795 }
1796
1797 /*
1798 * vm_page_try_to_free()
1799 *
1800 * Attempt to free the page. If we cannot free it, we do nothing.
1801 * 1 is returned on success, 0 on failure.
1802 */
1803 int
1804 vm_page_try_to_free(vm_page_t m)
1805 {
1806
1807 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
1808 if (m->object != NULL)
1809 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
1810 if (m->dirty || m->hold_count || m->busy || m->wire_count ||
1811 (m->oflags & VPO_BUSY) || (m->flags & PG_UNMANAGED)) {
1812 return (0);
1813 }
1814 pmap_remove_all(m);
1815 if (m->dirty)
1816 return (0);
1817 vm_page_free(m);
1818 return (1);
1819 }
1820
1821 /*
1822 * vm_page_cache
1823 *
1824 * Put the specified page onto the page cache queue (if appropriate).
1825 *
1826 * This routine may not block.
1827 */
1828 void
1829 vm_page_cache(vm_page_t m)
1830 {
1831 vm_object_t object;
1832 vm_page_t next, prev, root;
1833
1834 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
1835 object = m->object;
1836 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1837 if ((m->flags & PG_UNMANAGED) || (m->oflags & VPO_BUSY) || m->busy ||
1838 m->hold_count || m->wire_count) {
1839 panic("vm_page_cache: attempting to cache busy page");
1840 }
1841 pmap_remove_all(m);
1842 if (m->dirty != 0)
1843 panic("vm_page_cache: page %p is dirty", m);
1844 if (m->valid == 0 || object->type == OBJT_DEFAULT ||
1845 (object->type == OBJT_SWAP &&
1846 !vm_pager_has_page(object, m->pindex, NULL, NULL))) {
1847 /*
1848 * Hypothesis: A cache-elgible page belonging to a
1849 * default object or swap object but without a backing
1850 * store must be zero filled.
1851 */
1852 vm_page_free(m);
1853 return;
1854 }
1855 KASSERT((m->flags & PG_CACHED) == 0,
1856 ("vm_page_cache: page %p is already cached", m));
1857 cnt.v_tcached++;
1858
1859 /*
1860 * Remove the page from the paging queues.
1861 */
1862 vm_pageq_remove(m);
1863
1864 /*
1865 * Remove the page from the object's collection of resident
1866 * pages.
1867 */
1868 if ((next = TAILQ_NEXT(m, listq)) != NULL && next->left == m) {
1869 /*
1870 * Since the page's successor in the list is also its parent
1871 * in the tree, its right subtree must be empty.
1872 */
1873 next->left = m->left;
1874 KASSERT(m->right == NULL,
1875 ("vm_page_cache: page %p has right child", m));
1876 } else if ((prev = TAILQ_PREV(m, pglist, listq)) != NULL &&
1877 prev->right == m) {
1878 /*
1879 * Since the page's predecessor in the list is also its parent
1880 * in the tree, its left subtree must be empty.
1881 */
1882 KASSERT(m->left == NULL,
1883 ("vm_page_cache: page %p has left child", m));
1884 prev->right = m->right;
1885 } else {
1886 if (m != object->root)
1887 vm_page_splay(m->pindex, object->root);
1888 if (m->left == NULL)
1889 root = m->right;
1890 else if (m->right == NULL)
1891 root = m->left;
1892 else {
1893 /*
1894 * Move the page's successor to the root, because
1895 * pages are usually removed in ascending order.
1896 */
1897 if (m->right != next)
1898 vm_page_splay(m->pindex, m->right);
1899 next->left = m->left;
1900 root = next;
1901 }
1902 object->root = root;
1903 }
1904 TAILQ_REMOVE(&object->memq, m, listq);
1905 object->resident_page_count--;
1906
1907 /*
1908 * Restore the default memory attribute to the page.
1909 */
1910 if (pmap_page_get_memattr(m) != VM_MEMATTR_DEFAULT)
1911 pmap_page_set_memattr(m, VM_MEMATTR_DEFAULT);
1912
1913 /*
1914 * Insert the page into the object's collection of cached pages
1915 * and the physical memory allocator's cache/free page queues.
1916 */
1917 vm_page_flag_clear(m, PG_ZERO);
1918 mtx_lock(&vm_page_queue_free_mtx);
1919 m->flags |= PG_CACHED;
1920 cnt.v_cache_count++;
1921 root = object->cache;
1922 if (root == NULL) {
1923 m->left = NULL;
1924 m->right = NULL;
1925 } else {
1926 root = vm_page_splay(m->pindex, root);
1927 if (m->pindex < root->pindex) {
1928 m->left = root->left;
1929 m->right = root;
1930 root->left = NULL;
1931 } else if (__predict_false(m->pindex == root->pindex))
1932 panic("vm_page_cache: offset already cached");
1933 else {
1934 m->right = root->right;
1935 m->left = root;
1936 root->right = NULL;
1937 }
1938 }
1939 object->cache = m;
1940 #if VM_NRESERVLEVEL > 0
1941 if (!vm_reserv_free_page(m)) {
1942 #else
1943 if (TRUE) {
1944 #endif
1945 vm_phys_set_pool(VM_FREEPOOL_CACHE, m, 0);
1946 vm_phys_free_pages(m, 0);
1947 }
1948 vm_page_free_wakeup();
1949 mtx_unlock(&vm_page_queue_free_mtx);
1950
1951 /*
1952 * Increment the vnode's hold count if this is the object's only
1953 * cached page. Decrement the vnode's hold count if this was
1954 * the object's only resident page.
1955 */
1956 if (object->type == OBJT_VNODE) {
1957 if (root == NULL && object->resident_page_count != 0)
1958 vhold(object->handle);
1959 else if (root != NULL && object->resident_page_count == 0)
1960 vdrop(object->handle);
1961 }
1962 }
1963
1964 /*
1965 * vm_page_dontneed
1966 *
1967 * Cache, deactivate, or do nothing as appropriate. This routine
1968 * is typically used by madvise() MADV_DONTNEED.
1969 *
1970 * Generally speaking we want to move the page into the cache so
1971 * it gets reused quickly. However, this can result in a silly syndrome
1972 * due to the page recycling too quickly. Small objects will not be
1973 * fully cached. On the otherhand, if we move the page to the inactive
1974 * queue we wind up with a problem whereby very large objects
1975 * unnecessarily blow away our inactive and cache queues.
1976 *
1977 * The solution is to move the pages based on a fixed weighting. We
1978 * either leave them alone, deactivate them, or move them to the cache,
1979 * where moving them to the cache has the highest weighting.
1980 * By forcing some pages into other queues we eventually force the
1981 * system to balance the queues, potentially recovering other unrelated
1982 * space from active. The idea is to not force this to happen too
1983 * often.
1984 */
1985 void
1986 vm_page_dontneed(vm_page_t m)
1987 {
1988 static int dnweight;
1989 int dnw;
1990 int head;
1991
1992 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
1993 dnw = ++dnweight;
1994
1995 /*
1996 * occassionally leave the page alone
1997 */
1998 if ((dnw & 0x01F0) == 0 ||
1999 VM_PAGE_INQUEUE2(m, PQ_INACTIVE)) {
2000 if (m->act_count >= ACT_INIT)
2001 --m->act_count;
2002 return;
2003 }
2004
2005 /*
2006 * Clear any references to the page. Otherwise, the page daemon will
2007 * immediately reactivate the page.
2008 */
2009 vm_page_flag_clear(m, PG_REFERENCED);
2010 pmap_clear_reference(m);
2011
2012 if (m->dirty == 0 && pmap_is_modified(m))
2013 vm_page_dirty(m);
2014
2015 if (m->dirty || (dnw & 0x0070) == 0) {
2016 /*
2017 * Deactivate the page 3 times out of 32.
2018 */
2019 head = 0;
2020 } else {
2021 /*
2022 * Cache the page 28 times out of every 32. Note that
2023 * the page is deactivated instead of cached, but placed
2024 * at the head of the queue instead of the tail.
2025 */
2026 head = 1;
2027 }
2028 _vm_page_deactivate(m, head);
2029 }
2030
2031 /*
2032 * Grab a page, waiting until we are waken up due to the page
2033 * changing state. We keep on waiting, if the page continues
2034 * to be in the object. If the page doesn't exist, first allocate it
2035 * and then conditionally zero it.
2036 *
2037 * This routine may block.
2038 */
2039 vm_page_t
2040 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags)
2041 {
2042 vm_page_t m;
2043
2044 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
2045 retrylookup:
2046 if ((m = vm_page_lookup(object, pindex)) != NULL) {
2047 if (vm_page_sleep_if_busy(m, TRUE, "pgrbwt")) {
2048 if ((allocflags & VM_ALLOC_RETRY) == 0)
2049 return (NULL);
2050 goto retrylookup;
2051 } else {
2052 if ((allocflags & VM_ALLOC_WIRED) != 0) {
2053 vm_page_lock_queues();
2054 vm_page_wire(m);
2055 vm_page_unlock_queues();
2056 }
2057 if ((allocflags & VM_ALLOC_NOBUSY) == 0)
2058 vm_page_busy(m);
2059 return (m);
2060 }
2061 }
2062 m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY);
2063 if (m == NULL) {
2064 VM_OBJECT_UNLOCK(object);
2065 VM_WAIT;
2066 VM_OBJECT_LOCK(object);
2067 if ((allocflags & VM_ALLOC_RETRY) == 0)
2068 return (NULL);
2069 goto retrylookup;
2070 } else if (m->valid != 0)
2071 return (m);
2072 if (allocflags & VM_ALLOC_ZERO && (m->flags & PG_ZERO) == 0)
2073 pmap_zero_page(m);
2074 return (m);
2075 }
2076
2077 /*
2078 * Mapping function for valid bits or for dirty bits in
2079 * a page. May not block.
2080 *
2081 * Inputs are required to range within a page.
2082 */
2083 int
2084 vm_page_bits(int base, int size)
2085 {
2086 int first_bit;
2087 int last_bit;
2088
2089 KASSERT(
2090 base + size <= PAGE_SIZE,
2091 ("vm_page_bits: illegal base/size %d/%d", base, size)
2092 );
2093
2094 if (size == 0) /* handle degenerate case */
2095 return (0);
2096
2097 first_bit = base >> DEV_BSHIFT;
2098 last_bit = (base + size - 1) >> DEV_BSHIFT;
2099
2100 return ((2 << last_bit) - (1 << first_bit));
2101 }
2102
2103 /*
2104 * vm_page_set_valid:
2105 *
2106 * Sets portions of a page valid. The arguments are expected
2107 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive
2108 * of any partial chunks touched by the range. The invalid portion of
2109 * such chunks will be zeroed.
2110 *
2111 * (base + size) must be less then or equal to PAGE_SIZE.
2112 */
2113 void
2114 vm_page_set_valid(vm_page_t m, int base, int size)
2115 {
2116 int endoff, frag;
2117
2118 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
2119 if (size == 0) /* handle degenerate case */
2120 return;
2121
2122 /*
2123 * If the base is not DEV_BSIZE aligned and the valid
2124 * bit is clear, we have to zero out a portion of the
2125 * first block.
2126 */
2127 if ((frag = base & ~(DEV_BSIZE - 1)) != base &&
2128 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0)
2129 pmap_zero_page_area(m, frag, base - frag);
2130
2131 /*
2132 * If the ending offset is not DEV_BSIZE aligned and the
2133 * valid bit is clear, we have to zero out a portion of
2134 * the last block.
2135 */
2136 endoff = base + size;
2137 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff &&
2138 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0)
2139 pmap_zero_page_area(m, endoff,
2140 DEV_BSIZE - (endoff & (DEV_BSIZE - 1)));
2141
2142 /*
2143 * Assert that no previously invalid block that is now being validated
2144 * is already dirty.
2145 */
2146 KASSERT((~m->valid & vm_page_bits(base, size) & m->dirty) == 0,
2147 ("vm_page_set_valid: page %p is dirty", m));
2148
2149 /*
2150 * Set valid bits inclusive of any overlap.
2151 */
2152 m->valid |= vm_page_bits(base, size);
2153 }
2154
2155 /*
2156 * vm_page_set_validclean:
2157 *
2158 * Sets portions of a page valid and clean. The arguments are expected
2159 * to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive
2160 * of any partial chunks touched by the range. The invalid portion of
2161 * such chunks will be zero'd.
2162 *
2163 * This routine may not block.
2164 *
2165 * (base + size) must be less then or equal to PAGE_SIZE.
2166 */
2167 void
2168 vm_page_set_validclean(vm_page_t m, int base, int size)
2169 {
2170 int pagebits;
2171 int frag;
2172 int endoff;
2173
2174 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
2175 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
2176 if (size == 0) /* handle degenerate case */
2177 return;
2178
2179 /*
2180 * If the base is not DEV_BSIZE aligned and the valid
2181 * bit is clear, we have to zero out a portion of the
2182 * first block.
2183 */
2184 if ((frag = base & ~(DEV_BSIZE - 1)) != base &&
2185 (m->valid & (1 << (base >> DEV_BSHIFT))) == 0)
2186 pmap_zero_page_area(m, frag, base - frag);
2187
2188 /*
2189 * If the ending offset is not DEV_BSIZE aligned and the
2190 * valid bit is clear, we have to zero out a portion of
2191 * the last block.
2192 */
2193 endoff = base + size;
2194 if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff &&
2195 (m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0)
2196 pmap_zero_page_area(m, endoff,
2197 DEV_BSIZE - (endoff & (DEV_BSIZE - 1)));
2198
2199 /*
2200 * Set valid, clear dirty bits. If validating the entire
2201 * page we can safely clear the pmap modify bit. We also
2202 * use this opportunity to clear the VPO_NOSYNC flag. If a process
2203 * takes a write fault on a MAP_NOSYNC memory area the flag will
2204 * be set again.
2205 *
2206 * We set valid bits inclusive of any overlap, but we can only
2207 * clear dirty bits for DEV_BSIZE chunks that are fully within
2208 * the range.
2209 */
2210 pagebits = vm_page_bits(base, size);
2211 m->valid |= pagebits;
2212 #if 0 /* NOT YET */
2213 if ((frag = base & (DEV_BSIZE - 1)) != 0) {
2214 frag = DEV_BSIZE - frag;
2215 base += frag;
2216 size -= frag;
2217 if (size < 0)
2218 size = 0;
2219 }
2220 pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1));
2221 #endif
2222 m->dirty &= ~pagebits;
2223 if (base == 0 && size == PAGE_SIZE) {
2224 pmap_clear_modify(m);
2225 m->oflags &= ~VPO_NOSYNC;
2226 }
2227 }
2228
2229 void
2230 vm_page_clear_dirty(vm_page_t m, int base, int size)
2231 {
2232
2233 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
2234 m->dirty &= ~vm_page_bits(base, size);
2235 }
2236
2237 /*
2238 * vm_page_set_invalid:
2239 *
2240 * Invalidates DEV_BSIZE'd chunks within a page. Both the
2241 * valid and dirty bits for the effected areas are cleared.
2242 *
2243 * May not block.
2244 */
2245 void
2246 vm_page_set_invalid(vm_page_t m, int base, int size)
2247 {
2248 int bits;
2249
2250 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
2251 bits = vm_page_bits(base, size);
2252 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
2253 if (m->valid == VM_PAGE_BITS_ALL && bits != 0)
2254 pmap_remove_all(m);
2255 m->valid &= ~bits;
2256 m->dirty &= ~bits;
2257 }
2258
2259 /*
2260 * vm_page_zero_invalid()
2261 *
2262 * The kernel assumes that the invalid portions of a page contain
2263 * garbage, but such pages can be mapped into memory by user code.
2264 * When this occurs, we must zero out the non-valid portions of the
2265 * page so user code sees what it expects.
2266 *
2267 * Pages are most often semi-valid when the end of a file is mapped
2268 * into memory and the file's size is not page aligned.
2269 */
2270 void
2271 vm_page_zero_invalid(vm_page_t m, boolean_t setvalid)
2272 {
2273 int b;
2274 int i;
2275
2276 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
2277 /*
2278 * Scan the valid bits looking for invalid sections that
2279 * must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the
2280 * valid bit may be set ) have already been zerod by
2281 * vm_page_set_validclean().
2282 */
2283 for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) {
2284 if (i == (PAGE_SIZE / DEV_BSIZE) ||
2285 (m->valid & (1 << i))
2286 ) {
2287 if (i > b) {
2288 pmap_zero_page_area(m,
2289 b << DEV_BSHIFT, (i - b) << DEV_BSHIFT);
2290 }
2291 b = i + 1;
2292 }
2293 }
2294
2295 /*
2296 * setvalid is TRUE when we can safely set the zero'd areas
2297 * as being valid. We can do this if there are no cache consistancy
2298 * issues. e.g. it is ok to do with UFS, but not ok to do with NFS.
2299 */
2300 if (setvalid)
2301 m->valid = VM_PAGE_BITS_ALL;
2302 }
2303
2304 /*
2305 * vm_page_is_valid:
2306 *
2307 * Is (partial) page valid? Note that the case where size == 0
2308 * will return FALSE in the degenerate case where the page is
2309 * entirely invalid, and TRUE otherwise.
2310 *
2311 * May not block.
2312 */
2313 int
2314 vm_page_is_valid(vm_page_t m, int base, int size)
2315 {
2316 int bits = vm_page_bits(base, size);
2317
2318 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
2319 if (m->valid && ((m->valid & bits) == bits))
2320 return 1;
2321 else
2322 return 0;
2323 }
2324
2325 /*
2326 * update dirty bits from pmap/mmu. May not block.
2327 */
2328 void
2329 vm_page_test_dirty(vm_page_t m)
2330 {
2331 if ((m->dirty != VM_PAGE_BITS_ALL) && pmap_is_modified(m)) {
2332 vm_page_dirty(m);
2333 }
2334 }
2335
2336 int so_zerocp_fullpage = 0;
2337
2338 /*
2339 * Replace the given page with a copy. The copied page assumes
2340 * the portion of the given page's "wire_count" that is not the
2341 * responsibility of this copy-on-write mechanism.
2342 *
2343 * The object containing the given page must have a non-zero
2344 * paging-in-progress count and be locked.
2345 */
2346 void
2347 vm_page_cowfault(vm_page_t m)
2348 {
2349 vm_page_t mnew;
2350 vm_object_t object;
2351 vm_pindex_t pindex;
2352
2353 object = m->object;
2354 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
2355 KASSERT(object->paging_in_progress != 0,
2356 ("vm_page_cowfault: object %p's paging-in-progress count is zero.",
2357 object));
2358 pindex = m->pindex;
2359
2360 retry_alloc:
2361 pmap_remove_all(m);
2362 vm_page_remove(m);
2363 mnew = vm_page_alloc(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
2364 if (mnew == NULL) {
2365 vm_page_insert(m, object, pindex);
2366 vm_page_unlock_queues();
2367 VM_OBJECT_UNLOCK(object);
2368 VM_WAIT;
2369 VM_OBJECT_LOCK(object);
2370 if (m == vm_page_lookup(object, pindex)) {
2371 vm_page_lock_queues();
2372 goto retry_alloc;
2373 } else {
2374 /*
2375 * Page disappeared during the wait.
2376 */
2377 vm_page_lock_queues();
2378 return;
2379 }
2380 }
2381
2382 if (m->cow == 0) {
2383 /*
2384 * check to see if we raced with an xmit complete when
2385 * waiting to allocate a page. If so, put things back
2386 * the way they were
2387 */
2388 vm_page_free(mnew);
2389 vm_page_insert(m, object, pindex);
2390 } else { /* clear COW & copy page */
2391 if (!so_zerocp_fullpage)
2392 pmap_copy_page(m, mnew);
2393 mnew->valid = VM_PAGE_BITS_ALL;
2394 vm_page_dirty(mnew);
2395 mnew->wire_count = m->wire_count - m->cow;
2396 m->wire_count = m->cow;
2397 }
2398 }
2399
2400 void
2401 vm_page_cowclear(vm_page_t m)
2402 {
2403
2404 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
2405 if (m->cow) {
2406 m->cow--;
2407 /*
2408 * let vm_fault add back write permission lazily
2409 */
2410 }
2411 /*
2412 * sf_buf_free() will free the page, so we needn't do it here
2413 */
2414 }
2415
2416 int
2417 vm_page_cowsetup(vm_page_t m)
2418 {
2419
2420 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
2421 if (m->cow == USHRT_MAX - 1)
2422 return (EBUSY);
2423 m->cow++;
2424 pmap_remove_write(m);
2425 return (0);
2426 }
2427
2428 #include "opt_ddb.h"
2429 #ifdef DDB
2430 #include <sys/kernel.h>
2431
2432 #include <ddb/ddb.h>
2433
2434 DB_SHOW_COMMAND(page, vm_page_print_page_info)
2435 {
2436 db_printf("cnt.v_free_count: %d\n", cnt.v_free_count);
2437 db_printf("cnt.v_cache_count: %d\n", cnt.v_cache_count);
2438 db_printf("cnt.v_inactive_count: %d\n", cnt.v_inactive_count);
2439 db_printf("cnt.v_active_count: %d\n", cnt.v_active_count);
2440 db_printf("cnt.v_wire_count: %d\n", cnt.v_wire_count);
2441 db_printf("cnt.v_free_reserved: %d\n", cnt.v_free_reserved);
2442 db_printf("cnt.v_free_min: %d\n", cnt.v_free_min);
2443 db_printf("cnt.v_free_target: %d\n", cnt.v_free_target);
2444 db_printf("cnt.v_cache_min: %d\n", cnt.v_cache_min);
2445 db_printf("cnt.v_inactive_target: %d\n", cnt.v_inactive_target);
2446 }
2447
2448 DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info)
2449 {
2450
2451 db_printf("PQ_FREE:");
2452 db_printf(" %d", cnt.v_free_count);
2453 db_printf("\n");
2454
2455 db_printf("PQ_CACHE:");
2456 db_printf(" %d", cnt.v_cache_count);
2457 db_printf("\n");
2458
2459 db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n",
2460 *vm_page_queues[PQ_ACTIVE].cnt,
2461 *vm_page_queues[PQ_INACTIVE].cnt);
2462 }
2463 #endif /* DDB */
Cache object: 545f66869be97b8babf59fe56e1d12e2
|