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.
69 * $FreeBSD: src/sys/vm/vm_fault.c,v 1.108.2.8 2002/02/26 05:49:27 silby Exp $
70 * $DragonFly: src/sys/vm/vm_fault.c,v 1.25 2006/05/17 17:47:58 dillon Exp $
74 * Page fault handling module.
77 #include <sys/param.h>
78 #include <sys/systm.h>
79 #include <sys/kernel.h>
81 #include <sys/vnode.h>
82 #include <sys/resourcevar.h>
83 #include <sys/vmmeter.h>
86 #include <vm/vm_param.h>
89 #include <vm/vm_map.h>
90 #include <vm/vm_object.h>
91 #include <vm/vm_page.h>
92 #include <vm/vm_pageout.h>
93 #include <vm/vm_kern.h>
94 #include <vm/vm_pager.h>
95 #include <vm/vnode_pager.h>
96 #include <vm/vm_extern.h>
98 #include <sys/thread2.h>
99 #include <vm/vm_page2.h>
101 static int vm_fault_additional_pages (vm_page_t, int,
102 int, vm_page_t *, int *);
103 static int vm_fault_ratelimit(struct vmspace *vmspace);
105 #define VM_FAULT_READ_AHEAD 8
106 #define VM_FAULT_READ_BEHIND 7
107 #define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1)
114 vm_object_t first_object;
115 vm_pindex_t first_pindex;
117 vm_map_entry_t entry;
118 int lookup_still_valid;
123 release_page(struct faultstate *fs)
125 vm_page_wakeup(fs->m);
126 vm_page_deactivate(fs->m);
131 unlock_map(struct faultstate *fs)
133 if (fs->lookup_still_valid) {
134 vm_map_lookup_done(fs->map, fs->entry, 0);
135 fs->lookup_still_valid = FALSE;
140 _unlock_things(struct faultstate *fs, int dealloc)
142 vm_object_pip_wakeup(fs->object);
143 if (fs->object != fs->first_object) {
144 vm_page_free(fs->first_m);
145 vm_object_pip_wakeup(fs->first_object);
149 vm_object_deallocate(fs->first_object);
152 if (fs->vp != NULL) {
158 #define unlock_things(fs) _unlock_things(fs, 0)
159 #define unlock_and_deallocate(fs) _unlock_things(fs, 1)
162 * TRYPAGER - used by vm_fault to calculate whether the pager for the
163 * current object *might* contain the page.
165 * default objects are zero-fill, there is no real pager.
168 #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \
169 (((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired))
174 * Handle a page fault occurring at the given address,
175 * requiring the given permissions, in the map specified.
176 * If successful, the page is inserted into the
177 * associated physical map.
179 * NOTE: the given address should be truncated to the
180 * proper page address.
182 * KERN_SUCCESS is returned if the page fault is handled; otherwise,
183 * a standard error specifying why the fault is fatal is returned.
186 * The map in question must be referenced, and remains so.
187 * Caller may hold no locks.
190 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, int fault_flags)
196 vm_object_t next_object;
197 vm_page_t marray[VM_FAULT_READ];
202 struct faultstate fs;
204 mycpu->gd_cnt.v_vm_faults++;
209 * Find the backing store object and offset into it to begin the
213 if ((result = vm_map_lookup(&fs.map, vaddr,
214 fault_type, &fs.entry, &fs.first_object,
215 &fs.first_pindex, &prot, &wired)) != KERN_SUCCESS) {
216 if ((result != KERN_PROTECTION_FAILURE) ||
217 ((fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE)) {
222 * If we are user-wiring a r/w segment, and it is COW, then
223 * we need to do the COW operation. Note that we don't COW
224 * currently RO sections now, because it is NOT desirable
225 * to COW .text. We simply keep .text from ever being COW'ed
226 * and take the heat that one cannot debug wired .text sections.
228 result = vm_map_lookup(&fs.map, vaddr,
229 VM_PROT_READ|VM_PROT_WRITE|VM_PROT_OVERRIDE_WRITE,
230 &fs.entry, &fs.first_object, &fs.first_pindex, &prot, &wired);
231 if (result != KERN_SUCCESS) {
236 * If we don't COW now, on a user wire, the user will never
237 * be able to write to the mapping. If we don't make this
238 * restriction, the bookkeeping would be nearly impossible.
240 if ((fs.entry->protection & VM_PROT_WRITE) == 0)
241 fs.entry->max_protection &= ~VM_PROT_WRITE;
244 map_generation = fs.map->timestamp;
246 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
247 panic("vm_fault: fault on nofault entry, addr: %lx",
252 * A system map entry may return a NULL object. No object means
253 * no pager means an unrecoverable kernel fault.
255 if (fs.first_object == NULL) {
256 panic("vm_fault: unrecoverable fault at %p in entry %p",
257 (void *)vaddr, fs.entry);
261 * Make a reference to this object to prevent its disposal while we
262 * are messing with it. Once we have the reference, the map is free
263 * to be diddled. Since objects reference their shadows (and copies),
264 * they will stay around as well.
266 * Bump the paging-in-progress count to prevent size changes (e.g.
267 * truncation operations) during I/O. This must be done after
268 * obtaining the vnode lock in order to avoid possible deadlocks.
270 vm_object_reference(fs.first_object);
271 fs.vp = vnode_pager_lock(fs.first_object);
272 vm_object_pip_add(fs.first_object, 1);
274 fs.lookup_still_valid = TRUE;
282 * Search for the page at object/offset.
285 fs.object = fs.first_object;
286 fs.pindex = fs.first_pindex;
290 * If the object is dead, we stop here
293 if (fs.object->flags & OBJ_DEAD) {
294 unlock_and_deallocate(&fs);
295 return (KERN_PROTECTION_FAILURE);
299 * See if page is resident. spl protection is required
300 * to avoid an interrupt unbusy/free race against our
301 * lookup. We must hold the protection through a page
302 * allocation or busy.
305 fs.m = vm_page_lookup(fs.object, fs.pindex);
309 * Wait/Retry if the page is busy. We have to do this
310 * if the page is busy via either PG_BUSY or
311 * vm_page_t->busy because the vm_pager may be using
312 * vm_page_t->busy for pageouts ( and even pageins if
313 * it is the vnode pager ), and we could end up trying
314 * to pagein and pageout the same page simultaneously.
316 * We can theoretically allow the busy case on a read
317 * fault if the page is marked valid, but since such
318 * pages are typically already pmap'd, putting that
319 * special case in might be more effort then it is
320 * worth. We cannot under any circumstances mess
321 * around with a vm_page_t->busy page except, perhaps,
324 if ((fs.m->flags & PG_BUSY) || fs.m->busy) {
326 vm_page_sleep_busy(fs.m, TRUE, "vmpfw");
327 mycpu->gd_cnt.v_intrans++;
328 vm_object_deallocate(fs.first_object);
334 vm_page_unqueue_nowakeup(fs.m);
336 if ((queue - fs.m->pc) == PQ_CACHE && vm_page_count_severe()) {
337 vm_page_activate(fs.m);
338 unlock_and_deallocate(&fs);
345 * Mark page busy for other processes, and the
346 * pagedaemon. If it still isn't completely valid
347 * (readable), jump to readrest, else break-out ( we
350 * We can release the spl once we have marked the
357 if (((fs.m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) &&
358 fs.m->object != kernel_object && fs.m->object != kmem_object) {
366 * Page is not resident, If this is the search termination
367 * or the pager might contain the page, allocate a new page.
369 * note: we are still in splvm().
372 if (TRYPAGER || fs.object == fs.first_object) {
373 if (fs.pindex >= fs.object->size) {
375 unlock_and_deallocate(&fs);
376 return (KERN_PROTECTION_FAILURE);
382 if (didlimit == 0 && curproc != NULL) {
384 vm_fault_ratelimit(curproc->p_vmspace);
387 unlock_and_deallocate(&fs);
388 tsleep(curproc, 0, "vmrate", limticks);
395 * Allocate a new page for this object/offset pair.
398 if (!vm_page_count_severe()) {
399 fs.m = vm_page_alloc(fs.object, fs.pindex,
400 (fs.vp || fs.object->backing_object)? VM_ALLOC_NORMAL: VM_ALLOC_NORMAL | VM_ALLOC_ZERO);
404 unlock_and_deallocate(&fs);
413 * We have found a valid page or we have allocated a new page.
414 * The page thus may not be valid or may not be entirely
417 * Attempt to fault-in the page if there is a chance that the
418 * pager has it, and potentially fault in additional pages
421 * We are NOT in splvm here and if TRYPAGER is true then
422 * fs.m will be non-NULL and will be PG_BUSY for us.
429 u_char behavior = vm_map_entry_behavior(fs.entry);
431 if (behavior == MAP_ENTRY_BEHAV_RANDOM) {
435 behind = (vaddr - fs.entry->start) >> PAGE_SHIFT;
436 if (behind > VM_FAULT_READ_BEHIND)
437 behind = VM_FAULT_READ_BEHIND;
439 ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1;
440 if (ahead > VM_FAULT_READ_AHEAD)
441 ahead = VM_FAULT_READ_AHEAD;
444 if ((fs.first_object->type != OBJT_DEVICE) &&
445 (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL ||
446 (behavior != MAP_ENTRY_BEHAV_RANDOM &&
447 fs.pindex >= fs.entry->lastr &&
448 fs.pindex < fs.entry->lastr + VM_FAULT_READ))
450 vm_pindex_t firstpindex, tmppindex;
452 if (fs.first_pindex < 2 * VM_FAULT_READ)
455 firstpindex = fs.first_pindex - 2 * VM_FAULT_READ;
458 * note: partially valid pages cannot be
459 * included in the lookahead - NFS piecemeal
460 * writes will barf on it badly.
462 * spl protection is required to avoid races
463 * between the lookup and an interrupt
464 * unbusy/free sequence occuring prior to
468 for (tmppindex = fs.first_pindex - 1;
469 tmppindex >= firstpindex;
473 mt = vm_page_lookup( fs.first_object, tmppindex);
474 if (mt == NULL || (mt->valid != VM_PAGE_BITS_ALL))
477 (mt->flags & (PG_BUSY | PG_FICTITIOUS | PG_UNMANAGED)) ||
482 vm_page_test_dirty(mt);
484 vm_page_protect(mt, VM_PROT_NONE);
485 vm_page_deactivate(mt);
497 * now we find out if any other pages should be paged
498 * in at this time this routine checks to see if the
499 * pages surrounding this fault reside in the same
500 * object as the page for this fault. If they do,
501 * then they are faulted in also into the object. The
502 * array "marray" returned contains an array of
503 * vm_page_t structs where one of them is the
504 * vm_page_t passed to the routine. The reqpage
505 * return value is the index into the marray for the
506 * vm_page_t passed to the routine.
508 * fs.m plus the additional pages are PG_BUSY'd.
510 faultcount = vm_fault_additional_pages(
511 fs.m, behind, ahead, marray, &reqpage);
514 * update lastr imperfectly (we do not know how much
515 * getpages will actually read), but good enough.
517 fs.entry->lastr = fs.pindex + faultcount - behind;
520 * Call the pager to retrieve the data, if any, after
521 * releasing the lock on the map. We hold a ref on
522 * fs.object and the pages are PG_BUSY'd.
527 vm_pager_get_pages(fs.object, marray, faultcount,
528 reqpage) : VM_PAGER_FAIL;
530 if (rv == VM_PAGER_OK) {
532 * Found the page. Leave it busy while we play
537 * Relookup in case pager changed page. Pager
538 * is responsible for disposition of old page
541 * XXX other code segments do relookups too.
542 * It's a bad abstraction that needs to be
545 fs.m = vm_page_lookup(fs.object, fs.pindex);
547 unlock_and_deallocate(&fs);
552 break; /* break to PAGE HAS BEEN FOUND */
555 * Remove the bogus page (which does not exist at this
556 * object/offset); before doing so, we must get back
557 * our object lock to preserve our invariant.
559 * Also wake up any other process that may want to bring
562 * If this is the top-level object, we must leave the
563 * busy page to prevent another process from rushing
564 * past us, and inserting the page in that object at
565 * the same time that we are.
568 if (rv == VM_PAGER_ERROR) {
570 printf("vm_fault: pager read error, pid %d (%s)\n", curproc->p_pid, curproc->p_comm);
572 printf("vm_fault: pager read error, thread %p (%s)\n", curthread, curproc->p_comm);
575 * Data outside the range of the pager or an I/O error
578 * XXX - the check for kernel_map is a kludge to work
579 * around having the machine panic on a kernel space
580 * fault w/ I/O error.
582 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) ||
583 (rv == VM_PAGER_BAD)) {
586 unlock_and_deallocate(&fs);
587 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE);
589 if (fs.object != fs.first_object) {
593 * XXX - we cannot just fall out at this
594 * point, m has been freed and is invalid!
600 * We get here if the object has default pager (or unwiring)
601 * or the pager doesn't have the page.
603 if (fs.object == fs.first_object)
607 * Move on to the next object. Lock the next object before
608 * unlocking the current one.
611 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset);
612 next_object = fs.object->backing_object;
613 if (next_object == NULL) {
615 * If there's no object left, fill the page in the top
618 if (fs.object != fs.first_object) {
619 vm_object_pip_wakeup(fs.object);
621 fs.object = fs.first_object;
622 fs.pindex = fs.first_pindex;
628 * Zero the page if necessary and mark it valid.
630 if ((fs.m->flags & PG_ZERO) == 0) {
631 vm_page_zero_fill(fs.m);
633 mycpu->gd_cnt.v_ozfod++;
635 mycpu->gd_cnt.v_zfod++;
636 fs.m->valid = VM_PAGE_BITS_ALL;
637 break; /* break to PAGE HAS BEEN FOUND */
639 if (fs.object != fs.first_object) {
640 vm_object_pip_wakeup(fs.object);
642 KASSERT(fs.object != next_object, ("object loop %p", next_object));
643 fs.object = next_object;
644 vm_object_pip_add(fs.object, 1);
648 KASSERT((fs.m->flags & PG_BUSY) != 0,
649 ("vm_fault: not busy after main loop"));
652 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
657 * If the page is being written, but isn't already owned by the
658 * top-level object, we have to copy it into a new page owned by the
662 if (fs.object != fs.first_object) {
664 * We only really need to copy if we want to write it.
667 if (fault_type & VM_PROT_WRITE) {
669 * This allows pages to be virtually copied from a
670 * backing_object into the first_object, where the
671 * backing object has no other refs to it, and cannot
672 * gain any more refs. Instead of a bcopy, we just
673 * move the page from the backing object to the
674 * first object. Note that we must mark the page
675 * dirty in the first object so that it will go out
676 * to swap when needed.
678 if (map_generation == fs.map->timestamp &&
680 * Only one shadow object
682 (fs.object->shadow_count == 1) &&
684 * No COW refs, except us
686 (fs.object->ref_count == 1) &&
688 * No one else can look this object up
690 (fs.object->handle == NULL) &&
692 * No other ways to look the object up
694 ((fs.object->type == OBJT_DEFAULT) ||
695 (fs.object->type == OBJT_SWAP)) &&
697 * We don't chase down the shadow chain
699 (fs.object == fs.first_object->backing_object) &&
702 * grab the lock if we need to
704 (fs.lookup_still_valid ||
705 lockmgr(&fs.map->lock, LK_EXCLUSIVE|LK_NOWAIT) == 0)
708 fs.lookup_still_valid = 1;
710 * get rid of the unnecessary page
712 vm_page_protect(fs.first_m, VM_PROT_NONE);
713 vm_page_free(fs.first_m);
717 * grab the page and put it into the
718 * process'es object. The page is
719 * automatically made dirty.
721 vm_page_rename(fs.m, fs.first_object, fs.first_pindex);
723 vm_page_busy(fs.first_m);
725 mycpu->gd_cnt.v_cow_optim++;
728 * Oh, well, lets copy it.
730 vm_page_copy(fs.m, fs.first_m);
735 * We no longer need the old page or object.
741 * fs.object != fs.first_object due to above
745 vm_object_pip_wakeup(fs.object);
748 * Only use the new page below...
751 mycpu->gd_cnt.v_cow_faults++;
753 fs.object = fs.first_object;
754 fs.pindex = fs.first_pindex;
757 prot &= ~VM_PROT_WRITE;
762 * We must verify that the maps have not changed since our last
766 if (!fs.lookup_still_valid &&
767 (fs.map->timestamp != map_generation)) {
768 vm_object_t retry_object;
769 vm_pindex_t retry_pindex;
770 vm_prot_t retry_prot;
773 * Since map entries may be pageable, make sure we can take a
774 * page fault on them.
778 * Unlock vnode before the lookup to avoid deadlock. E.G.
779 * avoid a deadlock between the inode and exec_map that can
780 * occur due to locks being obtained in different orders.
788 if (fs.map->infork) {
790 unlock_and_deallocate(&fs);
795 * To avoid trying to write_lock the map while another process
796 * has it read_locked (in vm_map_wire), we do not try for
797 * write permission. If the page is still writable, we will
798 * get write permission. If it is not, or has been marked
799 * needs_copy, we enter the mapping without write permission,
800 * and will merely take another fault.
802 result = vm_map_lookup(&fs.map, vaddr, fault_type & ~VM_PROT_WRITE,
803 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired);
804 map_generation = fs.map->timestamp;
807 * If we don't need the page any longer, put it on the active
808 * list (the easiest thing to do here). If no one needs it,
809 * pageout will grab it eventually.
812 if (result != KERN_SUCCESS) {
814 unlock_and_deallocate(&fs);
817 fs.lookup_still_valid = TRUE;
819 if ((retry_object != fs.first_object) ||
820 (retry_pindex != fs.first_pindex)) {
822 unlock_and_deallocate(&fs);
826 * Check whether the protection has changed or the object has
827 * been copied while we left the map unlocked. Changing from
828 * read to write permission is OK - we leave the page
829 * write-protected, and catch the write fault. Changing from
830 * write to read permission means that we can't mark the page
831 * write-enabled after all.
837 * Put this page into the physical map. We had to do the unlock above
838 * because pmap_enter may cause other faults. We don't put the page
839 * back on the active queue until later so that the page-out daemon
840 * won't find us (yet).
843 if (prot & VM_PROT_WRITE) {
844 vm_page_flag_set(fs.m, PG_WRITEABLE);
845 vm_object_set_writeable_dirty(fs.m->object);
848 * If the fault is a write, we know that this page is being
849 * written NOW so dirty it explicitly to save on
850 * pmap_is_modified() calls later.
852 * If this is a NOSYNC mmap we do not want to set PG_NOSYNC
853 * if the page is already dirty to prevent data written with
854 * the expectation of being synced from not being synced.
855 * Likewise if this entry does not request NOSYNC then make
856 * sure the page isn't marked NOSYNC. Applications sharing
857 * data should use the same flags to avoid ping ponging.
859 * Also tell the backing pager, if any, that it should remove
860 * any swap backing since the page is now dirty.
862 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) {
863 if (fs.m->dirty == 0)
864 vm_page_flag_set(fs.m, PG_NOSYNC);
866 vm_page_flag_clear(fs.m, PG_NOSYNC);
868 if (fault_flags & VM_FAULT_DIRTY) {
871 vm_pager_page_unswapped(fs.m);
877 * Page had better still be busy
880 KASSERT(fs.m->flags & PG_BUSY,
881 ("vm_fault: page %p not busy!", fs.m));
886 * Sanity check: page must be completely valid or it is not fit to
887 * map into user space. vm_pager_get_pages() ensures this.
890 if (fs.m->valid != VM_PAGE_BITS_ALL) {
891 vm_page_zero_invalid(fs.m, TRUE);
892 printf("Warning: page %p partially invalid on fault\n", fs.m);
895 pmap_enter(fs.map->pmap, vaddr, fs.m, prot, wired);
897 if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) {
898 pmap_prefault(fs.map->pmap, vaddr, fs.entry);
901 vm_page_flag_clear(fs.m, PG_ZERO);
902 vm_page_flag_set(fs.m, PG_MAPPED|PG_REFERENCED);
903 if (fault_flags & VM_FAULT_HOLD)
907 * If the page is not wired down, then put it where the pageout daemon
911 if (fault_flags & VM_FAULT_WIRE_MASK) {
915 vm_page_unwire(fs.m, 1);
917 vm_page_activate(fs.m);
920 if (curproc && (curproc->p_flag & P_SWAPPEDOUT) == 0 &&
923 curproc->p_stats->p_ru.ru_majflt++;
925 curproc->p_stats->p_ru.ru_minflt++;
930 * Unlock everything, and return
933 vm_page_wakeup(fs.m);
934 vm_object_deallocate(fs.first_object);
936 return (KERN_SUCCESS);
941 * quick version of vm_fault
944 vm_fault_quick(caddr_t v, int prot)
948 if (prot & VM_PROT_WRITE)
949 r = subyte(v, fubyte(v));
956 * Wire down a range of virtual addresses in a map. The entry in question
957 * should be marked in-transition and the map must be locked. We must
958 * release the map temporarily while faulting-in the page to avoid a
959 * deadlock. Note that the entry may be clipped while we are blocked but
960 * will never be freed.
963 vm_fault_wire(vm_map_t map, vm_map_entry_t entry, boolean_t user_wire)
965 boolean_t fictitious;
973 pmap = vm_map_pmap(map);
974 start = entry->start;
976 fictitious = entry->object.vm_object &&
977 (entry->object.vm_object->type == OBJT_DEVICE);
983 * We simulate a fault to get the page and enter it in the physical
986 for (va = start; va < end; va += PAGE_SIZE) {
988 rv = vm_fault(map, va, VM_PROT_READ,
991 rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE,
992 VM_FAULT_CHANGE_WIRING);
997 if ((pa = pmap_extract(pmap, va)) == 0)
999 pmap_change_wiring(pmap, va, FALSE);
1001 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1);
1008 return (KERN_SUCCESS);
1012 * Unwire a range of virtual addresses in a map. The map should be
1016 vm_fault_unwire(vm_map_t map, vm_map_entry_t entry)
1018 boolean_t fictitious;
1025 pmap = vm_map_pmap(map);
1026 start = entry->start;
1028 fictitious = entry->object.vm_object &&
1029 (entry->object.vm_object->type == OBJT_DEVICE);
1032 * Since the pages are wired down, we must be able to get their
1033 * mappings from the physical map system.
1035 for (va = start; va < end; va += PAGE_SIZE) {
1036 pa = pmap_extract(pmap, va);
1038 pmap_change_wiring(pmap, va, FALSE);
1040 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1);
1046 * Reduce the rate at which memory is allocated to a process based
1047 * on the perceived load on the VM system. As the load increases
1048 * the allocation burst rate goes down and the delay increases.
1050 * Rate limiting does not apply when faulting active or inactive
1051 * pages. When faulting 'cache' pages, rate limiting only applies
1052 * if the system currently has a severe page deficit.
1054 * XXX vm_pagesupply should be increased when a page is freed.
1056 * We sleep up to 1/10 of a second.
1059 vm_fault_ratelimit(struct vmspace *vmspace)
1061 if (vm_load_enable == 0)
1063 if (vmspace->vm_pagesupply > 0) {
1064 --vmspace->vm_pagesupply;
1068 if (vm_load_debug) {
1069 printf("load %-4d give %d pgs, wait %d, pid %-5d (%s)\n",
1071 (1000 - vm_load ) / 10, vm_load * hz / 10000,
1072 curproc->p_pid, curproc->p_comm);
1075 vmspace->vm_pagesupply = (1000 - vm_load) / 10;
1076 return(vm_load * hz / 10000);
1081 * vm_fault_copy_entry
1083 * Copy all of the pages from a wired-down map entry to another.
1085 * In/out conditions:
1086 * The source and destination maps must be locked for write.
1087 * The source map entry must be wired down (or be a sharing map
1088 * entry corresponding to a main map entry that is wired down).
1092 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
1093 vm_map_entry_t dst_entry, vm_map_entry_t src_entry)
1095 vm_object_t dst_object;
1096 vm_object_t src_object;
1097 vm_ooffset_t dst_offset;
1098 vm_ooffset_t src_offset;
1108 src_object = src_entry->object.vm_object;
1109 src_offset = src_entry->offset;
1112 * Create the top-level object for the destination entry. (Doesn't
1113 * actually shadow anything - we copy the pages directly.)
1115 dst_object = vm_object_allocate(OBJT_DEFAULT,
1116 (vm_size_t) OFF_TO_IDX(dst_entry->end - dst_entry->start));
1118 dst_entry->object.vm_object = dst_object;
1119 dst_entry->offset = 0;
1121 prot = dst_entry->max_protection;
1124 * Loop through all of the pages in the entry's range, copying each
1125 * one from the source object (it should be there) to the destination
1128 for (vaddr = dst_entry->start, dst_offset = 0;
1129 vaddr < dst_entry->end;
1130 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) {
1133 * Allocate a page in the destination object
1136 dst_m = vm_page_alloc(dst_object,
1137 OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL);
1138 if (dst_m == NULL) {
1141 } while (dst_m == NULL);
1144 * Find the page in the source object, and copy it in.
1145 * (Because the source is wired down, the page will be in
1148 src_m = vm_page_lookup(src_object,
1149 OFF_TO_IDX(dst_offset + src_offset));
1151 panic("vm_fault_copy_wired: page missing");
1153 vm_page_copy(src_m, dst_m);
1156 * Enter it in the pmap...
1159 vm_page_flag_clear(dst_m, PG_ZERO);
1160 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE);
1161 vm_page_flag_set(dst_m, PG_WRITEABLE|PG_MAPPED);
1164 * Mark it no longer busy, and put it on the active list.
1166 vm_page_activate(dst_m);
1167 vm_page_wakeup(dst_m);
1173 * This routine checks around the requested page for other pages that
1174 * might be able to be faulted in. This routine brackets the viable
1175 * pages for the pages to be paged in.
1178 * m, rbehind, rahead
1181 * marray (array of vm_page_t), reqpage (index of requested page)
1184 * number of pages in marray
1187 vm_fault_additional_pages(vm_page_t m, int rbehind, int rahead,
1188 vm_page_t *marray, int *reqpage)
1192 vm_pindex_t pindex, startpindex, endpindex, tpindex;
1194 int cbehind, cahead;
1200 * we don't fault-ahead for device pager
1202 if (object->type == OBJT_DEVICE) {
1209 * if the requested page is not available, then give up now
1212 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) {
1216 if ((cbehind == 0) && (cahead == 0)) {
1222 if (rahead > cahead) {
1226 if (rbehind > cbehind) {
1231 * try to do any readahead that we might have free pages for.
1233 if ((rahead + rbehind) >
1234 ((vmstats.v_free_count + vmstats.v_cache_count) - vmstats.v_free_reserved)) {
1235 pagedaemon_wakeup();
1242 * scan backward for the read behind pages -- in memory
1244 * Assume that if the page is not found an interrupt will not
1245 * create it. Theoretically interrupts can only remove (busy)
1246 * pages, not create new associations.
1249 if (rbehind > pindex) {
1253 startpindex = pindex - rbehind;
1257 for ( tpindex = pindex - 1; tpindex >= startpindex; tpindex -= 1) {
1258 if (vm_page_lookup( object, tpindex)) {
1259 startpindex = tpindex + 1;
1266 for(i = 0, tpindex = startpindex; tpindex < pindex; i++, tpindex++) {
1268 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
1271 for (j = 0; j < i; j++) {
1272 vm_page_free(marray[j]);
1288 /* page offset of the required page */
1291 tpindex = pindex + 1;
1295 * scan forward for the read ahead pages
1297 endpindex = tpindex + rahead;
1298 if (endpindex > object->size)
1299 endpindex = object->size;
1302 for( ; tpindex < endpindex; i++, tpindex++) {
1304 if (vm_page_lookup(object, tpindex)) {
1308 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
1317 /* return number of bytes of pages */