4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 * Copyright (c) 1994 John S. Dyson
8 * Copyright (c) 1994 David Greenman
12 * This code is derived from software contributed to Berkeley by
13 * The Mach Operating System project at Carnegie-Mellon University.
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
18 * 1. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 * 3. All advertising materials mentioning features or use of this software
24 * must display the following acknowledgement:
25 * This product includes software developed by the University of
26 * California, Berkeley and its contributors.
27 * 4. Neither the name of the University nor the names of its contributors
28 * may be used to endorse or promote products derived from this software
29 * without specific prior written permission.
31 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
32 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
33 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
34 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
35 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
39 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
40 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
43 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94
46 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
47 * All rights reserved.
49 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
51 * Permission to use, copy, modify and distribute this software and
52 * its documentation is hereby granted, provided that both the copyright
53 * notice and this permission notice appear in all copies of the
54 * software, derivative works or modified versions, and any portions
55 * thereof, and that both notices appear in supporting documentation.
57 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
58 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
59 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
61 * Carnegie Mellon requests users of this software to return to
63 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
64 * School of Computer Science
65 * Carnegie Mellon University
66 * Pittsburgh PA 15213-3890
68 * any improvements or extensions that they make and grant Carnegie the
69 * rights to redistribute these changes.
71 * $FreeBSD: src/sys/vm/vm_fault.c,v 1.108.2.8 2002/02/26 05:49:27 silby Exp $
72 * $DragonFly: src/sys/vm/vm_fault.c,v 1.47 2008/07/01 02:02:56 dillon Exp $
76 * Page fault handling module.
79 #include <sys/param.h>
80 #include <sys/systm.h>
81 #include <sys/kernel.h>
83 #include <sys/vnode.h>
84 #include <sys/resourcevar.h>
85 #include <sys/vmmeter.h>
86 #include <sys/vkernel.h>
88 #include <sys/sysctl.h>
90 #include <cpu/lwbuf.h>
93 #include <vm/vm_param.h>
95 #include <vm/vm_map.h>
96 #include <vm/vm_object.h>
97 #include <vm/vm_page.h>
98 #include <vm/vm_pageout.h>
99 #include <vm/vm_kern.h>
100 #include <vm/vm_pager.h>
101 #include <vm/vnode_pager.h>
102 #include <vm/vm_extern.h>
104 #include <sys/thread2.h>
105 #include <vm/vm_page2.h>
113 vm_object_t first_object;
114 vm_prot_t first_prot;
116 vm_map_entry_t entry;
117 int lookup_still_valid;
126 static int debug_cluster = 0;
127 SYSCTL_INT(_vm, OID_AUTO, debug_cluster, CTLFLAG_RW, &debug_cluster, 0, "");
128 int vm_shared_fault = 1;
129 SYSCTL_INT(_vm, OID_AUTO, shared_fault, CTLFLAG_RW, &vm_shared_fault, 0,
130 "Allow shared token on vm_object");
131 static long vm_shared_hit = 0;
132 SYSCTL_LONG(_vm, OID_AUTO, shared_hit, CTLFLAG_RW, &vm_shared_hit, 0,
133 "Successful shared faults");
134 static long vm_shared_miss = 0;
135 SYSCTL_LONG(_vm, OID_AUTO, shared_miss, CTLFLAG_RW, &vm_shared_miss, 0,
136 "Unsuccessful shared faults");
138 static int vm_fault_object(struct faultstate *, vm_pindex_t, vm_prot_t);
139 static int vm_fault_vpagetable(struct faultstate *, vm_pindex_t *, vpte_t, int);
141 static int vm_fault_additional_pages (vm_page_t, int, int, vm_page_t *, int *);
143 static void vm_set_nosync(vm_page_t m, vm_map_entry_t entry);
144 static void vm_prefault(pmap_t pmap, vm_offset_t addra,
145 vm_map_entry_t entry, int prot, int fault_flags);
146 static void vm_prefault_quick(pmap_t pmap, vm_offset_t addra,
147 vm_map_entry_t entry, int prot, int fault_flags);
150 release_page(struct faultstate *fs)
152 vm_page_deactivate(fs->m);
153 vm_page_wakeup(fs->m);
158 * NOTE: Once unlocked any cached fs->entry becomes invalid, any reuse
159 * requires relocking and then checking the timestamp.
161 * NOTE: vm_map_lock_read() does not bump fs->map->timestamp so we do
162 * not have to update fs->map_generation here.
164 * NOTE: This function can fail due to a deadlock against the caller's
165 * holding of a vm_page BUSY.
168 relock_map(struct faultstate *fs)
172 if (fs->lookup_still_valid == FALSE && fs->map) {
173 error = vm_map_lock_read_to(fs->map);
175 fs->lookup_still_valid = TRUE;
183 unlock_map(struct faultstate *fs)
185 if (fs->lookup_still_valid && fs->map) {
186 vm_map_lookup_done(fs->map, fs->entry, 0);
187 fs->lookup_still_valid = FALSE;
192 * Clean up after a successful call to vm_fault_object() so another call
193 * to vm_fault_object() can be made.
196 _cleanup_successful_fault(struct faultstate *fs, int relock)
198 if (fs->object != fs->first_object) {
199 vm_page_free(fs->first_m);
200 vm_object_pip_wakeup(fs->object);
203 fs->object = fs->first_object;
204 if (relock && fs->lookup_still_valid == FALSE) {
206 vm_map_lock_read(fs->map);
207 fs->lookup_still_valid = TRUE;
212 _unlock_things(struct faultstate *fs, int dealloc)
214 _cleanup_successful_fault(fs, 0);
216 /*vm_object_deallocate(fs->first_object);*/
217 /*fs->first_object = NULL; drop used later on */
220 if (fs->vp != NULL) {
226 #define unlock_things(fs) _unlock_things(fs, 0)
227 #define unlock_and_deallocate(fs) _unlock_things(fs, 1)
228 #define cleanup_successful_fault(fs) _cleanup_successful_fault(fs, 1)
233 * Determine if the pager for the current object *might* contain the page.
235 * We only need to try the pager if this is not a default object (default
236 * objects are zero-fill and have no real pager), and if we are not taking
237 * a wiring fault or if the FS entry is wired.
239 #define TRYPAGER(fs) \
240 (fs->object->type != OBJT_DEFAULT && \
241 (((fs->fault_flags & VM_FAULT_WIRE_MASK) == 0) || fs->wired))
246 * Handle a page fault occuring at the given address, requiring the given
247 * permissions, in the map specified. If successful, the page is inserted
248 * into the associated physical map.
250 * NOTE: The given address should be truncated to the proper page address.
252 * KERN_SUCCESS is returned if the page fault is handled; otherwise,
253 * a standard error specifying why the fault is fatal is returned.
255 * The map in question must be referenced, and remains so.
256 * The caller may hold no locks.
257 * No other requirements.
260 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, int fault_flags)
263 vm_pindex_t first_pindex;
264 struct faultstate fs;
268 vm_page_pcpu_cache();
270 fs.fault_flags = fault_flags;
274 if ((lp = curthread->td_lwp) != NULL)
275 lp->lwp_flags |= LWP_PAGING;
277 lwkt_gettoken(&map->token);
281 * Find the vm_map_entry representing the backing store and resolve
282 * the top level object and page index. This may have the side
283 * effect of executing a copy-on-write on the map entry and/or
284 * creating a shadow object, but will not COW any actual VM pages.
286 * On success fs.map is left read-locked and various other fields
287 * are initialized but not otherwise referenced or locked.
289 * NOTE! vm_map_lookup will try to upgrade the fault_type to
290 * VM_FAULT_WRITE if the map entry is a virtual page table and also
291 * writable, so we can set the 'A'accessed bit in the virtual page
295 result = vm_map_lookup(&fs.map, vaddr, fault_type,
296 &fs.entry, &fs.first_object,
297 &first_pindex, &fs.first_prot, &fs.wired);
300 * If the lookup failed or the map protections are incompatible,
301 * the fault generally fails. However, if the caller is trying
302 * to do a user wiring we have more work to do.
304 if (result != KERN_SUCCESS) {
305 if (result != KERN_PROTECTION_FAILURE ||
306 (fs.fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE)
308 if (result == KERN_INVALID_ADDRESS && growstack &&
309 map != &kernel_map && curproc != NULL) {
310 result = vm_map_growstack(curproc, vaddr);
311 if (result == KERN_SUCCESS) {
315 result = KERN_FAILURE;
321 * If we are user-wiring a r/w segment, and it is COW, then
322 * we need to do the COW operation. Note that we don't
323 * currently COW RO sections now, because it is NOT desirable
324 * to COW .text. We simply keep .text from ever being COW'ed
325 * and take the heat that one cannot debug wired .text sections.
327 result = vm_map_lookup(&fs.map, vaddr,
328 VM_PROT_READ|VM_PROT_WRITE|
329 VM_PROT_OVERRIDE_WRITE,
330 &fs.entry, &fs.first_object,
331 &first_pindex, &fs.first_prot,
333 if (result != KERN_SUCCESS) {
334 result = KERN_FAILURE;
339 * If we don't COW now, on a user wire, the user will never
340 * be able to write to the mapping. If we don't make this
341 * restriction, the bookkeeping would be nearly impossible.
343 * XXX We have a shared lock, this will have a MP race but
344 * I don't see how it can hurt anything.
346 if ((fs.entry->protection & VM_PROT_WRITE) == 0)
347 fs.entry->max_protection &= ~VM_PROT_WRITE;
351 * fs.map is read-locked
353 * Misc checks. Save the map generation number to detect races.
355 fs.map_generation = fs.map->timestamp;
356 fs.lookup_still_valid = TRUE;
358 fs.object = fs.first_object; /* so unlock_and_deallocate works */
362 if (fs.entry->eflags & (MAP_ENTRY_NOFAULT | MAP_ENTRY_KSTACK)) {
363 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
364 panic("vm_fault: fault on nofault entry, addr: %p",
367 if ((fs.entry->eflags & MAP_ENTRY_KSTACK) &&
368 vaddr >= fs.entry->start &&
369 vaddr < fs.entry->start + PAGE_SIZE) {
370 panic("vm_fault: fault on stack guard, addr: %p",
376 * A system map entry may return a NULL object. No object means
377 * no pager means an unrecoverable kernel fault.
379 if (fs.first_object == NULL) {
380 panic("vm_fault: unrecoverable fault at %p in entry %p",
381 (void *)vaddr, fs.entry);
385 * Fail here if not a trivial anonymous page fault and TDF_NOFAULT
388 if ((curthread->td_flags & TDF_NOFAULT) &&
389 (fs.first_object->type == OBJT_VNODE ||
390 fs.first_object->backing_object)) {
391 result = KERN_FAILURE;
397 * Attempt to shortcut the fault if the lookup returns a
398 * terminal object and the page is present. This allows us
399 * to obtain a shared token on the object instead of an exclusive
400 * token, which theoretically should allow concurrent faults.
402 * We cannot acquire a shared token on kernel_map, at least not
403 * on i386, because the i386 pmap code uses the kernel_object for
404 * its page table page management, resulting in a shared->exclusive
405 * sequence which will deadlock. This will not happen normally
406 * anyway, except on well cached pageable kmem (like pipe buffers),
407 * so it should not impact performance.
409 if (vm_shared_fault &&
410 fs.first_object->backing_object == NULL &&
411 fs.entry->maptype == VM_MAPTYPE_NORMAL &&
412 fs.map != &kernel_map) {
414 vm_object_hold_shared(fs.first_object);
415 /*fs.vp = vnode_pager_lock(fs.first_object);*/
416 fs.m = vm_page_lookup_busy_try(fs.first_object,
419 if (error == 0 && fs.m) {
421 * Activate the page and figure out if we can
422 * short-cut a quick mapping.
424 * WARNING! We cannot call swap_pager_unswapped()
425 * with a shared token! Note that we
426 * have to test fs.first_prot here.
428 vm_page_activate(fs.m);
429 if (fs.m->valid == VM_PAGE_BITS_ALL &&
430 ((fs.m->flags & PG_SWAPPED) == 0 ||
431 (fs.first_prot & VM_PROT_WRITE) == 0 ||
432 (fs.fault_flags & VM_FAULT_DIRTY) == 0)) {
433 fs.lookup_still_valid = TRUE;
435 fs.object = fs.first_object;
436 fs.prot = fs.first_prot;
438 fault_type = fs.first_prot;
439 if (fs.prot & VM_PROT_WRITE) {
440 vm_object_set_writeable_dirty(
442 vm_set_nosync(fs.m, fs.entry);
443 if (fs.fault_flags & VM_FAULT_DIRTY) {
446 swap_pager_unswapped(fs.m);
449 result = KERN_SUCCESS;
450 fault_flags |= VM_FAULT_BURST_QUICK;
451 fault_flags &= ~VM_FAULT_BURST;
455 vm_page_wakeup(fs.m);
458 vm_object_drop(fs.first_object); /* XXX drop on shared tok?*/
463 * Bump the paging-in-progress count to prevent size changes (e.g.
464 * truncation operations) during I/O. This must be done after
465 * obtaining the vnode lock in order to avoid possible deadlocks.
467 vm_object_hold(fs.first_object);
469 fs.vp = vnode_pager_lock(fs.first_object);
472 fs.lookup_still_valid = TRUE;
474 fs.object = fs.first_object; /* so unlock_and_deallocate works */
479 * If the entry is wired we cannot change the page protection.
482 fault_type = fs.first_prot;
485 * The page we want is at (first_object, first_pindex), but if the
486 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the
487 * page table to figure out the actual pindex.
489 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION
492 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
493 result = vm_fault_vpagetable(&fs, &first_pindex,
494 fs.entry->aux.master_pde,
496 if (result == KERN_TRY_AGAIN) {
497 vm_object_drop(fs.first_object);
500 if (result != KERN_SUCCESS)
505 * Now we have the actual (object, pindex), fault in the page. If
506 * vm_fault_object() fails it will unlock and deallocate the FS
507 * data. If it succeeds everything remains locked and fs->object
508 * will have an additional PIP count if it is not equal to
511 * vm_fault_object will set fs->prot for the pmap operation. It is
512 * allowed to set VM_PROT_WRITE if fault_type == VM_PROT_READ if the
513 * page can be safely written. However, it will force a read-only
514 * mapping for a read fault if the memory is managed by a virtual
517 * If the fault code uses the shared object lock shortcut
518 * we must not try to burst (we can't allocate VM pages).
520 result = vm_fault_object(&fs, first_pindex, fault_type);
522 fault_flags &= ~VM_FAULT_BURST;
524 if (result == KERN_TRY_AGAIN) {
525 vm_object_drop(fs.first_object);
528 if (result != KERN_SUCCESS)
533 * On success vm_fault_object() does not unlock or deallocate, and fs.m
534 * will contain a busied page.
536 * Enter the page into the pmap and do pmap-related adjustments.
538 vm_page_flag_set(fs.m, PG_REFERENCED);
539 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot, fs.wired, fs.entry);
540 mycpu->gd_cnt.v_vm_faults++;
541 if (curthread->td_lwp)
542 ++curthread->td_lwp->lwp_ru.ru_minflt;
544 /*KKASSERT(fs.m->queue == PQ_NONE); page-in op may deactivate page */
545 KKASSERT(fs.m->flags & PG_BUSY);
548 * If the page is not wired down, then put it where the pageout daemon
551 if (fs.fault_flags & VM_FAULT_WIRE_MASK) {
555 vm_page_unwire(fs.m, 1);
557 vm_page_activate(fs.m);
559 vm_page_wakeup(fs.m);
562 * Burst in a few more pages if possible. The fs.map should still
563 * be locked. To avoid interlocking against a vnode->getblk
564 * operation we had to be sure to unbusy our primary vm_page above
567 if (fault_flags & VM_FAULT_BURST) {
568 if ((fs.fault_flags & VM_FAULT_WIRE_MASK) == 0
570 vm_prefault(fs.map->pmap, vaddr,
571 fs.entry, fs.prot, fault_flags);
574 if (fault_flags & VM_FAULT_BURST_QUICK) {
575 if ((fs.fault_flags & VM_FAULT_WIRE_MASK) == 0
577 vm_prefault_quick(fs.map->pmap, vaddr,
578 fs.entry, fs.prot, fault_flags);
583 * Unlock everything, and return
587 if (curthread->td_lwp) {
589 curthread->td_lwp->lwp_ru.ru_majflt++;
591 curthread->td_lwp->lwp_ru.ru_minflt++;
595 /*vm_object_deallocate(fs.first_object);*/
597 /*fs.first_object = NULL; must still drop later */
599 result = KERN_SUCCESS;
602 vm_object_drop(fs.first_object);
604 lwkt_reltoken(&map->token);
606 lp->lwp_flags &= ~LWP_PAGING;
611 * Fault in the specified virtual address in the current process map,
612 * returning a held VM page or NULL. See vm_fault_page() for more
618 vm_fault_page_quick(vm_offset_t va, vm_prot_t fault_type, int *errorp)
620 struct lwp *lp = curthread->td_lwp;
623 m = vm_fault_page(&lp->lwp_vmspace->vm_map, va,
624 fault_type, VM_FAULT_NORMAL, errorp);
629 * Fault in the specified virtual address in the specified map, doing all
630 * necessary manipulation of the object store and all necessary I/O. Return
631 * a held VM page or NULL, and set *errorp. The related pmap is not
634 * The returned page will be properly dirtied if VM_PROT_WRITE was specified,
635 * and marked PG_REFERENCED as well.
637 * If the page cannot be faulted writable and VM_PROT_WRITE was specified, an
638 * error will be returned.
643 vm_fault_page(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
644 int fault_flags, int *errorp)
646 vm_pindex_t first_pindex;
647 struct faultstate fs;
649 vm_prot_t orig_fault_type = fault_type;
652 fs.fault_flags = fault_flags;
653 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0);
655 lwkt_gettoken(&map->token);
659 * Find the vm_map_entry representing the backing store and resolve
660 * the top level object and page index. This may have the side
661 * effect of executing a copy-on-write on the map entry and/or
662 * creating a shadow object, but will not COW any actual VM pages.
664 * On success fs.map is left read-locked and various other fields
665 * are initialized but not otherwise referenced or locked.
667 * NOTE! vm_map_lookup will upgrade the fault_type to VM_FAULT_WRITE
668 * if the map entry is a virtual page table and also writable,
669 * so we can set the 'A'accessed bit in the virtual page table entry.
672 result = vm_map_lookup(&fs.map, vaddr, fault_type,
673 &fs.entry, &fs.first_object,
674 &first_pindex, &fs.first_prot, &fs.wired);
676 if (result != KERN_SUCCESS) {
683 * fs.map is read-locked
685 * Misc checks. Save the map generation number to detect races.
687 fs.map_generation = fs.map->timestamp;
688 fs.lookup_still_valid = TRUE;
690 fs.object = fs.first_object; /* so unlock_and_deallocate works */
694 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
695 panic("vm_fault: fault on nofault entry, addr: %lx",
700 * A system map entry may return a NULL object. No object means
701 * no pager means an unrecoverable kernel fault.
703 if (fs.first_object == NULL) {
704 panic("vm_fault: unrecoverable fault at %p in entry %p",
705 (void *)vaddr, fs.entry);
709 * Fail here if not a trivial anonymous page fault and TDF_NOFAULT
712 if ((curthread->td_flags & TDF_NOFAULT) &&
713 (fs.first_object->type == OBJT_VNODE ||
714 fs.first_object->backing_object)) {
715 *errorp = KERN_FAILURE;
721 * Make a reference to this object to prevent its disposal while we
722 * are messing with it. Once we have the reference, the map is free
723 * to be diddled. Since objects reference their shadows (and copies),
724 * they will stay around as well.
726 * The reference should also prevent an unexpected collapse of the
727 * parent that might move pages from the current object into the
728 * parent unexpectedly, resulting in corruption.
730 * Bump the paging-in-progress count to prevent size changes (e.g.
731 * truncation operations) during I/O. This must be done after
732 * obtaining the vnode lock in order to avoid possible deadlocks.
734 vm_object_hold(fs.first_object);
735 fs.vp = vnode_pager_lock(fs.first_object);
738 fs.lookup_still_valid = TRUE;
740 fs.object = fs.first_object; /* so unlock_and_deallocate works */
745 * If the entry is wired we cannot change the page protection.
748 fault_type = fs.first_prot;
751 * The page we want is at (first_object, first_pindex), but if the
752 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the
753 * page table to figure out the actual pindex.
755 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION
758 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
759 result = vm_fault_vpagetable(&fs, &first_pindex,
760 fs.entry->aux.master_pde,
762 if (result == KERN_TRY_AGAIN) {
763 vm_object_drop(fs.first_object);
766 if (result != KERN_SUCCESS) {
774 * Now we have the actual (object, pindex), fault in the page. If
775 * vm_fault_object() fails it will unlock and deallocate the FS
776 * data. If it succeeds everything remains locked and fs->object
777 * will have an additinal PIP count if it is not equal to
781 result = vm_fault_object(&fs, first_pindex, fault_type);
783 if (result == KERN_TRY_AGAIN) {
784 vm_object_drop(fs.first_object);
787 if (result != KERN_SUCCESS) {
793 if ((orig_fault_type & VM_PROT_WRITE) &&
794 (fs.prot & VM_PROT_WRITE) == 0) {
795 *errorp = KERN_PROTECTION_FAILURE;
796 unlock_and_deallocate(&fs);
802 * DO NOT UPDATE THE PMAP!!! This function may be called for
803 * a pmap unrelated to the current process pmap, in which case
804 * the current cpu core will not be listed in the pmap's pm_active
805 * mask. Thus invalidation interlocks will fail to work properly.
807 * (for example, 'ps' uses procfs to read program arguments from
808 * each process's stack).
810 * In addition to the above this function will be called to acquire
811 * a page that might already be faulted in, re-faulting it
812 * continuously is a waste of time.
814 * XXX could this have been the cause of our random seg-fault
815 * issues? procfs accesses user stacks.
817 vm_page_flag_set(fs.m, PG_REFERENCED);
819 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot, fs.wired, NULL);
820 mycpu->gd_cnt.v_vm_faults++;
821 if (curthread->td_lwp)
822 ++curthread->td_lwp->lwp_ru.ru_minflt;
826 * On success vm_fault_object() does not unlock or deallocate, and fs.m
827 * will contain a busied page. So we must unlock here after having
828 * messed with the pmap.
833 * Return a held page. We are not doing any pmap manipulation so do
834 * not set PG_MAPPED. However, adjust the page flags according to
835 * the fault type because the caller may not use a managed pmapping
836 * (so we don't want to lose the fact that the page will be dirtied
837 * if a write fault was specified).
840 vm_page_activate(fs.m);
841 if (fault_type & VM_PROT_WRITE)
844 if (curthread->td_lwp) {
846 curthread->td_lwp->lwp_ru.ru_majflt++;
848 curthread->td_lwp->lwp_ru.ru_minflt++;
853 * Unlock everything, and return the held page.
855 vm_page_wakeup(fs.m);
856 /*vm_object_deallocate(fs.first_object);*/
857 /*fs.first_object = NULL; */
862 vm_object_drop(fs.first_object);
864 lwkt_reltoken(&map->token);
869 * Fault in the specified (object,offset), dirty the returned page as
870 * needed. If the requested fault_type cannot be done NULL and an
873 * A held (but not busied) page is returned.
878 vm_fault_object_page(vm_object_t object, vm_ooffset_t offset,
879 vm_prot_t fault_type, int fault_flags,
880 int shared, int *errorp)
883 vm_pindex_t first_pindex;
884 struct faultstate fs;
885 struct vm_map_entry entry;
887 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
888 bzero(&entry, sizeof(entry));
889 entry.object.vm_object = object;
890 entry.maptype = VM_MAPTYPE_NORMAL;
891 entry.protection = entry.max_protection = fault_type;
894 fs.fault_flags = fault_flags;
896 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0);
900 fs.first_object = object;
901 first_pindex = OFF_TO_IDX(offset);
903 fs.first_prot = fault_type;
906 /*fs.map_generation = 0; unused */
909 * Make a reference to this object to prevent its disposal while we
910 * are messing with it. Once we have the reference, the map is free
911 * to be diddled. Since objects reference their shadows (and copies),
912 * they will stay around as well.
914 * The reference should also prevent an unexpected collapse of the
915 * parent that might move pages from the current object into the
916 * parent unexpectedly, resulting in corruption.
918 * Bump the paging-in-progress count to prevent size changes (e.g.
919 * truncation operations) during I/O. This must be done after
920 * obtaining the vnode lock in order to avoid possible deadlocks.
922 fs.vp = vnode_pager_lock(fs.first_object);
924 fs.lookup_still_valid = TRUE;
926 fs.object = fs.first_object; /* so unlock_and_deallocate works */
929 /* XXX future - ability to operate on VM object using vpagetable */
930 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
931 result = vm_fault_vpagetable(&fs, &first_pindex,
932 fs.entry->aux.master_pde,
934 if (result == KERN_TRY_AGAIN)
936 if (result != KERN_SUCCESS) {
944 * Now we have the actual (object, pindex), fault in the page. If
945 * vm_fault_object() fails it will unlock and deallocate the FS
946 * data. If it succeeds everything remains locked and fs->object
947 * will have an additinal PIP count if it is not equal to
950 result = vm_fault_object(&fs, first_pindex, fault_type);
952 if (result == KERN_TRY_AGAIN)
954 if (result != KERN_SUCCESS) {
959 if ((fault_type & VM_PROT_WRITE) && (fs.prot & VM_PROT_WRITE) == 0) {
960 *errorp = KERN_PROTECTION_FAILURE;
961 unlock_and_deallocate(&fs);
966 * On success vm_fault_object() does not unlock or deallocate, so we
967 * do it here. Note that the returned fs.m will be busied.
972 * Return a held page. We are not doing any pmap manipulation so do
973 * not set PG_MAPPED. However, adjust the page flags according to
974 * the fault type because the caller may not use a managed pmapping
975 * (so we don't want to lose the fact that the page will be dirtied
976 * if a write fault was specified).
979 vm_page_activate(fs.m);
980 if ((fault_type & VM_PROT_WRITE) || (fault_flags & VM_FAULT_DIRTY))
982 if (fault_flags & VM_FAULT_UNSWAP)
983 swap_pager_unswapped(fs.m);
986 * Indicate that the page was accessed.
988 vm_page_flag_set(fs.m, PG_REFERENCED);
990 if (curthread->td_lwp) {
992 curthread->td_lwp->lwp_ru.ru_majflt++;
994 curthread->td_lwp->lwp_ru.ru_minflt++;
999 * Unlock everything, and return the held page.
1001 vm_page_wakeup(fs.m);
1002 /*vm_object_deallocate(fs.first_object);*/
1003 /*fs.first_object = NULL; */
1010 * Translate the virtual page number (first_pindex) that is relative
1011 * to the address space into a logical page number that is relative to the
1012 * backing object. Use the virtual page table pointed to by (vpte).
1014 * This implements an N-level page table. Any level can terminate the
1015 * scan by setting VPTE_PS. A linear mapping is accomplished by setting
1016 * VPTE_PS in the master page directory entry set via mcontrol(MADV_SETMAP).
1020 vm_fault_vpagetable(struct faultstate *fs, vm_pindex_t *pindex,
1021 vpte_t vpte, int fault_type)
1024 struct lwbuf lwb_cache;
1025 int vshift = VPTE_FRAME_END - PAGE_SHIFT; /* index bits remaining */
1026 int result = KERN_SUCCESS;
1029 ASSERT_LWKT_TOKEN_HELD(vm_object_token(fs->first_object));
1032 * We cannot proceed if the vpte is not valid, not readable
1033 * for a read fault, or not writable for a write fault.
1035 if ((vpte & VPTE_V) == 0) {
1036 unlock_and_deallocate(fs);
1037 return (KERN_FAILURE);
1039 if ((fault_type & VM_PROT_READ) && (vpte & VPTE_R) == 0) {
1040 unlock_and_deallocate(fs);
1041 return (KERN_FAILURE);
1043 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_W) == 0) {
1044 unlock_and_deallocate(fs);
1045 return (KERN_FAILURE);
1047 if ((vpte & VPTE_PS) || vshift == 0)
1049 KKASSERT(vshift >= VPTE_PAGE_BITS);
1052 * Get the page table page. Nominally we only read the page
1053 * table, but since we are actively setting VPTE_M and VPTE_A,
1054 * tell vm_fault_object() that we are writing it.
1056 * There is currently no real need to optimize this.
1058 result = vm_fault_object(fs, (vpte & VPTE_FRAME) >> PAGE_SHIFT,
1059 VM_PROT_READ|VM_PROT_WRITE);
1060 if (result != KERN_SUCCESS)
1064 * Process the returned fs.m and look up the page table
1065 * entry in the page table page.
1067 vshift -= VPTE_PAGE_BITS;
1068 lwb = lwbuf_alloc(fs->m, &lwb_cache);
1069 ptep = ((vpte_t *)lwbuf_kva(lwb) +
1070 ((*pindex >> vshift) & VPTE_PAGE_MASK));
1074 * Page table write-back. If the vpte is valid for the
1075 * requested operation, do a write-back to the page table.
1077 * XXX VPTE_M is not set properly for page directory pages.
1078 * It doesn't get set in the page directory if the page table
1079 * is modified during a read access.
1081 vm_page_activate(fs->m);
1082 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_V) &&
1084 if ((vpte & (VPTE_M|VPTE_A)) != (VPTE_M|VPTE_A)) {
1085 atomic_set_long(ptep, VPTE_M | VPTE_A);
1086 vm_page_dirty(fs->m);
1089 if ((fault_type & VM_PROT_READ) && (vpte & VPTE_V) &&
1091 if ((vpte & VPTE_A) == 0) {
1092 atomic_set_long(ptep, VPTE_A);
1093 vm_page_dirty(fs->m);
1097 vm_page_flag_set(fs->m, PG_REFERENCED);
1098 vm_page_wakeup(fs->m);
1100 cleanup_successful_fault(fs);
1103 * Combine remaining address bits with the vpte.
1105 /* JG how many bits from each? */
1106 *pindex = ((vpte & VPTE_FRAME) >> PAGE_SHIFT) +
1107 (*pindex & ((1L << vshift) - 1));
1108 return (KERN_SUCCESS);
1113 * This is the core of the vm_fault code.
1115 * Do all operations required to fault-in (fs.first_object, pindex). Run
1116 * through the shadow chain as necessary and do required COW or virtual
1117 * copy operations. The caller has already fully resolved the vm_map_entry
1118 * and, if appropriate, has created a copy-on-write layer. All we need to
1119 * do is iterate the object chain.
1121 * On failure (fs) is unlocked and deallocated and the caller may return or
1122 * retry depending on the failure code. On success (fs) is NOT unlocked or
1123 * deallocated, fs.m will contained a resolved, busied page, and fs.object
1124 * will have an additional PIP count if it is not equal to fs.first_object.
1126 * fs->first_object must be held on call.
1130 vm_fault_object(struct faultstate *fs,
1131 vm_pindex_t first_pindex, vm_prot_t fault_type)
1133 vm_object_t next_object;
1137 ASSERT_LWKT_TOKEN_HELD(vm_object_token(fs->first_object));
1138 fs->prot = fs->first_prot;
1139 fs->object = fs->first_object;
1140 pindex = first_pindex;
1142 vm_object_chain_acquire(fs->first_object);
1143 vm_object_pip_add(fs->first_object, 1);
1146 * If a read fault occurs we try to make the page writable if
1147 * possible. There are three cases where we cannot make the
1148 * page mapping writable:
1150 * (1) The mapping is read-only or the VM object is read-only,
1151 * fs->prot above will simply not have VM_PROT_WRITE set.
1153 * (2) If the mapping is a virtual page table we need to be able
1154 * to detect writes so we can set VPTE_M in the virtual page
1157 * (3) If the VM page is read-only or copy-on-write, upgrading would
1158 * just result in an unnecessary COW fault.
1160 * VM_PROT_VPAGED is set if faulting via a virtual page table and
1161 * causes adjustments to the 'M'odify bit to also turn off write
1162 * access to force a re-fault.
1164 if (fs->entry->maptype == VM_MAPTYPE_VPAGETABLE) {
1165 if ((fault_type & VM_PROT_WRITE) == 0)
1166 fs->prot &= ~VM_PROT_WRITE;
1169 /* vm_object_hold(fs->object); implied b/c object == first_object */
1173 * The entire backing chain from first_object to object
1174 * inclusive is chainlocked.
1176 * If the object is dead, we stop here
1178 * vm_shared_fault (fs->shared != 0) case: nothing special.
1180 if (fs->object->flags & OBJ_DEAD) {
1181 vm_object_pip_wakeup(fs->first_object);
1182 vm_object_chain_release_all(fs->first_object,
1184 if (fs->object != fs->first_object)
1185 vm_object_drop(fs->object);
1186 unlock_and_deallocate(fs);
1187 return (KERN_PROTECTION_FAILURE);
1191 * See if the page is resident. Wait/Retry if the page is
1192 * busy (lots of stuff may have changed so we can't continue
1195 * We can theoretically allow the soft-busy case on a read
1196 * fault if the page is marked valid, but since such
1197 * pages are typically already pmap'd, putting that
1198 * special case in might be more effort then it is
1199 * worth. We cannot under any circumstances mess
1200 * around with a vm_page_t->busy page except, perhaps,
1203 * vm_shared_fault (fs->shared != 0) case:
1204 * error nothing special
1205 * fs->m relock excl if I/O needed
1208 fs->m = vm_page_lookup_busy_try(fs->object, pindex,
1211 vm_object_pip_wakeup(fs->first_object);
1212 vm_object_chain_release_all(fs->first_object,
1214 if (fs->object != fs->first_object)
1215 vm_object_drop(fs->object);
1217 vm_page_sleep_busy(fs->m, TRUE, "vmpfw");
1218 mycpu->gd_cnt.v_intrans++;
1219 /*vm_object_deallocate(fs->first_object);*/
1220 /*fs->first_object = NULL;*/
1222 return (KERN_TRY_AGAIN);
1226 * The page is busied for us.
1228 * If reactivating a page from PQ_CACHE we may have
1231 int queue = fs->m->queue;
1232 vm_page_unqueue_nowakeup(fs->m);
1234 if ((queue - fs->m->pc) == PQ_CACHE &&
1235 vm_page_count_severe()) {
1236 vm_page_activate(fs->m);
1237 vm_page_wakeup(fs->m);
1239 vm_object_pip_wakeup(fs->first_object);
1240 vm_object_chain_release_all(fs->first_object,
1242 if (fs->object != fs->first_object)
1243 vm_object_drop(fs->object);
1244 unlock_and_deallocate(fs);
1246 return (KERN_TRY_AGAIN);
1250 * If it still isn't completely valid (readable),
1251 * or if a read-ahead-mark is set on the VM page,
1252 * jump to readrest, else we found the page and
1255 * We can release the spl once we have marked the
1258 if (fs->m->object != &kernel_object) {
1259 if ((fs->m->valid & VM_PAGE_BITS_ALL) !=
1262 vm_object_drop(fs->object);
1263 vm_object_hold(fs->object);
1268 if (fs->m->flags & PG_RAM) {
1271 vm_page_flag_clear(fs->m, PG_RAM);
1273 vm_object_drop(fs->object);
1274 vm_object_hold(fs->object);
1280 break; /* break to PAGE HAS BEEN FOUND */
1284 vm_object_drop(fs->object);
1285 vm_object_hold(fs->object);
1290 * Page is not resident, If this is the search termination
1291 * or the pager might contain the page, allocate a new page.
1293 if (TRYPAGER(fs) || fs->object == fs->first_object) {
1295 * If the page is beyond the object size we fail
1297 if (pindex >= fs->object->size) {
1298 vm_object_pip_wakeup(fs->first_object);
1299 vm_object_chain_release_all(fs->first_object,
1301 if (fs->object != fs->first_object)
1302 vm_object_drop(fs->object);
1303 unlock_and_deallocate(fs);
1304 return (KERN_PROTECTION_FAILURE);
1308 * Allocate a new page for this object/offset pair.
1310 * It is possible for the allocation to race, so
1314 if (!vm_page_count_severe()) {
1315 fs->m = vm_page_alloc(fs->object, pindex,
1316 ((fs->vp || fs->object->backing_object) ?
1317 VM_ALLOC_NULL_OK | VM_ALLOC_NORMAL :
1318 VM_ALLOC_NULL_OK | VM_ALLOC_NORMAL |
1319 VM_ALLOC_USE_GD | VM_ALLOC_ZERO));
1321 if (fs->m == NULL) {
1322 vm_object_pip_wakeup(fs->first_object);
1323 vm_object_chain_release_all(fs->first_object,
1325 if (fs->object != fs->first_object)
1326 vm_object_drop(fs->object);
1327 unlock_and_deallocate(fs);
1329 return (KERN_TRY_AGAIN);
1333 * Fall through to readrest. We have a new page which
1334 * will have to be paged (since m->valid will be 0).
1340 * We have found an invalid or partially valid page, a
1341 * page with a read-ahead mark which might be partially or
1342 * fully valid (and maybe dirty too), or we have allocated
1345 * Attempt to fault-in the page if there is a chance that the
1346 * pager has it, and potentially fault in additional pages
1349 * If TRYPAGER is true then fs.m will be non-NULL and busied
1355 u_char behavior = vm_map_entry_behavior(fs->entry);
1357 if (behavior == MAP_ENTRY_BEHAV_RANDOM)
1364 * If sequential access is detected then attempt
1365 * to deactivate/cache pages behind the scan to
1366 * prevent resource hogging.
1368 * Use of PG_RAM to detect sequential access
1369 * also simulates multi-zone sequential access
1370 * detection for free.
1372 * NOTE: Partially valid dirty pages cannot be
1373 * deactivated without causing NFS picemeal
1376 if ((fs->first_object->type != OBJT_DEVICE) &&
1377 (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL ||
1378 (behavior != MAP_ENTRY_BEHAV_RANDOM &&
1379 (fs->m->flags & PG_RAM)))
1381 vm_pindex_t scan_pindex;
1382 int scan_count = 16;
1384 if (first_pindex < 16) {
1388 scan_pindex = first_pindex - 16;
1389 if (scan_pindex < 16)
1390 scan_count = scan_pindex;
1395 while (scan_count) {
1398 mt = vm_page_lookup(fs->first_object,
1402 if (vm_page_busy_try(mt, TRUE))
1405 if (mt->valid != VM_PAGE_BITS_ALL) {
1410 (PG_FICTITIOUS | PG_UNMANAGED |
1418 vm_page_test_dirty(mt);
1422 vm_page_deactivate(mt);
1437 * Avoid deadlocking against the map when doing I/O.
1438 * fs.object and the page is PG_BUSY'd.
1440 * NOTE: Once unlocked, fs->entry can become stale
1441 * so this will NULL it out.
1443 * NOTE: fs->entry is invalid until we relock the
1444 * map and verify that the timestamp has not
1450 * Acquire the page data. We still hold a ref on
1451 * fs.object and the page has been PG_BUSY's.
1453 * The pager may replace the page (for example, in
1454 * order to enter a fictitious page into the
1455 * object). If it does so it is responsible for
1456 * cleaning up the passed page and properly setting
1457 * the new page PG_BUSY.
1459 * If we got here through a PG_RAM read-ahead
1460 * mark the page may be partially dirty and thus
1461 * not freeable. Don't bother checking to see
1462 * if the pager has the page because we can't free
1463 * it anyway. We have to depend on the get_page
1464 * operation filling in any gaps whether there is
1465 * backing store or not.
1467 rv = vm_pager_get_page(fs->object, &fs->m, seqaccess);
1469 if (rv == VM_PAGER_OK) {
1471 * Relookup in case pager changed page. Pager
1472 * is responsible for disposition of old page
1475 * XXX other code segments do relookups too.
1476 * It's a bad abstraction that needs to be
1479 fs->m = vm_page_lookup(fs->object, pindex);
1480 if (fs->m == NULL) {
1481 vm_object_pip_wakeup(fs->first_object);
1482 vm_object_chain_release_all(
1483 fs->first_object, fs->object);
1484 if (fs->object != fs->first_object)
1485 vm_object_drop(fs->object);
1486 unlock_and_deallocate(fs);
1487 return (KERN_TRY_AGAIN);
1491 break; /* break to PAGE HAS BEEN FOUND */
1495 * Remove the bogus page (which does not exist at this
1496 * object/offset); before doing so, we must get back
1497 * our object lock to preserve our invariant.
1499 * Also wake up any other process that may want to bring
1502 * If this is the top-level object, we must leave the
1503 * busy page to prevent another process from rushing
1504 * past us, and inserting the page in that object at
1505 * the same time that we are.
1507 if (rv == VM_PAGER_ERROR) {
1509 kprintf("vm_fault: pager read error, "
1514 kprintf("vm_fault: pager read error, "
1522 * Data outside the range of the pager or an I/O error
1524 * The page may have been wired during the pagein,
1525 * e.g. by the buffer cache, and cannot simply be
1526 * freed. Call vnode_pager_freepage() to deal with it.
1529 * XXX - the check for kernel_map is a kludge to work
1530 * around having the machine panic on a kernel space
1531 * fault w/ I/O error.
1533 if (((fs->map != &kernel_map) &&
1534 (rv == VM_PAGER_ERROR)) || (rv == VM_PAGER_BAD)) {
1535 vnode_pager_freepage(fs->m);
1537 vm_object_pip_wakeup(fs->first_object);
1538 vm_object_chain_release_all(fs->first_object,
1540 if (fs->object != fs->first_object)
1541 vm_object_drop(fs->object);
1542 unlock_and_deallocate(fs);
1543 if (rv == VM_PAGER_ERROR)
1544 return (KERN_FAILURE);
1546 return (KERN_PROTECTION_FAILURE);
1549 if (fs->object != fs->first_object) {
1550 vnode_pager_freepage(fs->m);
1553 * XXX - we cannot just fall out at this
1554 * point, m has been freed and is invalid!
1560 * We get here if the object has a default pager (or unwiring)
1561 * or the pager doesn't have the page.
1563 if (fs->object == fs->first_object)
1564 fs->first_m = fs->m;
1567 * Move on to the next object. The chain lock should prevent
1568 * the backing_object from getting ripped out from under us.
1570 * vm_shared_fault case:
1572 * If the next object is the last object and
1573 * vnode-backed (thus possibly shared), we can try a
1574 * shared object lock. There is no 'chain' for this
1575 * last object if vnode-backed (otherwise we would
1576 * need an exclusive lock).
1578 * fs->shared mode is very fragile and only works
1579 * under certain specific conditions, and is only
1580 * handled for those conditions in our loop. Essentially
1581 * it is designed only to be able to 'dip into' the
1582 * vnode's object and extract an already-cached page.
1585 if ((next_object = fs->object->backing_object) != NULL) {
1586 fs->shared = vm_object_hold_maybe_shared(next_object);
1587 vm_object_chain_acquire(next_object);
1588 KKASSERT(next_object == fs->object->backing_object);
1589 pindex += OFF_TO_IDX(fs->object->backing_object_offset);
1592 if (next_object == NULL) {
1594 * If there's no object left, fill the page in the top
1595 * object with zeros.
1597 if (fs->object != fs->first_object) {
1598 if (fs->first_object->backing_object !=
1600 vm_object_hold(fs->first_object->backing_object);
1602 vm_object_chain_release_all(
1603 fs->first_object->backing_object,
1605 if (fs->first_object->backing_object !=
1607 vm_object_drop(fs->first_object->backing_object);
1609 vm_object_pip_wakeup(fs->object);
1610 vm_object_drop(fs->object);
1611 fs->object = fs->first_object;
1612 pindex = first_pindex;
1613 fs->m = fs->first_m;
1618 * Zero the page if necessary and mark it valid.
1620 if ((fs->m->flags & PG_ZERO) == 0) {
1621 vm_page_zero_fill(fs->m);
1624 pmap_page_assertzero(VM_PAGE_TO_PHYS(fs->m));
1626 vm_page_flag_clear(fs->m, PG_ZERO);
1627 mycpu->gd_cnt.v_ozfod++;
1629 mycpu->gd_cnt.v_zfod++;
1630 fs->m->valid = VM_PAGE_BITS_ALL;
1631 break; /* break to PAGE HAS BEEN FOUND */
1633 if (fs->object != fs->first_object) {
1634 vm_object_pip_wakeup(fs->object);
1635 vm_object_lock_swap();
1636 vm_object_drop(fs->object);
1638 KASSERT(fs->object != next_object,
1639 ("object loop %p", next_object));
1640 fs->object = next_object;
1641 vm_object_pip_add(fs->object, 1);
1645 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
1648 * object still held.
1650 * If the page is being written, but isn't already owned by the
1651 * top-level object, we have to copy it into a new page owned by the
1654 KASSERT((fs->m->flags & PG_BUSY) != 0,
1655 ("vm_fault: not busy after main loop"));
1657 if (fs->object != fs->first_object) {
1659 * We only really need to copy if we want to write it.
1661 if (fault_type & VM_PROT_WRITE) {
1663 * This allows pages to be virtually copied from a
1664 * backing_object into the first_object, where the
1665 * backing object has no other refs to it, and cannot
1666 * gain any more refs. Instead of a bcopy, we just
1667 * move the page from the backing object to the
1668 * first object. Note that we must mark the page
1669 * dirty in the first object so that it will go out
1670 * to swap when needed.
1674 * Map, if present, has not changed
1677 fs->map_generation == fs->map->timestamp) &&
1679 * Only one shadow object
1681 (fs->object->shadow_count == 1) &&
1683 * No COW refs, except us
1685 (fs->object->ref_count == 1) &&
1687 * No one else can look this object up
1689 (fs->object->handle == NULL) &&
1691 * No other ways to look the object up
1693 ((fs->object->type == OBJT_DEFAULT) ||
1694 (fs->object->type == OBJT_SWAP)) &&
1696 * We don't chase down the shadow chain
1698 (fs->object == fs->first_object->backing_object) &&
1701 * grab the lock if we need to
1703 (fs->lookup_still_valid ||
1705 lockmgr(&fs->map->lock, LK_EXCLUSIVE|LK_NOWAIT) == 0)
1708 * (first_m) and (m) are both busied. We have
1709 * move (m) into (first_m)'s object/pindex
1710 * in an atomic fashion, then free (first_m).
1712 * first_object is held so second remove
1713 * followed by the rename should wind
1714 * up being atomic. vm_page_free() might
1715 * block so we don't do it until after the
1718 fs->lookup_still_valid = 1;
1719 vm_page_protect(fs->first_m, VM_PROT_NONE);
1720 vm_page_remove(fs->first_m);
1721 vm_page_rename(fs->m, fs->first_object,
1723 vm_page_free(fs->first_m);
1724 fs->first_m = fs->m;
1726 mycpu->gd_cnt.v_cow_optim++;
1729 * Oh, well, lets copy it.
1731 * Why are we unmapping the original page
1732 * here? Well, in short, not all accessors
1733 * of user memory go through the pmap. The
1734 * procfs code doesn't have access user memory
1735 * via a local pmap, so vm_fault_page*()
1736 * can't call pmap_enter(). And the umtx*()
1737 * code may modify the COW'd page via a DMAP
1738 * or kernel mapping and not via the pmap,
1739 * leaving the original page still mapped
1740 * read-only into the pmap.
1742 * So we have to remove the page from at
1743 * least the current pmap if it is in it.
1744 * Just remove it from all pmaps.
1746 vm_page_copy(fs->m, fs->first_m);
1747 vm_page_protect(fs->m, VM_PROT_NONE);
1748 vm_page_event(fs->m, VMEVENT_COW);
1753 * We no longer need the old page or object.
1759 * We intend to revert to first_object, undo the
1760 * chain lock through to that.
1762 if (fs->first_object->backing_object != fs->object)
1763 vm_object_hold(fs->first_object->backing_object);
1764 vm_object_chain_release_all(
1765 fs->first_object->backing_object,
1767 if (fs->first_object->backing_object != fs->object)
1768 vm_object_drop(fs->first_object->backing_object);
1771 * fs->object != fs->first_object due to above
1774 vm_object_pip_wakeup(fs->object);
1775 vm_object_drop(fs->object);
1778 * Only use the new page below...
1781 mycpu->gd_cnt.v_cow_faults++;
1782 fs->m = fs->first_m;
1783 fs->object = fs->first_object;
1784 pindex = first_pindex;
1787 * If it wasn't a write fault avoid having to copy
1788 * the page by mapping it read-only.
1790 fs->prot &= ~VM_PROT_WRITE;
1795 * Relock the map if necessary, then check the generation count.
1796 * relock_map() will update fs->timestamp to account for the
1797 * relocking if necessary.
1799 * If the count has changed after relocking then all sorts of
1800 * crap may have happened and we have to retry.
1802 * NOTE: The relock_map() can fail due to a deadlock against
1803 * the vm_page we are holding BUSY.
1805 if (fs->lookup_still_valid == FALSE && fs->map) {
1806 if (relock_map(fs) ||
1807 fs->map->timestamp != fs->map_generation) {
1809 vm_object_pip_wakeup(fs->first_object);
1810 vm_object_chain_release_all(fs->first_object,
1812 if (fs->object != fs->first_object)
1813 vm_object_drop(fs->object);
1814 unlock_and_deallocate(fs);
1815 return (KERN_TRY_AGAIN);
1820 * If the fault is a write, we know that this page is being
1821 * written NOW so dirty it explicitly to save on pmap_is_modified()
1824 * If this is a NOSYNC mmap we do not want to set PG_NOSYNC
1825 * if the page is already dirty to prevent data written with
1826 * the expectation of being synced from not being synced.
1827 * Likewise if this entry does not request NOSYNC then make
1828 * sure the page isn't marked NOSYNC. Applications sharing
1829 * data should use the same flags to avoid ping ponging.
1831 * Also tell the backing pager, if any, that it should remove
1832 * any swap backing since the page is now dirty.
1834 vm_page_activate(fs->m);
1835 if (fs->prot & VM_PROT_WRITE) {
1836 vm_object_set_writeable_dirty(fs->m->object);
1837 vm_set_nosync(fs->m, fs->entry);
1838 if (fs->fault_flags & VM_FAULT_DIRTY) {
1839 vm_page_dirty(fs->m);
1840 swap_pager_unswapped(fs->m);
1844 vm_object_pip_wakeup(fs->first_object);
1845 vm_object_chain_release_all(fs->first_object, fs->object);
1846 if (fs->object != fs->first_object)
1847 vm_object_drop(fs->object);
1850 * Page had better still be busy. We are still locked up and
1851 * fs->object will have another PIP reference if it is not equal
1852 * to fs->first_object.
1854 KASSERT(fs->m->flags & PG_BUSY,
1855 ("vm_fault: page %p not busy!", fs->m));
1858 * Sanity check: page must be completely valid or it is not fit to
1859 * map into user space. vm_pager_get_pages() ensures this.
1861 if (fs->m->valid != VM_PAGE_BITS_ALL) {
1862 vm_page_zero_invalid(fs->m, TRUE);
1863 kprintf("Warning: page %p partially invalid on fault\n", fs->m);
1865 vm_page_flag_clear(fs->m, PG_ZERO);
1867 return (KERN_SUCCESS);
1871 * Wire down a range of virtual addresses in a map. The entry in question
1872 * should be marked in-transition and the map must be locked. We must
1873 * release the map temporarily while faulting-in the page to avoid a
1874 * deadlock. Note that the entry may be clipped while we are blocked but
1875 * will never be freed.
1880 vm_fault_wire(vm_map_t map, vm_map_entry_t entry, boolean_t user_wire)
1882 boolean_t fictitious;
1891 lwkt_gettoken(&map->token);
1893 pmap = vm_map_pmap(map);
1894 start = entry->start;
1896 fictitious = entry->object.vm_object &&
1897 (entry->object.vm_object->type == OBJT_DEVICE);
1898 if (entry->eflags & MAP_ENTRY_KSTACK)
1904 * We simulate a fault to get the page and enter it in the physical
1907 for (va = start; va < end; va += PAGE_SIZE) {
1909 rv = vm_fault(map, va, VM_PROT_READ,
1910 VM_FAULT_USER_WIRE);
1912 rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE,
1913 VM_FAULT_CHANGE_WIRING);
1916 while (va > start) {
1918 if ((pa = pmap_extract(pmap, va)) == 0)
1920 pmap_change_wiring(pmap, va, FALSE, entry);
1922 m = PHYS_TO_VM_PAGE(pa);
1923 vm_page_busy_wait(m, FALSE, "vmwrpg");
1924 vm_page_unwire(m, 1);
1934 lwkt_reltoken(&map->token);
1939 * Unwire a range of virtual addresses in a map. The map should be
1943 vm_fault_unwire(vm_map_t map, vm_map_entry_t entry)
1945 boolean_t fictitious;
1953 lwkt_gettoken(&map->token);
1955 pmap = vm_map_pmap(map);
1956 start = entry->start;
1958 fictitious = entry->object.vm_object &&
1959 (entry->object.vm_object->type == OBJT_DEVICE);
1960 if (entry->eflags & MAP_ENTRY_KSTACK)
1964 * Since the pages are wired down, we must be able to get their
1965 * mappings from the physical map system.
1967 for (va = start; va < end; va += PAGE_SIZE) {
1968 pa = pmap_extract(pmap, va);
1970 pmap_change_wiring(pmap, va, FALSE, entry);
1972 m = PHYS_TO_VM_PAGE(pa);
1973 vm_page_busy_wait(m, FALSE, "vmwupg");
1974 vm_page_unwire(m, 1);
1979 lwkt_reltoken(&map->token);
1983 * Copy all of the pages from a wired-down map entry to another.
1985 * The source and destination maps must be locked for write.
1986 * The source and destination maps token must be held
1987 * The source map entry must be wired down (or be a sharing map
1988 * entry corresponding to a main map entry that is wired down).
1990 * No other requirements.
1992 * XXX do segment optimization
1995 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
1996 vm_map_entry_t dst_entry, vm_map_entry_t src_entry)
1998 vm_object_t dst_object;
1999 vm_object_t src_object;
2000 vm_ooffset_t dst_offset;
2001 vm_ooffset_t src_offset;
2007 src_object = src_entry->object.vm_object;
2008 src_offset = src_entry->offset;
2011 * Create the top-level object for the destination entry. (Doesn't
2012 * actually shadow anything - we copy the pages directly.)
2014 vm_map_entry_allocate_object(dst_entry);
2015 dst_object = dst_entry->object.vm_object;
2017 prot = dst_entry->max_protection;
2020 * Loop through all of the pages in the entry's range, copying each
2021 * one from the source object (it should be there) to the destination
2024 vm_object_hold(src_object);
2025 vm_object_hold(dst_object);
2026 for (vaddr = dst_entry->start, dst_offset = 0;
2027 vaddr < dst_entry->end;
2028 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) {
2031 * Allocate a page in the destination object
2034 dst_m = vm_page_alloc(dst_object,
2035 OFF_TO_IDX(dst_offset),
2037 if (dst_m == NULL) {
2040 } while (dst_m == NULL);
2043 * Find the page in the source object, and copy it in.
2044 * (Because the source is wired down, the page will be in
2047 src_m = vm_page_lookup(src_object,
2048 OFF_TO_IDX(dst_offset + src_offset));
2050 panic("vm_fault_copy_wired: page missing");
2052 vm_page_copy(src_m, dst_m);
2053 vm_page_event(src_m, VMEVENT_COW);
2056 * Enter it in the pmap...
2059 vm_page_flag_clear(dst_m, PG_ZERO);
2060 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE, dst_entry);
2063 * Mark it no longer busy, and put it on the active list.
2065 vm_page_activate(dst_m);
2066 vm_page_wakeup(dst_m);
2068 vm_object_drop(dst_object);
2069 vm_object_drop(src_object);
2075 * This routine checks around the requested page for other pages that
2076 * might be able to be faulted in. This routine brackets the viable
2077 * pages for the pages to be paged in.
2080 * m, rbehind, rahead
2083 * marray (array of vm_page_t), reqpage (index of requested page)
2086 * number of pages in marray
2089 vm_fault_additional_pages(vm_page_t m, int rbehind, int rahead,
2090 vm_page_t *marray, int *reqpage)
2094 vm_pindex_t pindex, startpindex, endpindex, tpindex;
2096 int cbehind, cahead;
2102 * we don't fault-ahead for device pager
2104 if (object->type == OBJT_DEVICE) {
2111 * if the requested page is not available, then give up now
2113 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) {
2114 *reqpage = 0; /* not used by caller, fix compiler warn */
2118 if ((cbehind == 0) && (cahead == 0)) {
2124 if (rahead > cahead) {
2128 if (rbehind > cbehind) {
2133 * Do not do any readahead if we have insufficient free memory.
2135 * XXX code was broken disabled before and has instability
2136 * with this conditonal fixed, so shortcut for now.
2138 if (burst_fault == 0 || vm_page_count_severe()) {
2145 * scan backward for the read behind pages -- in memory
2147 * Assume that if the page is not found an interrupt will not
2148 * create it. Theoretically interrupts can only remove (busy)
2149 * pages, not create new associations.
2152 if (rbehind > pindex) {
2156 startpindex = pindex - rbehind;
2159 vm_object_hold(object);
2160 for (tpindex = pindex; tpindex > startpindex; --tpindex) {
2161 if (vm_page_lookup(object, tpindex - 1))
2166 while (tpindex < pindex) {
2167 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM |
2170 for (j = 0; j < i; j++) {
2171 vm_page_free(marray[j]);
2173 vm_object_drop(object);
2182 vm_object_drop(object);
2188 * Assign requested page
2195 * Scan forwards for read-ahead pages
2197 tpindex = pindex + 1;
2198 endpindex = tpindex + rahead;
2199 if (endpindex > object->size)
2200 endpindex = object->size;
2202 vm_object_hold(object);
2203 while (tpindex < endpindex) {
2204 if (vm_page_lookup(object, tpindex))
2206 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM |
2214 vm_object_drop(object);
2222 * vm_prefault() provides a quick way of clustering pagefaults into a
2223 * processes address space. It is a "cousin" of pmap_object_init_pt,
2224 * except it runs at page fault time instead of mmap time.
2226 * vm.fast_fault Enables pre-faulting zero-fill pages
2228 * vm.prefault_pages Number of pages (1/2 negative, 1/2 positive) to
2229 * prefault. Scan stops in either direction when
2230 * a page is found to already exist.
2232 * This code used to be per-platform pmap_prefault(). It is now
2233 * machine-independent and enhanced to also pre-fault zero-fill pages
2234 * (see vm.fast_fault) as well as make them writable, which greatly
2235 * reduces the number of page faults programs incur.
2237 * Application performance when pre-faulting zero-fill pages is heavily
2238 * dependent on the application. Very tiny applications like /bin/echo
2239 * lose a little performance while applications of any appreciable size
2240 * gain performance. Prefaulting multiple pages also reduces SMP
2241 * congestion and can improve SMP performance significantly.
2243 * NOTE! prot may allow writing but this only applies to the top level
2244 * object. If we wind up mapping a page extracted from a backing
2245 * object we have to make sure it is read-only.
2247 * NOTE! The caller has already handled any COW operations on the
2248 * vm_map_entry via the normal fault code. Do NOT call this
2249 * shortcut unless the normal fault code has run on this entry.
2251 * The related map must be locked.
2252 * No other requirements.
2254 static int vm_prefault_pages = 8;
2255 SYSCTL_INT(_vm, OID_AUTO, prefault_pages, CTLFLAG_RW, &vm_prefault_pages, 0,
2256 "Maximum number of pages to pre-fault");
2257 static int vm_fast_fault = 1;
2258 SYSCTL_INT(_vm, OID_AUTO, fast_fault, CTLFLAG_RW, &vm_fast_fault, 0,
2259 "Burst fault zero-fill regions");
2262 * Set PG_NOSYNC if the map entry indicates so, but only if the page
2263 * is not already dirty by other means. This will prevent passive
2264 * filesystem syncing as well as 'sync' from writing out the page.
2267 vm_set_nosync(vm_page_t m, vm_map_entry_t entry)
2269 if (entry->eflags & MAP_ENTRY_NOSYNC) {
2271 vm_page_flag_set(m, PG_NOSYNC);
2273 vm_page_flag_clear(m, PG_NOSYNC);
2278 vm_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry, int prot,
2294 * Get stable max count value, disabled if set to 0
2296 maxpages = vm_prefault_pages;
2302 * We do not currently prefault mappings that use virtual page
2303 * tables. We do not prefault foreign pmaps.
2305 if (entry->maptype == VM_MAPTYPE_VPAGETABLE)
2307 lp = curthread->td_lwp;
2308 if (lp == NULL || (pmap != vmspace_pmap(lp->lwp_vmspace)))
2312 * Limit pre-fault count to 1024 pages.
2314 if (maxpages > 1024)
2317 object = entry->object.vm_object;
2318 KKASSERT(object != NULL);
2319 KKASSERT(object == entry->object.vm_object);
2320 vm_object_hold(object);
2321 vm_object_chain_acquire(object);
2325 for (i = 0; i < maxpages; ++i) {
2326 vm_object_t lobject;
2327 vm_object_t nobject;
2332 * This can eat a lot of time on a heavily contended
2333 * machine so yield on the tick if needed.
2339 * Calculate the page to pre-fault, stopping the scan in
2340 * each direction separately if the limit is reached.
2345 addr = addra - ((i + 1) >> 1) * PAGE_SIZE;
2349 addr = addra + ((i + 2) >> 1) * PAGE_SIZE;
2351 if (addr < entry->start) {
2357 if (addr >= entry->end) {
2365 * Skip pages already mapped, and stop scanning in that
2366 * direction. When the scan terminates in both directions
2369 if (pmap_prefault_ok(pmap, addr) == 0) {
2380 * Follow the VM object chain to obtain the page to be mapped
2383 * If we reach the terminal object without finding a page
2384 * and we determine it would be advantageous, then allocate
2385 * a zero-fill page for the base object. The base object
2386 * is guaranteed to be OBJT_DEFAULT for this case.
2388 * In order to not have to check the pager via *haspage*()
2389 * we stop if any non-default object is encountered. e.g.
2390 * a vnode or swap object would stop the loop.
2392 index = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
2397 KKASSERT(lobject == entry->object.vm_object);
2398 /*vm_object_hold(lobject); implied */
2400 while ((m = vm_page_lookup_busy_try(lobject, pindex,
2401 TRUE, &error)) == NULL) {
2402 if (lobject->type != OBJT_DEFAULT)
2404 if (lobject->backing_object == NULL) {
2405 if (vm_fast_fault == 0)
2407 if ((prot & VM_PROT_WRITE) == 0 ||
2408 vm_page_count_min(0)) {
2413 * NOTE: Allocated from base object
2415 m = vm_page_alloc(object, index,
2424 /* lobject = object .. not needed */
2427 if (lobject->backing_object_offset & PAGE_MASK)
2429 nobject = lobject->backing_object;
2430 vm_object_hold(nobject);
2431 KKASSERT(nobject == lobject->backing_object);
2432 pindex += lobject->backing_object_offset >> PAGE_SHIFT;
2433 if (lobject != object) {
2434 vm_object_lock_swap();
2435 vm_object_drop(lobject);
2438 pprot &= ~VM_PROT_WRITE;
2439 vm_object_chain_acquire(lobject);
2443 * NOTE: A non-NULL (m) will be associated with lobject if
2444 * it was found there, otherwise it is probably a
2445 * zero-fill page associated with the base object.
2447 * Give-up if no page is available.
2450 if (lobject != object) {
2451 if (object->backing_object != lobject)
2452 vm_object_hold(object->backing_object);
2453 vm_object_chain_release_all(
2454 object->backing_object, lobject);
2455 if (object->backing_object != lobject)
2456 vm_object_drop(object->backing_object);
2457 vm_object_drop(lobject);
2463 * The object must be marked dirty if we are mapping a
2464 * writable page. m->object is either lobject or object,
2465 * both of which are still held. Do this before we
2466 * potentially drop the object.
2468 if (pprot & VM_PROT_WRITE)
2469 vm_object_set_writeable_dirty(m->object);
2472 * Do not conditionalize on PG_RAM. If pages are present in
2473 * the VM system we assume optimal caching. If caching is
2474 * not optimal the I/O gravy train will be restarted when we
2475 * hit an unavailable page. We do not want to try to restart
2476 * the gravy train now because we really don't know how much
2477 * of the object has been cached. The cost for restarting
2478 * the gravy train should be low (since accesses will likely
2479 * be I/O bound anyway).
2481 if (lobject != object) {
2482 if (object->backing_object != lobject)
2483 vm_object_hold(object->backing_object);
2484 vm_object_chain_release_all(object->backing_object,
2486 if (object->backing_object != lobject)
2487 vm_object_drop(object->backing_object);
2488 vm_object_drop(lobject);
2492 * Enter the page into the pmap if appropriate. If we had
2493 * allocated the page we have to place it on a queue. If not
2494 * we just have to make sure it isn't on the cache queue
2495 * (pages on the cache queue are not allowed to be mapped).
2499 * Page must be zerod.
2501 if ((m->flags & PG_ZERO) == 0) {
2502 vm_page_zero_fill(m);
2505 pmap_page_assertzero(
2506 VM_PAGE_TO_PHYS(m));
2508 vm_page_flag_clear(m, PG_ZERO);
2509 mycpu->gd_cnt.v_ozfod++;
2511 mycpu->gd_cnt.v_zfod++;
2512 m->valid = VM_PAGE_BITS_ALL;
2515 * Handle dirty page case
2517 if (pprot & VM_PROT_WRITE)
2518 vm_set_nosync(m, entry);
2519 pmap_enter(pmap, addr, m, pprot, 0, entry);
2520 mycpu->gd_cnt.v_vm_faults++;
2521 if (curthread->td_lwp)
2522 ++curthread->td_lwp->lwp_ru.ru_minflt;
2523 vm_page_deactivate(m);
2524 if (pprot & VM_PROT_WRITE) {
2525 /*vm_object_set_writeable_dirty(m->object);*/
2526 vm_set_nosync(m, entry);
2527 if (fault_flags & VM_FAULT_DIRTY) {
2530 swap_pager_unswapped(m);
2535 /* couldn't busy page, no wakeup */
2537 ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
2538 (m->flags & PG_FICTITIOUS) == 0) {
2540 * A fully valid page not undergoing soft I/O can
2541 * be immediately entered into the pmap.
2543 if ((m->queue - m->pc) == PQ_CACHE)
2544 vm_page_deactivate(m);
2545 if (pprot & VM_PROT_WRITE) {
2546 /*vm_object_set_writeable_dirty(m->object);*/
2547 vm_set_nosync(m, entry);
2548 if (fault_flags & VM_FAULT_DIRTY) {
2551 swap_pager_unswapped(m);
2554 if (pprot & VM_PROT_WRITE)
2555 vm_set_nosync(m, entry);
2556 pmap_enter(pmap, addr, m, pprot, 0, entry);
2557 mycpu->gd_cnt.v_vm_faults++;
2558 if (curthread->td_lwp)
2559 ++curthread->td_lwp->lwp_ru.ru_minflt;
2565 vm_object_chain_release(object);
2566 vm_object_drop(object);
2570 vm_prefault_quick(pmap_t pmap, vm_offset_t addra,
2571 vm_map_entry_t entry, int prot, int fault_flags)
2584 * Get stable max count value, disabled if set to 0
2586 maxpages = vm_prefault_pages;
2592 * We do not currently prefault mappings that use virtual page
2593 * tables. We do not prefault foreign pmaps.
2595 if (entry->maptype == VM_MAPTYPE_VPAGETABLE)
2597 lp = curthread->td_lwp;
2598 if (lp == NULL || (pmap != vmspace_pmap(lp->lwp_vmspace)))
2602 * Limit pre-fault count to 1024 pages.
2604 if (maxpages > 1024)
2607 object = entry->object.vm_object;
2608 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2609 KKASSERT(object->backing_object == NULL);
2613 for (i = 0; i < maxpages; ++i) {
2617 * Calculate the page to pre-fault, stopping the scan in
2618 * each direction separately if the limit is reached.
2623 addr = addra - ((i + 1) >> 1) * PAGE_SIZE;
2627 addr = addra + ((i + 2) >> 1) * PAGE_SIZE;
2629 if (addr < entry->start) {
2635 if (addr >= entry->end) {
2643 * Skip pages already mapped, and stop scanning in that
2644 * direction. When the scan terminates in both directions
2647 if (pmap_prefault_ok(pmap, addr) == 0) {
2658 * Follow the VM object chain to obtain the page to be mapped
2659 * into the pmap. This version of the prefault code only
2660 * works with terminal objects.
2662 * WARNING! We cannot call swap_pager_unswapped() with a
2665 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
2667 m = vm_page_lookup_busy_try(object, pindex, TRUE, &error);
2668 if (m == NULL || error)
2671 if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
2672 (m->flags & PG_FICTITIOUS) == 0 &&
2673 ((m->flags & PG_SWAPPED) == 0 ||
2674 (prot & VM_PROT_WRITE) == 0 ||
2675 (fault_flags & VM_FAULT_DIRTY) == 0)) {
2677 * A fully valid page not undergoing soft I/O can
2678 * be immediately entered into the pmap.
2680 if ((m->queue - m->pc) == PQ_CACHE)
2681 vm_page_deactivate(m);
2682 if (prot & VM_PROT_WRITE) {
2683 vm_object_set_writeable_dirty(m->object);
2684 vm_set_nosync(m, entry);
2685 if (fault_flags & VM_FAULT_DIRTY) {
2688 swap_pager_unswapped(m);
2691 pmap_enter(pmap, addr, m, prot, 0, entry);
2692 mycpu->gd_cnt.v_vm_faults++;
2693 if (curthread->td_lwp)
2694 ++curthread->td_lwp->lwp_ru.ru_minflt;