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 <sys/param.h>
78 #include <sys/systm.h>
79 #include <sys/kernel.h>
81 #include <sys/mutex.h>
83 #include <sys/resourcevar.h>
84 #include <sys/sysctl.h>
85 #include <sys/vmmeter.h>
86 #include <sys/vnode.h>
89 #include <vm/vm_param.h>
91 #include <vm/vm_map.h>
92 #include <vm/vm_object.h>
93 #include <vm/vm_page.h>
94 #include <vm/vm_pageout.h>
95 #include <vm/vm_kern.h>
96 #include <vm/vm_pager.h>
97 #include <vm/vnode_pager.h>
98 #include <vm/vm_extern.h>
100 #include <sys/mount.h> /* XXX Temporary for VFS_LOCK_GIANT() */
104 #define PAGEORDER_SIZE (PFBAK+PFFOR)
106 static int prefault_pageorder[] = {
107 -1 * PAGE_SIZE, 1 * PAGE_SIZE,
108 -2 * PAGE_SIZE, 2 * PAGE_SIZE,
109 -3 * PAGE_SIZE, 3 * PAGE_SIZE,
110 -4 * PAGE_SIZE, 4 * PAGE_SIZE
113 static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *);
114 static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t);
116 #define VM_FAULT_READ_AHEAD 8
117 #define VM_FAULT_READ_BEHIND 7
118 #define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1)
125 vm_object_t first_object;
126 vm_pindex_t first_pindex;
128 vm_map_entry_t entry;
129 int lookup_still_valid;
134 release_page(struct faultstate *fs)
136 vm_page_lock_queues();
137 vm_page_wakeup(fs->m);
138 vm_page_deactivate(fs->m);
139 vm_page_unlock_queues();
144 unlock_map(struct faultstate *fs)
146 if (fs->lookup_still_valid) {
147 vm_map_lookup_done(fs->map, fs->entry);
148 fs->lookup_still_valid = FALSE;
153 unlock_and_deallocate(struct faultstate *fs)
156 vm_object_pip_wakeup(fs->object);
157 VM_OBJECT_UNLOCK(fs->object);
158 if (fs->object != fs->first_object) {
159 VM_OBJECT_LOCK(fs->first_object);
160 vm_page_lock_queues();
161 vm_page_free(fs->first_m);
162 vm_page_unlock_queues();
163 vm_object_pip_wakeup(fs->first_object);
164 VM_OBJECT_UNLOCK(fs->first_object);
167 vm_object_deallocate(fs->first_object);
169 if (fs->vp != NULL) {
172 vfslocked = VFS_LOCK_GIANT(fs->vp->v_mount);
175 VFS_UNLOCK_GIANT(vfslocked);
180 * TRYPAGER - used by vm_fault to calculate whether the pager for the
181 * current object *might* contain the page.
183 * default objects are zero-fill, there is no real pager.
185 #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \
186 (((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired))
191 * Handle a page fault occurring at the given address,
192 * requiring the given permissions, in the map specified.
193 * If successful, the page is inserted into the
194 * associated physical map.
196 * NOTE: the given address should be truncated to the
197 * proper page address.
199 * KERN_SUCCESS is returned if the page fault is handled; otherwise,
200 * a standard error specifying why the fault is fatal is returned.
203 * The map in question must be referenced, and remains so.
204 * Caller may hold no locks.
207 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
211 int is_first_object_locked, result;
212 boolean_t growstack, wired;
214 vm_object_t next_object;
215 vm_page_t marray[VM_FAULT_READ];
218 struct faultstate fs;
222 atomic_add_int(&cnt.v_vm_faults, 1);
227 * Find the backing store object and offset into it to begin the
231 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry,
232 &fs.first_object, &fs.first_pindex, &prot, &wired);
233 if (result != KERN_SUCCESS) {
234 if (result != KERN_PROTECTION_FAILURE ||
235 (fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE) {
236 if (growstack && result == KERN_INVALID_ADDRESS &&
237 map != kernel_map && curproc != NULL) {
238 result = vm_map_growstack(curproc, vaddr);
239 if (result != KERN_SUCCESS)
240 return (KERN_FAILURE);
248 * If we are user-wiring a r/w segment, and it is COW, then
249 * we need to do the COW operation. Note that we don't COW
250 * currently RO sections now, because it is NOT desirable
251 * to COW .text. We simply keep .text from ever being COW'ed
252 * and take the heat that one cannot debug wired .text sections.
254 result = vm_map_lookup(&fs.map, vaddr,
255 VM_PROT_READ|VM_PROT_WRITE|VM_PROT_OVERRIDE_WRITE,
256 &fs.entry, &fs.first_object, &fs.first_pindex, &prot, &wired);
257 if (result != KERN_SUCCESS)
261 * If we don't COW now, on a user wire, the user will never
262 * be able to write to the mapping. If we don't make this
263 * restriction, the bookkeeping would be nearly impossible.
265 * XXX The following assignment modifies the map without
266 * holding a write lock on it.
268 if ((fs.entry->protection & VM_PROT_WRITE) == 0)
269 fs.entry->max_protection &= ~VM_PROT_WRITE;
272 map_generation = fs.map->timestamp;
274 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
275 panic("vm_fault: fault on nofault entry, addr: %lx",
280 * Make a reference to this object to prevent its disposal while we
281 * are messing with it. Once we have the reference, the map is free
282 * to be diddled. Since objects reference their shadows (and copies),
283 * they will stay around as well.
285 * Bump the paging-in-progress count to prevent size changes (e.g.
286 * truncation operations) during I/O. This must be done after
287 * obtaining the vnode lock in order to avoid possible deadlocks.
289 * XXX vnode_pager_lock() can block without releasing the map lock.
291 if (fs.first_object->flags & OBJ_NEEDGIANT)
293 VM_OBJECT_LOCK(fs.first_object);
294 vm_object_reference_locked(fs.first_object);
295 fs.vp = vnode_pager_lock(fs.first_object);
296 KASSERT(fs.vp == NULL || !fs.map->system_map,
297 ("vm_fault: vnode-backed object mapped by system map"));
298 KASSERT((fs.first_object->flags & OBJ_NEEDGIANT) == 0 ||
300 ("vm_fault: Object requiring giant mapped by system map"));
301 if (fs.first_object->flags & OBJ_NEEDGIANT)
303 vm_object_pip_add(fs.first_object, 1);
305 fs.lookup_still_valid = TRUE;
313 * Search for the page at object/offset.
315 fs.object = fs.first_object;
316 fs.pindex = fs.first_pindex;
319 * If the object is dead, we stop here
321 if (fs.object->flags & OBJ_DEAD) {
322 unlock_and_deallocate(&fs);
323 return (KERN_PROTECTION_FAILURE);
327 * See if page is resident
329 fs.m = vm_page_lookup(fs.object, fs.pindex);
334 * check for page-based copy on write.
335 * We check fs.object == fs.first_object so
336 * as to ensure the legacy COW mechanism is
337 * used when the page in question is part of
338 * a shadow object. Otherwise, vm_page_cowfault()
339 * removes the page from the backing object,
340 * which is not what we want.
342 vm_page_lock_queues();
344 (fault_type & VM_PROT_WRITE) &&
345 (fs.object == fs.first_object)) {
346 vm_page_cowfault(fs.m);
347 vm_page_unlock_queues();
348 unlock_and_deallocate(&fs);
353 * Wait/Retry if the page is busy. We have to do this
354 * if the page is busy via either PG_BUSY or
355 * vm_page_t->busy because the vm_pager may be using
356 * vm_page_t->busy for pageouts ( and even pageins if
357 * it is the vnode pager ), and we could end up trying
358 * to pagein and pageout the same page simultaneously.
360 * We can theoretically allow the busy case on a read
361 * fault if the page is marked valid, but since such
362 * pages are typically already pmap'd, putting that
363 * special case in might be more effort then it is
364 * worth. We cannot under any circumstances mess
365 * around with a vm_page_t->busy page except, perhaps,
368 if ((fs.m->flags & PG_BUSY) || fs.m->busy) {
369 vm_page_unlock_queues();
370 VM_OBJECT_UNLOCK(fs.object);
371 if (fs.object != fs.first_object) {
372 VM_OBJECT_LOCK(fs.first_object);
373 vm_page_lock_queues();
374 vm_page_free(fs.first_m);
375 vm_page_unlock_queues();
376 vm_object_pip_wakeup(fs.first_object);
377 VM_OBJECT_UNLOCK(fs.first_object);
384 vfslck = VFS_LOCK_GIANT(fs.vp->v_mount);
387 VFS_UNLOCK_GIANT(vfslck);
389 VM_OBJECT_LOCK(fs.object);
390 if (fs.m == vm_page_lookup(fs.object,
392 vm_page_sleep_if_busy(fs.m, TRUE,
395 vm_object_pip_wakeup(fs.object);
396 VM_OBJECT_UNLOCK(fs.object);
397 atomic_add_int(&cnt.v_intrans, 1);
398 vm_object_deallocate(fs.first_object);
403 vm_pageq_remove_nowakeup(fs.m);
405 if (VM_PAGE_RESOLVEQUEUE(fs.m, queue) == PQ_CACHE &&
406 vm_page_count_severe()) {
407 vm_page_activate(fs.m);
408 vm_page_unlock_queues();
409 unlock_and_deallocate(&fs);
415 * Mark page busy for other processes, and the
416 * pagedaemon. If it still isn't completely valid
417 * (readable), jump to readrest, else break-out ( we
421 vm_page_unlock_queues();
422 if (((fs.m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) &&
423 fs.m->object != kernel_object && fs.m->object != kmem_object) {
431 * Page is not resident, If this is the search termination
432 * or the pager might contain the page, allocate a new page.
434 if (TRYPAGER || fs.object == fs.first_object) {
435 if (fs.pindex >= fs.object->size) {
436 unlock_and_deallocate(&fs);
437 return (KERN_PROTECTION_FAILURE);
441 * Allocate a new page for this object/offset pair.
444 if (!vm_page_count_severe()) {
445 fs.m = vm_page_alloc(fs.object, fs.pindex,
446 (fs.vp || fs.object->backing_object)? VM_ALLOC_NORMAL: VM_ALLOC_ZERO);
449 unlock_and_deallocate(&fs);
457 * We have found a valid page or we have allocated a new page.
458 * The page thus may not be valid or may not be entirely
461 * Attempt to fault-in the page if there is a chance that the
462 * pager has it, and potentially fault in additional pages
469 u_char behavior = vm_map_entry_behavior(fs.entry);
471 if (behavior == MAP_ENTRY_BEHAV_RANDOM) {
475 behind = (vaddr - fs.entry->start) >> PAGE_SHIFT;
476 if (behind > VM_FAULT_READ_BEHIND)
477 behind = VM_FAULT_READ_BEHIND;
479 ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1;
480 if (ahead > VM_FAULT_READ_AHEAD)
481 ahead = VM_FAULT_READ_AHEAD;
483 is_first_object_locked = FALSE;
484 if ((behavior == MAP_ENTRY_BEHAV_SEQUENTIAL ||
485 (behavior != MAP_ENTRY_BEHAV_RANDOM &&
486 fs.pindex >= fs.entry->lastr &&
487 fs.pindex < fs.entry->lastr + VM_FAULT_READ)) &&
488 (fs.first_object == fs.object ||
489 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object))) &&
490 fs.first_object->type != OBJT_DEVICE) {
491 vm_pindex_t firstpindex, tmppindex;
493 if (fs.first_pindex < 2 * VM_FAULT_READ)
496 firstpindex = fs.first_pindex - 2 * VM_FAULT_READ;
498 vm_page_lock_queues();
500 * note: partially valid pages cannot be
501 * included in the lookahead - NFS piecemeal
502 * writes will barf on it badly.
504 for (tmppindex = fs.first_pindex - 1;
505 tmppindex >= firstpindex;
509 mt = vm_page_lookup(fs.first_object, tmppindex);
510 if (mt == NULL || (mt->valid != VM_PAGE_BITS_ALL))
513 (mt->flags & (PG_BUSY | PG_FICTITIOUS | PG_UNMANAGED)) ||
519 vm_page_deactivate(mt);
524 vm_page_unlock_queues();
528 if (is_first_object_locked)
529 VM_OBJECT_UNLOCK(fs.first_object);
531 * now we find out if any other pages should be paged
532 * in at this time this routine checks to see if the
533 * pages surrounding this fault reside in the same
534 * object as the page for this fault. If they do,
535 * then they are faulted in also into the object. The
536 * array "marray" returned contains an array of
537 * vm_page_t structs where one of them is the
538 * vm_page_t passed to the routine. The reqpage
539 * return value is the index into the marray for the
540 * vm_page_t passed to the routine.
542 * fs.m plus the additional pages are PG_BUSY'd.
544 * XXX vm_fault_additional_pages() can block
545 * without releasing the map lock.
547 faultcount = vm_fault_additional_pages(
548 fs.m, behind, ahead, marray, &reqpage);
551 * update lastr imperfectly (we do not know how much
552 * getpages will actually read), but good enough.
554 * XXX The following assignment modifies the map
555 * without holding a write lock on it.
557 fs.entry->lastr = fs.pindex + faultcount - behind;
560 * Call the pager to retrieve the data, if any, after
561 * releasing the lock on the map. We hold a ref on
562 * fs.object and the pages are PG_BUSY'd.
567 vm_pager_get_pages(fs.object, marray, faultcount,
568 reqpage) : VM_PAGER_FAIL;
570 if (rv == VM_PAGER_OK) {
572 * Found the page. Leave it busy while we play
577 * Relookup in case pager changed page. Pager
578 * is responsible for disposition of old page
581 fs.m = vm_page_lookup(fs.object, fs.pindex);
583 unlock_and_deallocate(&fs);
588 break; /* break to PAGE HAS BEEN FOUND */
591 * Remove the bogus page (which does not exist at this
592 * object/offset); before doing so, we must get back
593 * our object lock to preserve our invariant.
595 * Also wake up any other process that may want to bring
598 * If this is the top-level object, we must leave the
599 * busy page to prevent another process from rushing
600 * past us, and inserting the page in that object at
601 * the same time that we are.
603 if (rv == VM_PAGER_ERROR)
604 printf("vm_fault: pager read error, pid %d (%s)\n",
605 curproc->p_pid, curproc->p_comm);
607 * Data outside the range of the pager or an I/O error
610 * XXX - the check for kernel_map is a kludge to work
611 * around having the machine panic on a kernel space
612 * fault w/ I/O error.
614 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) ||
615 (rv == VM_PAGER_BAD)) {
616 vm_page_lock_queues();
618 vm_page_unlock_queues();
620 unlock_and_deallocate(&fs);
621 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE);
623 if (fs.object != fs.first_object) {
624 vm_page_lock_queues();
626 vm_page_unlock_queues();
629 * XXX - we cannot just fall out at this
630 * point, m has been freed and is invalid!
636 * We get here if the object has default pager (or unwiring)
637 * or the pager doesn't have the page.
639 if (fs.object == fs.first_object)
643 * Move on to the next object. Lock the next object before
644 * unlocking the current one.
646 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset);
647 next_object = fs.object->backing_object;
648 if (next_object == NULL) {
650 * If there's no object left, fill the page in the top
653 if (fs.object != fs.first_object) {
654 vm_object_pip_wakeup(fs.object);
655 VM_OBJECT_UNLOCK(fs.object);
657 fs.object = fs.first_object;
658 fs.pindex = fs.first_pindex;
660 VM_OBJECT_LOCK(fs.object);
665 * Zero the page if necessary and mark it valid.
667 if ((fs.m->flags & PG_ZERO) == 0) {
668 pmap_zero_page(fs.m);
670 atomic_add_int(&cnt.v_ozfod, 1);
672 atomic_add_int(&cnt.v_zfod, 1);
673 fs.m->valid = VM_PAGE_BITS_ALL;
674 break; /* break to PAGE HAS BEEN FOUND */
676 KASSERT(fs.object != next_object,
677 ("object loop %p", next_object));
678 VM_OBJECT_LOCK(next_object);
679 vm_object_pip_add(next_object, 1);
680 if (fs.object != fs.first_object)
681 vm_object_pip_wakeup(fs.object);
682 VM_OBJECT_UNLOCK(fs.object);
683 fs.object = next_object;
687 KASSERT((fs.m->flags & PG_BUSY) != 0,
688 ("vm_fault: not busy after main loop"));
691 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
696 * If the page is being written, but isn't already owned by the
697 * top-level object, we have to copy it into a new page owned by the
700 if (fs.object != fs.first_object) {
702 * We only really need to copy if we want to write it.
704 if (fault_type & VM_PROT_WRITE) {
706 * This allows pages to be virtually copied from a
707 * backing_object into the first_object, where the
708 * backing object has no other refs to it, and cannot
709 * gain any more refs. Instead of a bcopy, we just
710 * move the page from the backing object to the
711 * first object. Note that we must mark the page
712 * dirty in the first object so that it will go out
713 * to swap when needed.
715 is_first_object_locked = FALSE;
718 * Only one shadow object
720 (fs.object->shadow_count == 1) &&
722 * No COW refs, except us
724 (fs.object->ref_count == 1) &&
726 * No one else can look this object up
728 (fs.object->handle == NULL) &&
730 * No other ways to look the object up
732 ((fs.object->type == OBJT_DEFAULT) ||
733 (fs.object->type == OBJT_SWAP)) &&
734 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) &&
736 * We don't chase down the shadow chain
738 fs.object == fs.first_object->backing_object) {
739 vm_page_lock_queues();
741 * get rid of the unnecessary page
743 vm_page_free(fs.first_m);
745 * grab the page and put it into the
746 * process'es object. The page is
747 * automatically made dirty.
749 vm_page_rename(fs.m, fs.first_object, fs.first_pindex);
751 vm_page_unlock_queues();
754 atomic_add_int(&cnt.v_cow_optim, 1);
757 * Oh, well, lets copy it.
759 pmap_copy_page(fs.m, fs.first_m);
760 fs.first_m->valid = VM_PAGE_BITS_ALL;
764 * We no longer need the old page or object.
769 * fs.object != fs.first_object due to above
772 vm_object_pip_wakeup(fs.object);
773 VM_OBJECT_UNLOCK(fs.object);
775 * Only use the new page below...
777 fs.object = fs.first_object;
778 fs.pindex = fs.first_pindex;
780 if (!is_first_object_locked)
781 VM_OBJECT_LOCK(fs.object);
782 atomic_add_int(&cnt.v_cow_faults, 1);
784 prot &= ~VM_PROT_WRITE;
789 * We must verify that the maps have not changed since our last
792 if (!fs.lookup_still_valid) {
793 vm_object_t retry_object;
794 vm_pindex_t retry_pindex;
795 vm_prot_t retry_prot;
797 if (!vm_map_trylock_read(fs.map)) {
799 unlock_and_deallocate(&fs);
802 fs.lookup_still_valid = TRUE;
803 if (fs.map->timestamp != map_generation) {
804 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type,
805 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired);
808 * If we don't need the page any longer, put it on the inactive
809 * list (the easiest thing to do here). If no one needs it,
810 * pageout will grab it eventually.
812 if (result != KERN_SUCCESS) {
814 unlock_and_deallocate(&fs);
817 * If retry of map lookup would have blocked then
818 * retry fault from start.
820 if (result == KERN_FAILURE)
824 if ((retry_object != fs.first_object) ||
825 (retry_pindex != fs.first_pindex)) {
827 unlock_and_deallocate(&fs);
832 * Check whether the protection has changed or the object has
833 * been copied while we left the map unlocked. Changing from
834 * read to write permission is OK - we leave the page
835 * write-protected, and catch the write fault. Changing from
836 * write to read permission means that we can't mark the page
837 * write-enabled after all.
842 if (prot & VM_PROT_WRITE) {
843 vm_page_lock_queues();
844 vm_page_flag_set(fs.m, PG_WRITEABLE);
845 vm_page_unlock_queues();
846 vm_object_set_writeable_dirty(fs.object);
849 * If the fault is a write, we know that this page is being
850 * written NOW so dirty it explicitly to save on
851 * pmap_is_modified() calls later.
853 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC
854 * if the page is already dirty to prevent data written with
855 * the expectation of being synced from not being synced.
856 * Likewise if this entry does not request NOSYNC then make
857 * sure the page isn't marked NOSYNC. Applications sharing
858 * data should use the same flags to avoid ping ponging.
860 * Also tell the backing pager, if any, that it should remove
861 * any swap backing since the page is now dirty.
863 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) {
864 if (fs.m->dirty == 0)
865 fs.m->oflags |= VPO_NOSYNC;
867 fs.m->oflags &= ~VPO_NOSYNC;
869 if (fault_flags & VM_FAULT_DIRTY) {
871 vm_pager_page_unswapped(fs.m);
876 * Page had better still be busy
878 KASSERT(fs.m->flags & PG_BUSY,
879 ("vm_fault: page %p not busy!", fs.m));
881 * Sanity check: page must be completely valid or it is not fit to
882 * map into user space. vm_pager_get_pages() ensures this.
884 if (fs.m->valid != VM_PAGE_BITS_ALL) {
885 vm_page_zero_invalid(fs.m, TRUE);
886 printf("Warning: page %p partially invalid on fault\n", fs.m);
888 VM_OBJECT_UNLOCK(fs.object);
891 * Put this page into the physical map. We had to do the unlock above
892 * because pmap_enter() may sleep. We don't put the page
893 * back on the active queue until later so that the pageout daemon
894 * won't find it (yet).
896 pmap_enter(fs.map->pmap, vaddr, fs.m, prot, wired);
897 if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) {
898 vm_fault_prefault(fs.map->pmap, vaddr, fs.entry);
900 VM_OBJECT_LOCK(fs.object);
901 vm_page_lock_queues();
902 vm_page_flag_set(fs.m, PG_REFERENCED);
905 * If the page is not wired down, then put it where the pageout daemon
908 if (fault_flags & VM_FAULT_WIRE_MASK) {
912 vm_page_unwire(fs.m, 1);
914 vm_page_activate(fs.m);
916 vm_page_wakeup(fs.m);
917 vm_page_unlock_queues();
920 * Unlock everything, and return
922 unlock_and_deallocate(&fs);
924 if ((curproc->p_sflag & PS_INMEM) && curproc->p_stats) {
926 curproc->p_stats->p_ru.ru_majflt++;
928 curproc->p_stats->p_ru.ru_minflt++;
931 PROC_UNLOCK(curproc);
933 return (KERN_SUCCESS);
937 * vm_fault_prefault provides a quick way of clustering
938 * pagefaults into a processes address space. It is a "cousin"
939 * of vm_map_pmap_enter, except it runs at page fault time instead
943 vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry)
946 vm_offset_t addr, starta;
951 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace))
954 object = entry->object.vm_object;
956 starta = addra - PFBAK * PAGE_SIZE;
957 if (starta < entry->start) {
958 starta = entry->start;
959 } else if (starta > addra) {
963 for (i = 0; i < PAGEORDER_SIZE; i++) {
964 vm_object_t backing_object, lobject;
966 addr = addra + prefault_pageorder[i];
967 if (addr > addra + (PFFOR * PAGE_SIZE))
970 if (addr < starta || addr >= entry->end)
973 if (!pmap_is_prefaultable(pmap, addr))
976 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
978 VM_OBJECT_LOCK(lobject);
979 while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
980 lobject->type == OBJT_DEFAULT &&
981 (backing_object = lobject->backing_object) != NULL) {
982 if (lobject->backing_object_offset & PAGE_MASK)
984 pindex += lobject->backing_object_offset >> PAGE_SHIFT;
985 VM_OBJECT_LOCK(backing_object);
986 VM_OBJECT_UNLOCK(lobject);
987 lobject = backing_object;
990 * give-up when a page is not in memory
993 VM_OBJECT_UNLOCK(lobject);
996 if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
998 (m->flags & (PG_BUSY | PG_FICTITIOUS)) == 0) {
1000 vm_page_lock_queues();
1001 if (VM_PAGE_INQUEUE1(m, PQ_CACHE))
1002 vm_page_deactivate(m);
1003 pmap_enter_quick(pmap, addr, m, entry->protection);
1004 vm_page_unlock_queues();
1006 VM_OBJECT_UNLOCK(lobject);
1013 * Ensure that the requested virtual address, which may be in userland,
1014 * is valid. Fault-in the page if necessary. Return -1 on failure.
1017 vm_fault_quick(caddr_t v, int prot)
1021 if (prot & VM_PROT_WRITE)
1022 r = subyte(v, fubyte(v));
1031 * Wire down a range of virtual addresses in a map.
1034 vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
1035 boolean_t user_wire, boolean_t fictitious)
1041 * We simulate a fault to get the page and enter it in the physical
1042 * map. For user wiring, we only ask for read access on currently
1043 * read-only sections.
1045 for (va = start; va < end; va += PAGE_SIZE) {
1046 rv = vm_fault(map, va,
1047 user_wire ? VM_PROT_READ : VM_PROT_READ | VM_PROT_WRITE,
1048 user_wire ? VM_FAULT_USER_WIRE : VM_FAULT_CHANGE_WIRING);
1051 vm_fault_unwire(map, start, va, fictitious);
1055 return (KERN_SUCCESS);
1061 * Unwire a range of virtual addresses in a map.
1064 vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
1065 boolean_t fictitious)
1071 pmap = vm_map_pmap(map);
1074 * Since the pages are wired down, we must be able to get their
1075 * mappings from the physical map system.
1077 for (va = start; va < end; va += PAGE_SIZE) {
1078 pa = pmap_extract(pmap, va);
1080 pmap_change_wiring(pmap, va, FALSE);
1082 vm_page_lock_queues();
1083 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1);
1084 vm_page_unlock_queues();
1092 * vm_fault_copy_entry
1094 * Copy all of the pages from a wired-down map entry to another.
1096 * In/out conditions:
1097 * The source and destination maps must be locked for write.
1098 * The source map entry must be wired down (or be a sharing map
1099 * entry corresponding to a main map entry that is wired down).
1102 vm_fault_copy_entry(dst_map, src_map, dst_entry, src_entry)
1105 vm_map_entry_t dst_entry;
1106 vm_map_entry_t src_entry;
1108 vm_object_t backing_object, dst_object, object;
1109 vm_object_t src_object;
1110 vm_ooffset_t dst_offset;
1111 vm_ooffset_t src_offset;
1122 src_object = src_entry->object.vm_object;
1123 src_offset = src_entry->offset;
1126 * Create the top-level object for the destination entry. (Doesn't
1127 * actually shadow anything - we copy the pages directly.)
1129 dst_object = vm_object_allocate(OBJT_DEFAULT,
1130 OFF_TO_IDX(dst_entry->end - dst_entry->start));
1132 VM_OBJECT_LOCK(dst_object);
1133 dst_entry->object.vm_object = dst_object;
1134 dst_entry->offset = 0;
1136 prot = dst_entry->max_protection;
1139 * Loop through all of the pages in the entry's range, copying each
1140 * one from the source object (it should be there) to the destination
1143 for (vaddr = dst_entry->start, dst_offset = 0;
1144 vaddr < dst_entry->end;
1145 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) {
1148 * Allocate a page in the destination object
1151 dst_m = vm_page_alloc(dst_object,
1152 OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL);
1153 if (dst_m == NULL) {
1154 VM_OBJECT_UNLOCK(dst_object);
1156 VM_OBJECT_LOCK(dst_object);
1158 } while (dst_m == NULL);
1161 * Find the page in the source object, and copy it in.
1162 * (Because the source is wired down, the page will be in
1165 VM_OBJECT_LOCK(src_object);
1166 object = src_object;
1168 while ((src_m = vm_page_lookup(object, pindex +
1169 OFF_TO_IDX(dst_offset + src_offset))) == NULL &&
1170 (src_entry->protection & VM_PROT_WRITE) == 0 &&
1171 (backing_object = object->backing_object) != NULL) {
1173 * Allow fallback to backing objects if we are reading.
1175 VM_OBJECT_LOCK(backing_object);
1176 pindex += OFF_TO_IDX(object->backing_object_offset);
1177 VM_OBJECT_UNLOCK(object);
1178 object = backing_object;
1181 panic("vm_fault_copy_wired: page missing");
1182 pmap_copy_page(src_m, dst_m);
1183 VM_OBJECT_UNLOCK(object);
1184 dst_m->valid = VM_PAGE_BITS_ALL;
1185 VM_OBJECT_UNLOCK(dst_object);
1188 * Enter it in the pmap...
1190 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE);
1191 VM_OBJECT_LOCK(dst_object);
1192 vm_page_lock_queues();
1193 if ((prot & VM_PROT_WRITE) != 0)
1194 vm_page_flag_set(dst_m, PG_WRITEABLE);
1197 * Mark it no longer busy, and put it on the active list.
1199 vm_page_activate(dst_m);
1200 vm_page_wakeup(dst_m);
1201 vm_page_unlock_queues();
1203 VM_OBJECT_UNLOCK(dst_object);
1208 * This routine checks around the requested page for other pages that
1209 * might be able to be faulted in. This routine brackets the viable
1210 * pages for the pages to be paged in.
1213 * m, rbehind, rahead
1216 * marray (array of vm_page_t), reqpage (index of requested page)
1219 * number of pages in marray
1221 * This routine can't block.
1224 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage)
1233 vm_pindex_t pindex, startpindex, endpindex, tpindex;
1235 int cbehind, cahead;
1237 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
1243 * we don't fault-ahead for device pager
1245 if (object->type == OBJT_DEVICE) {
1252 * if the requested page is not available, then give up now
1254 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) {
1258 if ((cbehind == 0) && (cahead == 0)) {
1264 if (rahead > cahead) {
1268 if (rbehind > cbehind) {
1273 * try to do any readahead that we might have free pages for.
1275 if ((rahead + rbehind) >
1276 ((cnt.v_free_count + cnt.v_cache_count) - cnt.v_free_reserved)) {
1277 pagedaemon_wakeup();
1284 * scan backward for the read behind pages -- in memory
1287 if (rbehind > pindex) {
1291 startpindex = pindex - rbehind;
1294 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL &&
1295 rtm->pindex >= startpindex)
1296 startpindex = rtm->pindex + 1;
1298 for (i = 0, tpindex = startpindex; tpindex < pindex; i++, tpindex++) {
1300 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
1302 vm_page_lock_queues();
1303 for (j = 0; j < i; j++) {
1304 vm_page_free(marray[j]);
1306 vm_page_unlock_queues();
1320 /* page offset of the required page */
1323 tpindex = pindex + 1;
1327 * scan forward for the read ahead pages
1329 endpindex = tpindex + rahead;
1330 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex)
1331 endpindex = rtm->pindex;
1332 if (endpindex > object->size)
1333 endpindex = object->size;
1335 for (; tpindex < endpindex; i++, tpindex++) {
1337 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
1345 /* return number of bytes of pages */