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. Neither the name of the University nor the names of its contributors
24 * may be used to endorse or promote products derived from this software
25 * without specific prior written permission.
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94
42 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
43 * All rights reserved.
45 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
47 * Permission to use, copy, modify and distribute this software and
48 * its documentation is hereby granted, provided that both the copyright
49 * notice and this permission notice appear in all copies of the
50 * software, derivative works or modified versions, and any portions
51 * thereof, and that both notices appear in supporting documentation.
53 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
54 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
55 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
57 * Carnegie Mellon requests users of this software to return to
59 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
60 * School of Computer Science
61 * Carnegie Mellon University
62 * Pittsburgh PA 15213-3890
64 * any improvements or extensions that they make and grant Carnegie the
65 * rights to redistribute these changes.
67 * $FreeBSD: src/sys/vm/vm_fault.c,v 1.108.2.8 2002/02/26 05:49:27 silby Exp $
68 * $DragonFly: src/sys/vm/vm_fault.c,v 1.47 2008/07/01 02:02:56 dillon Exp $
72 * Page fault handling module.
75 #include <sys/param.h>
76 #include <sys/systm.h>
77 #include <sys/kernel.h>
79 #include <sys/vnode.h>
80 #include <sys/resourcevar.h>
81 #include <sys/vmmeter.h>
82 #include <sys/vkernel.h>
84 #include <sys/sysctl.h>
86 #include <cpu/lwbuf.h>
89 #include <vm/vm_param.h>
91 #include <vm/vm_map.h>
92 #include <vm/vm_object.h>
93 #include <vm/vm_page.h>
94 #include <vm/vm_pageout.h>
95 #include <vm/vm_kern.h>
96 #include <vm/vm_pager.h>
97 #include <vm/vnode_pager.h>
98 #include <vm/vm_extern.h>
100 #include <sys/thread2.h>
101 #include <vm/vm_page2.h>
109 vm_object_t first_object;
110 vm_prot_t first_prot;
112 vm_map_entry_t entry;
113 int lookup_still_valid;
123 static int debug_fault = 0;
124 SYSCTL_INT(_vm, OID_AUTO, debug_fault, CTLFLAG_RW, &debug_fault, 0, "");
125 static int debug_cluster = 0;
126 SYSCTL_INT(_vm, OID_AUTO, debug_cluster, CTLFLAG_RW, &debug_cluster, 0, "");
127 int vm_shared_fault = 1;
128 TUNABLE_INT("vm.shared_fault", &vm_shared_fault);
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_count = 0;
135 SYSCTL_LONG(_vm, OID_AUTO, shared_count, CTLFLAG_RW, &vm_shared_count, 0,
136 "Shared fault attempts");
137 static long vm_shared_miss = 0;
138 SYSCTL_LONG(_vm, OID_AUTO, shared_miss, CTLFLAG_RW, &vm_shared_miss, 0,
139 "Unsuccessful shared faults");
141 static int vm_fault_object(struct faultstate *, vm_pindex_t, vm_prot_t, int);
142 static int vm_fault_vpagetable(struct faultstate *, vm_pindex_t *,
145 static int vm_fault_additional_pages (vm_page_t, int, int, vm_page_t *, int *);
147 static void vm_set_nosync(vm_page_t m, vm_map_entry_t entry);
148 static void vm_prefault(pmap_t pmap, vm_offset_t addra,
149 vm_map_entry_t entry, int prot, int fault_flags);
150 static void vm_prefault_quick(pmap_t pmap, vm_offset_t addra,
151 vm_map_entry_t entry, int prot, int fault_flags);
154 release_page(struct faultstate *fs)
156 vm_page_deactivate(fs->m);
157 vm_page_wakeup(fs->m);
162 * NOTE: Once unlocked any cached fs->entry becomes invalid, any reuse
163 * requires relocking and then checking the timestamp.
165 * NOTE: vm_map_lock_read() does not bump fs->map->timestamp so we do
166 * not have to update fs->map_generation here.
168 * NOTE: This function can fail due to a deadlock against the caller's
169 * holding of a vm_page BUSY.
172 relock_map(struct faultstate *fs)
176 if (fs->lookup_still_valid == FALSE && fs->map) {
177 error = vm_map_lock_read_to(fs->map);
179 fs->lookup_still_valid = TRUE;
187 unlock_map(struct faultstate *fs)
189 if (fs->lookup_still_valid && fs->map) {
190 vm_map_lookup_done(fs->map, fs->entry, 0);
191 fs->lookup_still_valid = FALSE;
196 * Clean up after a successful call to vm_fault_object() so another call
197 * to vm_fault_object() can be made.
200 _cleanup_successful_fault(struct faultstate *fs, int relock)
203 * We allocated a junk page for a COW operation that did
204 * not occur, the page must be freed.
206 if (fs->object != fs->first_object) {
207 KKASSERT(fs->first_shared == 0);
208 vm_page_free(fs->first_m);
209 vm_object_pip_wakeup(fs->object);
216 fs->object = fs->first_object;
217 if (relock && fs->lookup_still_valid == FALSE) {
219 vm_map_lock_read(fs->map);
220 fs->lookup_still_valid = TRUE;
225 _unlock_things(struct faultstate *fs, int dealloc)
227 _cleanup_successful_fault(fs, 0);
229 /*vm_object_deallocate(fs->first_object);*/
230 /*fs->first_object = NULL; drop used later on */
233 if (fs->vp != NULL) {
239 #define unlock_things(fs) _unlock_things(fs, 0)
240 #define unlock_and_deallocate(fs) _unlock_things(fs, 1)
241 #define cleanup_successful_fault(fs) _cleanup_successful_fault(fs, 1)
246 * Determine if the pager for the current object *might* contain the page.
248 * We only need to try the pager if this is not a default object (default
249 * objects are zero-fill and have no real pager), and if we are not taking
250 * a wiring fault or if the FS entry is wired.
252 #define TRYPAGER(fs) \
253 (fs->object->type != OBJT_DEFAULT && \
254 (((fs->fault_flags & VM_FAULT_WIRE_MASK) == 0) || fs->wired))
259 * Handle a page fault occuring at the given address, requiring the given
260 * permissions, in the map specified. If successful, the page is inserted
261 * into the associated physical map.
263 * NOTE: The given address should be truncated to the proper page address.
265 * KERN_SUCCESS is returned if the page fault is handled; otherwise,
266 * a standard error specifying why the fault is fatal is returned.
268 * The map in question must be referenced, and remains so.
269 * The caller may hold no locks.
270 * No other requirements.
273 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, int fault_flags)
276 vm_pindex_t first_pindex;
277 struct faultstate fs;
282 vm_page_pcpu_cache();
284 fs.fault_flags = fault_flags;
286 fs.shared = vm_shared_fault;
287 fs.first_shared = vm_shared_fault;
293 * vm_map interactions
295 if ((lp = curthread->td_lwp) != NULL)
296 lp->lwp_flags |= LWP_PAGING;
297 lwkt_gettoken(&map->token);
301 * Find the vm_map_entry representing the backing store and resolve
302 * the top level object and page index. This may have the side
303 * effect of executing a copy-on-write on the map entry and/or
304 * creating a shadow object, but will not COW any actual VM pages.
306 * On success fs.map is left read-locked and various other fields
307 * are initialized but not otherwise referenced or locked.
309 * NOTE! vm_map_lookup will try to upgrade the fault_type to
310 * VM_FAULT_WRITE if the map entry is a virtual page table and also
311 * writable, so we can set the 'A'accessed bit in the virtual page
315 result = vm_map_lookup(&fs.map, vaddr, fault_type,
316 &fs.entry, &fs.first_object,
317 &first_pindex, &fs.first_prot, &fs.wired);
320 * If the lookup failed or the map protections are incompatible,
321 * the fault generally fails. However, if the caller is trying
322 * to do a user wiring we have more work to do.
324 if (result != KERN_SUCCESS) {
325 if (result != KERN_PROTECTION_FAILURE ||
326 (fs.fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE)
328 if (result == KERN_INVALID_ADDRESS && growstack &&
329 map != &kernel_map && curproc != NULL) {
330 result = vm_map_growstack(curproc, vaddr);
331 if (result == KERN_SUCCESS) {
336 result = KERN_FAILURE;
342 * If we are user-wiring a r/w segment, and it is COW, then
343 * we need to do the COW operation. Note that we don't
344 * currently COW RO sections now, because it is NOT desirable
345 * to COW .text. We simply keep .text from ever being COW'ed
346 * and take the heat that one cannot debug wired .text sections.
348 result = vm_map_lookup(&fs.map, vaddr,
349 VM_PROT_READ|VM_PROT_WRITE|
350 VM_PROT_OVERRIDE_WRITE,
351 &fs.entry, &fs.first_object,
352 &first_pindex, &fs.first_prot,
354 if (result != KERN_SUCCESS) {
355 result = KERN_FAILURE;
360 * If we don't COW now, on a user wire, the user will never
361 * be able to write to the mapping. If we don't make this
362 * restriction, the bookkeeping would be nearly impossible.
364 * XXX We have a shared lock, this will have a MP race but
365 * I don't see how it can hurt anything.
367 if ((fs.entry->protection & VM_PROT_WRITE) == 0)
368 fs.entry->max_protection &= ~VM_PROT_WRITE;
372 * fs.map is read-locked
374 * Misc checks. Save the map generation number to detect races.
376 fs.map_generation = fs.map->timestamp;
377 fs.lookup_still_valid = TRUE;
379 fs.object = fs.first_object; /* so unlock_and_deallocate works */
381 if (fs.entry->eflags & (MAP_ENTRY_NOFAULT | MAP_ENTRY_KSTACK)) {
382 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
383 panic("vm_fault: fault on nofault entry, addr: %p",
386 if ((fs.entry->eflags & MAP_ENTRY_KSTACK) &&
387 vaddr >= fs.entry->start &&
388 vaddr < fs.entry->start + PAGE_SIZE) {
389 panic("vm_fault: fault on stack guard, addr: %p",
395 * A system map entry may return a NULL object. No object means
396 * no pager means an unrecoverable kernel fault.
398 if (fs.first_object == NULL) {
399 panic("vm_fault: unrecoverable fault at %p in entry %p",
400 (void *)vaddr, fs.entry);
404 * Fail here if not a trivial anonymous page fault and TDF_NOFAULT
407 if ((curthread->td_flags & TDF_NOFAULT) &&
409 fs.first_object->type == OBJT_VNODE ||
410 fs.first_object->backing_object)) {
411 result = KERN_FAILURE;
417 * If the entry is wired we cannot change the page protection.
420 fault_type = fs.first_prot;
423 * We generally want to avoid unnecessary exclusive modes on backing
424 * and terminal objects because this can seriously interfere with
425 * heavily fork()'d processes (particularly /bin/sh scripts).
427 * However, we also want to avoid unnecessary retries due to needed
428 * shared->exclusive promotion for common faults. Exclusive mode is
429 * always needed if any page insertion, rename, or free occurs in an
430 * object (and also indirectly if any I/O is done).
432 * The main issue here is going to be fs.first_shared. If the
433 * first_object has a backing object which isn't shadowed and the
434 * process is single-threaded we might as well use an exclusive
435 * lock/chain right off the bat.
437 if (fs.first_shared && fs.first_object->backing_object &&
438 LIST_EMPTY(&fs.first_object->shadow_head) &&
439 curthread->td_proc && curthread->td_proc->p_nthreads == 1) {
444 * swap_pager_unswapped() needs an exclusive object
446 if (fault_flags & (VM_FAULT_UNSWAP | VM_FAULT_DIRTY)) {
451 * Obtain a top-level object lock, shared or exclusive depending
452 * on fs.first_shared. If a shared lock winds up being insufficient
453 * we will retry with an exclusive lock.
455 * The vnode pager lock is always shared.
458 vm_object_hold_shared(fs.first_object);
460 vm_object_hold(fs.first_object);
462 fs.vp = vnode_pager_lock(fs.first_object);
465 * The page we want is at (first_object, first_pindex), but if the
466 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the
467 * page table to figure out the actual pindex.
469 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION
472 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
473 result = vm_fault_vpagetable(&fs, &first_pindex,
474 fs.entry->aux.master_pde,
476 if (result == KERN_TRY_AGAIN) {
477 vm_object_drop(fs.first_object);
481 if (result != KERN_SUCCESS)
486 * Now we have the actual (object, pindex), fault in the page. If
487 * vm_fault_object() fails it will unlock and deallocate the FS
488 * data. If it succeeds everything remains locked and fs->object
489 * will have an additional PIP count if it is not equal to
492 * vm_fault_object will set fs->prot for the pmap operation. It is
493 * allowed to set VM_PROT_WRITE if fault_type == VM_PROT_READ if the
494 * page can be safely written. However, it will force a read-only
495 * mapping for a read fault if the memory is managed by a virtual
498 * If the fault code uses the shared object lock shortcut
499 * we must not try to burst (we can't allocate VM pages).
501 result = vm_fault_object(&fs, first_pindex, fault_type, 1);
503 if (debug_fault > 0) {
505 kprintf("VM_FAULT result %d addr=%jx type=%02x flags=%02x "
506 "fs.m=%p fs.prot=%02x fs.wired=%02x fs.entry=%p\n",
507 result, (intmax_t)vaddr, fault_type, fault_flags,
508 fs.m, fs.prot, fs.wired, fs.entry);
511 if (result == KERN_TRY_AGAIN) {
512 vm_object_drop(fs.first_object);
516 if (result != KERN_SUCCESS)
520 * On success vm_fault_object() does not unlock or deallocate, and fs.m
521 * will contain a busied page.
523 * Enter the page into the pmap and do pmap-related adjustments.
525 KKASSERT(fs.lookup_still_valid == TRUE);
526 vm_page_flag_set(fs.m, PG_REFERENCED);
527 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot, fs.wired, fs.entry);
528 mycpu->gd_cnt.v_vm_faults++;
529 if (curthread->td_lwp)
530 ++curthread->td_lwp->lwp_ru.ru_minflt;
532 /*KKASSERT(fs.m->queue == PQ_NONE); page-in op may deactivate page */
533 KKASSERT(fs.m->flags & PG_BUSY);
536 * If the page is not wired down, then put it where the pageout daemon
539 if (fs.fault_flags & VM_FAULT_WIRE_MASK) {
543 vm_page_unwire(fs.m, 1);
545 vm_page_activate(fs.m);
547 vm_page_wakeup(fs.m);
550 * Burst in a few more pages if possible. The fs.map should still
551 * be locked. To avoid interlocking against a vnode->getblk
552 * operation we had to be sure to unbusy our primary vm_page above
555 * A normal burst can continue down backing store, only execute
556 * if we are holding an exclusive lock, otherwise the exclusive
557 * locks the burst code gets might cause excessive SMP collisions.
559 * A quick burst can be utilized when there is no backing object
560 * (i.e. a shared file mmap).
562 if ((fault_flags & VM_FAULT_BURST) &&
563 (fs.fault_flags & VM_FAULT_WIRE_MASK) == 0 &&
565 if (fs.first_shared == 0 && fs.shared == 0) {
566 vm_prefault(fs.map->pmap, vaddr,
567 fs.entry, fs.prot, fault_flags);
569 vm_prefault_quick(fs.map->pmap, vaddr,
570 fs.entry, fs.prot, fault_flags);
575 * Unlock everything, and return
579 if (curthread->td_lwp) {
581 curthread->td_lwp->lwp_ru.ru_majflt++;
583 curthread->td_lwp->lwp_ru.ru_minflt++;
587 /*vm_object_deallocate(fs.first_object);*/
589 /*fs.first_object = NULL; must still drop later */
591 result = KERN_SUCCESS;
594 vm_object_drop(fs.first_object);
596 lwkt_reltoken(&map->token);
598 lp->lwp_flags &= ~LWP_PAGING;
599 if (vm_shared_fault && fs.shared == 0)
605 * Fault in the specified virtual address in the current process map,
606 * returning a held VM page or NULL. See vm_fault_page() for more
612 vm_fault_page_quick(vm_offset_t va, vm_prot_t fault_type, int *errorp)
614 struct lwp *lp = curthread->td_lwp;
617 m = vm_fault_page(&lp->lwp_vmspace->vm_map, va,
618 fault_type, VM_FAULT_NORMAL, errorp);
623 * Fault in the specified virtual address in the specified map, doing all
624 * necessary manipulation of the object store and all necessary I/O. Return
625 * a held VM page or NULL, and set *errorp. The related pmap is not
628 * The returned page will be properly dirtied if VM_PROT_WRITE was specified,
629 * and marked PG_REFERENCED as well.
631 * If the page cannot be faulted writable and VM_PROT_WRITE was specified, an
632 * error will be returned.
637 vm_fault_page(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
638 int fault_flags, int *errorp)
640 vm_pindex_t first_pindex;
641 struct faultstate fs;
644 vm_prot_t orig_fault_type = fault_type;
647 fs.fault_flags = fault_flags;
648 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0);
651 * Dive the pmap (concurrency possible). If we find the
652 * appropriate page we can terminate early and quickly.
654 fs.m = pmap_fault_page_quick(map->pmap, vaddr, fault_type);
661 * Otherwise take a concurrency hit and do a formal page
664 fs.shared = vm_shared_fault;
665 fs.first_shared = vm_shared_fault;
667 lwkt_gettoken(&map->token);
670 * swap_pager_unswapped() needs an exclusive object
672 if (fault_flags & (VM_FAULT_UNSWAP | VM_FAULT_DIRTY)) {
678 * Find the vm_map_entry representing the backing store and resolve
679 * the top level object and page index. This may have the side
680 * effect of executing a copy-on-write on the map entry and/or
681 * creating a shadow object, but will not COW any actual VM pages.
683 * On success fs.map is left read-locked and various other fields
684 * are initialized but not otherwise referenced or locked.
686 * NOTE! vm_map_lookup will upgrade the fault_type to VM_FAULT_WRITE
687 * if the map entry is a virtual page table and also writable,
688 * so we can set the 'A'accessed bit in the virtual page table entry.
691 result = vm_map_lookup(&fs.map, vaddr, fault_type,
692 &fs.entry, &fs.first_object,
693 &first_pindex, &fs.first_prot, &fs.wired);
695 if (result != KERN_SUCCESS) {
702 * fs.map is read-locked
704 * Misc checks. Save the map generation number to detect races.
706 fs.map_generation = fs.map->timestamp;
707 fs.lookup_still_valid = TRUE;
709 fs.object = fs.first_object; /* so unlock_and_deallocate works */
711 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
712 panic("vm_fault: fault on nofault entry, addr: %lx",
717 * A system map entry may return a NULL object. No object means
718 * no pager means an unrecoverable kernel fault.
720 if (fs.first_object == NULL) {
721 panic("vm_fault: unrecoverable fault at %p in entry %p",
722 (void *)vaddr, fs.entry);
726 * Fail here if not a trivial anonymous page fault and TDF_NOFAULT
729 if ((curthread->td_flags & TDF_NOFAULT) &&
731 fs.first_object->type == OBJT_VNODE ||
732 fs.first_object->backing_object)) {
733 *errorp = KERN_FAILURE;
739 * If the entry is wired we cannot change the page protection.
742 fault_type = fs.first_prot;
745 * Make a reference to this object to prevent its disposal while we
746 * are messing with it. Once we have the reference, the map is free
747 * to be diddled. Since objects reference their shadows (and copies),
748 * they will stay around as well.
750 * The reference should also prevent an unexpected collapse of the
751 * parent that might move pages from the current object into the
752 * parent unexpectedly, resulting in corruption.
754 * Bump the paging-in-progress count to prevent size changes (e.g.
755 * truncation operations) during I/O. This must be done after
756 * obtaining the vnode lock in order to avoid possible deadlocks.
759 vm_object_hold_shared(fs.first_object);
761 vm_object_hold(fs.first_object);
763 fs.vp = vnode_pager_lock(fs.first_object); /* shared */
766 * The page we want is at (first_object, first_pindex), but if the
767 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the
768 * page table to figure out the actual pindex.
770 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION
773 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
774 result = vm_fault_vpagetable(&fs, &first_pindex,
775 fs.entry->aux.master_pde,
777 if (result == KERN_TRY_AGAIN) {
778 vm_object_drop(fs.first_object);
782 if (result != KERN_SUCCESS) {
790 * Now we have the actual (object, pindex), fault in the page. If
791 * vm_fault_object() fails it will unlock and deallocate the FS
792 * data. If it succeeds everything remains locked and fs->object
793 * will have an additinal PIP count if it is not equal to
797 result = vm_fault_object(&fs, first_pindex, fault_type, 1);
799 if (result == KERN_TRY_AGAIN) {
800 vm_object_drop(fs.first_object);
804 if (result != KERN_SUCCESS) {
810 if ((orig_fault_type & VM_PROT_WRITE) &&
811 (fs.prot & VM_PROT_WRITE) == 0) {
812 *errorp = KERN_PROTECTION_FAILURE;
813 unlock_and_deallocate(&fs);
819 * DO NOT UPDATE THE PMAP!!! This function may be called for
820 * a pmap unrelated to the current process pmap, in which case
821 * the current cpu core will not be listed in the pmap's pm_active
822 * mask. Thus invalidation interlocks will fail to work properly.
824 * (for example, 'ps' uses procfs to read program arguments from
825 * each process's stack).
827 * In addition to the above this function will be called to acquire
828 * a page that might already be faulted in, re-faulting it
829 * continuously is a waste of time.
831 * XXX could this have been the cause of our random seg-fault
832 * issues? procfs accesses user stacks.
834 vm_page_flag_set(fs.m, PG_REFERENCED);
836 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot, fs.wired, NULL);
837 mycpu->gd_cnt.v_vm_faults++;
838 if (curthread->td_lwp)
839 ++curthread->td_lwp->lwp_ru.ru_minflt;
843 * On success vm_fault_object() does not unlock or deallocate, and fs.m
844 * will contain a busied page. So we must unlock here after having
845 * messed with the pmap.
850 * Return a held page. We are not doing any pmap manipulation so do
851 * not set PG_MAPPED. However, adjust the page flags according to
852 * the fault type because the caller may not use a managed pmapping
853 * (so we don't want to lose the fact that the page will be dirtied
854 * if a write fault was specified).
857 vm_page_activate(fs.m);
858 if (fault_type & VM_PROT_WRITE)
861 if (curthread->td_lwp) {
863 curthread->td_lwp->lwp_ru.ru_majflt++;
865 curthread->td_lwp->lwp_ru.ru_minflt++;
870 * Unlock everything, and return the held page.
872 vm_page_wakeup(fs.m);
873 /*vm_object_deallocate(fs.first_object);*/
874 /*fs.first_object = NULL; */
879 vm_object_drop(fs.first_object);
881 lwkt_reltoken(&map->token);
886 * Fault in the specified (object,offset), dirty the returned page as
887 * needed. If the requested fault_type cannot be done NULL and an
890 * A held (but not busied) page is returned.
892 * The passed in object must be held as specified by the shared
896 vm_fault_object_page(vm_object_t object, vm_ooffset_t offset,
897 vm_prot_t fault_type, int fault_flags,
898 int *sharedp, int *errorp)
901 vm_pindex_t first_pindex;
902 struct faultstate fs;
903 struct vm_map_entry entry;
905 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
906 bzero(&entry, sizeof(entry));
907 entry.object.vm_object = object;
908 entry.maptype = VM_MAPTYPE_NORMAL;
909 entry.protection = entry.max_protection = fault_type;
912 fs.fault_flags = fault_flags;
914 fs.shared = vm_shared_fault;
915 fs.first_shared = *sharedp;
917 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0);
920 * Might require swap block adjustments
922 if (fs.first_shared && (fault_flags & (VM_FAULT_UNSWAP | VM_FAULT_DIRTY))) {
924 vm_object_upgrade(object);
928 * Retry loop as needed (typically for shared->exclusive transitions)
931 *sharedp = fs.first_shared;
932 first_pindex = OFF_TO_IDX(offset);
933 fs.first_object = object;
935 fs.first_prot = fault_type;
937 /*fs.map_generation = 0; unused */
940 * Make a reference to this object to prevent its disposal while we
941 * are messing with it. Once we have the reference, the map is free
942 * to be diddled. Since objects reference their shadows (and copies),
943 * they will stay around as well.
945 * The reference should also prevent an unexpected collapse of the
946 * parent that might move pages from the current object into the
947 * parent unexpectedly, resulting in corruption.
949 * Bump the paging-in-progress count to prevent size changes (e.g.
950 * truncation operations) during I/O. This must be done after
951 * obtaining the vnode lock in order to avoid possible deadlocks.
954 fs.vp = vnode_pager_lock(fs.first_object);
956 fs.lookup_still_valid = TRUE;
958 fs.object = fs.first_object; /* so unlock_and_deallocate works */
961 /* XXX future - ability to operate on VM object using vpagetable */
962 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
963 result = vm_fault_vpagetable(&fs, &first_pindex,
964 fs.entry->aux.master_pde,
966 if (result == KERN_TRY_AGAIN) {
967 if (fs.first_shared == 0 && *sharedp)
968 vm_object_upgrade(object);
971 if (result != KERN_SUCCESS) {
979 * Now we have the actual (object, pindex), fault in the page. If
980 * vm_fault_object() fails it will unlock and deallocate the FS
981 * data. If it succeeds everything remains locked and fs->object
982 * will have an additinal PIP count if it is not equal to
985 * On KERN_TRY_AGAIN vm_fault_object() leaves fs.first_object intact.
986 * We may have to upgrade its lock to handle the requested fault.
988 result = vm_fault_object(&fs, first_pindex, fault_type, 0);
990 if (result == KERN_TRY_AGAIN) {
991 if (fs.first_shared == 0 && *sharedp)
992 vm_object_upgrade(object);
995 if (result != KERN_SUCCESS) {
1000 if ((fault_type & VM_PROT_WRITE) && (fs.prot & VM_PROT_WRITE) == 0) {
1001 *errorp = KERN_PROTECTION_FAILURE;
1002 unlock_and_deallocate(&fs);
1007 * On success vm_fault_object() does not unlock or deallocate, so we
1008 * do it here. Note that the returned fs.m will be busied.
1013 * Return a held page. We are not doing any pmap manipulation so do
1014 * not set PG_MAPPED. However, adjust the page flags according to
1015 * the fault type because the caller may not use a managed pmapping
1016 * (so we don't want to lose the fact that the page will be dirtied
1017 * if a write fault was specified).
1020 vm_page_activate(fs.m);
1021 if ((fault_type & VM_PROT_WRITE) || (fault_flags & VM_FAULT_DIRTY))
1022 vm_page_dirty(fs.m);
1023 if (fault_flags & VM_FAULT_UNSWAP)
1024 swap_pager_unswapped(fs.m);
1027 * Indicate that the page was accessed.
1029 vm_page_flag_set(fs.m, PG_REFERENCED);
1031 if (curthread->td_lwp) {
1033 curthread->td_lwp->lwp_ru.ru_majflt++;
1035 curthread->td_lwp->lwp_ru.ru_minflt++;
1040 * Unlock everything, and return the held page.
1042 vm_page_wakeup(fs.m);
1043 /*vm_object_deallocate(fs.first_object);*/
1044 /*fs.first_object = NULL; */
1051 * Translate the virtual page number (first_pindex) that is relative
1052 * to the address space into a logical page number that is relative to the
1053 * backing object. Use the virtual page table pointed to by (vpte).
1055 * This implements an N-level page table. Any level can terminate the
1056 * scan by setting VPTE_PS. A linear mapping is accomplished by setting
1057 * VPTE_PS in the master page directory entry set via mcontrol(MADV_SETMAP).
1061 vm_fault_vpagetable(struct faultstate *fs, vm_pindex_t *pindex,
1062 vpte_t vpte, int fault_type, int allow_nofault)
1065 struct lwbuf lwb_cache;
1066 int vshift = VPTE_FRAME_END - PAGE_SHIFT; /* index bits remaining */
1067 int result = KERN_SUCCESS;
1070 ASSERT_LWKT_TOKEN_HELD(vm_object_token(fs->first_object));
1073 * We cannot proceed if the vpte is not valid, not readable
1074 * for a read fault, or not writable for a write fault.
1076 if ((vpte & VPTE_V) == 0) {
1077 unlock_and_deallocate(fs);
1078 return (KERN_FAILURE);
1080 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_RW) == 0) {
1081 unlock_and_deallocate(fs);
1082 return (KERN_FAILURE);
1084 if ((vpte & VPTE_PS) || vshift == 0)
1086 KKASSERT(vshift >= VPTE_PAGE_BITS);
1089 * Get the page table page. Nominally we only read the page
1090 * table, but since we are actively setting VPTE_M and VPTE_A,
1091 * tell vm_fault_object() that we are writing it.
1093 * There is currently no real need to optimize this.
1095 result = vm_fault_object(fs, (vpte & VPTE_FRAME) >> PAGE_SHIFT,
1096 VM_PROT_READ|VM_PROT_WRITE,
1098 if (result != KERN_SUCCESS)
1102 * Process the returned fs.m and look up the page table
1103 * entry in the page table page.
1105 vshift -= VPTE_PAGE_BITS;
1106 lwb = lwbuf_alloc(fs->m, &lwb_cache);
1107 ptep = ((vpte_t *)lwbuf_kva(lwb) +
1108 ((*pindex >> vshift) & VPTE_PAGE_MASK));
1112 * Page table write-back. If the vpte is valid for the
1113 * requested operation, do a write-back to the page table.
1115 * XXX VPTE_M is not set properly for page directory pages.
1116 * It doesn't get set in the page directory if the page table
1117 * is modified during a read access.
1119 vm_page_activate(fs->m);
1120 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_V) &&
1122 if ((vpte & (VPTE_M|VPTE_A)) != (VPTE_M|VPTE_A)) {
1123 atomic_set_long(ptep, VPTE_M | VPTE_A);
1124 vm_page_dirty(fs->m);
1127 if ((fault_type & VM_PROT_READ) && (vpte & VPTE_V)) {
1128 if ((vpte & VPTE_A) == 0) {
1129 atomic_set_long(ptep, VPTE_A);
1130 vm_page_dirty(fs->m);
1134 vm_page_flag_set(fs->m, PG_REFERENCED);
1135 vm_page_wakeup(fs->m);
1137 cleanup_successful_fault(fs);
1140 * Combine remaining address bits with the vpte.
1142 /* JG how many bits from each? */
1143 *pindex = ((vpte & VPTE_FRAME) >> PAGE_SHIFT) +
1144 (*pindex & ((1L << vshift) - 1));
1145 return (KERN_SUCCESS);
1150 * This is the core of the vm_fault code.
1152 * Do all operations required to fault-in (fs.first_object, pindex). Run
1153 * through the shadow chain as necessary and do required COW or virtual
1154 * copy operations. The caller has already fully resolved the vm_map_entry
1155 * and, if appropriate, has created a copy-on-write layer. All we need to
1156 * do is iterate the object chain.
1158 * On failure (fs) is unlocked and deallocated and the caller may return or
1159 * retry depending on the failure code. On success (fs) is NOT unlocked or
1160 * deallocated, fs.m will contained a resolved, busied page, and fs.object
1161 * will have an additional PIP count if it is not equal to fs.first_object.
1163 * If locks based on fs->first_shared or fs->shared are insufficient,
1164 * clear the appropriate field(s) and return RETRY. COWs require that
1165 * first_shared be 0, while page allocations (or frees) require that
1166 * shared be 0. Renames require that both be 0.
1168 * fs->first_object must be held on call.
1172 vm_fault_object(struct faultstate *fs, vm_pindex_t first_pindex,
1173 vm_prot_t fault_type, int allow_nofault)
1175 vm_object_t next_object;
1179 ASSERT_LWKT_TOKEN_HELD(vm_object_token(fs->first_object));
1180 fs->prot = fs->first_prot;
1181 fs->object = fs->first_object;
1182 pindex = first_pindex;
1184 vm_object_chain_acquire(fs->first_object, fs->shared);
1185 vm_object_pip_add(fs->first_object, 1);
1188 * If a read fault occurs we try to make the page writable if
1189 * possible. There are three cases where we cannot make the
1190 * page mapping writable:
1192 * (1) The mapping is read-only or the VM object is read-only,
1193 * fs->prot above will simply not have VM_PROT_WRITE set.
1195 * (2) If the mapping is a virtual page table we need to be able
1196 * to detect writes so we can set VPTE_M in the virtual page
1199 * (3) If the VM page is read-only or copy-on-write, upgrading would
1200 * just result in an unnecessary COW fault.
1202 * VM_PROT_VPAGED is set if faulting via a virtual page table and
1203 * causes adjustments to the 'M'odify bit to also turn off write
1204 * access to force a re-fault.
1206 if (fs->entry->maptype == VM_MAPTYPE_VPAGETABLE) {
1207 if ((fault_type & VM_PROT_WRITE) == 0)
1208 fs->prot &= ~VM_PROT_WRITE;
1211 if (curthread->td_lwp && curthread->td_lwp->lwp_vmspace &&
1212 pmap_emulate_ad_bits(&curthread->td_lwp->lwp_vmspace->vm_pmap)) {
1213 if ((fault_type & VM_PROT_WRITE) == 0)
1214 fs->prot &= ~VM_PROT_WRITE;
1217 /* vm_object_hold(fs->object); implied b/c object == first_object */
1221 * The entire backing chain from first_object to object
1222 * inclusive is chainlocked.
1224 * If the object is dead, we stop here
1226 if (fs->object->flags & OBJ_DEAD) {
1227 vm_object_pip_wakeup(fs->first_object);
1228 vm_object_chain_release_all(fs->first_object,
1230 if (fs->object != fs->first_object)
1231 vm_object_drop(fs->object);
1232 unlock_and_deallocate(fs);
1233 return (KERN_PROTECTION_FAILURE);
1237 * See if the page is resident. Wait/Retry if the page is
1238 * busy (lots of stuff may have changed so we can't continue
1241 * We can theoretically allow the soft-busy case on a read
1242 * fault if the page is marked valid, but since such
1243 * pages are typically already pmap'd, putting that
1244 * special case in might be more effort then it is
1245 * worth. We cannot under any circumstances mess
1246 * around with a vm_page_t->busy page except, perhaps,
1249 fs->m = vm_page_lookup_busy_try(fs->object, pindex,
1252 vm_object_pip_wakeup(fs->first_object);
1253 vm_object_chain_release_all(fs->first_object,
1255 if (fs->object != fs->first_object)
1256 vm_object_drop(fs->object);
1258 vm_page_sleep_busy(fs->m, TRUE, "vmpfw");
1259 mycpu->gd_cnt.v_intrans++;
1260 /*vm_object_deallocate(fs->first_object);*/
1261 /*fs->first_object = NULL;*/
1263 return (KERN_TRY_AGAIN);
1267 * The page is busied for us.
1269 * If reactivating a page from PQ_CACHE we may have
1272 int queue = fs->m->queue;
1273 vm_page_unqueue_nowakeup(fs->m);
1275 if ((queue - fs->m->pc) == PQ_CACHE &&
1276 vm_page_count_severe()) {
1277 vm_page_activate(fs->m);
1278 vm_page_wakeup(fs->m);
1280 vm_object_pip_wakeup(fs->first_object);
1281 vm_object_chain_release_all(fs->first_object,
1283 if (fs->object != fs->first_object)
1284 vm_object_drop(fs->object);
1285 unlock_and_deallocate(fs);
1286 if (allow_nofault == 0 ||
1287 (curthread->td_flags & TDF_NOFAULT) == 0) {
1290 return (KERN_TRY_AGAIN);
1294 * If it still isn't completely valid (readable),
1295 * or if a read-ahead-mark is set on the VM page,
1296 * jump to readrest, else we found the page and
1299 * We can release the spl once we have marked the
1302 if (fs->m->object != &kernel_object) {
1303 if ((fs->m->valid & VM_PAGE_BITS_ALL) !=
1307 if (fs->m->flags & PG_RAM) {
1310 vm_page_flag_clear(fs->m, PG_RAM);
1314 break; /* break to PAGE HAS BEEN FOUND */
1318 * Page is not resident, If this is the search termination
1319 * or the pager might contain the page, allocate a new page.
1321 if (TRYPAGER(fs) || fs->object == fs->first_object) {
1323 * Allocating, must be exclusive.
1325 if (fs->object == fs->first_object &&
1327 fs->first_shared = 0;
1328 vm_object_pip_wakeup(fs->first_object);
1329 vm_object_chain_release_all(fs->first_object,
1331 if (fs->object != fs->first_object)
1332 vm_object_drop(fs->object);
1333 unlock_and_deallocate(fs);
1334 return (KERN_TRY_AGAIN);
1336 if (fs->object != fs->first_object &&
1338 fs->first_shared = 0;
1340 vm_object_pip_wakeup(fs->first_object);
1341 vm_object_chain_release_all(fs->first_object,
1343 if (fs->object != fs->first_object)
1344 vm_object_drop(fs->object);
1345 unlock_and_deallocate(fs);
1346 return (KERN_TRY_AGAIN);
1350 * If the page is beyond the object size we fail
1352 if (pindex >= fs->object->size) {
1353 vm_object_pip_wakeup(fs->first_object);
1354 vm_object_chain_release_all(fs->first_object,
1356 if (fs->object != fs->first_object)
1357 vm_object_drop(fs->object);
1358 unlock_and_deallocate(fs);
1359 return (KERN_PROTECTION_FAILURE);
1363 * Allocate a new page for this object/offset pair.
1365 * It is possible for the allocation to race, so
1369 if (!vm_page_count_severe()) {
1370 fs->m = vm_page_alloc(fs->object, pindex,
1371 ((fs->vp || fs->object->backing_object) ?
1372 VM_ALLOC_NULL_OK | VM_ALLOC_NORMAL :
1373 VM_ALLOC_NULL_OK | VM_ALLOC_NORMAL |
1374 VM_ALLOC_USE_GD | VM_ALLOC_ZERO));
1376 if (fs->m == NULL) {
1377 vm_object_pip_wakeup(fs->first_object);
1378 vm_object_chain_release_all(fs->first_object,
1380 if (fs->object != fs->first_object)
1381 vm_object_drop(fs->object);
1382 unlock_and_deallocate(fs);
1383 if (allow_nofault == 0 ||
1384 (curthread->td_flags & TDF_NOFAULT) == 0) {
1387 return (KERN_TRY_AGAIN);
1391 * Fall through to readrest. We have a new page which
1392 * will have to be paged (since m->valid will be 0).
1398 * We have found an invalid or partially valid page, a
1399 * page with a read-ahead mark which might be partially or
1400 * fully valid (and maybe dirty too), or we have allocated
1403 * Attempt to fault-in the page if there is a chance that the
1404 * pager has it, and potentially fault in additional pages
1407 * If TRYPAGER is true then fs.m will be non-NULL and busied
1413 u_char behavior = vm_map_entry_behavior(fs->entry);
1415 if (behavior == MAP_ENTRY_BEHAV_RANDOM)
1421 * Doing I/O may synchronously insert additional
1422 * pages so we can't be shared at this point either.
1424 * NOTE: We can't free fs->m here in the allocated
1425 * case (fs->object != fs->first_object) as
1426 * this would require an exclusively locked
1429 if (fs->object == fs->first_object &&
1431 vm_page_deactivate(fs->m);
1432 vm_page_wakeup(fs->m);
1434 fs->first_shared = 0;
1435 vm_object_pip_wakeup(fs->first_object);
1436 vm_object_chain_release_all(fs->first_object,
1438 if (fs->object != fs->first_object)
1439 vm_object_drop(fs->object);
1440 unlock_and_deallocate(fs);
1441 return (KERN_TRY_AGAIN);
1443 if (fs->object != fs->first_object &&
1445 vm_page_deactivate(fs->m);
1446 vm_page_wakeup(fs->m);
1448 fs->first_shared = 0;
1450 vm_object_pip_wakeup(fs->first_object);
1451 vm_object_chain_release_all(fs->first_object,
1453 if (fs->object != fs->first_object)
1454 vm_object_drop(fs->object);
1455 unlock_and_deallocate(fs);
1456 return (KERN_TRY_AGAIN);
1460 * Avoid deadlocking against the map when doing I/O.
1461 * fs.object and the page is PG_BUSY'd.
1463 * NOTE: Once unlocked, fs->entry can become stale
1464 * so this will NULL it out.
1466 * NOTE: fs->entry is invalid until we relock the
1467 * map and verify that the timestamp has not
1473 * Acquire the page data. We still hold a ref on
1474 * fs.object and the page has been PG_BUSY's.
1476 * The pager may replace the page (for example, in
1477 * order to enter a fictitious page into the
1478 * object). If it does so it is responsible for
1479 * cleaning up the passed page and properly setting
1480 * the new page PG_BUSY.
1482 * If we got here through a PG_RAM read-ahead
1483 * mark the page may be partially dirty and thus
1484 * not freeable. Don't bother checking to see
1485 * if the pager has the page because we can't free
1486 * it anyway. We have to depend on the get_page
1487 * operation filling in any gaps whether there is
1488 * backing store or not.
1490 rv = vm_pager_get_page(fs->object, &fs->m, seqaccess);
1492 if (rv == VM_PAGER_OK) {
1494 * Relookup in case pager changed page. Pager
1495 * is responsible for disposition of old page
1498 * XXX other code segments do relookups too.
1499 * It's a bad abstraction that needs to be
1502 fs->m = vm_page_lookup(fs->object, pindex);
1503 if (fs->m == NULL) {
1504 vm_object_pip_wakeup(fs->first_object);
1505 vm_object_chain_release_all(
1506 fs->first_object, fs->object);
1507 if (fs->object != fs->first_object)
1508 vm_object_drop(fs->object);
1509 unlock_and_deallocate(fs);
1510 return (KERN_TRY_AGAIN);
1513 break; /* break to PAGE HAS BEEN FOUND */
1517 * Remove the bogus page (which does not exist at this
1518 * object/offset); before doing so, we must get back
1519 * our object lock to preserve our invariant.
1521 * Also wake up any other process that may want to bring
1524 * If this is the top-level object, we must leave the
1525 * busy page to prevent another process from rushing
1526 * past us, and inserting the page in that object at
1527 * the same time that we are.
1529 if (rv == VM_PAGER_ERROR) {
1531 kprintf("vm_fault: pager read error, "
1536 kprintf("vm_fault: pager read error, "
1544 * Data outside the range of the pager or an I/O error
1546 * The page may have been wired during the pagein,
1547 * e.g. by the buffer cache, and cannot simply be
1548 * freed. Call vnode_pager_freepage() to deal with it.
1550 * Also note that we cannot free the page if we are
1551 * holding the related object shared. XXX not sure
1552 * what to do in that case.
1554 if (fs->object != fs->first_object) {
1555 vnode_pager_freepage(fs->m);
1558 * XXX - we cannot just fall out at this
1559 * point, m has been freed and is invalid!
1563 * XXX - the check for kernel_map is a kludge to work
1564 * around having the machine panic on a kernel space
1565 * fault w/ I/O error.
1567 if (((fs->map != &kernel_map) &&
1568 (rv == VM_PAGER_ERROR)) || (rv == VM_PAGER_BAD)) {
1570 if (fs->first_shared) {
1571 vm_page_deactivate(fs->m);
1572 vm_page_wakeup(fs->m);
1574 vnode_pager_freepage(fs->m);
1578 vm_object_pip_wakeup(fs->first_object);
1579 vm_object_chain_release_all(fs->first_object,
1581 if (fs->object != fs->first_object)
1582 vm_object_drop(fs->object);
1583 unlock_and_deallocate(fs);
1584 if (rv == VM_PAGER_ERROR)
1585 return (KERN_FAILURE);
1587 return (KERN_PROTECTION_FAILURE);
1593 * We get here if the object has a default pager (or unwiring)
1594 * or the pager doesn't have the page.
1596 * fs->first_m will be used for the COW unless we find a
1597 * deeper page to be mapped read-only, in which case the
1598 * unlock*(fs) will free first_m.
1600 if (fs->object == fs->first_object)
1601 fs->first_m = fs->m;
1604 * Move on to the next object. The chain lock should prevent
1605 * the backing_object from getting ripped out from under us.
1607 * The object lock for the next object is governed by
1610 if ((next_object = fs->object->backing_object) != NULL) {
1612 vm_object_hold_shared(next_object);
1614 vm_object_hold(next_object);
1615 vm_object_chain_acquire(next_object, fs->shared);
1616 KKASSERT(next_object == fs->object->backing_object);
1617 pindex += OFF_TO_IDX(fs->object->backing_object_offset);
1620 if (next_object == NULL) {
1622 * If there's no object left, fill the page in the top
1623 * object with zeros.
1625 if (fs->object != fs->first_object) {
1627 if (fs->first_object->backing_object !=
1629 vm_object_hold(fs->first_object->backing_object);
1632 vm_object_chain_release_all(
1633 fs->first_object->backing_object,
1636 if (fs->first_object->backing_object !=
1638 vm_object_drop(fs->first_object->backing_object);
1641 vm_object_pip_wakeup(fs->object);
1642 vm_object_drop(fs->object);
1643 fs->object = fs->first_object;
1644 pindex = first_pindex;
1645 fs->m = fs->first_m;
1650 * Zero the page if necessary and mark it valid.
1652 if ((fs->m->flags & PG_ZERO) == 0) {
1653 vm_page_zero_fill(fs->m);
1656 pmap_page_assertzero(VM_PAGE_TO_PHYS(fs->m));
1658 vm_page_flag_clear(fs->m, PG_ZERO);
1659 mycpu->gd_cnt.v_ozfod++;
1661 mycpu->gd_cnt.v_zfod++;
1662 fs->m->valid = VM_PAGE_BITS_ALL;
1663 break; /* break to PAGE HAS BEEN FOUND */
1665 if (fs->object != fs->first_object) {
1666 vm_object_pip_wakeup(fs->object);
1667 vm_object_lock_swap();
1668 vm_object_drop(fs->object);
1670 KASSERT(fs->object != next_object,
1671 ("object loop %p", next_object));
1672 fs->object = next_object;
1673 vm_object_pip_add(fs->object, 1);
1677 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
1680 * object still held.
1682 * local shared variable may be different from fs->shared.
1684 * If the page is being written, but isn't already owned by the
1685 * top-level object, we have to copy it into a new page owned by the
1688 KASSERT((fs->m->flags & PG_BUSY) != 0,
1689 ("vm_fault: not busy after main loop"));
1691 if (fs->object != fs->first_object) {
1693 * We only really need to copy if we want to write it.
1695 if (fault_type & VM_PROT_WRITE) {
1697 * This allows pages to be virtually copied from a
1698 * backing_object into the first_object, where the
1699 * backing object has no other refs to it, and cannot
1700 * gain any more refs. Instead of a bcopy, we just
1701 * move the page from the backing object to the
1702 * first object. Note that we must mark the page
1703 * dirty in the first object so that it will go out
1704 * to swap when needed.
1708 * Must be holding exclusive locks
1710 fs->first_shared == 0 &&
1713 * Map, if present, has not changed
1716 fs->map_generation == fs->map->timestamp) &&
1718 * Only one shadow object
1720 (fs->object->shadow_count == 1) &&
1722 * No COW refs, except us
1724 (fs->object->ref_count == 1) &&
1726 * No one else can look this object up
1728 (fs->object->handle == NULL) &&
1730 * No other ways to look the object up
1732 ((fs->object->type == OBJT_DEFAULT) ||
1733 (fs->object->type == OBJT_SWAP)) &&
1735 * We don't chase down the shadow chain
1737 (fs->object == fs->first_object->backing_object) &&
1740 * grab the lock if we need to
1742 (fs->lookup_still_valid ||
1744 lockmgr(&fs->map->lock, LK_EXCLUSIVE|LK_NOWAIT) == 0)
1747 * (first_m) and (m) are both busied. We have
1748 * move (m) into (first_m)'s object/pindex
1749 * in an atomic fashion, then free (first_m).
1751 * first_object is held so second remove
1752 * followed by the rename should wind
1753 * up being atomic. vm_page_free() might
1754 * block so we don't do it until after the
1757 fs->lookup_still_valid = 1;
1758 vm_page_protect(fs->first_m, VM_PROT_NONE);
1759 vm_page_remove(fs->first_m);
1760 vm_page_rename(fs->m, fs->first_object,
1762 vm_page_free(fs->first_m);
1763 fs->first_m = fs->m;
1765 mycpu->gd_cnt.v_cow_optim++;
1768 * Oh, well, lets copy it.
1770 * Why are we unmapping the original page
1771 * here? Well, in short, not all accessors
1772 * of user memory go through the pmap. The
1773 * procfs code doesn't have access user memory
1774 * via a local pmap, so vm_fault_page*()
1775 * can't call pmap_enter(). And the umtx*()
1776 * code may modify the COW'd page via a DMAP
1777 * or kernel mapping and not via the pmap,
1778 * leaving the original page still mapped
1779 * read-only into the pmap.
1781 * So we have to remove the page from at
1782 * least the current pmap if it is in it.
1783 * Just remove it from all pmaps.
1785 KKASSERT(fs->first_shared == 0);
1786 vm_page_copy(fs->m, fs->first_m);
1787 vm_page_protect(fs->m, VM_PROT_NONE);
1788 vm_page_event(fs->m, VMEVENT_COW);
1792 * We no longer need the old page or object.
1798 * We intend to revert to first_object, undo the
1799 * chain lock through to that.
1802 if (fs->first_object->backing_object != fs->object)
1803 vm_object_hold(fs->first_object->backing_object);
1805 vm_object_chain_release_all(
1806 fs->first_object->backing_object,
1809 if (fs->first_object->backing_object != fs->object)
1810 vm_object_drop(fs->first_object->backing_object);
1814 * fs->object != fs->first_object due to above
1817 vm_object_pip_wakeup(fs->object);
1818 vm_object_drop(fs->object);
1821 * Only use the new page below...
1823 mycpu->gd_cnt.v_cow_faults++;
1824 fs->m = fs->first_m;
1825 fs->object = fs->first_object;
1826 pindex = first_pindex;
1829 * If it wasn't a write fault avoid having to copy
1830 * the page by mapping it read-only.
1832 fs->prot &= ~VM_PROT_WRITE;
1837 * Relock the map if necessary, then check the generation count.
1838 * relock_map() will update fs->timestamp to account for the
1839 * relocking if necessary.
1841 * If the count has changed after relocking then all sorts of
1842 * crap may have happened and we have to retry.
1844 * NOTE: The relock_map() can fail due to a deadlock against
1845 * the vm_page we are holding BUSY.
1847 if (fs->lookup_still_valid == FALSE && fs->map) {
1848 if (relock_map(fs) ||
1849 fs->map->timestamp != fs->map_generation) {
1851 vm_object_pip_wakeup(fs->first_object);
1852 vm_object_chain_release_all(fs->first_object,
1854 if (fs->object != fs->first_object)
1855 vm_object_drop(fs->object);
1856 unlock_and_deallocate(fs);
1857 return (KERN_TRY_AGAIN);
1862 * If the fault is a write, we know that this page is being
1863 * written NOW so dirty it explicitly to save on pmap_is_modified()
1866 * If this is a NOSYNC mmap we do not want to set PG_NOSYNC
1867 * if the page is already dirty to prevent data written with
1868 * the expectation of being synced from not being synced.
1869 * Likewise if this entry does not request NOSYNC then make
1870 * sure the page isn't marked NOSYNC. Applications sharing
1871 * data should use the same flags to avoid ping ponging.
1873 * Also tell the backing pager, if any, that it should remove
1874 * any swap backing since the page is now dirty.
1876 vm_page_activate(fs->m);
1877 if (fs->prot & VM_PROT_WRITE) {
1878 vm_object_set_writeable_dirty(fs->m->object);
1879 vm_set_nosync(fs->m, fs->entry);
1880 if (fs->fault_flags & VM_FAULT_DIRTY) {
1881 vm_page_dirty(fs->m);
1882 swap_pager_unswapped(fs->m);
1886 vm_object_pip_wakeup(fs->first_object);
1887 vm_object_chain_release_all(fs->first_object, fs->object);
1888 if (fs->object != fs->first_object)
1889 vm_object_drop(fs->object);
1892 * Page had better still be busy. We are still locked up and
1893 * fs->object will have another PIP reference if it is not equal
1894 * to fs->first_object.
1896 KASSERT(fs->m->flags & PG_BUSY,
1897 ("vm_fault: page %p not busy!", fs->m));
1900 * Sanity check: page must be completely valid or it is not fit to
1901 * map into user space. vm_pager_get_pages() ensures this.
1903 if (fs->m->valid != VM_PAGE_BITS_ALL) {
1904 vm_page_zero_invalid(fs->m, TRUE);
1905 kprintf("Warning: page %p partially invalid on fault\n", fs->m);
1907 vm_page_flag_clear(fs->m, PG_ZERO);
1909 return (KERN_SUCCESS);
1913 * Hold each of the physical pages that are mapped by the specified range of
1914 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid
1915 * and allow the specified types of access, "prot". If all of the implied
1916 * pages are successfully held, then the number of held pages is returned
1917 * together with pointers to those pages in the array "ma". However, if any
1918 * of the pages cannot be held, -1 is returned.
1921 vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
1922 vm_prot_t prot, vm_page_t *ma, int max_count)
1924 vm_offset_t start, end;
1925 int i, npages, error;
1927 start = trunc_page(addr);
1928 end = round_page(addr + len);
1930 npages = howmany(end - start, PAGE_SIZE);
1932 if (npages > max_count)
1935 for (i = 0; i < npages; i++) {
1936 // XXX error handling
1937 ma[i] = vm_fault_page_quick(start + (i * PAGE_SIZE),
1946 * Wire down a range of virtual addresses in a map. The entry in question
1947 * should be marked in-transition and the map must be locked. We must
1948 * release the map temporarily while faulting-in the page to avoid a
1949 * deadlock. Note that the entry may be clipped while we are blocked but
1950 * will never be freed.
1955 vm_fault_wire(vm_map_t map, vm_map_entry_t entry, boolean_t user_wire)
1957 boolean_t fictitious;
1966 lwkt_gettoken(&map->token);
1968 pmap = vm_map_pmap(map);
1969 start = entry->start;
1971 fictitious = entry->object.vm_object &&
1972 ((entry->object.vm_object->type == OBJT_DEVICE) ||
1973 (entry->object.vm_object->type == OBJT_MGTDEVICE));
1974 if (entry->eflags & MAP_ENTRY_KSTACK)
1980 * We simulate a fault to get the page and enter it in the physical
1983 for (va = start; va < end; va += PAGE_SIZE) {
1985 rv = vm_fault(map, va, VM_PROT_READ,
1986 VM_FAULT_USER_WIRE);
1988 rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE,
1989 VM_FAULT_CHANGE_WIRING);
1992 while (va > start) {
1994 if ((pa = pmap_extract(pmap, va)) == 0)
1996 pmap_change_wiring(pmap, va, FALSE, entry);
1998 m = PHYS_TO_VM_PAGE(pa);
1999 vm_page_busy_wait(m, FALSE, "vmwrpg");
2000 vm_page_unwire(m, 1);
2010 lwkt_reltoken(&map->token);
2015 * Unwire a range of virtual addresses in a map. The map should be
2019 vm_fault_unwire(vm_map_t map, vm_map_entry_t entry)
2021 boolean_t fictitious;
2029 lwkt_gettoken(&map->token);
2031 pmap = vm_map_pmap(map);
2032 start = entry->start;
2034 fictitious = entry->object.vm_object &&
2035 ((entry->object.vm_object->type == OBJT_DEVICE) ||
2036 (entry->object.vm_object->type == OBJT_MGTDEVICE));
2037 if (entry->eflags & MAP_ENTRY_KSTACK)
2041 * Since the pages are wired down, we must be able to get their
2042 * mappings from the physical map system.
2044 for (va = start; va < end; va += PAGE_SIZE) {
2045 pa = pmap_extract(pmap, va);
2047 pmap_change_wiring(pmap, va, FALSE, entry);
2049 m = PHYS_TO_VM_PAGE(pa);
2050 vm_page_busy_wait(m, FALSE, "vmwupg");
2051 vm_page_unwire(m, 1);
2056 lwkt_reltoken(&map->token);
2060 * Copy all of the pages from a wired-down map entry to another.
2062 * The source and destination maps must be locked for write.
2063 * The source and destination maps token must be held
2064 * The source map entry must be wired down (or be a sharing map
2065 * entry corresponding to a main map entry that is wired down).
2067 * No other requirements.
2069 * XXX do segment optimization
2072 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
2073 vm_map_entry_t dst_entry, vm_map_entry_t src_entry)
2075 vm_object_t dst_object;
2076 vm_object_t src_object;
2077 vm_ooffset_t dst_offset;
2078 vm_ooffset_t src_offset;
2084 src_object = src_entry->object.vm_object;
2085 src_offset = src_entry->offset;
2088 * Create the top-level object for the destination entry. (Doesn't
2089 * actually shadow anything - we copy the pages directly.)
2091 vm_map_entry_allocate_object(dst_entry);
2092 dst_object = dst_entry->object.vm_object;
2094 prot = dst_entry->max_protection;
2097 * Loop through all of the pages in the entry's range, copying each
2098 * one from the source object (it should be there) to the destination
2101 vm_object_hold(src_object);
2102 vm_object_hold(dst_object);
2103 for (vaddr = dst_entry->start, dst_offset = 0;
2104 vaddr < dst_entry->end;
2105 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) {
2108 * Allocate a page in the destination object
2111 dst_m = vm_page_alloc(dst_object,
2112 OFF_TO_IDX(dst_offset),
2114 if (dst_m == NULL) {
2117 } while (dst_m == NULL);
2120 * Find the page in the source object, and copy it in.
2121 * (Because the source is wired down, the page will be in
2124 src_m = vm_page_lookup(src_object,
2125 OFF_TO_IDX(dst_offset + src_offset));
2127 panic("vm_fault_copy_wired: page missing");
2129 vm_page_copy(src_m, dst_m);
2130 vm_page_event(src_m, VMEVENT_COW);
2133 * Enter it in the pmap...
2136 vm_page_flag_clear(dst_m, PG_ZERO);
2137 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE, dst_entry);
2140 * Mark it no longer busy, and put it on the active list.
2142 vm_page_activate(dst_m);
2143 vm_page_wakeup(dst_m);
2145 vm_object_drop(dst_object);
2146 vm_object_drop(src_object);
2152 * This routine checks around the requested page for other pages that
2153 * might be able to be faulted in. This routine brackets the viable
2154 * pages for the pages to be paged in.
2157 * m, rbehind, rahead
2160 * marray (array of vm_page_t), reqpage (index of requested page)
2163 * number of pages in marray
2166 vm_fault_additional_pages(vm_page_t m, int rbehind, int rahead,
2167 vm_page_t *marray, int *reqpage)
2171 vm_pindex_t pindex, startpindex, endpindex, tpindex;
2173 int cbehind, cahead;
2179 * we don't fault-ahead for device pager
2181 if ((object->type == OBJT_DEVICE) ||
2182 (object->type == OBJT_MGTDEVICE)) {
2189 * if the requested page is not available, then give up now
2191 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) {
2192 *reqpage = 0; /* not used by caller, fix compiler warn */
2196 if ((cbehind == 0) && (cahead == 0)) {
2202 if (rahead > cahead) {
2206 if (rbehind > cbehind) {
2211 * Do not do any readahead if we have insufficient free memory.
2213 * XXX code was broken disabled before and has instability
2214 * with this conditonal fixed, so shortcut for now.
2216 if (burst_fault == 0 || vm_page_count_severe()) {
2223 * scan backward for the read behind pages -- in memory
2225 * Assume that if the page is not found an interrupt will not
2226 * create it. Theoretically interrupts can only remove (busy)
2227 * pages, not create new associations.
2230 if (rbehind > pindex) {
2234 startpindex = pindex - rbehind;
2237 vm_object_hold(object);
2238 for (tpindex = pindex; tpindex > startpindex; --tpindex) {
2239 if (vm_page_lookup(object, tpindex - 1))
2244 while (tpindex < pindex) {
2245 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM |
2248 for (j = 0; j < i; j++) {
2249 vm_page_free(marray[j]);
2251 vm_object_drop(object);
2260 vm_object_drop(object);
2266 * Assign requested page
2273 * Scan forwards for read-ahead pages
2275 tpindex = pindex + 1;
2276 endpindex = tpindex + rahead;
2277 if (endpindex > object->size)
2278 endpindex = object->size;
2280 vm_object_hold(object);
2281 while (tpindex < endpindex) {
2282 if (vm_page_lookup(object, tpindex))
2284 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM |
2292 vm_object_drop(object);
2300 * vm_prefault() provides a quick way of clustering pagefaults into a
2301 * processes address space. It is a "cousin" of pmap_object_init_pt,
2302 * except it runs at page fault time instead of mmap time.
2304 * vm.fast_fault Enables pre-faulting zero-fill pages
2306 * vm.prefault_pages Number of pages (1/2 negative, 1/2 positive) to
2307 * prefault. Scan stops in either direction when
2308 * a page is found to already exist.
2310 * This code used to be per-platform pmap_prefault(). It is now
2311 * machine-independent and enhanced to also pre-fault zero-fill pages
2312 * (see vm.fast_fault) as well as make them writable, which greatly
2313 * reduces the number of page faults programs incur.
2315 * Application performance when pre-faulting zero-fill pages is heavily
2316 * dependent on the application. Very tiny applications like /bin/echo
2317 * lose a little performance while applications of any appreciable size
2318 * gain performance. Prefaulting multiple pages also reduces SMP
2319 * congestion and can improve SMP performance significantly.
2321 * NOTE! prot may allow writing but this only applies to the top level
2322 * object. If we wind up mapping a page extracted from a backing
2323 * object we have to make sure it is read-only.
2325 * NOTE! The caller has already handled any COW operations on the
2326 * vm_map_entry via the normal fault code. Do NOT call this
2327 * shortcut unless the normal fault code has run on this entry.
2329 * The related map must be locked.
2330 * No other requirements.
2332 static int vm_prefault_pages = 8;
2333 SYSCTL_INT(_vm, OID_AUTO, prefault_pages, CTLFLAG_RW, &vm_prefault_pages, 0,
2334 "Maximum number of pages to pre-fault");
2335 static int vm_fast_fault = 1;
2336 SYSCTL_INT(_vm, OID_AUTO, fast_fault, CTLFLAG_RW, &vm_fast_fault, 0,
2337 "Burst fault zero-fill regions");
2340 * Set PG_NOSYNC if the map entry indicates so, but only if the page
2341 * is not already dirty by other means. This will prevent passive
2342 * filesystem syncing as well as 'sync' from writing out the page.
2345 vm_set_nosync(vm_page_t m, vm_map_entry_t entry)
2347 if (entry->eflags & MAP_ENTRY_NOSYNC) {
2349 vm_page_flag_set(m, PG_NOSYNC);
2351 vm_page_flag_clear(m, PG_NOSYNC);
2356 vm_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry, int prot,
2372 * Get stable max count value, disabled if set to 0
2374 maxpages = vm_prefault_pages;
2380 * We do not currently prefault mappings that use virtual page
2381 * tables. We do not prefault foreign pmaps.
2383 if (entry->maptype == VM_MAPTYPE_VPAGETABLE)
2385 lp = curthread->td_lwp;
2386 if (lp == NULL || (pmap != vmspace_pmap(lp->lwp_vmspace)))
2390 * Limit pre-fault count to 1024 pages.
2392 if (maxpages > 1024)
2395 object = entry->object.vm_object;
2396 KKASSERT(object != NULL);
2397 KKASSERT(object == entry->object.vm_object);
2398 vm_object_hold(object);
2399 vm_object_chain_acquire(object, 0);
2403 for (i = 0; i < maxpages; ++i) {
2404 vm_object_t lobject;
2405 vm_object_t nobject;
2410 * This can eat a lot of time on a heavily contended
2411 * machine so yield on the tick if needed.
2417 * Calculate the page to pre-fault, stopping the scan in
2418 * each direction separately if the limit is reached.
2423 addr = addra - ((i + 1) >> 1) * PAGE_SIZE;
2427 addr = addra + ((i + 2) >> 1) * PAGE_SIZE;
2429 if (addr < entry->start) {
2435 if (addr >= entry->end) {
2443 * Skip pages already mapped, and stop scanning in that
2444 * direction. When the scan terminates in both directions
2447 if (pmap_prefault_ok(pmap, addr) == 0) {
2458 * Follow the VM object chain to obtain the page to be mapped
2461 * If we reach the terminal object without finding a page
2462 * and we determine it would be advantageous, then allocate
2463 * a zero-fill page for the base object. The base object
2464 * is guaranteed to be OBJT_DEFAULT for this case.
2466 * In order to not have to check the pager via *haspage*()
2467 * we stop if any non-default object is encountered. e.g.
2468 * a vnode or swap object would stop the loop.
2470 index = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
2475 KKASSERT(lobject == entry->object.vm_object);
2476 /*vm_object_hold(lobject); implied */
2478 while ((m = vm_page_lookup_busy_try(lobject, pindex,
2479 TRUE, &error)) == NULL) {
2480 if (lobject->type != OBJT_DEFAULT)
2482 if (lobject->backing_object == NULL) {
2483 if (vm_fast_fault == 0)
2485 if ((prot & VM_PROT_WRITE) == 0 ||
2486 vm_page_count_min(0)) {
2491 * NOTE: Allocated from base object
2493 m = vm_page_alloc(object, index,
2502 /* lobject = object .. not needed */
2505 if (lobject->backing_object_offset & PAGE_MASK)
2507 nobject = lobject->backing_object;
2508 vm_object_hold(nobject);
2509 KKASSERT(nobject == lobject->backing_object);
2510 pindex += lobject->backing_object_offset >> PAGE_SHIFT;
2511 if (lobject != object) {
2512 vm_object_lock_swap();
2513 vm_object_drop(lobject);
2516 pprot &= ~VM_PROT_WRITE;
2517 vm_object_chain_acquire(lobject, 0);
2521 * NOTE: A non-NULL (m) will be associated with lobject if
2522 * it was found there, otherwise it is probably a
2523 * zero-fill page associated with the base object.
2525 * Give-up if no page is available.
2528 if (lobject != object) {
2530 if (object->backing_object != lobject)
2531 vm_object_hold(object->backing_object);
2533 vm_object_chain_release_all(
2534 object->backing_object, lobject);
2536 if (object->backing_object != lobject)
2537 vm_object_drop(object->backing_object);
2539 vm_object_drop(lobject);
2545 * The object must be marked dirty if we are mapping a
2546 * writable page. m->object is either lobject or object,
2547 * both of which are still held. Do this before we
2548 * potentially drop the object.
2550 if (pprot & VM_PROT_WRITE)
2551 vm_object_set_writeable_dirty(m->object);
2554 * Do not conditionalize on PG_RAM. If pages are present in
2555 * the VM system we assume optimal caching. If caching is
2556 * not optimal the I/O gravy train will be restarted when we
2557 * hit an unavailable page. We do not want to try to restart
2558 * the gravy train now because we really don't know how much
2559 * of the object has been cached. The cost for restarting
2560 * the gravy train should be low (since accesses will likely
2561 * be I/O bound anyway).
2563 if (lobject != object) {
2565 if (object->backing_object != lobject)
2566 vm_object_hold(object->backing_object);
2568 vm_object_chain_release_all(object->backing_object,
2571 if (object->backing_object != lobject)
2572 vm_object_drop(object->backing_object);
2574 vm_object_drop(lobject);
2578 * Enter the page into the pmap if appropriate. If we had
2579 * allocated the page we have to place it on a queue. If not
2580 * we just have to make sure it isn't on the cache queue
2581 * (pages on the cache queue are not allowed to be mapped).
2585 * Page must be zerod.
2587 if ((m->flags & PG_ZERO) == 0) {
2588 vm_page_zero_fill(m);
2591 pmap_page_assertzero(
2592 VM_PAGE_TO_PHYS(m));
2594 vm_page_flag_clear(m, PG_ZERO);
2595 mycpu->gd_cnt.v_ozfod++;
2597 mycpu->gd_cnt.v_zfod++;
2598 m->valid = VM_PAGE_BITS_ALL;
2601 * Handle dirty page case
2603 if (pprot & VM_PROT_WRITE)
2604 vm_set_nosync(m, entry);
2605 pmap_enter(pmap, addr, m, pprot, 0, entry);
2606 mycpu->gd_cnt.v_vm_faults++;
2607 if (curthread->td_lwp)
2608 ++curthread->td_lwp->lwp_ru.ru_minflt;
2609 vm_page_deactivate(m);
2610 if (pprot & VM_PROT_WRITE) {
2611 /*vm_object_set_writeable_dirty(m->object);*/
2612 vm_set_nosync(m, entry);
2613 if (fault_flags & VM_FAULT_DIRTY) {
2616 swap_pager_unswapped(m);
2621 /* couldn't busy page, no wakeup */
2623 ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
2624 (m->flags & PG_FICTITIOUS) == 0) {
2626 * A fully valid page not undergoing soft I/O can
2627 * be immediately entered into the pmap.
2629 if ((m->queue - m->pc) == PQ_CACHE)
2630 vm_page_deactivate(m);
2631 if (pprot & VM_PROT_WRITE) {
2632 /*vm_object_set_writeable_dirty(m->object);*/
2633 vm_set_nosync(m, entry);
2634 if (fault_flags & VM_FAULT_DIRTY) {
2637 swap_pager_unswapped(m);
2640 if (pprot & VM_PROT_WRITE)
2641 vm_set_nosync(m, entry);
2642 pmap_enter(pmap, addr, m, pprot, 0, entry);
2643 mycpu->gd_cnt.v_vm_faults++;
2644 if (curthread->td_lwp)
2645 ++curthread->td_lwp->lwp_ru.ru_minflt;
2651 vm_object_chain_release(object);
2652 vm_object_drop(object);
2656 * Object can be held shared
2659 vm_prefault_quick(pmap_t pmap, vm_offset_t addra,
2660 vm_map_entry_t entry, int prot, int fault_flags)
2673 * Get stable max count value, disabled if set to 0
2675 maxpages = vm_prefault_pages;
2681 * We do not currently prefault mappings that use virtual page
2682 * tables. We do not prefault foreign pmaps.
2684 if (entry->maptype == VM_MAPTYPE_VPAGETABLE)
2686 lp = curthread->td_lwp;
2687 if (lp == NULL || (pmap != vmspace_pmap(lp->lwp_vmspace)))
2689 object = entry->object.vm_object;
2690 if (object->backing_object != NULL)
2692 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2695 * Limit pre-fault count to 1024 pages.
2697 if (maxpages > 1024)
2702 for (i = 0; i < maxpages; ++i) {
2706 * Calculate the page to pre-fault, stopping the scan in
2707 * each direction separately if the limit is reached.
2712 addr = addra - ((i + 1) >> 1) * PAGE_SIZE;
2716 addr = addra + ((i + 2) >> 1) * PAGE_SIZE;
2718 if (addr < entry->start) {
2724 if (addr >= entry->end) {
2732 * Skip pages already mapped, and stop scanning in that
2733 * direction. When the scan terminates in both directions
2736 if (pmap_prefault_ok(pmap, addr) == 0) {
2747 * Follow the VM object chain to obtain the page to be mapped
2748 * into the pmap. This version of the prefault code only
2749 * works with terminal objects.
2751 * WARNING! We cannot call swap_pager_unswapped() with a
2754 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
2756 m = vm_page_lookup_busy_try(object, pindex, TRUE, &error);
2757 if (m == NULL || error)
2760 if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
2761 (m->flags & PG_FICTITIOUS) == 0 &&
2762 ((m->flags & PG_SWAPPED) == 0 ||
2763 (prot & VM_PROT_WRITE) == 0 ||
2764 (fault_flags & VM_FAULT_DIRTY) == 0)) {
2766 * A fully valid page not undergoing soft I/O can
2767 * be immediately entered into the pmap.
2769 if ((m->queue - m->pc) == PQ_CACHE)
2770 vm_page_deactivate(m);
2771 if (prot & VM_PROT_WRITE) {
2772 vm_object_set_writeable_dirty(m->object);
2773 vm_set_nosync(m, entry);
2774 if (fault_flags & VM_FAULT_DIRTY) {
2777 swap_pager_unswapped(m);
2780 pmap_enter(pmap, addr, m, prot, 0, entry);
2781 mycpu->gd_cnt.v_vm_faults++;
2782 if (curthread->td_lwp)
2783 ++curthread->td_lwp->lwp_ru.ru_minflt;