2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * Copyright (c) 1994 John S. Dyson
6 * Copyright (c) 1994 David Greenman
10 * This code is derived from software contributed to Berkeley by
11 * The Mach Operating System project at Carnegie-Mellon University.
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. All advertising materials mentioning features or use of this software
22 * must display the following acknowledgement:
23 * This product includes software developed by the University of
24 * California, Berkeley and its contributors.
25 * 4. Neither the name of the University nor the names of its contributors
26 * may be used to endorse or promote products derived from this software
27 * without specific prior written permission.
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
41 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94
44 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
45 * All rights reserved.
47 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
49 * Permission to use, copy, modify and distribute this software and
50 * its documentation is hereby granted, provided that both the copyright
51 * notice and this permission notice appear in all copies of the
52 * software, derivative works or modified versions, and any portions
53 * thereof, and that both notices appear in supporting documentation.
55 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
56 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
57 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
59 * Carnegie Mellon requests users of this software to return to
61 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
62 * School of Computer Science
63 * Carnegie Mellon University
64 * Pittsburgh PA 15213-3890
66 * any improvements or extensions that they make and grant Carnegie the
67 * rights to redistribute these changes.
71 * Page fault handling module.
74 #include <sys/cdefs.h>
75 __FBSDID("$FreeBSD$");
77 #include "opt_ktrace.h"
80 #include <sys/param.h>
81 #include <sys/systm.h>
82 #include <sys/kernel.h>
84 #include <sys/mutex.h>
86 #include <sys/resourcevar.h>
87 #include <sys/sysctl.h>
88 #include <sys/vmmeter.h>
89 #include <sys/vnode.h>
91 #include <sys/ktrace.h>
95 #include <vm/vm_param.h>
97 #include <vm/vm_map.h>
98 #include <vm/vm_object.h>
99 #include <vm/vm_page.h>
100 #include <vm/vm_pageout.h>
101 #include <vm/vm_kern.h>
102 #include <vm/vm_pager.h>
103 #include <vm/vm_extern.h>
105 #include <sys/mount.h> /* XXX Temporary for VFS_LOCK_GIANT() */
109 #define PAGEORDER_SIZE (PFBAK+PFFOR)
111 static int prefault_pageorder[] = {
112 -1 * PAGE_SIZE, 1 * PAGE_SIZE,
113 -2 * PAGE_SIZE, 2 * PAGE_SIZE,
114 -3 * PAGE_SIZE, 3 * PAGE_SIZE,
115 -4 * PAGE_SIZE, 4 * PAGE_SIZE
118 static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *);
119 static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t);
121 #define VM_FAULT_READ_BEHIND 8
122 #define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX)
123 #define VM_FAULT_NINCR (VM_FAULT_READ_MAX / VM_FAULT_READ_BEHIND)
124 #define VM_FAULT_SUM (VM_FAULT_NINCR * (VM_FAULT_NINCR + 1) / 2)
125 #define VM_FAULT_CACHE_BEHIND (VM_FAULT_READ_BEHIND * VM_FAULT_SUM)
132 vm_object_t first_object;
133 vm_pindex_t first_pindex;
135 vm_map_entry_t entry;
136 int lookup_still_valid;
141 static void vm_fault_cache_behind(const struct faultstate *fs, int distance);
144 release_page(struct faultstate *fs)
147 vm_page_wakeup(fs->m);
149 vm_page_deactivate(fs->m);
150 vm_page_unlock(fs->m);
155 unlock_map(struct faultstate *fs)
158 if (fs->lookup_still_valid) {
159 vm_map_lookup_done(fs->map, fs->entry);
160 fs->lookup_still_valid = FALSE;
165 unlock_and_deallocate(struct faultstate *fs)
168 vm_object_pip_wakeup(fs->object);
169 VM_OBJECT_UNLOCK(fs->object);
170 if (fs->object != fs->first_object) {
171 VM_OBJECT_LOCK(fs->first_object);
172 vm_page_lock(fs->first_m);
173 vm_page_free(fs->first_m);
174 vm_page_unlock(fs->first_m);
175 vm_object_pip_wakeup(fs->first_object);
176 VM_OBJECT_UNLOCK(fs->first_object);
179 vm_object_deallocate(fs->first_object);
181 if (fs->vp != NULL) {
185 VFS_UNLOCK_GIANT(fs->vfslocked);
190 * TRYPAGER - used by vm_fault to calculate whether the pager for the
191 * current object *might* contain the page.
193 * default objects are zero-fill, there is no real pager.
195 #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \
196 ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 || wired))
201 * Handle a page fault occurring at the given address,
202 * requiring the given permissions, in the map specified.
203 * If successful, the page is inserted into the
204 * associated physical map.
206 * NOTE: the given address should be truncated to the
207 * proper page address.
209 * KERN_SUCCESS is returned if the page fault is handled; otherwise,
210 * a standard error specifying why the fault is fatal is returned.
212 * The map in question must be referenced, and remains so.
213 * Caller may hold no locks.
216 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
223 if ((td->td_pflags & TDP_NOFAULTING) != 0)
224 return (KERN_PROTECTION_FAILURE);
226 if (map != kernel_map && KTRPOINT(td, KTR_FAULT))
227 ktrfault(vaddr, fault_type);
229 result = vm_fault_hold(map, trunc_page(vaddr), fault_type, fault_flags,
232 if (map != kernel_map && KTRPOINT(td, KTR_FAULTEND))
239 vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
240 int fault_flags, vm_page_t *m_hold)
244 int alloc_req, era, faultcount, nera, reqpage, result;
245 boolean_t growstack, is_first_object_locked, wired;
247 vm_object_t next_object;
248 vm_page_t marray[VM_FAULT_READ_MAX];
250 struct faultstate fs;
256 PCPU_INC(cnt.v_vm_faults);
259 faultcount = reqpage = 0;
264 * Find the backing store object and offset into it to begin the
268 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry,
269 &fs.first_object, &fs.first_pindex, &prot, &wired);
270 if (result != KERN_SUCCESS) {
271 if (growstack && result == KERN_INVALID_ADDRESS &&
273 result = vm_map_growstack(curproc, vaddr);
274 if (result != KERN_SUCCESS)
275 return (KERN_FAILURE);
282 map_generation = fs.map->timestamp;
284 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
285 if ((curthread->td_pflags & TDP_DEVMEMIO) != 0) {
286 vm_map_unlock_read(fs.map);
287 return (KERN_FAILURE);
289 panic("vm_fault: fault on nofault entry, addr: %lx",
293 if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION &&
294 fs.entry->wiring_thread != curthread) {
295 vm_map_unlock_read(fs.map);
297 if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) &&
298 (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) {
303 fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP;
304 vm_map_unlock_and_wait(fs.map, 0);
306 vm_map_unlock(fs.map);
311 * Make a reference to this object to prevent its disposal while we
312 * are messing with it. Once we have the reference, the map is free
313 * to be diddled. Since objects reference their shadows (and copies),
314 * they will stay around as well.
316 * Bump the paging-in-progress count to prevent size changes (e.g.
317 * truncation operations) during I/O. This must be done after
318 * obtaining the vnode lock in order to avoid possible deadlocks.
320 VM_OBJECT_LOCK(fs.first_object);
321 vm_object_reference_locked(fs.first_object);
322 vm_object_pip_add(fs.first_object, 1);
324 fs.lookup_still_valid = TRUE;
327 fault_type = prot | (fault_type & VM_PROT_COPY);
332 * Search for the page at object/offset.
334 fs.object = fs.first_object;
335 fs.pindex = fs.first_pindex;
338 * If the object is dead, we stop here
340 if (fs.object->flags & OBJ_DEAD) {
341 unlock_and_deallocate(&fs);
342 return (KERN_PROTECTION_FAILURE);
346 * See if page is resident
348 fs.m = vm_page_lookup(fs.object, fs.pindex);
351 * check for page-based copy on write.
352 * We check fs.object == fs.first_object so
353 * as to ensure the legacy COW mechanism is
354 * used when the page in question is part of
355 * a shadow object. Otherwise, vm_page_cowfault()
356 * removes the page from the backing object,
357 * which is not what we want.
361 (fault_type & VM_PROT_WRITE) &&
362 (fs.object == fs.first_object)) {
363 vm_page_cowfault(fs.m);
364 unlock_and_deallocate(&fs);
369 * Wait/Retry if the page is busy. We have to do this
370 * if the page is busy via either VPO_BUSY or
371 * vm_page_t->busy because the vm_pager may be using
372 * vm_page_t->busy for pageouts ( and even pageins if
373 * it is the vnode pager ), and we could end up trying
374 * to pagein and pageout the same page simultaneously.
376 * We can theoretically allow the busy case on a read
377 * fault if the page is marked valid, but since such
378 * pages are typically already pmap'd, putting that
379 * special case in might be more effort then it is
380 * worth. We cannot under any circumstances mess
381 * around with a vm_page_t->busy page except, perhaps,
384 if ((fs.m->oflags & VPO_BUSY) || fs.m->busy) {
386 * Reference the page before unlocking and
387 * sleeping so that the page daemon is less
388 * likely to reclaim it.
390 vm_page_aflag_set(fs.m, PGA_REFERENCED);
391 vm_page_unlock(fs.m);
392 if (fs.object != fs.first_object) {
393 if (!VM_OBJECT_TRYLOCK(
395 VM_OBJECT_UNLOCK(fs.object);
396 VM_OBJECT_LOCK(fs.first_object);
397 VM_OBJECT_LOCK(fs.object);
399 vm_page_lock(fs.first_m);
400 vm_page_free(fs.first_m);
401 vm_page_unlock(fs.first_m);
402 vm_object_pip_wakeup(fs.first_object);
403 VM_OBJECT_UNLOCK(fs.first_object);
407 if (fs.m == vm_page_lookup(fs.object,
409 vm_page_sleep_if_busy(fs.m, TRUE,
412 vm_object_pip_wakeup(fs.object);
413 VM_OBJECT_UNLOCK(fs.object);
414 PCPU_INC(cnt.v_intrans);
415 vm_object_deallocate(fs.first_object);
418 vm_pageq_remove(fs.m);
419 vm_page_unlock(fs.m);
422 * Mark page busy for other processes, and the
423 * pagedaemon. If it still isn't completely valid
424 * (readable), jump to readrest, else break-out ( we
428 if (fs.m->valid != VM_PAGE_BITS_ALL)
434 * Page is not resident, If this is the search termination
435 * or the pager might contain the page, allocate a new page.
437 if (TRYPAGER || fs.object == fs.first_object) {
438 if (fs.pindex >= fs.object->size) {
439 unlock_and_deallocate(&fs);
440 return (KERN_PROTECTION_FAILURE);
444 * Allocate a new page for this object/offset pair.
446 * Unlocked read of the p_flag is harmless. At
447 * worst, the P_KILLED might be not observed
448 * there, and allocation can fail, causing
449 * restart and new reading of the p_flag.
452 if (!vm_page_count_severe() || P_KILLED(curproc)) {
453 #if VM_NRESERVLEVEL > 0
454 if ((fs.object->flags & OBJ_COLORED) == 0) {
455 fs.object->flags |= OBJ_COLORED;
456 fs.object->pg_color = atop(vaddr) -
460 alloc_req = P_KILLED(curproc) ?
461 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL;
462 if (fs.object->type != OBJT_VNODE &&
463 fs.object->backing_object == NULL)
464 alloc_req |= VM_ALLOC_ZERO;
465 fs.m = vm_page_alloc(fs.object, fs.pindex,
469 unlock_and_deallocate(&fs);
472 } else if (fs.m->valid == VM_PAGE_BITS_ALL)
478 * We have found a valid page or we have allocated a new page.
479 * The page thus may not be valid or may not be entirely
482 * Attempt to fault-in the page if there is a chance that the
483 * pager has it, and potentially fault in additional pages
488 u_char behavior = vm_map_entry_behavior(fs.entry);
490 if (behavior == MAP_ENTRY_BEHAV_RANDOM ||
494 } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) {
496 ahead = atop(fs.entry->end - vaddr) - 1;
497 if (ahead > VM_FAULT_READ_AHEAD_MAX)
498 ahead = VM_FAULT_READ_AHEAD_MAX;
499 if (fs.pindex == fs.entry->next_read)
500 vm_fault_cache_behind(&fs,
504 * If this is a sequential page fault, then
505 * arithmetically increase the number of pages
506 * in the read-ahead window. Otherwise, reset
507 * the read-ahead window to its smallest size.
509 behind = atop(vaddr - fs.entry->start);
510 if (behind > VM_FAULT_READ_BEHIND)
511 behind = VM_FAULT_READ_BEHIND;
512 ahead = atop(fs.entry->end - vaddr) - 1;
513 era = fs.entry->read_ahead;
514 if (fs.pindex == fs.entry->next_read) {
516 if (nera > VM_FAULT_READ_AHEAD_MAX)
517 nera = VM_FAULT_READ_AHEAD_MAX;
521 if (era == VM_FAULT_READ_AHEAD_MAX)
522 vm_fault_cache_behind(&fs,
523 VM_FAULT_CACHE_BEHIND);
524 } else if (ahead > VM_FAULT_READ_AHEAD_MIN)
525 ahead = VM_FAULT_READ_AHEAD_MIN;
527 fs.entry->read_ahead = ahead;
531 * Call the pager to retrieve the data, if any, after
532 * releasing the lock on the map. We hold a ref on
533 * fs.object and the pages are VPO_BUSY'd.
538 if (fs.object->type == OBJT_VNODE) {
539 vp = fs.object->handle;
542 else if (fs.vp != NULL) {
546 locked = VOP_ISLOCKED(vp);
548 if (VFS_NEEDSGIANT(vp->v_mount) && !fs.vfslocked) {
550 if (!mtx_trylock(&Giant)) {
551 VM_OBJECT_UNLOCK(fs.object);
553 VM_OBJECT_LOCK(fs.object);
557 if (locked != LK_EXCLUSIVE)
559 /* Do not sleep for vnode lock while fs.m is busy */
560 error = vget(vp, locked | LK_CANRECURSE |
561 LK_NOWAIT, curthread);
565 vfslocked = fs.vfslocked;
566 fs.vfslocked = 0; /* Keep Giant */
569 unlock_and_deallocate(&fs);
570 error = vget(vp, locked | LK_RETRY |
571 LK_CANRECURSE, curthread);
574 fs.vfslocked = vfslocked;
576 ("vm_fault: vget failed"));
582 KASSERT(fs.vp == NULL || !fs.map->system_map,
583 ("vm_fault: vnode-backed object mapped by system map"));
586 * now we find out if any other pages should be paged
587 * in at this time this routine checks to see if the
588 * pages surrounding this fault reside in the same
589 * object as the page for this fault. If they do,
590 * then they are faulted in also into the object. The
591 * array "marray" returned contains an array of
592 * vm_page_t structs where one of them is the
593 * vm_page_t passed to the routine. The reqpage
594 * return value is the index into the marray for the
595 * vm_page_t passed to the routine.
597 * fs.m plus the additional pages are VPO_BUSY'd.
599 faultcount = vm_fault_additional_pages(
600 fs.m, behind, ahead, marray, &reqpage);
603 vm_pager_get_pages(fs.object, marray, faultcount,
604 reqpage) : VM_PAGER_FAIL;
606 if (rv == VM_PAGER_OK) {
608 * Found the page. Leave it busy while we play
613 * Relookup in case pager changed page. Pager
614 * is responsible for disposition of old page
617 fs.m = vm_page_lookup(fs.object, fs.pindex);
619 unlock_and_deallocate(&fs);
624 break; /* break to PAGE HAS BEEN FOUND */
627 * Remove the bogus page (which does not exist at this
628 * object/offset); before doing so, we must get back
629 * our object lock to preserve our invariant.
631 * Also wake up any other process that may want to bring
634 * If this is the top-level object, we must leave the
635 * busy page to prevent another process from rushing
636 * past us, and inserting the page in that object at
637 * the same time that we are.
639 if (rv == VM_PAGER_ERROR)
640 printf("vm_fault: pager read error, pid %d (%s)\n",
641 curproc->p_pid, curproc->p_comm);
643 * Data outside the range of the pager or an I/O error
646 * XXX - the check for kernel_map is a kludge to work
647 * around having the machine panic on a kernel space
648 * fault w/ I/O error.
650 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) ||
651 (rv == VM_PAGER_BAD)) {
654 vm_page_unlock(fs.m);
656 unlock_and_deallocate(&fs);
657 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE);
659 if (fs.object != fs.first_object) {
662 vm_page_unlock(fs.m);
665 * XXX - we cannot just fall out at this
666 * point, m has been freed and is invalid!
672 * We get here if the object has default pager (or unwiring)
673 * or the pager doesn't have the page.
675 if (fs.object == fs.first_object)
679 * Move on to the next object. Lock the next object before
680 * unlocking the current one.
682 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset);
683 next_object = fs.object->backing_object;
684 if (next_object == NULL) {
686 * If there's no object left, fill the page in the top
689 if (fs.object != fs.first_object) {
690 vm_object_pip_wakeup(fs.object);
691 VM_OBJECT_UNLOCK(fs.object);
693 fs.object = fs.first_object;
694 fs.pindex = fs.first_pindex;
696 VM_OBJECT_LOCK(fs.object);
701 * Zero the page if necessary and mark it valid.
703 if ((fs.m->flags & PG_ZERO) == 0) {
704 pmap_zero_page(fs.m);
706 PCPU_INC(cnt.v_ozfod);
708 PCPU_INC(cnt.v_zfod);
709 fs.m->valid = VM_PAGE_BITS_ALL;
710 break; /* break to PAGE HAS BEEN FOUND */
712 KASSERT(fs.object != next_object,
713 ("object loop %p", next_object));
714 VM_OBJECT_LOCK(next_object);
715 vm_object_pip_add(next_object, 1);
716 if (fs.object != fs.first_object)
717 vm_object_pip_wakeup(fs.object);
718 VM_OBJECT_UNLOCK(fs.object);
719 fs.object = next_object;
723 KASSERT((fs.m->oflags & VPO_BUSY) != 0,
724 ("vm_fault: not busy after main loop"));
727 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
732 * If the page is being written, but isn't already owned by the
733 * top-level object, we have to copy it into a new page owned by the
736 if (fs.object != fs.first_object) {
738 * We only really need to copy if we want to write it.
740 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) {
742 * This allows pages to be virtually copied from a
743 * backing_object into the first_object, where the
744 * backing object has no other refs to it, and cannot
745 * gain any more refs. Instead of a bcopy, we just
746 * move the page from the backing object to the
747 * first object. Note that we must mark the page
748 * dirty in the first object so that it will go out
749 * to swap when needed.
751 is_first_object_locked = FALSE;
754 * Only one shadow object
756 (fs.object->shadow_count == 1) &&
758 * No COW refs, except us
760 (fs.object->ref_count == 1) &&
762 * No one else can look this object up
764 (fs.object->handle == NULL) &&
766 * No other ways to look the object up
768 ((fs.object->type == OBJT_DEFAULT) ||
769 (fs.object->type == OBJT_SWAP)) &&
770 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) &&
772 * We don't chase down the shadow chain
774 fs.object == fs.first_object->backing_object) {
776 * get rid of the unnecessary page
778 vm_page_lock(fs.first_m);
779 vm_page_free(fs.first_m);
780 vm_page_unlock(fs.first_m);
782 * grab the page and put it into the
783 * process'es object. The page is
784 * automatically made dirty.
787 vm_page_rename(fs.m, fs.first_object, fs.first_pindex);
788 vm_page_unlock(fs.m);
792 PCPU_INC(cnt.v_cow_optim);
795 * Oh, well, lets copy it.
797 pmap_copy_page(fs.m, fs.first_m);
798 fs.first_m->valid = VM_PAGE_BITS_ALL;
799 if (wired && (fault_flags &
800 VM_FAULT_CHANGE_WIRING) == 0) {
801 vm_page_lock(fs.first_m);
802 vm_page_wire(fs.first_m);
803 vm_page_unlock(fs.first_m);
806 vm_page_unwire(fs.m, FALSE);
807 vm_page_unlock(fs.m);
810 * We no longer need the old page or object.
815 * fs.object != fs.first_object due to above
818 vm_object_pip_wakeup(fs.object);
819 VM_OBJECT_UNLOCK(fs.object);
821 * Only use the new page below...
823 fs.object = fs.first_object;
824 fs.pindex = fs.first_pindex;
826 if (!is_first_object_locked)
827 VM_OBJECT_LOCK(fs.object);
828 PCPU_INC(cnt.v_cow_faults);
831 prot &= ~VM_PROT_WRITE;
836 * We must verify that the maps have not changed since our last
839 if (!fs.lookup_still_valid) {
840 vm_object_t retry_object;
841 vm_pindex_t retry_pindex;
842 vm_prot_t retry_prot;
844 if (!vm_map_trylock_read(fs.map)) {
846 unlock_and_deallocate(&fs);
849 fs.lookup_still_valid = TRUE;
850 if (fs.map->timestamp != map_generation) {
851 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type,
852 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired);
855 * If we don't need the page any longer, put it on the inactive
856 * list (the easiest thing to do here). If no one needs it,
857 * pageout will grab it eventually.
859 if (result != KERN_SUCCESS) {
861 unlock_and_deallocate(&fs);
864 * If retry of map lookup would have blocked then
865 * retry fault from start.
867 if (result == KERN_FAILURE)
871 if ((retry_object != fs.first_object) ||
872 (retry_pindex != fs.first_pindex)) {
874 unlock_and_deallocate(&fs);
879 * Check whether the protection has changed or the object has
880 * been copied while we left the map unlocked. Changing from
881 * read to write permission is OK - we leave the page
882 * write-protected, and catch the write fault. Changing from
883 * write to read permission means that we can't mark the page
884 * write-enabled after all.
890 * If the page was filled by a pager, update the map entry's
891 * last read offset. Since the pager does not return the
892 * actual set of pages that it read, this update is based on
893 * the requested set. Typically, the requested and actual
896 * XXX The following assignment modifies the map
897 * without holding a write lock on it.
900 fs.entry->next_read = fs.pindex + faultcount - reqpage;
902 if ((prot & VM_PROT_WRITE) != 0 ||
903 (fault_flags & VM_FAULT_DIRTY) != 0) {
904 vm_object_set_writeable_dirty(fs.object);
907 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC
908 * if the page is already dirty to prevent data written with
909 * the expectation of being synced from not being synced.
910 * Likewise if this entry does not request NOSYNC then make
911 * sure the page isn't marked NOSYNC. Applications sharing
912 * data should use the same flags to avoid ping ponging.
914 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) {
915 if (fs.m->dirty == 0)
916 fs.m->oflags |= VPO_NOSYNC;
918 fs.m->oflags &= ~VPO_NOSYNC;
922 * If the fault is a write, we know that this page is being
923 * written NOW so dirty it explicitly to save on
924 * pmap_is_modified() calls later.
926 * Also tell the backing pager, if any, that it should remove
927 * any swap backing since the page is now dirty.
929 if (((fault_type & VM_PROT_WRITE) != 0 &&
930 (fault_flags & VM_FAULT_CHANGE_WIRING) == 0) ||
931 (fault_flags & VM_FAULT_DIRTY) != 0) {
933 vm_pager_page_unswapped(fs.m);
938 * Page had better still be busy
940 KASSERT(fs.m->oflags & VPO_BUSY,
941 ("vm_fault: page %p not busy!", fs.m));
943 * Page must be completely valid or it is not fit to
944 * map into user space. vm_pager_get_pages() ensures this.
946 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL,
947 ("vm_fault: page %p partially invalid", fs.m));
948 VM_OBJECT_UNLOCK(fs.object);
951 * Put this page into the physical map. We had to do the unlock above
952 * because pmap_enter() may sleep. We don't put the page
953 * back on the active queue until later so that the pageout daemon
954 * won't find it (yet).
956 pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired);
957 if ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && wired == 0)
958 vm_fault_prefault(fs.map->pmap, vaddr, fs.entry);
959 VM_OBJECT_LOCK(fs.object);
963 * If the page is not wired down, then put it where the pageout daemon
966 if (fault_flags & VM_FAULT_CHANGE_WIRING) {
970 vm_page_unwire(fs.m, 1);
972 vm_page_activate(fs.m);
973 if (m_hold != NULL) {
977 vm_page_unlock(fs.m);
978 vm_page_wakeup(fs.m);
981 * Unlock everything, and return
983 unlock_and_deallocate(&fs);
985 curthread->td_ru.ru_majflt++;
987 curthread->td_ru.ru_minflt++;
989 return (KERN_SUCCESS);
993 * Speed up the reclamation of up to "distance" pages that precede the
994 * faulting pindex within the first object of the shadow chain.
997 vm_fault_cache_behind(const struct faultstate *fs, int distance)
999 vm_object_t first_object, object;
1000 vm_page_t m, m_prev;
1003 object = fs->object;
1004 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1005 first_object = fs->first_object;
1006 if (first_object != object) {
1007 if (!VM_OBJECT_TRYLOCK(first_object)) {
1008 VM_OBJECT_UNLOCK(object);
1009 VM_OBJECT_LOCK(first_object);
1010 VM_OBJECT_LOCK(object);
1013 if (first_object->type != OBJT_DEVICE &&
1014 first_object->type != OBJT_PHYS && first_object->type != OBJT_SG) {
1015 if (fs->first_pindex < distance)
1018 pindex = fs->first_pindex - distance;
1019 if (pindex < OFF_TO_IDX(fs->entry->offset))
1020 pindex = OFF_TO_IDX(fs->entry->offset);
1021 m = first_object != object ? fs->first_m : fs->m;
1022 KASSERT((m->oflags & VPO_BUSY) != 0,
1023 ("vm_fault_cache_behind: page %p is not busy", m));
1024 m_prev = vm_page_prev(m);
1025 while ((m = m_prev) != NULL && m->pindex >= pindex &&
1026 m->valid == VM_PAGE_BITS_ALL) {
1027 m_prev = vm_page_prev(m);
1028 if (m->busy != 0 || (m->oflags & VPO_BUSY) != 0)
1031 if (m->hold_count == 0 && m->wire_count == 0) {
1033 vm_page_aflag_clear(m, PGA_REFERENCED);
1035 vm_page_deactivate(m);
1042 if (first_object != object)
1043 VM_OBJECT_UNLOCK(first_object);
1047 * vm_fault_prefault provides a quick way of clustering
1048 * pagefaults into a processes address space. It is a "cousin"
1049 * of vm_map_pmap_enter, except it runs at page fault time instead
1053 vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry)
1056 vm_offset_t addr, starta;
1061 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace))
1064 object = entry->object.vm_object;
1066 starta = addra - PFBAK * PAGE_SIZE;
1067 if (starta < entry->start) {
1068 starta = entry->start;
1069 } else if (starta > addra) {
1073 for (i = 0; i < PAGEORDER_SIZE; i++) {
1074 vm_object_t backing_object, lobject;
1076 addr = addra + prefault_pageorder[i];
1077 if (addr > addra + (PFFOR * PAGE_SIZE))
1080 if (addr < starta || addr >= entry->end)
1083 if (!pmap_is_prefaultable(pmap, addr))
1086 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
1088 VM_OBJECT_LOCK(lobject);
1089 while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
1090 lobject->type == OBJT_DEFAULT &&
1091 (backing_object = lobject->backing_object) != NULL) {
1092 KASSERT((lobject->backing_object_offset & PAGE_MASK) ==
1093 0, ("vm_fault_prefault: unaligned object offset"));
1094 pindex += lobject->backing_object_offset >> PAGE_SHIFT;
1095 VM_OBJECT_LOCK(backing_object);
1096 VM_OBJECT_UNLOCK(lobject);
1097 lobject = backing_object;
1100 * give-up when a page is not in memory
1103 VM_OBJECT_UNLOCK(lobject);
1106 if (m->valid == VM_PAGE_BITS_ALL &&
1107 (m->flags & PG_FICTITIOUS) == 0)
1108 pmap_enter_quick(pmap, addr, m, entry->protection);
1109 VM_OBJECT_UNLOCK(lobject);
1114 * Hold each of the physical pages that are mapped by the specified range of
1115 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid
1116 * and allow the specified types of access, "prot". If all of the implied
1117 * pages are successfully held, then the number of held pages is returned
1118 * together with pointers to those pages in the array "ma". However, if any
1119 * of the pages cannot be held, -1 is returned.
1122 vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
1123 vm_prot_t prot, vm_page_t *ma, int max_count)
1125 vm_offset_t end, va;
1128 boolean_t pmap_failed;
1132 end = round_page(addr + len);
1133 addr = trunc_page(addr);
1136 * Check for illegal addresses.
1138 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map))
1141 if (atop(end - addr) > max_count)
1142 panic("vm_fault_quick_hold_pages: count > max_count");
1143 count = atop(end - addr);
1146 * Most likely, the physical pages are resident in the pmap, so it is
1147 * faster to try pmap_extract_and_hold() first.
1149 pmap_failed = FALSE;
1150 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) {
1151 *mp = pmap_extract_and_hold(map->pmap, va, prot);
1154 else if ((prot & VM_PROT_WRITE) != 0 &&
1155 (*mp)->dirty != VM_PAGE_BITS_ALL) {
1157 * Explicitly dirty the physical page. Otherwise, the
1158 * caller's changes may go unnoticed because they are
1159 * performed through an unmanaged mapping or by a DMA
1162 * The object lock is not held here.
1163 * See vm_page_clear_dirty_mask().
1170 * One or more pages could not be held by the pmap. Either no
1171 * page was mapped at the specified virtual address or that
1172 * mapping had insufficient permissions. Attempt to fault in
1173 * and hold these pages.
1175 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE)
1176 if (*mp == NULL && vm_fault_hold(map, va, prot,
1177 VM_FAULT_NORMAL, mp) != KERN_SUCCESS)
1182 for (mp = ma; mp < ma + count; mp++)
1185 vm_page_unhold(*mp);
1186 vm_page_unlock(*mp);
1194 * Wire down a range of virtual addresses in a map.
1197 vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
1198 boolean_t fictitious)
1204 * We simulate a fault to get the page and enter it in the physical
1205 * map. For user wiring, we only ask for read access on currently
1206 * read-only sections.
1208 for (va = start; va < end; va += PAGE_SIZE) {
1209 rv = vm_fault(map, va, VM_PROT_NONE, VM_FAULT_CHANGE_WIRING);
1212 vm_fault_unwire(map, start, va, fictitious);
1216 return (KERN_SUCCESS);
1222 * Unwire a range of virtual addresses in a map.
1225 vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
1226 boolean_t fictitious)
1233 pmap = vm_map_pmap(map);
1236 * Since the pages are wired down, we must be able to get their
1237 * mappings from the physical map system.
1239 for (va = start; va < end; va += PAGE_SIZE) {
1240 pa = pmap_extract(pmap, va);
1242 pmap_change_wiring(pmap, va, FALSE);
1244 m = PHYS_TO_VM_PAGE(pa);
1246 vm_page_unwire(m, TRUE);
1255 * vm_fault_copy_entry
1257 * Create new shadow object backing dst_entry with private copy of
1258 * all underlying pages. When src_entry is equal to dst_entry,
1259 * function implements COW for wired-down map entry. Otherwise,
1260 * it forks wired entry into dst_map.
1262 * In/out conditions:
1263 * The source and destination maps must be locked for write.
1264 * The source map entry must be wired down (or be a sharing map
1265 * entry corresponding to a main map entry that is wired down).
1268 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
1269 vm_map_entry_t dst_entry, vm_map_entry_t src_entry,
1270 vm_ooffset_t *fork_charge)
1272 vm_object_t backing_object, dst_object, object, src_object;
1273 vm_pindex_t dst_pindex, pindex, src_pindex;
1274 vm_prot_t access, prot;
1284 upgrade = src_entry == dst_entry;
1286 src_object = src_entry->object.vm_object;
1287 src_pindex = OFF_TO_IDX(src_entry->offset);
1290 * Create the top-level object for the destination entry. (Doesn't
1291 * actually shadow anything - we copy the pages directly.)
1293 dst_object = vm_object_allocate(OBJT_DEFAULT,
1294 OFF_TO_IDX(dst_entry->end - dst_entry->start));
1295 #if VM_NRESERVLEVEL > 0
1296 dst_object->flags |= OBJ_COLORED;
1297 dst_object->pg_color = atop(dst_entry->start);
1300 VM_OBJECT_LOCK(dst_object);
1301 KASSERT(upgrade || dst_entry->object.vm_object == NULL,
1302 ("vm_fault_copy_entry: vm_object not NULL"));
1303 dst_entry->object.vm_object = dst_object;
1304 dst_entry->offset = 0;
1305 dst_object->charge = dst_entry->end - dst_entry->start;
1306 if (fork_charge != NULL) {
1307 KASSERT(dst_entry->cred == NULL,
1308 ("vm_fault_copy_entry: leaked swp charge"));
1309 dst_object->cred = curthread->td_ucred;
1310 crhold(dst_object->cred);
1311 *fork_charge += dst_object->charge;
1313 dst_object->cred = dst_entry->cred;
1314 dst_entry->cred = NULL;
1316 access = prot = dst_entry->protection;
1318 * If not an upgrade, then enter the mappings in the pmap as
1319 * read and/or execute accesses. Otherwise, enter them as
1322 * A writeable large page mapping is only created if all of
1323 * the constituent small page mappings are modified. Marking
1324 * PTEs as modified on inception allows promotion to happen
1325 * without taking potentially large number of soft faults.
1328 access &= ~VM_PROT_WRITE;
1331 * Loop through all of the virtual pages within the entry's
1332 * range, copying each page from the source object to the
1333 * destination object. Since the source is wired, those pages
1334 * must exist. In contrast, the destination is pageable.
1335 * Since the destination object does share any backing storage
1336 * with the source object, all of its pages must be dirtied,
1337 * regardless of whether they can be written.
1339 for (vaddr = dst_entry->start, dst_pindex = 0;
1340 vaddr < dst_entry->end;
1341 vaddr += PAGE_SIZE, dst_pindex++) {
1344 * Allocate a page in the destination object.
1347 dst_m = vm_page_alloc(dst_object, dst_pindex,
1349 if (dst_m == NULL) {
1350 VM_OBJECT_UNLOCK(dst_object);
1352 VM_OBJECT_LOCK(dst_object);
1354 } while (dst_m == NULL);
1357 * Find the page in the source object, and copy it in.
1358 * Because the source is wired down, the page will be
1361 VM_OBJECT_LOCK(src_object);
1362 object = src_object;
1363 pindex = src_pindex + dst_pindex;
1364 while ((src_m = vm_page_lookup(object, pindex)) == NULL &&
1365 (backing_object = object->backing_object) != NULL) {
1367 * Unless the source mapping is read-only or
1368 * it is presently being upgraded from
1369 * read-only, the first object in the shadow
1370 * chain should provide all of the pages. In
1371 * other words, this loop body should never be
1372 * executed when the source mapping is already
1375 KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 ||
1377 ("vm_fault_copy_entry: main object missing page"));
1379 VM_OBJECT_LOCK(backing_object);
1380 pindex += OFF_TO_IDX(object->backing_object_offset);
1381 VM_OBJECT_UNLOCK(object);
1382 object = backing_object;
1384 KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing"));
1385 pmap_copy_page(src_m, dst_m);
1386 VM_OBJECT_UNLOCK(object);
1387 dst_m->valid = VM_PAGE_BITS_ALL;
1388 dst_m->dirty = VM_PAGE_BITS_ALL;
1389 VM_OBJECT_UNLOCK(dst_object);
1392 * Enter it in the pmap. If a wired, copy-on-write
1393 * mapping is being replaced by a write-enabled
1394 * mapping, then wire that new mapping.
1396 pmap_enter(dst_map->pmap, vaddr, access, dst_m, prot, upgrade);
1399 * Mark it no longer busy, and put it on the active list.
1401 VM_OBJECT_LOCK(dst_object);
1404 vm_page_lock(src_m);
1405 vm_page_unwire(src_m, 0);
1406 vm_page_unlock(src_m);
1408 vm_page_lock(dst_m);
1409 vm_page_wire(dst_m);
1410 vm_page_unlock(dst_m);
1412 vm_page_lock(dst_m);
1413 vm_page_activate(dst_m);
1414 vm_page_unlock(dst_m);
1416 vm_page_wakeup(dst_m);
1418 VM_OBJECT_UNLOCK(dst_object);
1420 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY);
1421 vm_object_deallocate(src_object);
1427 * This routine checks around the requested page for other pages that
1428 * might be able to be faulted in. This routine brackets the viable
1429 * pages for the pages to be paged in.
1432 * m, rbehind, rahead
1435 * marray (array of vm_page_t), reqpage (index of requested page)
1438 * number of pages in marray
1441 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage)
1450 vm_pindex_t pindex, startpindex, endpindex, tpindex;
1452 int cbehind, cahead;
1454 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
1458 cbehind = cahead = 0;
1461 * if the requested page is not available, then give up now
1463 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) {
1467 if ((cbehind == 0) && (cahead == 0)) {
1473 if (rahead > cahead) {
1477 if (rbehind > cbehind) {
1482 * scan backward for the read behind pages -- in memory
1485 if (rbehind > pindex) {
1489 startpindex = pindex - rbehind;
1492 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL &&
1493 rtm->pindex >= startpindex)
1494 startpindex = rtm->pindex + 1;
1496 /* tpindex is unsigned; beware of numeric underflow. */
1497 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex &&
1498 tpindex < pindex; i++, tpindex--) {
1500 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL |
1501 VM_ALLOC_IFNOTCACHED);
1504 * Shift the allocated pages to the
1505 * beginning of the array.
1507 for (j = 0; j < i; j++) {
1508 marray[j] = marray[j + tpindex + 1 -
1514 marray[tpindex - startpindex] = rtm;
1522 /* page offset of the required page */
1525 tpindex = pindex + 1;
1529 * scan forward for the read ahead pages
1531 endpindex = tpindex + rahead;
1532 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex)
1533 endpindex = rtm->pindex;
1534 if (endpindex > object->size)
1535 endpindex = object->size;
1537 for (; tpindex < endpindex; i++, tpindex++) {
1539 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL |
1540 VM_ALLOC_IFNOTCACHED);
1548 /* return number of pages */
1553 * Block entry into the machine-independent layer's page fault handler by
1554 * the calling thread. Subsequent calls to vm_fault() by that thread will
1555 * return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of
1556 * spurious page faults.
1559 vm_fault_disable_pagefaults(void)
1562 return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR));
1566 vm_fault_enable_pagefaults(int save)
1569 curthread_pflags_restore(save);