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>
88 #include <sys/racct.h>
89 #include <sys/resourcevar.h>
90 #include <sys/rwlock.h>
91 #include <sys/sysctl.h>
92 #include <sys/vmmeter.h>
93 #include <sys/vnode.h>
95 #include <sys/ktrace.h>
99 #include <vm/vm_param.h>
101 #include <vm/vm_map.h>
102 #include <vm/vm_object.h>
103 #include <vm/vm_page.h>
104 #include <vm/vm_pageout.h>
105 #include <vm/vm_kern.h>
106 #include <vm/vm_pager.h>
107 #include <vm/vm_extern.h>
108 #include <vm/vm_reserv.h>
113 #define VM_FAULT_READ_DEFAULT (1 + VM_FAULT_READ_AHEAD_INIT)
114 #define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX)
116 #define VM_FAULT_DONTNEED_MIN 1048576
123 vm_object_t first_object;
124 vm_pindex_t first_pindex;
126 vm_map_entry_t entry;
128 bool lookup_still_valid;
132 static void vm_fault_dontneed(const struct faultstate *fs, vm_offset_t vaddr,
134 static void vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra,
135 int backward, int forward, bool obj_locked);
138 release_page(struct faultstate *fs)
141 vm_page_xunbusy(fs->m);
143 vm_page_deactivate(fs->m);
144 vm_page_unlock(fs->m);
149 unlock_map(struct faultstate *fs)
152 if (fs->lookup_still_valid) {
153 vm_map_lookup_done(fs->map, fs->entry);
154 fs->lookup_still_valid = false;
159 unlock_vp(struct faultstate *fs)
162 if (fs->vp != NULL) {
169 unlock_and_deallocate(struct faultstate *fs)
172 vm_object_pip_wakeup(fs->object);
173 VM_OBJECT_WUNLOCK(fs->object);
174 if (fs->object != fs->first_object) {
175 VM_OBJECT_WLOCK(fs->first_object);
176 vm_page_lock(fs->first_m);
177 vm_page_free(fs->first_m);
178 vm_page_unlock(fs->first_m);
179 vm_object_pip_wakeup(fs->first_object);
180 VM_OBJECT_WUNLOCK(fs->first_object);
183 vm_object_deallocate(fs->first_object);
189 vm_fault_dirty(vm_map_entry_t entry, vm_page_t m, vm_prot_t prot,
190 vm_prot_t fault_type, int fault_flags, bool set_wd)
194 if (((prot & VM_PROT_WRITE) == 0 &&
195 (fault_flags & VM_FAULT_DIRTY) == 0) ||
196 (m->oflags & VPO_UNMANAGED) != 0)
199 VM_OBJECT_ASSERT_LOCKED(m->object);
201 need_dirty = ((fault_type & VM_PROT_WRITE) != 0 &&
202 (fault_flags & VM_FAULT_WIRE) == 0) ||
203 (fault_flags & VM_FAULT_DIRTY) != 0;
206 vm_object_set_writeable_dirty(m->object);
209 * If two callers of vm_fault_dirty() with set_wd ==
210 * FALSE, one for the map entry with MAP_ENTRY_NOSYNC
211 * flag set, other with flag clear, race, it is
212 * possible for the no-NOSYNC thread to see m->dirty
213 * != 0 and not clear VPO_NOSYNC. Take vm_page lock
214 * around manipulation of VPO_NOSYNC and
215 * vm_page_dirty() call, to avoid the race and keep
216 * m->oflags consistent.
221 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC
222 * if the page is already dirty to prevent data written with
223 * the expectation of being synced from not being synced.
224 * Likewise if this entry does not request NOSYNC then make
225 * sure the page isn't marked NOSYNC. Applications sharing
226 * data should use the same flags to avoid ping ponging.
228 if ((entry->eflags & MAP_ENTRY_NOSYNC) != 0) {
230 m->oflags |= VPO_NOSYNC;
233 m->oflags &= ~VPO_NOSYNC;
237 * If the fault is a write, we know that this page is being
238 * written NOW so dirty it explicitly to save on
239 * pmap_is_modified() calls later.
241 * Also, since the page is now dirty, we can possibly tell
242 * the pager to release any swap backing the page. Calling
243 * the pager requires a write lock on the object.
250 vm_pager_page_unswapped(m);
254 vm_fault_fill_hold(vm_page_t *m_hold, vm_page_t m)
257 if (m_hold != NULL) {
266 * Unlocks fs.first_object and fs.map on success.
269 vm_fault_soft_fast(struct faultstate *fs, vm_offset_t vaddr, vm_prot_t prot,
270 int fault_type, int fault_flags, boolean_t wired, vm_page_t *m_hold)
273 #if (defined(__aarch64__) || defined(__amd64__) || (defined(__arm__) && \
274 __ARM_ARCH >= 6) || defined(__i386__) || defined(__riscv)) && \
281 MPASS(fs->vp == NULL);
282 m = vm_page_lookup(fs->first_object, fs->first_pindex);
283 /* A busy page can be mapped for read|execute access. */
284 if (m == NULL || ((prot & VM_PROT_WRITE) != 0 &&
285 vm_page_busied(m)) || m->valid != VM_PAGE_BITS_ALL)
286 return (KERN_FAILURE);
289 #if (defined(__aarch64__) || defined(__amd64__) || (defined(__arm__) && \
290 __ARM_ARCH >= 6) || defined(__i386__) || defined(__riscv)) && \
292 if ((m->flags & PG_FICTITIOUS) == 0 &&
293 (m_super = vm_reserv_to_superpage(m)) != NULL &&
294 rounddown2(vaddr, pagesizes[m_super->psind]) >= fs->entry->start &&
295 roundup2(vaddr + 1, pagesizes[m_super->psind]) <= fs->entry->end &&
296 (vaddr & (pagesizes[m_super->psind] - 1)) == (VM_PAGE_TO_PHYS(m) &
297 (pagesizes[m_super->psind] - 1)) && !wired &&
298 pmap_ps_enabled(fs->map->pmap)) {
299 flags = PS_ALL_VALID;
300 if ((prot & VM_PROT_WRITE) != 0) {
302 * Create a superpage mapping allowing write access
303 * only if none of the constituent pages are busy and
304 * all of them are already dirty (except possibly for
305 * the page that was faulted on).
307 flags |= PS_NONE_BUSY;
308 if ((fs->first_object->flags & OBJ_UNMANAGED) == 0)
309 flags |= PS_ALL_DIRTY;
311 if (vm_page_ps_test(m_super, flags, m)) {
313 psind = m_super->psind;
314 vaddr = rounddown2(vaddr, pagesizes[psind]);
315 /* Preset the modified bit for dirty superpages. */
316 if ((flags & PS_ALL_DIRTY) != 0)
317 fault_type |= VM_PROT_WRITE;
321 rv = pmap_enter(fs->map->pmap, vaddr, m_map, prot, fault_type |
322 PMAP_ENTER_NOSLEEP | (wired ? PMAP_ENTER_WIRED : 0), psind);
323 if (rv != KERN_SUCCESS)
325 vm_fault_fill_hold(m_hold, m);
326 vm_fault_dirty(fs->entry, m, prot, fault_type, fault_flags, false);
327 if (psind == 0 && !wired)
328 vm_fault_prefault(fs, vaddr, PFBAK, PFFOR, true);
329 VM_OBJECT_RUNLOCK(fs->first_object);
330 vm_map_lookup_done(fs->map, fs->entry);
331 curthread->td_ru.ru_minflt++;
332 return (KERN_SUCCESS);
336 vm_fault_restore_map_lock(struct faultstate *fs)
339 VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
340 MPASS(fs->first_object->paging_in_progress > 0);
342 if (!vm_map_trylock_read(fs->map)) {
343 VM_OBJECT_WUNLOCK(fs->first_object);
344 vm_map_lock_read(fs->map);
345 VM_OBJECT_WLOCK(fs->first_object);
347 fs->lookup_still_valid = true;
351 vm_fault_populate_check_page(vm_page_t m)
355 * Check each page to ensure that the pager is obeying the
356 * interface: the page must be installed in the object, fully
357 * valid, and exclusively busied.
360 MPASS(m->valid == VM_PAGE_BITS_ALL);
361 MPASS(vm_page_xbusied(m));
365 vm_fault_populate_cleanup(vm_object_t object, vm_pindex_t first,
371 VM_OBJECT_ASSERT_WLOCKED(object);
372 MPASS(first <= last);
373 for (pidx = first, m = vm_page_lookup(object, pidx);
374 pidx <= last; pidx++, m = vm_page_next(m)) {
375 vm_fault_populate_check_page(m);
377 vm_page_deactivate(m);
384 vm_fault_populate(struct faultstate *fs, vm_prot_t prot, int fault_type,
385 int fault_flags, boolean_t wired, vm_page_t *m_hold)
390 vm_pindex_t map_first, map_last, pager_first, pager_last, pidx;
391 int i, npages, psind, rv;
393 MPASS(fs->object == fs->first_object);
394 VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
395 MPASS(fs->first_object->paging_in_progress > 0);
396 MPASS(fs->first_object->backing_object == NULL);
397 MPASS(fs->lookup_still_valid);
399 pager_first = OFF_TO_IDX(fs->entry->offset);
400 pager_last = pager_first + atop(fs->entry->end - fs->entry->start) - 1;
405 * Call the pager (driver) populate() method.
407 * There is no guarantee that the method will be called again
408 * if the current fault is for read, and a future fault is
409 * for write. Report the entry's maximum allowed protection
412 rv = vm_pager_populate(fs->first_object, fs->first_pindex,
413 fault_type, fs->entry->max_protection, &pager_first, &pager_last);
415 VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
416 if (rv == VM_PAGER_BAD) {
418 * VM_PAGER_BAD is the backdoor for a pager to request
419 * normal fault handling.
421 vm_fault_restore_map_lock(fs);
422 if (fs->map->timestamp != fs->map_generation)
423 return (KERN_RESOURCE_SHORTAGE); /* RetryFault */
424 return (KERN_NOT_RECEIVER);
426 if (rv != VM_PAGER_OK)
427 return (KERN_FAILURE); /* AKA SIGSEGV */
429 /* Ensure that the driver is obeying the interface. */
430 MPASS(pager_first <= pager_last);
431 MPASS(fs->first_pindex <= pager_last);
432 MPASS(fs->first_pindex >= pager_first);
433 MPASS(pager_last < fs->first_object->size);
435 vm_fault_restore_map_lock(fs);
436 if (fs->map->timestamp != fs->map_generation) {
437 vm_fault_populate_cleanup(fs->first_object, pager_first,
439 return (KERN_RESOURCE_SHORTAGE); /* RetryFault */
443 * The map is unchanged after our last unlock. Process the fault.
445 * The range [pager_first, pager_last] that is given to the
446 * pager is only a hint. The pager may populate any range
447 * within the object that includes the requested page index.
448 * In case the pager expanded the range, clip it to fit into
451 map_first = OFF_TO_IDX(fs->entry->offset);
452 if (map_first > pager_first) {
453 vm_fault_populate_cleanup(fs->first_object, pager_first,
455 pager_first = map_first;
457 map_last = map_first + atop(fs->entry->end - fs->entry->start) - 1;
458 if (map_last < pager_last) {
459 vm_fault_populate_cleanup(fs->first_object, map_last + 1,
461 pager_last = map_last;
463 for (pidx = pager_first, m = vm_page_lookup(fs->first_object, pidx);
465 pidx += npages, m = vm_page_next(&m[npages - 1])) {
466 vaddr = fs->entry->start + IDX_TO_OFF(pidx) - fs->entry->offset;
467 #if defined(__aarch64__) || defined(__amd64__) || (defined(__arm__) && \
468 __ARM_ARCH >= 6) || defined(__i386__) || defined(__riscv)
470 if (psind > 0 && ((vaddr & (pagesizes[psind] - 1)) != 0 ||
471 pidx + OFF_TO_IDX(pagesizes[psind]) - 1 > pager_last ||
472 !pmap_ps_enabled(fs->map->pmap) || wired))
477 npages = atop(pagesizes[psind]);
478 for (i = 0; i < npages; i++) {
479 vm_fault_populate_check_page(&m[i]);
480 vm_fault_dirty(fs->entry, &m[i], prot, fault_type,
483 VM_OBJECT_WUNLOCK(fs->first_object);
484 rv = pmap_enter(fs->map->pmap, vaddr, m, prot, fault_type |
485 (wired ? PMAP_ENTER_WIRED : 0), psind);
486 #if defined(__amd64__)
487 if (psind > 0 && rv == KERN_FAILURE) {
488 for (i = 0; i < npages; i++) {
489 rv = pmap_enter(fs->map->pmap, vaddr + ptoa(i),
490 &m[i], prot, fault_type |
491 (wired ? PMAP_ENTER_WIRED : 0), 0);
492 MPASS(rv == KERN_SUCCESS);
496 MPASS(rv == KERN_SUCCESS);
498 VM_OBJECT_WLOCK(fs->first_object);
500 for (i = 0; i < npages; i++) {
501 vm_page_change_lock(&m[i], &m_mtx);
502 if ((fault_flags & VM_FAULT_WIRE) != 0)
505 vm_page_activate(&m[i]);
506 if (m_hold != NULL && m[i].pindex == fs->first_pindex) {
510 vm_page_xunbusy_maybelocked(&m[i]);
515 curthread->td_ru.ru_majflt++;
516 return (KERN_SUCCESS);
522 * Handle a page fault occurring at the given address,
523 * requiring the given permissions, in the map specified.
524 * If successful, the page is inserted into the
525 * associated physical map.
527 * NOTE: the given address should be truncated to the
528 * proper page address.
530 * KERN_SUCCESS is returned if the page fault is handled; otherwise,
531 * a standard error specifying why the fault is fatal is returned.
533 * The map in question must be referenced, and remains so.
534 * Caller may hold no locks.
537 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
544 if ((td->td_pflags & TDP_NOFAULTING) != 0)
545 return (KERN_PROTECTION_FAILURE);
547 if (map != kernel_map && KTRPOINT(td, KTR_FAULT))
548 ktrfault(vaddr, fault_type);
550 result = vm_fault_hold(map, trunc_page(vaddr), fault_type, fault_flags,
553 if (map != kernel_map && KTRPOINT(td, KTR_FAULTEND))
560 vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
561 int fault_flags, vm_page_t *m_hold)
563 struct faultstate fs;
565 struct domainset *dset;
566 vm_object_t next_object, retry_object;
567 vm_offset_t e_end, e_start;
568 vm_pindex_t retry_pindex;
569 vm_prot_t prot, retry_prot;
570 int ahead, alloc_req, behind, cluster_offset, error, era, faultcount;
571 int locked, nera, result, rv;
573 boolean_t wired; /* Passed by reference. */
574 bool dead, hardfault, is_first_object_locked;
576 VM_CNT_INC(v_vm_faults);
585 * Find the backing store object and offset into it to begin the
589 result = vm_map_lookup(&fs.map, vaddr, fault_type |
590 VM_PROT_FAULT_LOOKUP, &fs.entry, &fs.first_object,
591 &fs.first_pindex, &prot, &wired);
592 if (result != KERN_SUCCESS) {
597 fs.map_generation = fs.map->timestamp;
599 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
600 panic("%s: fault on nofault entry, addr: %#lx",
601 __func__, (u_long)vaddr);
604 if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION &&
605 fs.entry->wiring_thread != curthread) {
606 vm_map_unlock_read(fs.map);
608 if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) &&
609 (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) {
611 fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP;
612 vm_map_unlock_and_wait(fs.map, 0);
614 vm_map_unlock(fs.map);
618 MPASS((fs.entry->eflags & MAP_ENTRY_GUARD) == 0);
621 fault_type = prot | (fault_type & VM_PROT_COPY);
623 KASSERT((fault_flags & VM_FAULT_WIRE) == 0,
624 ("!wired && VM_FAULT_WIRE"));
627 * Try to avoid lock contention on the top-level object through
628 * special-case handling of some types of page faults, specifically,
629 * those that are both (1) mapping an existing page from the top-
630 * level object and (2) not having to mark that object as containing
631 * dirty pages. Under these conditions, a read lock on the top-level
632 * object suffices, allowing multiple page faults of a similar type to
633 * run in parallel on the same top-level object.
635 if (fs.vp == NULL /* avoid locked vnode leak */ &&
636 (fault_flags & (VM_FAULT_WIRE | VM_FAULT_DIRTY)) == 0 &&
637 /* avoid calling vm_object_set_writeable_dirty() */
638 ((prot & VM_PROT_WRITE) == 0 ||
639 (fs.first_object->type != OBJT_VNODE &&
640 (fs.first_object->flags & OBJ_TMPFS_NODE) == 0) ||
641 (fs.first_object->flags & OBJ_MIGHTBEDIRTY) != 0)) {
642 VM_OBJECT_RLOCK(fs.first_object);
643 if ((prot & VM_PROT_WRITE) == 0 ||
644 (fs.first_object->type != OBJT_VNODE &&
645 (fs.first_object->flags & OBJ_TMPFS_NODE) == 0) ||
646 (fs.first_object->flags & OBJ_MIGHTBEDIRTY) != 0) {
647 rv = vm_fault_soft_fast(&fs, vaddr, prot, fault_type,
648 fault_flags, wired, m_hold);
649 if (rv == KERN_SUCCESS)
652 if (!VM_OBJECT_TRYUPGRADE(fs.first_object)) {
653 VM_OBJECT_RUNLOCK(fs.first_object);
654 VM_OBJECT_WLOCK(fs.first_object);
657 VM_OBJECT_WLOCK(fs.first_object);
661 * Make a reference to this object to prevent its disposal while we
662 * are messing with it. Once we have the reference, the map is free
663 * to be diddled. Since objects reference their shadows (and copies),
664 * they will stay around as well.
666 * Bump the paging-in-progress count to prevent size changes (e.g.
667 * truncation operations) during I/O.
669 vm_object_reference_locked(fs.first_object);
670 vm_object_pip_add(fs.first_object, 1);
672 fs.lookup_still_valid = true;
677 * Search for the page at object/offset.
679 fs.object = fs.first_object;
680 fs.pindex = fs.first_pindex;
683 * If the object is marked for imminent termination,
684 * we retry here, since the collapse pass has raced
685 * with us. Otherwise, if we see terminally dead
686 * object, return fail.
688 if ((fs.object->flags & OBJ_DEAD) != 0) {
689 dead = fs.object->type == OBJT_DEAD;
690 unlock_and_deallocate(&fs);
692 return (KERN_PROTECTION_FAILURE);
698 * See if page is resident
700 fs.m = vm_page_lookup(fs.object, fs.pindex);
703 * Wait/Retry if the page is busy. We have to do this
704 * if the page is either exclusive or shared busy
705 * because the vm_pager may be using read busy for
706 * pageouts (and even pageins if it is the vnode
707 * pager), and we could end up trying to pagein and
708 * pageout the same page simultaneously.
710 * We can theoretically allow the busy case on a read
711 * fault if the page is marked valid, but since such
712 * pages are typically already pmap'd, putting that
713 * special case in might be more effort then it is
714 * worth. We cannot under any circumstances mess
715 * around with a shared busied page except, perhaps,
718 if (vm_page_busied(fs.m)) {
720 * Reference the page before unlocking and
721 * sleeping so that the page daemon is less
722 * likely to reclaim it.
724 vm_page_aflag_set(fs.m, PGA_REFERENCED);
725 if (fs.object != fs.first_object) {
726 if (!VM_OBJECT_TRYWLOCK(
728 VM_OBJECT_WUNLOCK(fs.object);
729 VM_OBJECT_WLOCK(fs.first_object);
730 VM_OBJECT_WLOCK(fs.object);
732 vm_page_lock(fs.first_m);
733 vm_page_free(fs.first_m);
734 vm_page_unlock(fs.first_m);
735 vm_object_pip_wakeup(fs.first_object);
736 VM_OBJECT_WUNLOCK(fs.first_object);
740 if (fs.m == vm_page_lookup(fs.object,
742 vm_page_sleep_if_busy(fs.m, "vmpfw");
744 vm_object_pip_wakeup(fs.object);
745 VM_OBJECT_WUNLOCK(fs.object);
746 VM_CNT_INC(v_intrans);
747 vm_object_deallocate(fs.first_object);
752 * Mark page busy for other processes, and the
753 * pagedaemon. If it still isn't completely valid
754 * (readable), jump to readrest, else break-out ( we
758 if (fs.m->valid != VM_PAGE_BITS_ALL)
760 break; /* break to PAGE HAS BEEN FOUND */
762 KASSERT(fs.m == NULL, ("fs.m should be NULL, not %p", fs.m));
765 * Page is not resident. If the pager might contain the page
766 * or this is the beginning of the search, allocate a new
767 * page. (Default objects are zero-fill, so there is no real
770 if (fs.object->type != OBJT_DEFAULT ||
771 fs.object == fs.first_object) {
772 if (fs.pindex >= fs.object->size) {
773 unlock_and_deallocate(&fs);
774 return (KERN_PROTECTION_FAILURE);
777 if (fs.object == fs.first_object &&
778 (fs.first_object->flags & OBJ_POPULATE) != 0 &&
779 fs.first_object->shadow_count == 0) {
780 rv = vm_fault_populate(&fs, prot, fault_type,
781 fault_flags, wired, m_hold);
785 unlock_and_deallocate(&fs);
787 case KERN_RESOURCE_SHORTAGE:
788 unlock_and_deallocate(&fs);
790 case KERN_NOT_RECEIVER:
792 * Pager's populate() method
793 * returned VM_PAGER_BAD.
797 panic("inconsistent return codes");
802 * Allocate a new page for this object/offset pair.
804 * Unlocked read of the p_flag is harmless. At
805 * worst, the P_KILLED might be not observed
806 * there, and allocation can fail, causing
807 * restart and new reading of the p_flag.
809 dset = fs.object->domain.dr_policy;
811 dset = curthread->td_domain.dr_policy;
812 if (!vm_page_count_severe_set(&dset->ds_mask) ||
814 #if VM_NRESERVLEVEL > 0
815 vm_object_color(fs.object, atop(vaddr) -
818 alloc_req = P_KILLED(curproc) ?
819 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL;
820 if (fs.object->type != OBJT_VNODE &&
821 fs.object->backing_object == NULL)
822 alloc_req |= VM_ALLOC_ZERO;
823 fs.m = vm_page_alloc(fs.object, fs.pindex,
827 unlock_and_deallocate(&fs);
835 * At this point, we have either allocated a new page or found
836 * an existing page that is only partially valid.
838 * We hold a reference on the current object and the page is
843 * If the pager for the current object might have the page,
844 * then determine the number of additional pages to read and
845 * potentially reprioritize previously read pages for earlier
846 * reclamation. These operations should only be performed
847 * once per page fault. Even if the current pager doesn't
848 * have the page, the number of additional pages to read will
849 * apply to subsequent objects in the shadow chain.
851 if (fs.object->type != OBJT_DEFAULT && nera == -1 &&
852 !P_KILLED(curproc)) {
853 KASSERT(fs.lookup_still_valid, ("map unlocked"));
854 era = fs.entry->read_ahead;
855 behavior = vm_map_entry_behavior(fs.entry);
856 if (behavior == MAP_ENTRY_BEHAV_RANDOM) {
858 } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) {
859 nera = VM_FAULT_READ_AHEAD_MAX;
860 if (vaddr == fs.entry->next_read)
861 vm_fault_dontneed(&fs, vaddr, nera);
862 } else if (vaddr == fs.entry->next_read) {
864 * This is a sequential fault. Arithmetically
865 * increase the requested number of pages in
866 * the read-ahead window. The requested
867 * number of pages is "# of sequential faults
868 * x (read ahead min + 1) + read ahead min"
870 nera = VM_FAULT_READ_AHEAD_MIN;
873 if (nera > VM_FAULT_READ_AHEAD_MAX)
874 nera = VM_FAULT_READ_AHEAD_MAX;
876 if (era == VM_FAULT_READ_AHEAD_MAX)
877 vm_fault_dontneed(&fs, vaddr, nera);
880 * This is a non-sequential fault.
886 * A read lock on the map suffices to update
887 * the read ahead count safely.
889 fs.entry->read_ahead = nera;
893 * Prepare for unlocking the map. Save the map
894 * entry's start and end addresses, which are used to
895 * optimize the size of the pager operation below.
896 * Even if the map entry's addresses change after
897 * unlocking the map, using the saved addresses is
900 e_start = fs.entry->start;
901 e_end = fs.entry->end;
905 * Call the pager to retrieve the page if there is a chance
906 * that the pager has it, and potentially retrieve additional
907 * pages at the same time.
909 if (fs.object->type != OBJT_DEFAULT) {
911 * Release the map lock before locking the vnode or
912 * sleeping in the pager. (If the current object has
913 * a shadow, then an earlier iteration of this loop
914 * may have already unlocked the map.)
918 if (fs.object->type == OBJT_VNODE &&
919 (vp = fs.object->handle) != fs.vp) {
921 * Perform an unlock in case the desired vnode
922 * changed while the map was unlocked during a
927 locked = VOP_ISLOCKED(vp);
928 if (locked != LK_EXCLUSIVE)
932 * We must not sleep acquiring the vnode lock
933 * while we have the page exclusive busied or
934 * the object's paging-in-progress count
935 * incremented. Otherwise, we could deadlock.
937 error = vget(vp, locked | LK_CANRECURSE |
938 LK_NOWAIT, curthread);
942 unlock_and_deallocate(&fs);
943 error = vget(vp, locked | LK_RETRY |
944 LK_CANRECURSE, curthread);
948 ("vm_fault: vget failed"));
953 KASSERT(fs.vp == NULL || !fs.map->system_map,
954 ("vm_fault: vnode-backed object mapped by system map"));
957 * Page in the requested page and hint the pager,
958 * that it may bring up surrounding pages.
960 if (nera == -1 || behavior == MAP_ENTRY_BEHAV_RANDOM ||
965 /* Is this a sequential fault? */
971 * Request a cluster of pages that is
972 * aligned to a VM_FAULT_READ_DEFAULT
973 * page offset boundary within the
974 * object. Alignment to a page offset
975 * boundary is more likely to coincide
976 * with the underlying file system
977 * block than alignment to a virtual
980 cluster_offset = fs.pindex %
981 VM_FAULT_READ_DEFAULT;
982 behind = ulmin(cluster_offset,
983 atop(vaddr - e_start));
984 ahead = VM_FAULT_READ_DEFAULT - 1 -
987 ahead = ulmin(ahead, atop(e_end - vaddr) - 1);
989 rv = vm_pager_get_pages(fs.object, &fs.m, 1,
991 if (rv == VM_PAGER_OK) {
992 faultcount = behind + 1 + ahead;
994 break; /* break to PAGE HAS BEEN FOUND */
996 if (rv == VM_PAGER_ERROR)
997 printf("vm_fault: pager read error, pid %d (%s)\n",
998 curproc->p_pid, curproc->p_comm);
1001 * If an I/O error occurred or the requested page was
1002 * outside the range of the pager, clean up and return
1005 if (rv == VM_PAGER_ERROR || rv == VM_PAGER_BAD) {
1007 if (fs.m->wire_count == 0)
1010 vm_page_xunbusy_maybelocked(fs.m);
1011 vm_page_unlock(fs.m);
1013 unlock_and_deallocate(&fs);
1014 return (rv == VM_PAGER_ERROR ? KERN_FAILURE :
1015 KERN_PROTECTION_FAILURE);
1019 * The requested page does not exist at this object/
1020 * offset. Remove the invalid page from the object,
1021 * waking up anyone waiting for it, and continue on to
1022 * the next object. However, if this is the top-level
1023 * object, we must leave the busy page in place to
1024 * prevent another process from rushing past us, and
1025 * inserting the page in that object at the same time
1028 if (fs.object != fs.first_object) {
1030 if (fs.m->wire_count == 0)
1033 vm_page_xunbusy_maybelocked(fs.m);
1034 vm_page_unlock(fs.m);
1040 * We get here if the object has default pager (or unwiring)
1041 * or the pager doesn't have the page.
1043 if (fs.object == fs.first_object)
1047 * Move on to the next object. Lock the next object before
1048 * unlocking the current one.
1050 next_object = fs.object->backing_object;
1051 if (next_object == NULL) {
1053 * If there's no object left, fill the page in the top
1054 * object with zeros.
1056 if (fs.object != fs.first_object) {
1057 vm_object_pip_wakeup(fs.object);
1058 VM_OBJECT_WUNLOCK(fs.object);
1060 fs.object = fs.first_object;
1061 fs.pindex = fs.first_pindex;
1063 VM_OBJECT_WLOCK(fs.object);
1068 * Zero the page if necessary and mark it valid.
1070 if ((fs.m->flags & PG_ZERO) == 0) {
1071 pmap_zero_page(fs.m);
1073 VM_CNT_INC(v_ozfod);
1076 fs.m->valid = VM_PAGE_BITS_ALL;
1077 /* Don't try to prefault neighboring pages. */
1079 break; /* break to PAGE HAS BEEN FOUND */
1081 KASSERT(fs.object != next_object,
1082 ("object loop %p", next_object));
1083 VM_OBJECT_WLOCK(next_object);
1084 vm_object_pip_add(next_object, 1);
1085 if (fs.object != fs.first_object)
1086 vm_object_pip_wakeup(fs.object);
1088 OFF_TO_IDX(fs.object->backing_object_offset);
1089 VM_OBJECT_WUNLOCK(fs.object);
1090 fs.object = next_object;
1094 vm_page_assert_xbusied(fs.m);
1097 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
1102 * If the page is being written, but isn't already owned by the
1103 * top-level object, we have to copy it into a new page owned by the
1106 if (fs.object != fs.first_object) {
1108 * We only really need to copy if we want to write it.
1110 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) {
1112 * This allows pages to be virtually copied from a
1113 * backing_object into the first_object, where the
1114 * backing object has no other refs to it, and cannot
1115 * gain any more refs. Instead of a bcopy, we just
1116 * move the page from the backing object to the
1117 * first object. Note that we must mark the page
1118 * dirty in the first object so that it will go out
1119 * to swap when needed.
1121 is_first_object_locked = false;
1124 * Only one shadow object
1126 (fs.object->shadow_count == 1) &&
1128 * No COW refs, except us
1130 (fs.object->ref_count == 1) &&
1132 * No one else can look this object up
1134 (fs.object->handle == NULL) &&
1136 * No other ways to look the object up
1138 ((fs.object->type == OBJT_DEFAULT) ||
1139 (fs.object->type == OBJT_SWAP)) &&
1140 (is_first_object_locked = VM_OBJECT_TRYWLOCK(fs.first_object)) &&
1142 * We don't chase down the shadow chain
1144 fs.object == fs.first_object->backing_object) {
1146 vm_page_dequeue(fs.m);
1147 vm_page_remove(fs.m);
1148 vm_page_unlock(fs.m);
1149 vm_page_lock(fs.first_m);
1150 vm_page_replace_checked(fs.m, fs.first_object,
1151 fs.first_pindex, fs.first_m);
1152 vm_page_free(fs.first_m);
1153 vm_page_unlock(fs.first_m);
1154 vm_page_dirty(fs.m);
1155 #if VM_NRESERVLEVEL > 0
1157 * Rename the reservation.
1159 vm_reserv_rename(fs.m, fs.first_object,
1160 fs.object, OFF_TO_IDX(
1161 fs.first_object->backing_object_offset));
1164 * Removing the page from the backing object
1167 vm_page_xbusy(fs.m);
1170 VM_CNT_INC(v_cow_optim);
1173 * Oh, well, lets copy it.
1175 pmap_copy_page(fs.m, fs.first_m);
1176 fs.first_m->valid = VM_PAGE_BITS_ALL;
1177 if (wired && (fault_flags &
1178 VM_FAULT_WIRE) == 0) {
1179 vm_page_lock(fs.first_m);
1180 vm_page_wire(fs.first_m);
1181 vm_page_unlock(fs.first_m);
1184 vm_page_unwire(fs.m, PQ_INACTIVE);
1185 vm_page_unlock(fs.m);
1188 * We no longer need the old page or object.
1193 * fs.object != fs.first_object due to above
1196 vm_object_pip_wakeup(fs.object);
1197 VM_OBJECT_WUNLOCK(fs.object);
1200 * We only try to prefault read-only mappings to the
1201 * neighboring pages when this copy-on-write fault is
1202 * a hard fault. In other cases, trying to prefault
1203 * is typically wasted effort.
1205 if (faultcount == 0)
1209 * Only use the new page below...
1211 fs.object = fs.first_object;
1212 fs.pindex = fs.first_pindex;
1214 if (!is_first_object_locked)
1215 VM_OBJECT_WLOCK(fs.object);
1216 VM_CNT_INC(v_cow_faults);
1217 curthread->td_cow++;
1219 prot &= ~VM_PROT_WRITE;
1224 * We must verify that the maps have not changed since our last
1227 if (!fs.lookup_still_valid) {
1228 if (!vm_map_trylock_read(fs.map)) {
1230 unlock_and_deallocate(&fs);
1233 fs.lookup_still_valid = true;
1234 if (fs.map->timestamp != fs.map_generation) {
1235 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type,
1236 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired);
1239 * If we don't need the page any longer, put it on the inactive
1240 * list (the easiest thing to do here). If no one needs it,
1241 * pageout will grab it eventually.
1243 if (result != KERN_SUCCESS) {
1245 unlock_and_deallocate(&fs);
1248 * If retry of map lookup would have blocked then
1249 * retry fault from start.
1251 if (result == KERN_FAILURE)
1255 if ((retry_object != fs.first_object) ||
1256 (retry_pindex != fs.first_pindex)) {
1258 unlock_and_deallocate(&fs);
1263 * Check whether the protection has changed or the object has
1264 * been copied while we left the map unlocked. Changing from
1265 * read to write permission is OK - we leave the page
1266 * write-protected, and catch the write fault. Changing from
1267 * write to read permission means that we can't mark the page
1268 * write-enabled after all.
1271 fault_type &= retry_prot;
1274 unlock_and_deallocate(&fs);
1278 /* Reassert because wired may have changed. */
1279 KASSERT(wired || (fault_flags & VM_FAULT_WIRE) == 0,
1280 ("!wired && VM_FAULT_WIRE"));
1285 * If the page was filled by a pager, save the virtual address that
1286 * should be faulted on next under a sequential access pattern to the
1287 * map entry. A read lock on the map suffices to update this address
1291 fs.entry->next_read = vaddr + ptoa(ahead) + PAGE_SIZE;
1293 vm_fault_dirty(fs.entry, fs.m, prot, fault_type, fault_flags, true);
1294 vm_page_assert_xbusied(fs.m);
1297 * Page must be completely valid or it is not fit to
1298 * map into user space. vm_pager_get_pages() ensures this.
1300 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL,
1301 ("vm_fault: page %p partially invalid", fs.m));
1302 VM_OBJECT_WUNLOCK(fs.object);
1305 * Put this page into the physical map. We had to do the unlock above
1306 * because pmap_enter() may sleep. We don't put the page
1307 * back on the active queue until later so that the pageout daemon
1308 * won't find it (yet).
1310 pmap_enter(fs.map->pmap, vaddr, fs.m, prot,
1311 fault_type | (wired ? PMAP_ENTER_WIRED : 0), 0);
1312 if (faultcount != 1 && (fault_flags & VM_FAULT_WIRE) == 0 &&
1314 vm_fault_prefault(&fs, vaddr,
1315 faultcount > 0 ? behind : PFBAK,
1316 faultcount > 0 ? ahead : PFFOR, false);
1317 VM_OBJECT_WLOCK(fs.object);
1321 * If the page is not wired down, then put it where the pageout daemon
1324 if ((fault_flags & VM_FAULT_WIRE) != 0)
1327 vm_page_activate(fs.m);
1328 if (m_hold != NULL) {
1332 vm_page_unlock(fs.m);
1333 vm_page_xunbusy(fs.m);
1336 * Unlock everything, and return
1338 unlock_and_deallocate(&fs);
1340 VM_CNT_INC(v_io_faults);
1341 curthread->td_ru.ru_majflt++;
1343 if (racct_enable && fs.object->type == OBJT_VNODE) {
1345 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) {
1346 racct_add_force(curproc, RACCT_WRITEBPS,
1347 PAGE_SIZE + behind * PAGE_SIZE);
1348 racct_add_force(curproc, RACCT_WRITEIOPS, 1);
1350 racct_add_force(curproc, RACCT_READBPS,
1351 PAGE_SIZE + ahead * PAGE_SIZE);
1352 racct_add_force(curproc, RACCT_READIOPS, 1);
1354 PROC_UNLOCK(curproc);
1358 curthread->td_ru.ru_minflt++;
1360 return (KERN_SUCCESS);
1364 * Speed up the reclamation of pages that precede the faulting pindex within
1365 * the first object of the shadow chain. Essentially, perform the equivalent
1366 * to madvise(..., MADV_DONTNEED) on a large cluster of pages that precedes
1367 * the faulting pindex by the cluster size when the pages read by vm_fault()
1368 * cross a cluster-size boundary. The cluster size is the greater of the
1369 * smallest superpage size and VM_FAULT_DONTNEED_MIN.
1371 * When "fs->first_object" is a shadow object, the pages in the backing object
1372 * that precede the faulting pindex are deactivated by vm_fault(). So, this
1373 * function must only be concerned with pages in the first object.
1376 vm_fault_dontneed(const struct faultstate *fs, vm_offset_t vaddr, int ahead)
1378 vm_map_entry_t entry;
1379 vm_object_t first_object, object;
1380 vm_offset_t end, start;
1381 vm_page_t m, m_next;
1382 vm_pindex_t pend, pstart;
1385 object = fs->object;
1386 VM_OBJECT_ASSERT_WLOCKED(object);
1387 first_object = fs->first_object;
1388 if (first_object != object) {
1389 if (!VM_OBJECT_TRYWLOCK(first_object)) {
1390 VM_OBJECT_WUNLOCK(object);
1391 VM_OBJECT_WLOCK(first_object);
1392 VM_OBJECT_WLOCK(object);
1395 /* Neither fictitious nor unmanaged pages can be reclaimed. */
1396 if ((first_object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0) {
1397 size = VM_FAULT_DONTNEED_MIN;
1398 if (MAXPAGESIZES > 1 && size < pagesizes[1])
1399 size = pagesizes[1];
1400 end = rounddown2(vaddr, size);
1401 if (vaddr - end >= size - PAGE_SIZE - ptoa(ahead) &&
1402 (entry = fs->entry)->start < end) {
1403 if (end - entry->start < size)
1404 start = entry->start;
1407 pmap_advise(fs->map->pmap, start, end, MADV_DONTNEED);
1408 pstart = OFF_TO_IDX(entry->offset) + atop(start -
1410 m_next = vm_page_find_least(first_object, pstart);
1411 pend = OFF_TO_IDX(entry->offset) + atop(end -
1413 while ((m = m_next) != NULL && m->pindex < pend) {
1414 m_next = TAILQ_NEXT(m, listq);
1415 if (m->valid != VM_PAGE_BITS_ALL ||
1420 * Don't clear PGA_REFERENCED, since it would
1421 * likely represent a reference by a different
1424 * Typically, at this point, prefetched pages
1425 * are still in the inactive queue. Only
1426 * pages that triggered page faults are in the
1430 if (!vm_page_inactive(m))
1431 vm_page_deactivate(m);
1436 if (first_object != object)
1437 VM_OBJECT_WUNLOCK(first_object);
1441 * vm_fault_prefault provides a quick way of clustering
1442 * pagefaults into a processes address space. It is a "cousin"
1443 * of vm_map_pmap_enter, except it runs at page fault time instead
1447 vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra,
1448 int backward, int forward, bool obj_locked)
1451 vm_map_entry_t entry;
1452 vm_object_t backing_object, lobject;
1453 vm_offset_t addr, starta;
1458 pmap = fs->map->pmap;
1459 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace))
1464 if (addra < backward * PAGE_SIZE) {
1465 starta = entry->start;
1467 starta = addra - backward * PAGE_SIZE;
1468 if (starta < entry->start)
1469 starta = entry->start;
1473 * Generate the sequence of virtual addresses that are candidates for
1474 * prefaulting in an outward spiral from the faulting virtual address,
1475 * "addra". Specifically, the sequence is "addra - PAGE_SIZE", "addra
1476 * + PAGE_SIZE", "addra - 2 * PAGE_SIZE", "addra + 2 * PAGE_SIZE", ...
1477 * If the candidate address doesn't have a backing physical page, then
1478 * the loop immediately terminates.
1480 for (i = 0; i < 2 * imax(backward, forward); i++) {
1481 addr = addra + ((i >> 1) + 1) * ((i & 1) == 0 ? -PAGE_SIZE :
1483 if (addr > addra + forward * PAGE_SIZE)
1486 if (addr < starta || addr >= entry->end)
1489 if (!pmap_is_prefaultable(pmap, addr))
1492 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
1493 lobject = entry->object.vm_object;
1495 VM_OBJECT_RLOCK(lobject);
1496 while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
1497 lobject->type == OBJT_DEFAULT &&
1498 (backing_object = lobject->backing_object) != NULL) {
1499 KASSERT((lobject->backing_object_offset & PAGE_MASK) ==
1500 0, ("vm_fault_prefault: unaligned object offset"));
1501 pindex += lobject->backing_object_offset >> PAGE_SHIFT;
1502 VM_OBJECT_RLOCK(backing_object);
1503 if (!obj_locked || lobject != entry->object.vm_object)
1504 VM_OBJECT_RUNLOCK(lobject);
1505 lobject = backing_object;
1508 if (!obj_locked || lobject != entry->object.vm_object)
1509 VM_OBJECT_RUNLOCK(lobject);
1512 if (m->valid == VM_PAGE_BITS_ALL &&
1513 (m->flags & PG_FICTITIOUS) == 0)
1514 pmap_enter_quick(pmap, addr, m, entry->protection);
1515 if (!obj_locked || lobject != entry->object.vm_object)
1516 VM_OBJECT_RUNLOCK(lobject);
1521 * Hold each of the physical pages that are mapped by the specified range of
1522 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid
1523 * and allow the specified types of access, "prot". If all of the implied
1524 * pages are successfully held, then the number of held pages is returned
1525 * together with pointers to those pages in the array "ma". However, if any
1526 * of the pages cannot be held, -1 is returned.
1529 vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
1530 vm_prot_t prot, vm_page_t *ma, int max_count)
1532 vm_offset_t end, va;
1535 boolean_t pmap_failed;
1539 end = round_page(addr + len);
1540 addr = trunc_page(addr);
1543 * Check for illegal addresses.
1545 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map))
1548 if (atop(end - addr) > max_count)
1549 panic("vm_fault_quick_hold_pages: count > max_count");
1550 count = atop(end - addr);
1553 * Most likely, the physical pages are resident in the pmap, so it is
1554 * faster to try pmap_extract_and_hold() first.
1556 pmap_failed = FALSE;
1557 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) {
1558 *mp = pmap_extract_and_hold(map->pmap, va, prot);
1561 else if ((prot & VM_PROT_WRITE) != 0 &&
1562 (*mp)->dirty != VM_PAGE_BITS_ALL) {
1564 * Explicitly dirty the physical page. Otherwise, the
1565 * caller's changes may go unnoticed because they are
1566 * performed through an unmanaged mapping or by a DMA
1569 * The object lock is not held here.
1570 * See vm_page_clear_dirty_mask().
1577 * One or more pages could not be held by the pmap. Either no
1578 * page was mapped at the specified virtual address or that
1579 * mapping had insufficient permissions. Attempt to fault in
1580 * and hold these pages.
1582 * If vm_fault_disable_pagefaults() was called,
1583 * i.e., TDP_NOFAULTING is set, we must not sleep nor
1584 * acquire MD VM locks, which means we must not call
1585 * vm_fault_hold(). Some (out of tree) callers mark
1586 * too wide a code area with vm_fault_disable_pagefaults()
1587 * already, use the VM_PROT_QUICK_NOFAULT flag to request
1588 * the proper behaviour explicitly.
1590 if ((prot & VM_PROT_QUICK_NOFAULT) != 0 &&
1591 (curthread->td_pflags & TDP_NOFAULTING) != 0)
1593 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE)
1594 if (*mp == NULL && vm_fault_hold(map, va, prot,
1595 VM_FAULT_NORMAL, mp) != KERN_SUCCESS)
1600 for (mp = ma; mp < ma + count; mp++)
1603 vm_page_unhold(*mp);
1604 vm_page_unlock(*mp);
1611 * vm_fault_copy_entry
1613 * Create new shadow object backing dst_entry with private copy of
1614 * all underlying pages. When src_entry is equal to dst_entry,
1615 * function implements COW for wired-down map entry. Otherwise,
1616 * it forks wired entry into dst_map.
1618 * In/out conditions:
1619 * The source and destination maps must be locked for write.
1620 * The source map entry must be wired down (or be a sharing map
1621 * entry corresponding to a main map entry that is wired down).
1624 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
1625 vm_map_entry_t dst_entry, vm_map_entry_t src_entry,
1626 vm_ooffset_t *fork_charge)
1628 vm_object_t backing_object, dst_object, object, src_object;
1629 vm_pindex_t dst_pindex, pindex, src_pindex;
1630 vm_prot_t access, prot;
1640 upgrade = src_entry == dst_entry;
1641 access = prot = dst_entry->protection;
1643 src_object = src_entry->object.vm_object;
1644 src_pindex = OFF_TO_IDX(src_entry->offset);
1646 if (upgrade && (dst_entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) {
1647 dst_object = src_object;
1648 vm_object_reference(dst_object);
1651 * Create the top-level object for the destination entry. (Doesn't
1652 * actually shadow anything - we copy the pages directly.)
1654 dst_object = vm_object_allocate(OBJT_DEFAULT,
1655 atop(dst_entry->end - dst_entry->start));
1656 #if VM_NRESERVLEVEL > 0
1657 dst_object->flags |= OBJ_COLORED;
1658 dst_object->pg_color = atop(dst_entry->start);
1660 dst_object->domain = src_object->domain;
1661 dst_object->charge = dst_entry->end - dst_entry->start;
1664 VM_OBJECT_WLOCK(dst_object);
1665 KASSERT(upgrade || dst_entry->object.vm_object == NULL,
1666 ("vm_fault_copy_entry: vm_object not NULL"));
1667 if (src_object != dst_object) {
1668 dst_entry->object.vm_object = dst_object;
1669 dst_entry->offset = 0;
1671 if (fork_charge != NULL) {
1672 KASSERT(dst_entry->cred == NULL,
1673 ("vm_fault_copy_entry: leaked swp charge"));
1674 dst_object->cred = curthread->td_ucred;
1675 crhold(dst_object->cred);
1676 *fork_charge += dst_object->charge;
1677 } else if ((dst_object->type == OBJT_DEFAULT ||
1678 dst_object->type == OBJT_SWAP) &&
1679 dst_object->cred == NULL) {
1680 KASSERT(dst_entry->cred != NULL, ("no cred for entry %p",
1682 dst_object->cred = dst_entry->cred;
1683 dst_entry->cred = NULL;
1687 * If not an upgrade, then enter the mappings in the pmap as
1688 * read and/or execute accesses. Otherwise, enter them as
1691 * A writeable large page mapping is only created if all of
1692 * the constituent small page mappings are modified. Marking
1693 * PTEs as modified on inception allows promotion to happen
1694 * without taking potentially large number of soft faults.
1697 access &= ~VM_PROT_WRITE;
1700 * Loop through all of the virtual pages within the entry's
1701 * range, copying each page from the source object to the
1702 * destination object. Since the source is wired, those pages
1703 * must exist. In contrast, the destination is pageable.
1704 * Since the destination object doesn't share any backing storage
1705 * with the source object, all of its pages must be dirtied,
1706 * regardless of whether they can be written.
1708 for (vaddr = dst_entry->start, dst_pindex = 0;
1709 vaddr < dst_entry->end;
1710 vaddr += PAGE_SIZE, dst_pindex++) {
1713 * Find the page in the source object, and copy it in.
1714 * Because the source is wired down, the page will be
1717 if (src_object != dst_object)
1718 VM_OBJECT_RLOCK(src_object);
1719 object = src_object;
1720 pindex = src_pindex + dst_pindex;
1721 while ((src_m = vm_page_lookup(object, pindex)) == NULL &&
1722 (backing_object = object->backing_object) != NULL) {
1724 * Unless the source mapping is read-only or
1725 * it is presently being upgraded from
1726 * read-only, the first object in the shadow
1727 * chain should provide all of the pages. In
1728 * other words, this loop body should never be
1729 * executed when the source mapping is already
1732 KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 ||
1734 ("vm_fault_copy_entry: main object missing page"));
1736 VM_OBJECT_RLOCK(backing_object);
1737 pindex += OFF_TO_IDX(object->backing_object_offset);
1738 if (object != dst_object)
1739 VM_OBJECT_RUNLOCK(object);
1740 object = backing_object;
1742 KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing"));
1744 if (object != dst_object) {
1746 * Allocate a page in the destination object.
1748 dst_m = vm_page_alloc(dst_object, (src_object ==
1749 dst_object ? src_pindex : 0) + dst_pindex,
1751 if (dst_m == NULL) {
1752 VM_OBJECT_WUNLOCK(dst_object);
1753 VM_OBJECT_RUNLOCK(object);
1754 vm_wait(dst_object);
1755 VM_OBJECT_WLOCK(dst_object);
1758 pmap_copy_page(src_m, dst_m);
1759 VM_OBJECT_RUNLOCK(object);
1760 dst_m->dirty = dst_m->valid = src_m->valid;
1763 if (vm_page_sleep_if_busy(dst_m, "fltupg"))
1765 if (dst_m->pindex >= dst_object->size)
1767 * We are upgrading. Index can occur
1768 * out of bounds if the object type is
1769 * vnode and the file was truncated.
1772 vm_page_xbusy(dst_m);
1774 VM_OBJECT_WUNLOCK(dst_object);
1777 * Enter it in the pmap. If a wired, copy-on-write
1778 * mapping is being replaced by a write-enabled
1779 * mapping, then wire that new mapping.
1781 * The page can be invalid if the user called
1782 * msync(MS_INVALIDATE) or truncated the backing vnode
1783 * or shared memory object. In this case, do not
1784 * insert it into pmap, but still do the copy so that
1785 * all copies of the wired map entry have similar
1788 if (dst_m->valid == VM_PAGE_BITS_ALL) {
1789 pmap_enter(dst_map->pmap, vaddr, dst_m, prot,
1790 access | (upgrade ? PMAP_ENTER_WIRED : 0), 0);
1794 * Mark it no longer busy, and put it on the active list.
1796 VM_OBJECT_WLOCK(dst_object);
1799 if (src_m != dst_m) {
1800 vm_page_lock(src_m);
1801 vm_page_unwire(src_m, PQ_INACTIVE);
1802 vm_page_unlock(src_m);
1803 vm_page_lock(dst_m);
1804 vm_page_wire(dst_m);
1805 vm_page_unlock(dst_m);
1807 KASSERT(dst_m->wire_count > 0,
1808 ("dst_m %p is not wired", dst_m));
1811 vm_page_lock(dst_m);
1812 vm_page_activate(dst_m);
1813 vm_page_unlock(dst_m);
1815 vm_page_xunbusy(dst_m);
1817 VM_OBJECT_WUNLOCK(dst_object);
1819 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY);
1820 vm_object_deallocate(src_object);
1825 * Block entry into the machine-independent layer's page fault handler by
1826 * the calling thread. Subsequent calls to vm_fault() by that thread will
1827 * return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of
1828 * spurious page faults.
1831 vm_fault_disable_pagefaults(void)
1834 return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR));
1838 vm_fault_enable_pagefaults(int save)
1841 curthread_pflags_restore(save);