2 * SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU)
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.
73 * Page fault handling module.
76 #include <sys/cdefs.h>
77 __FBSDID("$FreeBSD$");
79 #include "opt_ktrace.h"
82 #include <sys/param.h>
83 #include <sys/systm.h>
84 #include <sys/kernel.h>
87 #include <sys/mutex.h>
89 #include <sys/racct.h>
90 #include <sys/refcount.h>
91 #include <sys/resourcevar.h>
92 #include <sys/rwlock.h>
93 #include <sys/signalvar.h>
94 #include <sys/sysctl.h>
95 #include <sys/sysent.h>
96 #include <sys/vmmeter.h>
97 #include <sys/vnode.h>
99 #include <sys/ktrace.h>
103 #include <vm/vm_param.h>
105 #include <vm/vm_map.h>
106 #include <vm/vm_object.h>
107 #include <vm/vm_page.h>
108 #include <vm/vm_pageout.h>
109 #include <vm/vm_kern.h>
110 #include <vm/vm_pager.h>
111 #include <vm/vm_extern.h>
112 #include <vm/vm_reserv.h>
117 #define VM_FAULT_READ_DEFAULT (1 + VM_FAULT_READ_AHEAD_INIT)
118 #define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX)
120 #define VM_FAULT_DONTNEED_MIN 1048576
127 vm_object_t first_object;
128 vm_pindex_t first_pindex;
130 vm_map_entry_t entry;
132 bool lookup_still_valid;
136 static void vm_fault_dontneed(const struct faultstate *fs, vm_offset_t vaddr,
138 static void vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra,
139 int backward, int forward, bool obj_locked);
141 static int vm_pfault_oom_attempts = 3;
142 SYSCTL_INT(_vm, OID_AUTO, pfault_oom_attempts, CTLFLAG_RWTUN,
143 &vm_pfault_oom_attempts, 0,
144 "Number of page allocation attempts in page fault handler before it "
145 "triggers OOM handling");
147 static int vm_pfault_oom_wait = 10;
148 SYSCTL_INT(_vm, OID_AUTO, pfault_oom_wait, CTLFLAG_RWTUN,
149 &vm_pfault_oom_wait, 0,
150 "Number of seconds to wait for free pages before retrying "
151 "the page fault handler");
154 release_page(struct faultstate *fs)
159 * fs->m's object lock might not be held, so the page must be
160 * kept busy until we are done with it.
163 vm_page_deactivate(fs->m);
164 vm_page_unlock(fs->m);
165 vm_page_xunbusy(fs->m);
171 unlock_map(struct faultstate *fs)
174 if (fs->lookup_still_valid) {
175 vm_map_lookup_done(fs->map, fs->entry);
176 fs->lookup_still_valid = false;
181 unlock_vp(struct faultstate *fs)
184 if (fs->vp != NULL) {
191 fault_deallocate(struct faultstate *fs)
194 vm_object_pip_wakeup(fs->object);
195 if (fs->object != fs->first_object) {
196 VM_OBJECT_WLOCK(fs->first_object);
197 vm_page_free(fs->first_m);
198 vm_object_pip_wakeup(fs->first_object);
199 VM_OBJECT_WUNLOCK(fs->first_object);
202 vm_object_deallocate(fs->first_object);
208 unlock_and_deallocate(struct faultstate *fs)
211 VM_OBJECT_WUNLOCK(fs->object);
212 fault_deallocate(fs);
216 vm_fault_dirty(vm_map_entry_t entry, vm_page_t m, vm_prot_t prot,
217 vm_prot_t fault_type, int fault_flags, bool excl)
221 if (((prot & VM_PROT_WRITE) == 0 &&
222 (fault_flags & VM_FAULT_DIRTY) == 0) ||
223 (m->oflags & VPO_UNMANAGED) != 0)
226 VM_OBJECT_ASSERT_LOCKED(m->object);
227 VM_PAGE_OBJECT_BUSY_ASSERT(m);
229 need_dirty = ((fault_type & VM_PROT_WRITE) != 0 &&
230 (fault_flags & VM_FAULT_WIRE) == 0) ||
231 (fault_flags & VM_FAULT_DIRTY) != 0;
233 vm_object_set_writeable_dirty(m->object);
237 * If two callers of vm_fault_dirty() with excl ==
238 * FALSE, one for the map entry with MAP_ENTRY_NOSYNC
239 * flag set, other with flag clear, race, it is
240 * possible for the no-NOSYNC thread to see m->dirty
241 * != 0 and not clear PGA_NOSYNC. Take vm_page lock
242 * around manipulation of PGA_NOSYNC and
243 * vm_page_dirty() call to avoid the race.
248 * If this is a NOSYNC mmap we do not want to set PGA_NOSYNC
249 * if the page is already dirty to prevent data written with
250 * the expectation of being synced from not being synced.
251 * Likewise if this entry does not request NOSYNC then make
252 * sure the page isn't marked NOSYNC. Applications sharing
253 * data should use the same flags to avoid ping ponging.
255 if ((entry->eflags & MAP_ENTRY_NOSYNC) != 0) {
257 vm_page_aflag_set(m, PGA_NOSYNC);
260 vm_page_aflag_clear(m, PGA_NOSYNC);
264 * If the fault is a write, we know that this page is being
265 * written NOW so dirty it explicitly to save on
266 * pmap_is_modified() calls later.
268 * Also, since the page is now dirty, we can possibly tell
269 * the pager to release any swap backing the page. Calling
270 * the pager requires a write lock on the object.
277 vm_pager_page_unswapped(m);
281 * Unlocks fs.first_object and fs.map on success.
284 vm_fault_soft_fast(struct faultstate *fs, vm_offset_t vaddr, vm_prot_t prot,
285 int fault_type, int fault_flags, boolean_t wired, vm_page_t *m_hold)
288 #if (defined(__aarch64__) || defined(__amd64__) || (defined(__arm__) && \
289 __ARM_ARCH >= 6) || defined(__i386__) || defined(__riscv)) && \
296 MPASS(fs->vp == NULL);
297 vm_object_busy(fs->first_object);
298 m = vm_page_lookup(fs->first_object, fs->first_pindex);
299 /* A busy page can be mapped for read|execute access. */
300 if (m == NULL || ((prot & VM_PROT_WRITE) != 0 &&
301 vm_page_busied(m)) || !vm_page_all_valid(m)) {
307 #if (defined(__aarch64__) || defined(__amd64__) || (defined(__arm__) && \
308 __ARM_ARCH >= 6) || defined(__i386__) || defined(__riscv)) && \
310 if ((m->flags & PG_FICTITIOUS) == 0 &&
311 (m_super = vm_reserv_to_superpage(m)) != NULL &&
312 rounddown2(vaddr, pagesizes[m_super->psind]) >= fs->entry->start &&
313 roundup2(vaddr + 1, pagesizes[m_super->psind]) <= fs->entry->end &&
314 (vaddr & (pagesizes[m_super->psind] - 1)) == (VM_PAGE_TO_PHYS(m) &
315 (pagesizes[m_super->psind] - 1)) && !wired &&
316 pmap_ps_enabled(fs->map->pmap)) {
317 flags = PS_ALL_VALID;
318 if ((prot & VM_PROT_WRITE) != 0) {
320 * Create a superpage mapping allowing write access
321 * only if none of the constituent pages are busy and
322 * all of them are already dirty (except possibly for
323 * the page that was faulted on).
325 flags |= PS_NONE_BUSY;
326 if ((fs->first_object->flags & OBJ_UNMANAGED) == 0)
327 flags |= PS_ALL_DIRTY;
329 if (vm_page_ps_test(m_super, flags, m)) {
331 psind = m_super->psind;
332 vaddr = rounddown2(vaddr, pagesizes[psind]);
333 /* Preset the modified bit for dirty superpages. */
334 if ((flags & PS_ALL_DIRTY) != 0)
335 fault_type |= VM_PROT_WRITE;
339 rv = pmap_enter(fs->map->pmap, vaddr, m_map, prot, fault_type |
340 PMAP_ENTER_NOSLEEP | (wired ? PMAP_ENTER_WIRED : 0), psind);
341 if (rv != KERN_SUCCESS)
343 if (m_hold != NULL) {
347 vm_fault_dirty(fs->entry, m, prot, fault_type, fault_flags, false);
348 if (psind == 0 && !wired)
349 vm_fault_prefault(fs, vaddr, PFBAK, PFFOR, true);
350 VM_OBJECT_RUNLOCK(fs->first_object);
351 vm_map_lookup_done(fs->map, fs->entry);
352 curthread->td_ru.ru_minflt++;
355 vm_object_unbusy(fs->first_object);
360 vm_fault_restore_map_lock(struct faultstate *fs)
363 VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
364 MPASS(REFCOUNT_COUNT(fs->first_object->paging_in_progress) > 0);
366 if (!vm_map_trylock_read(fs->map)) {
367 VM_OBJECT_WUNLOCK(fs->first_object);
368 vm_map_lock_read(fs->map);
369 VM_OBJECT_WLOCK(fs->first_object);
371 fs->lookup_still_valid = true;
375 vm_fault_populate_check_page(vm_page_t m)
379 * Check each page to ensure that the pager is obeying the
380 * interface: the page must be installed in the object, fully
381 * valid, and exclusively busied.
384 MPASS(vm_page_all_valid(m));
385 MPASS(vm_page_xbusied(m));
389 vm_fault_populate_cleanup(vm_object_t object, vm_pindex_t first,
395 VM_OBJECT_ASSERT_WLOCKED(object);
396 MPASS(first <= last);
397 for (pidx = first, m = vm_page_lookup(object, pidx);
398 pidx <= last; pidx++, m = vm_page_next(m)) {
399 vm_fault_populate_check_page(m);
401 vm_page_deactivate(m);
408 vm_fault_populate(struct faultstate *fs, vm_prot_t prot, int fault_type,
409 int fault_flags, boolean_t wired, vm_page_t *m_hold)
414 vm_pindex_t map_first, map_last, pager_first, pager_last, pidx;
415 int i, npages, psind, rv;
417 MPASS(fs->object == fs->first_object);
418 VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
419 MPASS(REFCOUNT_COUNT(fs->first_object->paging_in_progress) > 0);
420 MPASS(fs->first_object->backing_object == NULL);
421 MPASS(fs->lookup_still_valid);
423 pager_first = OFF_TO_IDX(fs->entry->offset);
424 pager_last = pager_first + atop(fs->entry->end - fs->entry->start) - 1;
429 * Call the pager (driver) populate() method.
431 * There is no guarantee that the method will be called again
432 * if the current fault is for read, and a future fault is
433 * for write. Report the entry's maximum allowed protection
436 rv = vm_pager_populate(fs->first_object, fs->first_pindex,
437 fault_type, fs->entry->max_protection, &pager_first, &pager_last);
439 VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
440 if (rv == VM_PAGER_BAD) {
442 * VM_PAGER_BAD is the backdoor for a pager to request
443 * normal fault handling.
445 vm_fault_restore_map_lock(fs);
446 if (fs->map->timestamp != fs->map_generation)
447 return (KERN_RESOURCE_SHORTAGE); /* RetryFault */
448 return (KERN_NOT_RECEIVER);
450 if (rv != VM_PAGER_OK)
451 return (KERN_FAILURE); /* AKA SIGSEGV */
453 /* Ensure that the driver is obeying the interface. */
454 MPASS(pager_first <= pager_last);
455 MPASS(fs->first_pindex <= pager_last);
456 MPASS(fs->first_pindex >= pager_first);
457 MPASS(pager_last < fs->first_object->size);
459 vm_fault_restore_map_lock(fs);
460 if (fs->map->timestamp != fs->map_generation) {
461 vm_fault_populate_cleanup(fs->first_object, pager_first,
463 return (KERN_RESOURCE_SHORTAGE); /* RetryFault */
467 * The map is unchanged after our last unlock. Process the fault.
469 * The range [pager_first, pager_last] that is given to the
470 * pager is only a hint. The pager may populate any range
471 * within the object that includes the requested page index.
472 * In case the pager expanded the range, clip it to fit into
475 map_first = OFF_TO_IDX(fs->entry->offset);
476 if (map_first > pager_first) {
477 vm_fault_populate_cleanup(fs->first_object, pager_first,
479 pager_first = map_first;
481 map_last = map_first + atop(fs->entry->end - fs->entry->start) - 1;
482 if (map_last < pager_last) {
483 vm_fault_populate_cleanup(fs->first_object, map_last + 1,
485 pager_last = map_last;
487 for (pidx = pager_first, m = vm_page_lookup(fs->first_object, pidx);
489 pidx += npages, m = vm_page_next(&m[npages - 1])) {
490 vaddr = fs->entry->start + IDX_TO_OFF(pidx) - fs->entry->offset;
491 #if defined(__aarch64__) || defined(__amd64__) || (defined(__arm__) && \
492 __ARM_ARCH >= 6) || defined(__i386__) || defined(__riscv)
494 if (psind > 0 && ((vaddr & (pagesizes[psind] - 1)) != 0 ||
495 pidx + OFF_TO_IDX(pagesizes[psind]) - 1 > pager_last ||
496 !pmap_ps_enabled(fs->map->pmap) || wired))
501 npages = atop(pagesizes[psind]);
502 for (i = 0; i < npages; i++) {
503 vm_fault_populate_check_page(&m[i]);
504 vm_fault_dirty(fs->entry, &m[i], prot, fault_type,
507 VM_OBJECT_WUNLOCK(fs->first_object);
508 rv = pmap_enter(fs->map->pmap, vaddr, m, prot, fault_type |
509 (wired ? PMAP_ENTER_WIRED : 0), psind);
510 #if defined(__amd64__)
511 if (psind > 0 && rv == KERN_FAILURE) {
512 for (i = 0; i < npages; i++) {
513 rv = pmap_enter(fs->map->pmap, vaddr + ptoa(i),
514 &m[i], prot, fault_type |
515 (wired ? PMAP_ENTER_WIRED : 0), 0);
516 MPASS(rv == KERN_SUCCESS);
520 MPASS(rv == KERN_SUCCESS);
522 VM_OBJECT_WLOCK(fs->first_object);
524 for (i = 0; i < npages; i++) {
525 if ((fault_flags & VM_FAULT_WIRE) != 0) {
528 vm_page_change_lock(&m[i], &m_mtx);
529 vm_page_activate(&m[i]);
531 if (m_hold != NULL && m[i].pindex == fs->first_pindex) {
535 vm_page_xunbusy(&m[i]);
540 curthread->td_ru.ru_majflt++;
541 return (KERN_SUCCESS);
544 static int prot_fault_translation;
545 SYSCTL_INT(_machdep, OID_AUTO, prot_fault_translation, CTLFLAG_RWTUN,
546 &prot_fault_translation, 0,
547 "Control signal to deliver on protection fault");
549 /* compat definition to keep common code for signal translation */
550 #define UCODE_PAGEFLT 12
552 _Static_assert(UCODE_PAGEFLT == T_PAGEFLT, "T_PAGEFLT");
558 * Handle a page fault occurring at the given address,
559 * requiring the given permissions, in the map specified.
560 * If successful, the page is inserted into the
561 * associated physical map.
563 * NOTE: the given address should be truncated to the
564 * proper page address.
566 * KERN_SUCCESS is returned if the page fault is handled; otherwise,
567 * a standard error specifying why the fault is fatal is returned.
569 * The map in question must be referenced, and remains so.
570 * Caller may hold no locks.
573 vm_fault_trap(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
574 int fault_flags, int *signo, int *ucode)
578 MPASS(signo == NULL || ucode != NULL);
580 if (map != kernel_map && KTRPOINT(curthread, KTR_FAULT))
581 ktrfault(vaddr, fault_type);
583 result = vm_fault(map, trunc_page(vaddr), fault_type, fault_flags,
585 KASSERT(result == KERN_SUCCESS || result == KERN_FAILURE ||
586 result == KERN_INVALID_ADDRESS ||
587 result == KERN_RESOURCE_SHORTAGE ||
588 result == KERN_PROTECTION_FAILURE ||
589 result == KERN_OUT_OF_BOUNDS,
590 ("Unexpected Mach error %d from vm_fault()", result));
592 if (map != kernel_map && KTRPOINT(curthread, KTR_FAULTEND))
595 if (result != KERN_SUCCESS && signo != NULL) {
598 case KERN_INVALID_ADDRESS:
600 *ucode = SEGV_MAPERR;
602 case KERN_RESOURCE_SHORTAGE:
606 case KERN_OUT_OF_BOUNDS:
610 case KERN_PROTECTION_FAILURE:
611 if (prot_fault_translation == 0) {
613 * Autodetect. This check also covers
614 * the images without the ABI-tag ELF
617 if (SV_CURPROC_ABI() == SV_ABI_FREEBSD &&
618 curproc->p_osrel >= P_OSREL_SIGSEGV) {
620 *ucode = SEGV_ACCERR;
623 *ucode = UCODE_PAGEFLT;
625 } else if (prot_fault_translation == 1) {
626 /* Always compat mode. */
628 *ucode = UCODE_PAGEFLT;
630 /* Always SIGSEGV mode. */
632 *ucode = SEGV_ACCERR;
636 KASSERT(0, ("Unexpected Mach error %d from vm_fault()",
645 vm_fault_lock_vnode(struct faultstate *fs)
650 if (fs->object->type != OBJT_VNODE)
651 return (KERN_SUCCESS);
652 vp = fs->object->handle;
654 ASSERT_VOP_LOCKED(vp, "saved vnode is not locked");
655 return (KERN_SUCCESS);
659 * Perform an unlock in case the desired vnode changed while
660 * the map was unlocked during a retry.
664 locked = VOP_ISLOCKED(vp);
665 if (locked != LK_EXCLUSIVE)
669 * We must not sleep acquiring the vnode lock while we have
670 * the page exclusive busied or the object's
671 * paging-in-progress count incremented. Otherwise, we could
674 error = vget(vp, locked | LK_CANRECURSE | LK_NOWAIT, curthread);
677 return (KERN_SUCCESS);
682 unlock_and_deallocate(fs);
683 error = vget(vp, locked | LK_RETRY | LK_CANRECURSE, curthread);
686 KASSERT(error == 0, ("vm_fault: vget failed %d", error));
687 return (KERN_RESOURCE_SHORTAGE);
691 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
692 int fault_flags, vm_page_t *m_hold)
694 struct faultstate fs;
695 struct domainset *dset;
696 vm_object_t next_object, retry_object;
697 vm_offset_t e_end, e_start;
698 vm_pindex_t retry_pindex;
699 vm_prot_t prot, retry_prot;
700 int ahead, alloc_req, behind, cluster_offset, era, faultcount;
701 int nera, oom, result, rv;
703 boolean_t wired; /* Passed by reference. */
704 bool dead, hardfault, is_first_object_locked;
706 VM_CNT_INC(v_vm_faults);
708 if ((curthread->td_pflags & TDP_NOFAULTING) != 0)
709 return (KERN_PROTECTION_FAILURE);
721 * Find the backing store object and offset into it to begin the
725 result = vm_map_lookup(&fs.map, vaddr, fault_type |
726 VM_PROT_FAULT_LOOKUP, &fs.entry, &fs.first_object,
727 &fs.first_pindex, &prot, &wired);
728 if (result != KERN_SUCCESS) {
733 fs.map_generation = fs.map->timestamp;
735 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
736 panic("%s: fault on nofault entry, addr: %#lx",
737 __func__, (u_long)vaddr);
740 if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION &&
741 fs.entry->wiring_thread != curthread) {
742 vm_map_unlock_read(fs.map);
744 if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) &&
745 (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) {
747 fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP;
748 vm_map_unlock_and_wait(fs.map, 0);
750 vm_map_unlock(fs.map);
754 MPASS((fs.entry->eflags & MAP_ENTRY_GUARD) == 0);
757 fault_type = prot | (fault_type & VM_PROT_COPY);
759 KASSERT((fault_flags & VM_FAULT_WIRE) == 0,
760 ("!wired && VM_FAULT_WIRE"));
763 * Try to avoid lock contention on the top-level object through
764 * special-case handling of some types of page faults, specifically,
765 * those that are mapping an existing page from the top-level object.
766 * Under this condition, a read lock on the object suffices, allowing
767 * multiple page faults of a similar type to run in parallel.
769 if (fs.vp == NULL /* avoid locked vnode leak */ &&
770 (fault_flags & (VM_FAULT_WIRE | VM_FAULT_DIRTY)) == 0) {
771 VM_OBJECT_RLOCK(fs.first_object);
772 rv = vm_fault_soft_fast(&fs, vaddr, prot, fault_type,
773 fault_flags, wired, m_hold);
774 if (rv == KERN_SUCCESS)
776 if (!VM_OBJECT_TRYUPGRADE(fs.first_object)) {
777 VM_OBJECT_RUNLOCK(fs.first_object);
778 VM_OBJECT_WLOCK(fs.first_object);
781 VM_OBJECT_WLOCK(fs.first_object);
785 * Make a reference to this object to prevent its disposal while we
786 * are messing with it. Once we have the reference, the map is free
787 * to be diddled. Since objects reference their shadows (and copies),
788 * they will stay around as well.
790 * Bump the paging-in-progress count to prevent size changes (e.g.
791 * truncation operations) during I/O.
793 vm_object_reference_locked(fs.first_object);
794 vm_object_pip_add(fs.first_object, 1);
796 fs.lookup_still_valid = true;
801 * Search for the page at object/offset.
803 fs.object = fs.first_object;
804 fs.pindex = fs.first_pindex;
807 * If the object is marked for imminent termination,
808 * we retry here, since the collapse pass has raced
809 * with us. Otherwise, if we see terminally dead
810 * object, return fail.
812 if ((fs.object->flags & OBJ_DEAD) != 0) {
813 dead = fs.object->type == OBJT_DEAD;
814 unlock_and_deallocate(&fs);
816 return (KERN_PROTECTION_FAILURE);
822 * See if page is resident
824 fs.m = vm_page_lookup(fs.object, fs.pindex);
827 * Wait/Retry if the page is busy. We have to do this
828 * if the page is either exclusive or shared busy
829 * because the vm_pager may be using read busy for
830 * pageouts (and even pageins if it is the vnode
831 * pager), and we could end up trying to pagein and
832 * pageout the same page simultaneously.
834 * We can theoretically allow the busy case on a read
835 * fault if the page is marked valid, but since such
836 * pages are typically already pmap'd, putting that
837 * special case in might be more effort then it is
838 * worth. We cannot under any circumstances mess
839 * around with a shared busied page except, perhaps,
842 if (vm_page_tryxbusy(fs.m) == 0) {
844 * Reference the page before unlocking and
845 * sleeping so that the page daemon is less
846 * likely to reclaim it.
848 vm_page_aflag_set(fs.m, PGA_REFERENCED);
849 if (fs.object != fs.first_object) {
850 if (!VM_OBJECT_TRYWLOCK(
852 VM_OBJECT_WUNLOCK(fs.object);
853 VM_OBJECT_WLOCK(fs.first_object);
854 VM_OBJECT_WLOCK(fs.object);
856 vm_page_free(fs.first_m);
857 vm_object_pip_wakeup(fs.first_object);
858 VM_OBJECT_WUNLOCK(fs.first_object);
862 if (fs.m == vm_page_lookup(fs.object,
864 vm_page_sleep_if_busy(fs.m, "vmpfw");
866 vm_object_pip_wakeup(fs.object);
867 VM_OBJECT_WUNLOCK(fs.object);
868 VM_CNT_INC(v_intrans);
869 vm_object_deallocate(fs.first_object);
874 * The page is marked busy for other processes and the
875 * pagedaemon. If it still isn't completely valid
876 * (readable), jump to readrest, else break-out ( we
879 if (!vm_page_all_valid(fs.m))
881 break; /* break to PAGE HAS BEEN FOUND */
883 KASSERT(fs.m == NULL, ("fs.m should be NULL, not %p", fs.m));
886 * Page is not resident. If the pager might contain the page
887 * or this is the beginning of the search, allocate a new
888 * page. (Default objects are zero-fill, so there is no real
891 if (fs.object->type != OBJT_DEFAULT ||
892 fs.object == fs.first_object) {
893 if ((fs.object->flags & OBJ_SIZEVNLOCK) != 0) {
894 rv = vm_fault_lock_vnode(&fs);
895 MPASS(rv == KERN_SUCCESS ||
896 rv == KERN_RESOURCE_SHORTAGE);
897 if (rv == KERN_RESOURCE_SHORTAGE)
900 if (fs.pindex >= fs.object->size) {
901 unlock_and_deallocate(&fs);
902 return (KERN_OUT_OF_BOUNDS);
905 if (fs.object == fs.first_object &&
906 (fs.first_object->flags & OBJ_POPULATE) != 0 &&
907 fs.first_object->shadow_count == 0) {
908 rv = vm_fault_populate(&fs, prot, fault_type,
909 fault_flags, wired, m_hold);
913 unlock_and_deallocate(&fs);
915 case KERN_RESOURCE_SHORTAGE:
916 unlock_and_deallocate(&fs);
918 case KERN_NOT_RECEIVER:
920 * Pager's populate() method
921 * returned VM_PAGER_BAD.
925 panic("inconsistent return codes");
930 * Allocate a new page for this object/offset pair.
932 * Unlocked read of the p_flag is harmless. At
933 * worst, the P_KILLED might be not observed
934 * there, and allocation can fail, causing
935 * restart and new reading of the p_flag.
937 dset = fs.object->domain.dr_policy;
939 dset = curthread->td_domain.dr_policy;
940 if (!vm_page_count_severe_set(&dset->ds_mask) ||
942 #if VM_NRESERVLEVEL > 0
943 vm_object_color(fs.object, atop(vaddr) -
946 alloc_req = P_KILLED(curproc) ?
947 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL;
948 if (fs.object->type != OBJT_VNODE &&
949 fs.object->backing_object == NULL)
950 alloc_req |= VM_ALLOC_ZERO;
951 fs.m = vm_page_alloc(fs.object, fs.pindex,
955 unlock_and_deallocate(&fs);
956 if (vm_pfault_oom_attempts < 0 ||
957 oom < vm_pfault_oom_attempts) {
960 vm_pfault_oom_wait * hz);
965 "proc %d (%s) failed to alloc page on fault, starting OOM\n",
966 curproc->p_pid, curproc->p_comm);
967 vm_pageout_oom(VM_OOM_MEM_PF);
974 * At this point, we have either allocated a new page or found
975 * an existing page that is only partially valid.
977 * We hold a reference on the current object and the page is
982 * If the pager for the current object might have the page,
983 * then determine the number of additional pages to read and
984 * potentially reprioritize previously read pages for earlier
985 * reclamation. These operations should only be performed
986 * once per page fault. Even if the current pager doesn't
987 * have the page, the number of additional pages to read will
988 * apply to subsequent objects in the shadow chain.
990 if (fs.object->type != OBJT_DEFAULT && nera == -1 &&
991 !P_KILLED(curproc)) {
992 KASSERT(fs.lookup_still_valid, ("map unlocked"));
993 era = fs.entry->read_ahead;
994 behavior = vm_map_entry_behavior(fs.entry);
995 if (behavior == MAP_ENTRY_BEHAV_RANDOM) {
997 } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) {
998 nera = VM_FAULT_READ_AHEAD_MAX;
999 if (vaddr == fs.entry->next_read)
1000 vm_fault_dontneed(&fs, vaddr, nera);
1001 } else if (vaddr == fs.entry->next_read) {
1003 * This is a sequential fault. Arithmetically
1004 * increase the requested number of pages in
1005 * the read-ahead window. The requested
1006 * number of pages is "# of sequential faults
1007 * x (read ahead min + 1) + read ahead min"
1009 nera = VM_FAULT_READ_AHEAD_MIN;
1012 if (nera > VM_FAULT_READ_AHEAD_MAX)
1013 nera = VM_FAULT_READ_AHEAD_MAX;
1015 if (era == VM_FAULT_READ_AHEAD_MAX)
1016 vm_fault_dontneed(&fs, vaddr, nera);
1019 * This is a non-sequential fault.
1025 * A read lock on the map suffices to update
1026 * the read ahead count safely.
1028 fs.entry->read_ahead = nera;
1032 * Prepare for unlocking the map. Save the map
1033 * entry's start and end addresses, which are used to
1034 * optimize the size of the pager operation below.
1035 * Even if the map entry's addresses change after
1036 * unlocking the map, using the saved addresses is
1039 e_start = fs.entry->start;
1040 e_end = fs.entry->end;
1044 * Call the pager to retrieve the page if there is a chance
1045 * that the pager has it, and potentially retrieve additional
1046 * pages at the same time.
1048 if (fs.object->type != OBJT_DEFAULT) {
1050 * Release the map lock before locking the vnode or
1051 * sleeping in the pager. (If the current object has
1052 * a shadow, then an earlier iteration of this loop
1053 * may have already unlocked the map.)
1057 rv = vm_fault_lock_vnode(&fs);
1058 MPASS(rv == KERN_SUCCESS ||
1059 rv == KERN_RESOURCE_SHORTAGE);
1060 if (rv == KERN_RESOURCE_SHORTAGE)
1062 KASSERT(fs.vp == NULL || !fs.map->system_map,
1063 ("vm_fault: vnode-backed object mapped by system map"));
1066 * Page in the requested page and hint the pager,
1067 * that it may bring up surrounding pages.
1069 if (nera == -1 || behavior == MAP_ENTRY_BEHAV_RANDOM ||
1070 P_KILLED(curproc)) {
1074 /* Is this a sequential fault? */
1080 * Request a cluster of pages that is
1081 * aligned to a VM_FAULT_READ_DEFAULT
1082 * page offset boundary within the
1083 * object. Alignment to a page offset
1084 * boundary is more likely to coincide
1085 * with the underlying file system
1086 * block than alignment to a virtual
1089 cluster_offset = fs.pindex %
1090 VM_FAULT_READ_DEFAULT;
1091 behind = ulmin(cluster_offset,
1092 atop(vaddr - e_start));
1093 ahead = VM_FAULT_READ_DEFAULT - 1 -
1096 ahead = ulmin(ahead, atop(e_end - vaddr) - 1);
1098 rv = vm_pager_get_pages(fs.object, &fs.m, 1,
1100 if (rv == VM_PAGER_OK) {
1101 faultcount = behind + 1 + ahead;
1103 break; /* break to PAGE HAS BEEN FOUND */
1105 if (rv == VM_PAGER_ERROR)
1106 printf("vm_fault: pager read error, pid %d (%s)\n",
1107 curproc->p_pid, curproc->p_comm);
1110 * If an I/O error occurred or the requested page was
1111 * outside the range of the pager, clean up and return
1114 if (rv == VM_PAGER_ERROR || rv == VM_PAGER_BAD) {
1115 if (!vm_page_wired(fs.m))
1118 vm_page_xunbusy(fs.m);
1120 unlock_and_deallocate(&fs);
1121 return (KERN_OUT_OF_BOUNDS);
1125 * The requested page does not exist at this object/
1126 * offset. Remove the invalid page from the object,
1127 * waking up anyone waiting for it, and continue on to
1128 * the next object. However, if this is the top-level
1129 * object, we must leave the busy page in place to
1130 * prevent another process from rushing past us, and
1131 * inserting the page in that object at the same time
1134 if (fs.object != fs.first_object) {
1135 if (!vm_page_wired(fs.m))
1138 vm_page_xunbusy(fs.m);
1144 * We get here if the object has default pager (or unwiring)
1145 * or the pager doesn't have the page.
1147 if (fs.object == fs.first_object)
1151 * Move on to the next object. Lock the next object before
1152 * unlocking the current one.
1154 next_object = fs.object->backing_object;
1155 if (next_object == NULL) {
1157 * If there's no object left, fill the page in the top
1158 * object with zeros.
1160 if (fs.object != fs.first_object) {
1161 vm_object_pip_wakeup(fs.object);
1162 VM_OBJECT_WUNLOCK(fs.object);
1164 fs.object = fs.first_object;
1165 fs.pindex = fs.first_pindex;
1167 VM_OBJECT_WLOCK(fs.object);
1172 * Zero the page if necessary and mark it valid.
1174 if ((fs.m->flags & PG_ZERO) == 0) {
1175 pmap_zero_page(fs.m);
1177 VM_CNT_INC(v_ozfod);
1180 vm_page_valid(fs.m);
1181 /* Don't try to prefault neighboring pages. */
1183 break; /* break to PAGE HAS BEEN FOUND */
1185 KASSERT(fs.object != next_object,
1186 ("object loop %p", next_object));
1187 VM_OBJECT_WLOCK(next_object);
1188 vm_object_pip_add(next_object, 1);
1189 if (fs.object != fs.first_object)
1190 vm_object_pip_wakeup(fs.object);
1192 OFF_TO_IDX(fs.object->backing_object_offset);
1193 VM_OBJECT_WUNLOCK(fs.object);
1194 fs.object = next_object;
1198 vm_page_assert_xbusied(fs.m);
1201 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
1206 * If the page is being written, but isn't already owned by the
1207 * top-level object, we have to copy it into a new page owned by the
1210 if (fs.object != fs.first_object) {
1212 * We only really need to copy if we want to write it.
1214 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) {
1216 * This allows pages to be virtually copied from a
1217 * backing_object into the first_object, where the
1218 * backing object has no other refs to it, and cannot
1219 * gain any more refs. Instead of a bcopy, we just
1220 * move the page from the backing object to the
1221 * first object. Note that we must mark the page
1222 * dirty in the first object so that it will go out
1223 * to swap when needed.
1225 is_first_object_locked = false;
1228 * Only one shadow object
1230 (fs.object->shadow_count == 1) &&
1232 * No COW refs, except us
1234 (fs.object->ref_count == 1) &&
1236 * No one else can look this object up
1238 (fs.object->handle == NULL) &&
1240 * No other ways to look the object up
1242 ((fs.object->flags & OBJ_ANON) != 0) &&
1243 (is_first_object_locked = VM_OBJECT_TRYWLOCK(fs.first_object)) &&
1245 * We don't chase down the shadow chain
1247 fs.object == fs.first_object->backing_object) {
1249 (void)vm_page_remove(fs.m);
1250 vm_page_replace_checked(fs.m, fs.first_object,
1251 fs.first_pindex, fs.first_m);
1252 vm_page_free(fs.first_m);
1253 vm_page_dirty(fs.m);
1254 #if VM_NRESERVLEVEL > 0
1256 * Rename the reservation.
1258 vm_reserv_rename(fs.m, fs.first_object,
1259 fs.object, OFF_TO_IDX(
1260 fs.first_object->backing_object_offset));
1262 VM_OBJECT_WUNLOCK(fs.object);
1265 VM_CNT_INC(v_cow_optim);
1267 VM_OBJECT_WUNLOCK(fs.object);
1269 * Oh, well, lets copy it.
1271 pmap_copy_page(fs.m, fs.first_m);
1272 vm_page_valid(fs.first_m);
1273 if (wired && (fault_flags &
1274 VM_FAULT_WIRE) == 0) {
1275 vm_page_wire(fs.first_m);
1276 vm_page_unwire(fs.m, PQ_INACTIVE);
1279 * We no longer need the old page or object.
1284 * fs.object != fs.first_object due to above
1287 vm_object_pip_wakeup(fs.object);
1290 * We only try to prefault read-only mappings to the
1291 * neighboring pages when this copy-on-write fault is
1292 * a hard fault. In other cases, trying to prefault
1293 * is typically wasted effort.
1295 if (faultcount == 0)
1299 * Only use the new page below...
1301 fs.object = fs.first_object;
1302 fs.pindex = fs.first_pindex;
1304 if (!is_first_object_locked)
1305 VM_OBJECT_WLOCK(fs.object);
1306 VM_CNT_INC(v_cow_faults);
1307 curthread->td_cow++;
1309 prot &= ~VM_PROT_WRITE;
1314 * We must verify that the maps have not changed since our last
1317 if (!fs.lookup_still_valid) {
1318 if (!vm_map_trylock_read(fs.map)) {
1320 unlock_and_deallocate(&fs);
1323 fs.lookup_still_valid = true;
1324 if (fs.map->timestamp != fs.map_generation) {
1325 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type,
1326 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired);
1329 * If we don't need the page any longer, put it on the inactive
1330 * list (the easiest thing to do here). If no one needs it,
1331 * pageout will grab it eventually.
1333 if (result != KERN_SUCCESS) {
1335 unlock_and_deallocate(&fs);
1338 * If retry of map lookup would have blocked then
1339 * retry fault from start.
1341 if (result == KERN_FAILURE)
1345 if ((retry_object != fs.first_object) ||
1346 (retry_pindex != fs.first_pindex)) {
1348 unlock_and_deallocate(&fs);
1353 * Check whether the protection has changed or the object has
1354 * been copied while we left the map unlocked. Changing from
1355 * read to write permission is OK - we leave the page
1356 * write-protected, and catch the write fault. Changing from
1357 * write to read permission means that we can't mark the page
1358 * write-enabled after all.
1361 fault_type &= retry_prot;
1364 unlock_and_deallocate(&fs);
1368 /* Reassert because wired may have changed. */
1369 KASSERT(wired || (fault_flags & VM_FAULT_WIRE) == 0,
1370 ("!wired && VM_FAULT_WIRE"));
1375 * If the page was filled by a pager, save the virtual address that
1376 * should be faulted on next under a sequential access pattern to the
1377 * map entry. A read lock on the map suffices to update this address
1381 fs.entry->next_read = vaddr + ptoa(ahead) + PAGE_SIZE;
1383 vm_page_assert_xbusied(fs.m);
1384 vm_fault_dirty(fs.entry, fs.m, prot, fault_type, fault_flags, true);
1387 * Page must be completely valid or it is not fit to
1388 * map into user space. vm_pager_get_pages() ensures this.
1390 KASSERT(vm_page_all_valid(fs.m),
1391 ("vm_fault: page %p partially invalid", fs.m));
1392 VM_OBJECT_WUNLOCK(fs.object);
1395 * Put this page into the physical map. We had to do the unlock above
1396 * because pmap_enter() may sleep. We don't put the page
1397 * back on the active queue until later so that the pageout daemon
1398 * won't find it (yet).
1400 pmap_enter(fs.map->pmap, vaddr, fs.m, prot,
1401 fault_type | (wired ? PMAP_ENTER_WIRED : 0), 0);
1402 if (faultcount != 1 && (fault_flags & VM_FAULT_WIRE) == 0 &&
1404 vm_fault_prefault(&fs, vaddr,
1405 faultcount > 0 ? behind : PFBAK,
1406 faultcount > 0 ? ahead : PFFOR, false);
1409 * If the page is not wired down, then put it where the pageout daemon
1412 if ((fault_flags & VM_FAULT_WIRE) != 0) {
1416 vm_page_activate(fs.m);
1417 vm_page_unlock(fs.m);
1419 if (m_hold != NULL) {
1423 vm_page_xunbusy(fs.m);
1426 * Unlock everything, and return
1428 fault_deallocate(&fs);
1430 VM_CNT_INC(v_io_faults);
1431 curthread->td_ru.ru_majflt++;
1433 if (racct_enable && fs.object->type == OBJT_VNODE) {
1435 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) {
1436 racct_add_force(curproc, RACCT_WRITEBPS,
1437 PAGE_SIZE + behind * PAGE_SIZE);
1438 racct_add_force(curproc, RACCT_WRITEIOPS, 1);
1440 racct_add_force(curproc, RACCT_READBPS,
1441 PAGE_SIZE + ahead * PAGE_SIZE);
1442 racct_add_force(curproc, RACCT_READIOPS, 1);
1444 PROC_UNLOCK(curproc);
1448 curthread->td_ru.ru_minflt++;
1450 return (KERN_SUCCESS);
1454 * Speed up the reclamation of pages that precede the faulting pindex within
1455 * the first object of the shadow chain. Essentially, perform the equivalent
1456 * to madvise(..., MADV_DONTNEED) on a large cluster of pages that precedes
1457 * the faulting pindex by the cluster size when the pages read by vm_fault()
1458 * cross a cluster-size boundary. The cluster size is the greater of the
1459 * smallest superpage size and VM_FAULT_DONTNEED_MIN.
1461 * When "fs->first_object" is a shadow object, the pages in the backing object
1462 * that precede the faulting pindex are deactivated by vm_fault(). So, this
1463 * function must only be concerned with pages in the first object.
1466 vm_fault_dontneed(const struct faultstate *fs, vm_offset_t vaddr, int ahead)
1468 vm_map_entry_t entry;
1469 vm_object_t first_object, object;
1470 vm_offset_t end, start;
1471 vm_page_t m, m_next;
1472 vm_pindex_t pend, pstart;
1475 object = fs->object;
1476 VM_OBJECT_ASSERT_WLOCKED(object);
1477 first_object = fs->first_object;
1478 if (first_object != object) {
1479 if (!VM_OBJECT_TRYWLOCK(first_object)) {
1480 VM_OBJECT_WUNLOCK(object);
1481 VM_OBJECT_WLOCK(first_object);
1482 VM_OBJECT_WLOCK(object);
1485 /* Neither fictitious nor unmanaged pages can be reclaimed. */
1486 if ((first_object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0) {
1487 size = VM_FAULT_DONTNEED_MIN;
1488 if (MAXPAGESIZES > 1 && size < pagesizes[1])
1489 size = pagesizes[1];
1490 end = rounddown2(vaddr, size);
1491 if (vaddr - end >= size - PAGE_SIZE - ptoa(ahead) &&
1492 (entry = fs->entry)->start < end) {
1493 if (end - entry->start < size)
1494 start = entry->start;
1497 pmap_advise(fs->map->pmap, start, end, MADV_DONTNEED);
1498 pstart = OFF_TO_IDX(entry->offset) + atop(start -
1500 m_next = vm_page_find_least(first_object, pstart);
1501 pend = OFF_TO_IDX(entry->offset) + atop(end -
1503 while ((m = m_next) != NULL && m->pindex < pend) {
1504 m_next = TAILQ_NEXT(m, listq);
1505 if (!vm_page_all_valid(m) ||
1510 * Don't clear PGA_REFERENCED, since it would
1511 * likely represent a reference by a different
1514 * Typically, at this point, prefetched pages
1515 * are still in the inactive queue. Only
1516 * pages that triggered page faults are in the
1520 if (!vm_page_inactive(m))
1521 vm_page_deactivate(m);
1526 if (first_object != object)
1527 VM_OBJECT_WUNLOCK(first_object);
1531 * vm_fault_prefault provides a quick way of clustering
1532 * pagefaults into a processes address space. It is a "cousin"
1533 * of vm_map_pmap_enter, except it runs at page fault time instead
1537 vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra,
1538 int backward, int forward, bool obj_locked)
1541 vm_map_entry_t entry;
1542 vm_object_t backing_object, lobject;
1543 vm_offset_t addr, starta;
1548 pmap = fs->map->pmap;
1549 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace))
1554 if (addra < backward * PAGE_SIZE) {
1555 starta = entry->start;
1557 starta = addra - backward * PAGE_SIZE;
1558 if (starta < entry->start)
1559 starta = entry->start;
1563 * Generate the sequence of virtual addresses that are candidates for
1564 * prefaulting in an outward spiral from the faulting virtual address,
1565 * "addra". Specifically, the sequence is "addra - PAGE_SIZE", "addra
1566 * + PAGE_SIZE", "addra - 2 * PAGE_SIZE", "addra + 2 * PAGE_SIZE", ...
1567 * If the candidate address doesn't have a backing physical page, then
1568 * the loop immediately terminates.
1570 for (i = 0; i < 2 * imax(backward, forward); i++) {
1571 addr = addra + ((i >> 1) + 1) * ((i & 1) == 0 ? -PAGE_SIZE :
1573 if (addr > addra + forward * PAGE_SIZE)
1576 if (addr < starta || addr >= entry->end)
1579 if (!pmap_is_prefaultable(pmap, addr))
1582 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
1583 lobject = entry->object.vm_object;
1585 VM_OBJECT_RLOCK(lobject);
1586 while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
1587 lobject->type == OBJT_DEFAULT &&
1588 (backing_object = lobject->backing_object) != NULL) {
1589 KASSERT((lobject->backing_object_offset & PAGE_MASK) ==
1590 0, ("vm_fault_prefault: unaligned object offset"));
1591 pindex += lobject->backing_object_offset >> PAGE_SHIFT;
1592 VM_OBJECT_RLOCK(backing_object);
1593 if (!obj_locked || lobject != entry->object.vm_object)
1594 VM_OBJECT_RUNLOCK(lobject);
1595 lobject = backing_object;
1598 if (!obj_locked || lobject != entry->object.vm_object)
1599 VM_OBJECT_RUNLOCK(lobject);
1602 if (vm_page_all_valid(m) &&
1603 (m->flags & PG_FICTITIOUS) == 0)
1604 pmap_enter_quick(pmap, addr, m, entry->protection);
1605 if (!obj_locked || lobject != entry->object.vm_object)
1606 VM_OBJECT_RUNLOCK(lobject);
1611 * Hold each of the physical pages that are mapped by the specified range of
1612 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid
1613 * and allow the specified types of access, "prot". If all of the implied
1614 * pages are successfully held, then the number of held pages is returned
1615 * together with pointers to those pages in the array "ma". However, if any
1616 * of the pages cannot be held, -1 is returned.
1619 vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
1620 vm_prot_t prot, vm_page_t *ma, int max_count)
1622 vm_offset_t end, va;
1625 boolean_t pmap_failed;
1629 end = round_page(addr + len);
1630 addr = trunc_page(addr);
1633 * Check for illegal addresses.
1635 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map))
1638 if (atop(end - addr) > max_count)
1639 panic("vm_fault_quick_hold_pages: count > max_count");
1640 count = atop(end - addr);
1643 * Most likely, the physical pages are resident in the pmap, so it is
1644 * faster to try pmap_extract_and_hold() first.
1646 pmap_failed = FALSE;
1647 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) {
1648 *mp = pmap_extract_and_hold(map->pmap, va, prot);
1651 else if ((prot & VM_PROT_WRITE) != 0 &&
1652 (*mp)->dirty != VM_PAGE_BITS_ALL) {
1654 * Explicitly dirty the physical page. Otherwise, the
1655 * caller's changes may go unnoticed because they are
1656 * performed through an unmanaged mapping or by a DMA
1659 * The object lock is not held here.
1660 * See vm_page_clear_dirty_mask().
1667 * One or more pages could not be held by the pmap. Either no
1668 * page was mapped at the specified virtual address or that
1669 * mapping had insufficient permissions. Attempt to fault in
1670 * and hold these pages.
1672 * If vm_fault_disable_pagefaults() was called,
1673 * i.e., TDP_NOFAULTING is set, we must not sleep nor
1674 * acquire MD VM locks, which means we must not call
1675 * vm_fault(). Some (out of tree) callers mark
1676 * too wide a code area with vm_fault_disable_pagefaults()
1677 * already, use the VM_PROT_QUICK_NOFAULT flag to request
1678 * the proper behaviour explicitly.
1680 if ((prot & VM_PROT_QUICK_NOFAULT) != 0 &&
1681 (curthread->td_pflags & TDP_NOFAULTING) != 0)
1683 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE)
1684 if (*mp == NULL && vm_fault(map, va, prot,
1685 VM_FAULT_NORMAL, mp) != KERN_SUCCESS)
1690 for (mp = ma; mp < ma + count; mp++)
1692 vm_page_unwire(*mp, PQ_INACTIVE);
1698 * vm_fault_copy_entry
1700 * Create new shadow object backing dst_entry with private copy of
1701 * all underlying pages. When src_entry is equal to dst_entry,
1702 * function implements COW for wired-down map entry. Otherwise,
1703 * it forks wired entry into dst_map.
1705 * In/out conditions:
1706 * The source and destination maps must be locked for write.
1707 * The source map entry must be wired down (or be a sharing map
1708 * entry corresponding to a main map entry that is wired down).
1711 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
1712 vm_map_entry_t dst_entry, vm_map_entry_t src_entry,
1713 vm_ooffset_t *fork_charge)
1715 vm_object_t backing_object, dst_object, object, src_object;
1716 vm_pindex_t dst_pindex, pindex, src_pindex;
1717 vm_prot_t access, prot;
1727 upgrade = src_entry == dst_entry;
1728 access = prot = dst_entry->protection;
1730 src_object = src_entry->object.vm_object;
1731 src_pindex = OFF_TO_IDX(src_entry->offset);
1733 if (upgrade && (dst_entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) {
1734 dst_object = src_object;
1735 vm_object_reference(dst_object);
1738 * Create the top-level object for the destination entry.
1739 * Doesn't actually shadow anything - we copy the pages
1742 dst_object = vm_object_allocate_anon(atop(dst_entry->end -
1743 dst_entry->start), NULL, NULL, 0);
1744 #if VM_NRESERVLEVEL > 0
1745 dst_object->flags |= OBJ_COLORED;
1746 dst_object->pg_color = atop(dst_entry->start);
1748 dst_object->domain = src_object->domain;
1749 dst_object->charge = dst_entry->end - dst_entry->start;
1752 VM_OBJECT_WLOCK(dst_object);
1753 KASSERT(upgrade || dst_entry->object.vm_object == NULL,
1754 ("vm_fault_copy_entry: vm_object not NULL"));
1755 if (src_object != dst_object) {
1756 dst_entry->object.vm_object = dst_object;
1757 dst_entry->offset = 0;
1758 dst_entry->eflags &= ~MAP_ENTRY_VN_EXEC;
1760 if (fork_charge != NULL) {
1761 KASSERT(dst_entry->cred == NULL,
1762 ("vm_fault_copy_entry: leaked swp charge"));
1763 dst_object->cred = curthread->td_ucred;
1764 crhold(dst_object->cred);
1765 *fork_charge += dst_object->charge;
1766 } else if ((dst_object->type == OBJT_DEFAULT ||
1767 dst_object->type == OBJT_SWAP) &&
1768 dst_object->cred == NULL) {
1769 KASSERT(dst_entry->cred != NULL, ("no cred for entry %p",
1771 dst_object->cred = dst_entry->cred;
1772 dst_entry->cred = NULL;
1776 * If not an upgrade, then enter the mappings in the pmap as
1777 * read and/or execute accesses. Otherwise, enter them as
1780 * A writeable large page mapping is only created if all of
1781 * the constituent small page mappings are modified. Marking
1782 * PTEs as modified on inception allows promotion to happen
1783 * without taking potentially large number of soft faults.
1786 access &= ~VM_PROT_WRITE;
1789 * Loop through all of the virtual pages within the entry's
1790 * range, copying each page from the source object to the
1791 * destination object. Since the source is wired, those pages
1792 * must exist. In contrast, the destination is pageable.
1793 * Since the destination object doesn't share any backing storage
1794 * with the source object, all of its pages must be dirtied,
1795 * regardless of whether they can be written.
1797 for (vaddr = dst_entry->start, dst_pindex = 0;
1798 vaddr < dst_entry->end;
1799 vaddr += PAGE_SIZE, dst_pindex++) {
1802 * Find the page in the source object, and copy it in.
1803 * Because the source is wired down, the page will be
1806 if (src_object != dst_object)
1807 VM_OBJECT_RLOCK(src_object);
1808 object = src_object;
1809 pindex = src_pindex + dst_pindex;
1810 while ((src_m = vm_page_lookup(object, pindex)) == NULL &&
1811 (backing_object = object->backing_object) != NULL) {
1813 * Unless the source mapping is read-only or
1814 * it is presently being upgraded from
1815 * read-only, the first object in the shadow
1816 * chain should provide all of the pages. In
1817 * other words, this loop body should never be
1818 * executed when the source mapping is already
1821 KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 ||
1823 ("vm_fault_copy_entry: main object missing page"));
1825 VM_OBJECT_RLOCK(backing_object);
1826 pindex += OFF_TO_IDX(object->backing_object_offset);
1827 if (object != dst_object)
1828 VM_OBJECT_RUNLOCK(object);
1829 object = backing_object;
1831 KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing"));
1833 if (object != dst_object) {
1835 * Allocate a page in the destination object.
1837 dst_m = vm_page_alloc(dst_object, (src_object ==
1838 dst_object ? src_pindex : 0) + dst_pindex,
1840 if (dst_m == NULL) {
1841 VM_OBJECT_WUNLOCK(dst_object);
1842 VM_OBJECT_RUNLOCK(object);
1843 vm_wait(dst_object);
1844 VM_OBJECT_WLOCK(dst_object);
1847 pmap_copy_page(src_m, dst_m);
1848 VM_OBJECT_RUNLOCK(object);
1849 dst_m->dirty = dst_m->valid = src_m->valid;
1852 if (vm_page_busy_acquire(dst_m, VM_ALLOC_WAITFAIL) == 0)
1854 if (dst_m->pindex >= dst_object->size) {
1856 * We are upgrading. Index can occur
1857 * out of bounds if the object type is
1858 * vnode and the file was truncated.
1860 vm_page_xunbusy(dst_m);
1864 VM_OBJECT_WUNLOCK(dst_object);
1867 * Enter it in the pmap. If a wired, copy-on-write
1868 * mapping is being replaced by a write-enabled
1869 * mapping, then wire that new mapping.
1871 * The page can be invalid if the user called
1872 * msync(MS_INVALIDATE) or truncated the backing vnode
1873 * or shared memory object. In this case, do not
1874 * insert it into pmap, but still do the copy so that
1875 * all copies of the wired map entry have similar
1878 if (vm_page_all_valid(dst_m)) {
1879 pmap_enter(dst_map->pmap, vaddr, dst_m, prot,
1880 access | (upgrade ? PMAP_ENTER_WIRED : 0), 0);
1884 * Mark it no longer busy, and put it on the active list.
1886 VM_OBJECT_WLOCK(dst_object);
1889 if (src_m != dst_m) {
1890 vm_page_unwire(src_m, PQ_INACTIVE);
1891 vm_page_wire(dst_m);
1893 KASSERT(vm_page_wired(dst_m),
1894 ("dst_m %p is not wired", dst_m));
1897 vm_page_lock(dst_m);
1898 vm_page_activate(dst_m);
1899 vm_page_unlock(dst_m);
1901 vm_page_xunbusy(dst_m);
1903 VM_OBJECT_WUNLOCK(dst_object);
1905 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY);
1906 vm_object_deallocate(src_object);
1911 * Block entry into the machine-independent layer's page fault handler by
1912 * the calling thread. Subsequent calls to vm_fault() by that thread will
1913 * return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of
1914 * spurious page faults.
1917 vm_fault_disable_pagefaults(void)
1920 return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR));
1924 vm_fault_enable_pagefaults(int save)
1927 curthread_pflags_restore(save);