pmap_unwire() and vm_object_unwire(). Retire vm_fault_{un,}wire(), since they are no longer used. (See r268327 and r269134 for the motivation behind this change.) Reviewed by: kib Sponsored by: EMC / Isilon Storage Division
1500 lines
41 KiB
C
1500 lines
41 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* Copyright (c) 1994 John S. Dyson
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* All rights reserved.
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* Copyright (c) 1994 David Greenman
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* All rights reserved.
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*
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*
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* This code is derived from software contributed to Berkeley by
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* The Mach Operating System project at Carnegie-Mellon University.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94
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*
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Authors: Avadis Tevanian, Jr., Michael Wayne Young
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*/
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/*
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* Page fault handling module.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_ktrace.h"
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#include "opt_vm.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/proc.h>
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#include <sys/resourcevar.h>
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#include <sys/rwlock.h>
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#include <sys/sysctl.h>
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#include <sys/vmmeter.h>
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#include <sys/vnode.h>
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#ifdef KTRACE
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#include <sys/ktrace.h>
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#endif
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/pmap.h>
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#include <vm/vm_map.h>
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#include <vm/vm_object.h>
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#include <vm/vm_page.h>
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#include <vm/vm_pageout.h>
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#include <vm/vm_kern.h>
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#include <vm/vm_pager.h>
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#include <vm/vm_extern.h>
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#define PFBAK 4
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#define PFFOR 4
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static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *);
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#define VM_FAULT_READ_BEHIND 8
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#define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX)
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#define VM_FAULT_NINCR (VM_FAULT_READ_MAX / VM_FAULT_READ_BEHIND)
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#define VM_FAULT_SUM (VM_FAULT_NINCR * (VM_FAULT_NINCR + 1) / 2)
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#define VM_FAULT_CACHE_BEHIND (VM_FAULT_READ_BEHIND * VM_FAULT_SUM)
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struct faultstate {
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vm_page_t m;
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vm_object_t object;
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vm_pindex_t pindex;
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vm_page_t first_m;
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vm_object_t first_object;
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vm_pindex_t first_pindex;
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vm_map_t map;
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vm_map_entry_t entry;
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int lookup_still_valid;
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struct vnode *vp;
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};
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static void vm_fault_cache_behind(const struct faultstate *fs, int distance);
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static void vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra,
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int faultcount, int reqpage);
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static inline void
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release_page(struct faultstate *fs)
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{
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vm_page_xunbusy(fs->m);
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vm_page_lock(fs->m);
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vm_page_deactivate(fs->m);
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vm_page_unlock(fs->m);
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fs->m = NULL;
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}
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static inline void
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unlock_map(struct faultstate *fs)
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{
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if (fs->lookup_still_valid) {
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vm_map_lookup_done(fs->map, fs->entry);
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fs->lookup_still_valid = FALSE;
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}
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}
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static void
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unlock_and_deallocate(struct faultstate *fs)
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{
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vm_object_pip_wakeup(fs->object);
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VM_OBJECT_WUNLOCK(fs->object);
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if (fs->object != fs->first_object) {
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VM_OBJECT_WLOCK(fs->first_object);
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vm_page_lock(fs->first_m);
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vm_page_free(fs->first_m);
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vm_page_unlock(fs->first_m);
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vm_object_pip_wakeup(fs->first_object);
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VM_OBJECT_WUNLOCK(fs->first_object);
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fs->first_m = NULL;
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}
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vm_object_deallocate(fs->first_object);
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unlock_map(fs);
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if (fs->vp != NULL) {
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vput(fs->vp);
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fs->vp = NULL;
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}
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}
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/*
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* TRYPAGER - used by vm_fault to calculate whether the pager for the
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* current object *might* contain the page.
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*
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* default objects are zero-fill, there is no real pager.
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*/
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#define TRYPAGER (fs.object->type != OBJT_DEFAULT && \
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((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 || wired))
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/*
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* vm_fault:
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*
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* Handle a page fault occurring at the given address,
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* requiring the given permissions, in the map specified.
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* If successful, the page is inserted into the
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* associated physical map.
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*
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* NOTE: the given address should be truncated to the
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* proper page address.
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*
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* KERN_SUCCESS is returned if the page fault is handled; otherwise,
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* a standard error specifying why the fault is fatal is returned.
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*
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* The map in question must be referenced, and remains so.
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* Caller may hold no locks.
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*/
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int
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vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
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int fault_flags)
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{
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struct thread *td;
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int result;
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td = curthread;
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if ((td->td_pflags & TDP_NOFAULTING) != 0)
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return (KERN_PROTECTION_FAILURE);
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#ifdef KTRACE
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if (map != kernel_map && KTRPOINT(td, KTR_FAULT))
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ktrfault(vaddr, fault_type);
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#endif
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result = vm_fault_hold(map, trunc_page(vaddr), fault_type, fault_flags,
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NULL);
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#ifdef KTRACE
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if (map != kernel_map && KTRPOINT(td, KTR_FAULTEND))
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ktrfaultend(result);
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#endif
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return (result);
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}
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int
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vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
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int fault_flags, vm_page_t *m_hold)
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{
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vm_prot_t prot;
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long ahead, behind;
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int alloc_req, era, faultcount, nera, reqpage, result;
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boolean_t growstack, is_first_object_locked, wired;
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int map_generation;
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vm_object_t next_object;
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vm_page_t marray[VM_FAULT_READ_MAX];
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int hardfault;
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struct faultstate fs;
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struct vnode *vp;
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int locked, error;
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hardfault = 0;
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growstack = TRUE;
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PCPU_INC(cnt.v_vm_faults);
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fs.vp = NULL;
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faultcount = reqpage = 0;
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RetryFault:;
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/*
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* Find the backing store object and offset into it to begin the
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* search.
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*/
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fs.map = map;
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result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry,
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&fs.first_object, &fs.first_pindex, &prot, &wired);
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if (result != KERN_SUCCESS) {
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if (growstack && result == KERN_INVALID_ADDRESS &&
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map != kernel_map) {
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result = vm_map_growstack(curproc, vaddr);
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if (result != KERN_SUCCESS)
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return (KERN_FAILURE);
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growstack = FALSE;
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goto RetryFault;
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}
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return (result);
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}
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map_generation = fs.map->timestamp;
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if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
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if ((curthread->td_pflags & TDP_DEVMEMIO) != 0) {
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vm_map_unlock_read(fs.map);
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return (KERN_FAILURE);
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}
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panic("vm_fault: fault on nofault entry, addr: %lx",
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(u_long)vaddr);
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}
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if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION &&
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fs.entry->wiring_thread != curthread) {
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vm_map_unlock_read(fs.map);
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vm_map_lock(fs.map);
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if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) &&
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(fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) {
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fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP;
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vm_map_unlock_and_wait(fs.map, 0);
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} else
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vm_map_unlock(fs.map);
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goto RetryFault;
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}
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/*
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* Make a reference to this object to prevent its disposal while we
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* are messing with it. Once we have the reference, the map is free
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* to be diddled. Since objects reference their shadows (and copies),
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* they will stay around as well.
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*
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* Bump the paging-in-progress count to prevent size changes (e.g.
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* truncation operations) during I/O. This must be done after
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* obtaining the vnode lock in order to avoid possible deadlocks.
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*/
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VM_OBJECT_WLOCK(fs.first_object);
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vm_object_reference_locked(fs.first_object);
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vm_object_pip_add(fs.first_object, 1);
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fs.lookup_still_valid = TRUE;
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if (wired)
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fault_type = prot | (fault_type & VM_PROT_COPY);
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fs.first_m = NULL;
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/*
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* Search for the page at object/offset.
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*/
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fs.object = fs.first_object;
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fs.pindex = fs.first_pindex;
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while (TRUE) {
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/*
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* If the object is dead, we stop here
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*/
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if (fs.object->flags & OBJ_DEAD) {
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unlock_and_deallocate(&fs);
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return (KERN_PROTECTION_FAILURE);
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}
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/*
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* See if page is resident
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*/
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fs.m = vm_page_lookup(fs.object, fs.pindex);
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if (fs.m != NULL) {
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/*
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* Wait/Retry if the page is busy. We have to do this
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* if the page is either exclusive or shared busy
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* because the vm_pager may be using read busy for
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* pageouts (and even pageins if it is the vnode
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* pager), and we could end up trying to pagein and
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* pageout the same page simultaneously.
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*
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* We can theoretically allow the busy case on a read
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* fault if the page is marked valid, but since such
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* pages are typically already pmap'd, putting that
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* special case in might be more effort then it is
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* worth. We cannot under any circumstances mess
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* around with a shared busied page except, perhaps,
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* to pmap it.
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*/
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if (vm_page_busied(fs.m)) {
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/*
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* Reference the page before unlocking and
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* sleeping so that the page daemon is less
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* likely to reclaim it.
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*/
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vm_page_aflag_set(fs.m, PGA_REFERENCED);
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if (fs.object != fs.first_object) {
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if (!VM_OBJECT_TRYWLOCK(
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fs.first_object)) {
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VM_OBJECT_WUNLOCK(fs.object);
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VM_OBJECT_WLOCK(fs.first_object);
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VM_OBJECT_WLOCK(fs.object);
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}
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vm_page_lock(fs.first_m);
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vm_page_free(fs.first_m);
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vm_page_unlock(fs.first_m);
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vm_object_pip_wakeup(fs.first_object);
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VM_OBJECT_WUNLOCK(fs.first_object);
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fs.first_m = NULL;
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}
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unlock_map(&fs);
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if (fs.m == vm_page_lookup(fs.object,
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fs.pindex)) {
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vm_page_sleep_if_busy(fs.m, "vmpfw");
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}
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vm_object_pip_wakeup(fs.object);
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VM_OBJECT_WUNLOCK(fs.object);
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PCPU_INC(cnt.v_intrans);
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vm_object_deallocate(fs.first_object);
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goto RetryFault;
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}
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vm_page_lock(fs.m);
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vm_page_remque(fs.m);
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vm_page_unlock(fs.m);
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/*
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* Mark page busy for other processes, and the
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* pagedaemon. If it still isn't completely valid
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* (readable), jump to readrest, else break-out ( we
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* found the page ).
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*/
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vm_page_xbusy(fs.m);
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if (fs.m->valid != VM_PAGE_BITS_ALL)
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goto readrest;
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break;
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}
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/*
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* Page is not resident, If this is the search termination
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* or the pager might contain the page, allocate a new page.
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*/
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if (TRYPAGER || fs.object == fs.first_object) {
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if (fs.pindex >= fs.object->size) {
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unlock_and_deallocate(&fs);
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return (KERN_PROTECTION_FAILURE);
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}
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/*
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* Allocate a new page for this object/offset pair.
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*
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* Unlocked read of the p_flag is harmless. At
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* worst, the P_KILLED might be not observed
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* there, and allocation can fail, causing
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* restart and new reading of the p_flag.
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*/
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fs.m = NULL;
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if (!vm_page_count_severe() || P_KILLED(curproc)) {
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#if VM_NRESERVLEVEL > 0
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if ((fs.object->flags & OBJ_COLORED) == 0) {
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fs.object->flags |= OBJ_COLORED;
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fs.object->pg_color = atop(vaddr) -
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fs.pindex;
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}
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#endif
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alloc_req = P_KILLED(curproc) ?
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VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL;
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if (fs.object->type != OBJT_VNODE &&
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fs.object->backing_object == NULL)
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alloc_req |= VM_ALLOC_ZERO;
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fs.m = vm_page_alloc(fs.object, fs.pindex,
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alloc_req);
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}
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if (fs.m == NULL) {
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unlock_and_deallocate(&fs);
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VM_WAITPFAULT;
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goto RetryFault;
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} else if (fs.m->valid == VM_PAGE_BITS_ALL)
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break;
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}
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readrest:
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/*
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* We have found a valid page or we have allocated a new page.
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* The page thus may not be valid or may not be entirely
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* valid.
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*
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* Attempt to fault-in the page if there is a chance that the
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* pager has it, and potentially fault in additional pages
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* at the same time.
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*/
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if (TRYPAGER) {
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int rv;
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u_char behavior = vm_map_entry_behavior(fs.entry);
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if (behavior == MAP_ENTRY_BEHAV_RANDOM ||
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P_KILLED(curproc)) {
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behind = 0;
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ahead = 0;
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} else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) {
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behind = 0;
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ahead = atop(fs.entry->end - vaddr) - 1;
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if (ahead > VM_FAULT_READ_AHEAD_MAX)
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ahead = VM_FAULT_READ_AHEAD_MAX;
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if (fs.pindex == fs.entry->next_read)
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vm_fault_cache_behind(&fs,
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VM_FAULT_READ_MAX);
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} else {
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/*
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* If this is a sequential page fault, then
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* arithmetically increase the number of pages
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* in the read-ahead window. Otherwise, reset
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* the read-ahead window to its smallest size.
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*/
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behind = atop(vaddr - fs.entry->start);
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if (behind > VM_FAULT_READ_BEHIND)
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behind = VM_FAULT_READ_BEHIND;
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ahead = atop(fs.entry->end - vaddr) - 1;
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era = fs.entry->read_ahead;
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if (fs.pindex == fs.entry->next_read) {
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nera = era + behind;
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if (nera > VM_FAULT_READ_AHEAD_MAX)
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nera = VM_FAULT_READ_AHEAD_MAX;
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behind = 0;
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if (ahead > nera)
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ahead = nera;
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if (era == VM_FAULT_READ_AHEAD_MAX)
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vm_fault_cache_behind(&fs,
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VM_FAULT_CACHE_BEHIND);
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} else if (ahead > VM_FAULT_READ_AHEAD_MIN)
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ahead = VM_FAULT_READ_AHEAD_MIN;
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if (era != ahead)
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fs.entry->read_ahead = ahead;
|
|
}
|
|
|
|
/*
|
|
* Call the pager to retrieve the data, if any, after
|
|
* releasing the lock on the map. We hold a ref on
|
|
* fs.object and the pages are exclusive busied.
|
|
*/
|
|
unlock_map(&fs);
|
|
|
|
if (fs.object->type == OBJT_VNODE) {
|
|
vp = fs.object->handle;
|
|
if (vp == fs.vp)
|
|
goto vnode_locked;
|
|
else if (fs.vp != NULL) {
|
|
vput(fs.vp);
|
|
fs.vp = NULL;
|
|
}
|
|
locked = VOP_ISLOCKED(vp);
|
|
|
|
if (locked != LK_EXCLUSIVE)
|
|
locked = LK_SHARED;
|
|
/* Do not sleep for vnode lock while fs.m is busy */
|
|
error = vget(vp, locked | LK_CANRECURSE |
|
|
LK_NOWAIT, curthread);
|
|
if (error != 0) {
|
|
vhold(vp);
|
|
release_page(&fs);
|
|
unlock_and_deallocate(&fs);
|
|
error = vget(vp, locked | LK_RETRY |
|
|
LK_CANRECURSE, curthread);
|
|
vdrop(vp);
|
|
fs.vp = vp;
|
|
KASSERT(error == 0,
|
|
("vm_fault: vget failed"));
|
|
goto RetryFault;
|
|
}
|
|
fs.vp = vp;
|
|
}
|
|
vnode_locked:
|
|
KASSERT(fs.vp == NULL || !fs.map->system_map,
|
|
("vm_fault: vnode-backed object mapped by system map"));
|
|
|
|
/*
|
|
* now we find out if any other pages should be paged
|
|
* in at this time this routine checks to see if the
|
|
* pages surrounding this fault reside in the same
|
|
* object as the page for this fault. If they do,
|
|
* then they are faulted in also into the object. The
|
|
* array "marray" returned contains an array of
|
|
* vm_page_t structs where one of them is the
|
|
* vm_page_t passed to the routine. The reqpage
|
|
* return value is the index into the marray for the
|
|
* vm_page_t passed to the routine.
|
|
*
|
|
* fs.m plus the additional pages are exclusive busied.
|
|
*/
|
|
faultcount = vm_fault_additional_pages(
|
|
fs.m, behind, ahead, marray, &reqpage);
|
|
|
|
rv = faultcount ?
|
|
vm_pager_get_pages(fs.object, marray, faultcount,
|
|
reqpage) : VM_PAGER_FAIL;
|
|
|
|
if (rv == VM_PAGER_OK) {
|
|
/*
|
|
* Found the page. Leave it busy while we play
|
|
* with it.
|
|
*/
|
|
|
|
/*
|
|
* Relookup in case pager changed page. Pager
|
|
* is responsible for disposition of old page
|
|
* if moved.
|
|
*/
|
|
fs.m = vm_page_lookup(fs.object, fs.pindex);
|
|
if (!fs.m) {
|
|
unlock_and_deallocate(&fs);
|
|
goto RetryFault;
|
|
}
|
|
|
|
hardfault++;
|
|
break; /* break to PAGE HAS BEEN FOUND */
|
|
}
|
|
/*
|
|
* Remove the bogus page (which does not exist at this
|
|
* object/offset); before doing so, we must get back
|
|
* our object lock to preserve our invariant.
|
|
*
|
|
* Also wake up any other process that may want to bring
|
|
* in this page.
|
|
*
|
|
* If this is the top-level object, we must leave the
|
|
* busy page to prevent another process from rushing
|
|
* past us, and inserting the page in that object at
|
|
* the same time that we are.
|
|
*/
|
|
if (rv == VM_PAGER_ERROR)
|
|
printf("vm_fault: pager read error, pid %d (%s)\n",
|
|
curproc->p_pid, curproc->p_comm);
|
|
/*
|
|
* Data outside the range of the pager or an I/O error
|
|
*/
|
|
/*
|
|
* XXX - the check for kernel_map is a kludge to work
|
|
* around having the machine panic on a kernel space
|
|
* fault w/ I/O error.
|
|
*/
|
|
if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) ||
|
|
(rv == VM_PAGER_BAD)) {
|
|
vm_page_lock(fs.m);
|
|
vm_page_free(fs.m);
|
|
vm_page_unlock(fs.m);
|
|
fs.m = NULL;
|
|
unlock_and_deallocate(&fs);
|
|
return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE);
|
|
}
|
|
if (fs.object != fs.first_object) {
|
|
vm_page_lock(fs.m);
|
|
vm_page_free(fs.m);
|
|
vm_page_unlock(fs.m);
|
|
fs.m = NULL;
|
|
/*
|
|
* XXX - we cannot just fall out at this
|
|
* point, m has been freed and is invalid!
|
|
*/
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We get here if the object has default pager (or unwiring)
|
|
* or the pager doesn't have the page.
|
|
*/
|
|
if (fs.object == fs.first_object)
|
|
fs.first_m = fs.m;
|
|
|
|
/*
|
|
* Move on to the next object. Lock the next object before
|
|
* unlocking the current one.
|
|
*/
|
|
fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset);
|
|
next_object = fs.object->backing_object;
|
|
if (next_object == NULL) {
|
|
/*
|
|
* If there's no object left, fill the page in the top
|
|
* object with zeros.
|
|
*/
|
|
if (fs.object != fs.first_object) {
|
|
vm_object_pip_wakeup(fs.object);
|
|
VM_OBJECT_WUNLOCK(fs.object);
|
|
|
|
fs.object = fs.first_object;
|
|
fs.pindex = fs.first_pindex;
|
|
fs.m = fs.first_m;
|
|
VM_OBJECT_WLOCK(fs.object);
|
|
}
|
|
fs.first_m = NULL;
|
|
|
|
/*
|
|
* Zero the page if necessary and mark it valid.
|
|
*/
|
|
if ((fs.m->flags & PG_ZERO) == 0) {
|
|
pmap_zero_page(fs.m);
|
|
} else {
|
|
PCPU_INC(cnt.v_ozfod);
|
|
}
|
|
PCPU_INC(cnt.v_zfod);
|
|
fs.m->valid = VM_PAGE_BITS_ALL;
|
|
/* Don't try to prefault neighboring pages. */
|
|
faultcount = 1;
|
|
break; /* break to PAGE HAS BEEN FOUND */
|
|
} else {
|
|
KASSERT(fs.object != next_object,
|
|
("object loop %p", next_object));
|
|
VM_OBJECT_WLOCK(next_object);
|
|
vm_object_pip_add(next_object, 1);
|
|
if (fs.object != fs.first_object)
|
|
vm_object_pip_wakeup(fs.object);
|
|
VM_OBJECT_WUNLOCK(fs.object);
|
|
fs.object = next_object;
|
|
}
|
|
}
|
|
|
|
vm_page_assert_xbusied(fs.m);
|
|
|
|
/*
|
|
* PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
|
|
* is held.]
|
|
*/
|
|
|
|
/*
|
|
* If the page is being written, but isn't already owned by the
|
|
* top-level object, we have to copy it into a new page owned by the
|
|
* top-level object.
|
|
*/
|
|
if (fs.object != fs.first_object) {
|
|
/*
|
|
* We only really need to copy if we want to write it.
|
|
*/
|
|
if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) {
|
|
/*
|
|
* This allows pages to be virtually copied from a
|
|
* backing_object into the first_object, where the
|
|
* backing object has no other refs to it, and cannot
|
|
* gain any more refs. Instead of a bcopy, we just
|
|
* move the page from the backing object to the
|
|
* first object. Note that we must mark the page
|
|
* dirty in the first object so that it will go out
|
|
* to swap when needed.
|
|
*/
|
|
is_first_object_locked = FALSE;
|
|
if (
|
|
/*
|
|
* Only one shadow object
|
|
*/
|
|
(fs.object->shadow_count == 1) &&
|
|
/*
|
|
* No COW refs, except us
|
|
*/
|
|
(fs.object->ref_count == 1) &&
|
|
/*
|
|
* No one else can look this object up
|
|
*/
|
|
(fs.object->handle == NULL) &&
|
|
/*
|
|
* No other ways to look the object up
|
|
*/
|
|
((fs.object->type == OBJT_DEFAULT) ||
|
|
(fs.object->type == OBJT_SWAP)) &&
|
|
(is_first_object_locked = VM_OBJECT_TRYWLOCK(fs.first_object)) &&
|
|
/*
|
|
* We don't chase down the shadow chain
|
|
*/
|
|
fs.object == fs.first_object->backing_object) {
|
|
/*
|
|
* get rid of the unnecessary page
|
|
*/
|
|
vm_page_lock(fs.first_m);
|
|
vm_page_free(fs.first_m);
|
|
vm_page_unlock(fs.first_m);
|
|
/*
|
|
* grab the page and put it into the
|
|
* process'es object. The page is
|
|
* automatically made dirty.
|
|
*/
|
|
if (vm_page_rename(fs.m, fs.first_object,
|
|
fs.first_pindex)) {
|
|
unlock_and_deallocate(&fs);
|
|
goto RetryFault;
|
|
}
|
|
vm_page_xbusy(fs.m);
|
|
fs.first_m = fs.m;
|
|
fs.m = NULL;
|
|
PCPU_INC(cnt.v_cow_optim);
|
|
} else {
|
|
/*
|
|
* Oh, well, lets copy it.
|
|
*/
|
|
pmap_copy_page(fs.m, fs.first_m);
|
|
fs.first_m->valid = VM_PAGE_BITS_ALL;
|
|
if (wired && (fault_flags &
|
|
VM_FAULT_CHANGE_WIRING) == 0) {
|
|
vm_page_lock(fs.first_m);
|
|
vm_page_wire(fs.first_m);
|
|
vm_page_unlock(fs.first_m);
|
|
|
|
vm_page_lock(fs.m);
|
|
vm_page_unwire(fs.m, PQ_INACTIVE);
|
|
vm_page_unlock(fs.m);
|
|
}
|
|
/*
|
|
* We no longer need the old page or object.
|
|
*/
|
|
release_page(&fs);
|
|
}
|
|
/*
|
|
* fs.object != fs.first_object due to above
|
|
* conditional
|
|
*/
|
|
vm_object_pip_wakeup(fs.object);
|
|
VM_OBJECT_WUNLOCK(fs.object);
|
|
/*
|
|
* Only use the new page below...
|
|
*/
|
|
fs.object = fs.first_object;
|
|
fs.pindex = fs.first_pindex;
|
|
fs.m = fs.first_m;
|
|
if (!is_first_object_locked)
|
|
VM_OBJECT_WLOCK(fs.object);
|
|
PCPU_INC(cnt.v_cow_faults);
|
|
curthread->td_cow++;
|
|
} else {
|
|
prot &= ~VM_PROT_WRITE;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We must verify that the maps have not changed since our last
|
|
* lookup.
|
|
*/
|
|
if (!fs.lookup_still_valid) {
|
|
vm_object_t retry_object;
|
|
vm_pindex_t retry_pindex;
|
|
vm_prot_t retry_prot;
|
|
|
|
if (!vm_map_trylock_read(fs.map)) {
|
|
release_page(&fs);
|
|
unlock_and_deallocate(&fs);
|
|
goto RetryFault;
|
|
}
|
|
fs.lookup_still_valid = TRUE;
|
|
if (fs.map->timestamp != map_generation) {
|
|
result = vm_map_lookup_locked(&fs.map, vaddr, fault_type,
|
|
&fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired);
|
|
|
|
/*
|
|
* If we don't need the page any longer, put it on the inactive
|
|
* list (the easiest thing to do here). If no one needs it,
|
|
* pageout will grab it eventually.
|
|
*/
|
|
if (result != KERN_SUCCESS) {
|
|
release_page(&fs);
|
|
unlock_and_deallocate(&fs);
|
|
|
|
/*
|
|
* If retry of map lookup would have blocked then
|
|
* retry fault from start.
|
|
*/
|
|
if (result == KERN_FAILURE)
|
|
goto RetryFault;
|
|
return (result);
|
|
}
|
|
if ((retry_object != fs.first_object) ||
|
|
(retry_pindex != fs.first_pindex)) {
|
|
release_page(&fs);
|
|
unlock_and_deallocate(&fs);
|
|
goto RetryFault;
|
|
}
|
|
|
|
/*
|
|
* Check whether the protection has changed or the object has
|
|
* been copied while we left the map unlocked. Changing from
|
|
* read to write permission is OK - we leave the page
|
|
* write-protected, and catch the write fault. Changing from
|
|
* write to read permission means that we can't mark the page
|
|
* write-enabled after all.
|
|
*/
|
|
prot &= retry_prot;
|
|
}
|
|
}
|
|
/*
|
|
* If the page was filled by a pager, update the map entry's
|
|
* last read offset. Since the pager does not return the
|
|
* actual set of pages that it read, this update is based on
|
|
* the requested set. Typically, the requested and actual
|
|
* sets are the same.
|
|
*
|
|
* XXX The following assignment modifies the map
|
|
* without holding a write lock on it.
|
|
*/
|
|
if (hardfault)
|
|
fs.entry->next_read = fs.pindex + faultcount - reqpage;
|
|
|
|
if ((prot & VM_PROT_WRITE) != 0 ||
|
|
(fault_flags & VM_FAULT_DIRTY) != 0) {
|
|
vm_object_set_writeable_dirty(fs.object);
|
|
|
|
/*
|
|
* If this is a NOSYNC mmap we do not want to set VPO_NOSYNC
|
|
* if the page is already dirty to prevent data written with
|
|
* the expectation of being synced from not being synced.
|
|
* Likewise if this entry does not request NOSYNC then make
|
|
* sure the page isn't marked NOSYNC. Applications sharing
|
|
* data should use the same flags to avoid ping ponging.
|
|
*/
|
|
if (fs.entry->eflags & MAP_ENTRY_NOSYNC) {
|
|
if (fs.m->dirty == 0)
|
|
fs.m->oflags |= VPO_NOSYNC;
|
|
} else {
|
|
fs.m->oflags &= ~VPO_NOSYNC;
|
|
}
|
|
|
|
/*
|
|
* If the fault is a write, we know that this page is being
|
|
* written NOW so dirty it explicitly to save on
|
|
* pmap_is_modified() calls later.
|
|
*
|
|
* Also tell the backing pager, if any, that it should remove
|
|
* any swap backing since the page is now dirty.
|
|
*/
|
|
if (((fault_type & VM_PROT_WRITE) != 0 &&
|
|
(fault_flags & VM_FAULT_CHANGE_WIRING) == 0) ||
|
|
(fault_flags & VM_FAULT_DIRTY) != 0) {
|
|
vm_page_dirty(fs.m);
|
|
vm_pager_page_unswapped(fs.m);
|
|
}
|
|
}
|
|
|
|
vm_page_assert_xbusied(fs.m);
|
|
|
|
/*
|
|
* Page must be completely valid or it is not fit to
|
|
* map into user space. vm_pager_get_pages() ensures this.
|
|
*/
|
|
KASSERT(fs.m->valid == VM_PAGE_BITS_ALL,
|
|
("vm_fault: page %p partially invalid", fs.m));
|
|
VM_OBJECT_WUNLOCK(fs.object);
|
|
|
|
/*
|
|
* Put this page into the physical map. We had to do the unlock above
|
|
* because pmap_enter() may sleep. We don't put the page
|
|
* back on the active queue until later so that the pageout daemon
|
|
* won't find it (yet).
|
|
*/
|
|
pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired);
|
|
if (faultcount != 1 && (fault_flags & VM_FAULT_CHANGE_WIRING) == 0 &&
|
|
wired == 0)
|
|
vm_fault_prefault(&fs, vaddr, faultcount, reqpage);
|
|
VM_OBJECT_WLOCK(fs.object);
|
|
vm_page_lock(fs.m);
|
|
|
|
/*
|
|
* If the page is not wired down, then put it where the pageout daemon
|
|
* can find it.
|
|
*/
|
|
if (fault_flags & VM_FAULT_CHANGE_WIRING) {
|
|
if (wired)
|
|
vm_page_wire(fs.m);
|
|
else
|
|
vm_page_unwire(fs.m, PQ_ACTIVE);
|
|
} else
|
|
vm_page_activate(fs.m);
|
|
if (m_hold != NULL) {
|
|
*m_hold = fs.m;
|
|
vm_page_hold(fs.m);
|
|
}
|
|
vm_page_unlock(fs.m);
|
|
vm_page_xunbusy(fs.m);
|
|
|
|
/*
|
|
* Unlock everything, and return
|
|
*/
|
|
unlock_and_deallocate(&fs);
|
|
if (hardfault) {
|
|
PCPU_INC(cnt.v_io_faults);
|
|
curthread->td_ru.ru_majflt++;
|
|
} else
|
|
curthread->td_ru.ru_minflt++;
|
|
|
|
return (KERN_SUCCESS);
|
|
}
|
|
|
|
/*
|
|
* Speed up the reclamation of up to "distance" pages that precede the
|
|
* faulting pindex within the first object of the shadow chain.
|
|
*/
|
|
static void
|
|
vm_fault_cache_behind(const struct faultstate *fs, int distance)
|
|
{
|
|
vm_object_t first_object, object;
|
|
vm_page_t m, m_prev;
|
|
vm_pindex_t pindex;
|
|
|
|
object = fs->object;
|
|
VM_OBJECT_ASSERT_WLOCKED(object);
|
|
first_object = fs->first_object;
|
|
if (first_object != object) {
|
|
if (!VM_OBJECT_TRYWLOCK(first_object)) {
|
|
VM_OBJECT_WUNLOCK(object);
|
|
VM_OBJECT_WLOCK(first_object);
|
|
VM_OBJECT_WLOCK(object);
|
|
}
|
|
}
|
|
/* Neither fictitious nor unmanaged pages can be cached. */
|
|
if ((first_object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0) {
|
|
if (fs->first_pindex < distance)
|
|
pindex = 0;
|
|
else
|
|
pindex = fs->first_pindex - distance;
|
|
if (pindex < OFF_TO_IDX(fs->entry->offset))
|
|
pindex = OFF_TO_IDX(fs->entry->offset);
|
|
m = first_object != object ? fs->first_m : fs->m;
|
|
vm_page_assert_xbusied(m);
|
|
m_prev = vm_page_prev(m);
|
|
while ((m = m_prev) != NULL && m->pindex >= pindex &&
|
|
m->valid == VM_PAGE_BITS_ALL) {
|
|
m_prev = vm_page_prev(m);
|
|
if (vm_page_busied(m))
|
|
continue;
|
|
vm_page_lock(m);
|
|
if (m->hold_count == 0 && m->wire_count == 0) {
|
|
pmap_remove_all(m);
|
|
vm_page_aflag_clear(m, PGA_REFERENCED);
|
|
if (m->dirty != 0)
|
|
vm_page_deactivate(m);
|
|
else
|
|
vm_page_cache(m);
|
|
}
|
|
vm_page_unlock(m);
|
|
}
|
|
}
|
|
if (first_object != object)
|
|
VM_OBJECT_WUNLOCK(first_object);
|
|
}
|
|
|
|
/*
|
|
* vm_fault_prefault provides a quick way of clustering
|
|
* pagefaults into a processes address space. It is a "cousin"
|
|
* of vm_map_pmap_enter, except it runs at page fault time instead
|
|
* of mmap time.
|
|
*/
|
|
static void
|
|
vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra,
|
|
int faultcount, int reqpage)
|
|
{
|
|
pmap_t pmap;
|
|
vm_map_entry_t entry;
|
|
vm_object_t backing_object, lobject;
|
|
vm_offset_t addr, starta;
|
|
vm_pindex_t pindex;
|
|
vm_page_t m;
|
|
int backward, forward, i;
|
|
|
|
pmap = fs->map->pmap;
|
|
if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace))
|
|
return;
|
|
|
|
if (faultcount > 0) {
|
|
backward = reqpage;
|
|
forward = faultcount - reqpage - 1;
|
|
} else {
|
|
backward = PFBAK;
|
|
forward = PFFOR;
|
|
}
|
|
entry = fs->entry;
|
|
|
|
starta = addra - backward * PAGE_SIZE;
|
|
if (starta < entry->start) {
|
|
starta = entry->start;
|
|
} else if (starta > addra) {
|
|
starta = 0;
|
|
}
|
|
|
|
/*
|
|
* Generate the sequence of virtual addresses that are candidates for
|
|
* prefaulting in an outward spiral from the faulting virtual address,
|
|
* "addra". Specifically, the sequence is "addra - PAGE_SIZE", "addra
|
|
* + PAGE_SIZE", "addra - 2 * PAGE_SIZE", "addra + 2 * PAGE_SIZE", ...
|
|
* If the candidate address doesn't have a backing physical page, then
|
|
* the loop immediately terminates.
|
|
*/
|
|
for (i = 0; i < 2 * imax(backward, forward); i++) {
|
|
addr = addra + ((i >> 1) + 1) * ((i & 1) == 0 ? -PAGE_SIZE :
|
|
PAGE_SIZE);
|
|
if (addr > addra + forward * PAGE_SIZE)
|
|
addr = 0;
|
|
|
|
if (addr < starta || addr >= entry->end)
|
|
continue;
|
|
|
|
if (!pmap_is_prefaultable(pmap, addr))
|
|
continue;
|
|
|
|
pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
|
|
lobject = entry->object.vm_object;
|
|
VM_OBJECT_RLOCK(lobject);
|
|
while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
|
|
lobject->type == OBJT_DEFAULT &&
|
|
(backing_object = lobject->backing_object) != NULL) {
|
|
KASSERT((lobject->backing_object_offset & PAGE_MASK) ==
|
|
0, ("vm_fault_prefault: unaligned object offset"));
|
|
pindex += lobject->backing_object_offset >> PAGE_SHIFT;
|
|
VM_OBJECT_RLOCK(backing_object);
|
|
VM_OBJECT_RUNLOCK(lobject);
|
|
lobject = backing_object;
|
|
}
|
|
if (m == NULL) {
|
|
VM_OBJECT_RUNLOCK(lobject);
|
|
break;
|
|
}
|
|
if (m->valid == VM_PAGE_BITS_ALL &&
|
|
(m->flags & PG_FICTITIOUS) == 0)
|
|
pmap_enter_quick(pmap, addr, m, entry->protection);
|
|
VM_OBJECT_RUNLOCK(lobject);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Hold each of the physical pages that are mapped by the specified range of
|
|
* virtual addresses, ["addr", "addr" + "len"), if those mappings are valid
|
|
* and allow the specified types of access, "prot". If all of the implied
|
|
* pages are successfully held, then the number of held pages is returned
|
|
* together with pointers to those pages in the array "ma". However, if any
|
|
* of the pages cannot be held, -1 is returned.
|
|
*/
|
|
int
|
|
vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
|
|
vm_prot_t prot, vm_page_t *ma, int max_count)
|
|
{
|
|
vm_offset_t end, va;
|
|
vm_page_t *mp;
|
|
int count;
|
|
boolean_t pmap_failed;
|
|
|
|
if (len == 0)
|
|
return (0);
|
|
end = round_page(addr + len);
|
|
addr = trunc_page(addr);
|
|
|
|
/*
|
|
* Check for illegal addresses.
|
|
*/
|
|
if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map))
|
|
return (-1);
|
|
|
|
if (atop(end - addr) > max_count)
|
|
panic("vm_fault_quick_hold_pages: count > max_count");
|
|
count = atop(end - addr);
|
|
|
|
/*
|
|
* Most likely, the physical pages are resident in the pmap, so it is
|
|
* faster to try pmap_extract_and_hold() first.
|
|
*/
|
|
pmap_failed = FALSE;
|
|
for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) {
|
|
*mp = pmap_extract_and_hold(map->pmap, va, prot);
|
|
if (*mp == NULL)
|
|
pmap_failed = TRUE;
|
|
else if ((prot & VM_PROT_WRITE) != 0 &&
|
|
(*mp)->dirty != VM_PAGE_BITS_ALL) {
|
|
/*
|
|
* Explicitly dirty the physical page. Otherwise, the
|
|
* caller's changes may go unnoticed because they are
|
|
* performed through an unmanaged mapping or by a DMA
|
|
* operation.
|
|
*
|
|
* The object lock is not held here.
|
|
* See vm_page_clear_dirty_mask().
|
|
*/
|
|
vm_page_dirty(*mp);
|
|
}
|
|
}
|
|
if (pmap_failed) {
|
|
/*
|
|
* One or more pages could not be held by the pmap. Either no
|
|
* page was mapped at the specified virtual address or that
|
|
* mapping had insufficient permissions. Attempt to fault in
|
|
* and hold these pages.
|
|
*/
|
|
for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE)
|
|
if (*mp == NULL && vm_fault_hold(map, va, prot,
|
|
VM_FAULT_NORMAL, mp) != KERN_SUCCESS)
|
|
goto error;
|
|
}
|
|
return (count);
|
|
error:
|
|
for (mp = ma; mp < ma + count; mp++)
|
|
if (*mp != NULL) {
|
|
vm_page_lock(*mp);
|
|
vm_page_unhold(*mp);
|
|
vm_page_unlock(*mp);
|
|
}
|
|
return (-1);
|
|
}
|
|
|
|
/*
|
|
* Routine:
|
|
* vm_fault_copy_entry
|
|
* Function:
|
|
* Create new shadow object backing dst_entry with private copy of
|
|
* all underlying pages. When src_entry is equal to dst_entry,
|
|
* function implements COW for wired-down map entry. Otherwise,
|
|
* it forks wired entry into dst_map.
|
|
*
|
|
* In/out conditions:
|
|
* The source and destination maps must be locked for write.
|
|
* The source map entry must be wired down (or be a sharing map
|
|
* entry corresponding to a main map entry that is wired down).
|
|
*/
|
|
void
|
|
vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
|
|
vm_map_entry_t dst_entry, vm_map_entry_t src_entry,
|
|
vm_ooffset_t *fork_charge)
|
|
{
|
|
vm_object_t backing_object, dst_object, object, src_object;
|
|
vm_pindex_t dst_pindex, pindex, src_pindex;
|
|
vm_prot_t access, prot;
|
|
vm_offset_t vaddr;
|
|
vm_page_t dst_m;
|
|
vm_page_t src_m;
|
|
boolean_t upgrade;
|
|
|
|
#ifdef lint
|
|
src_map++;
|
|
#endif /* lint */
|
|
|
|
upgrade = src_entry == dst_entry;
|
|
access = prot = dst_entry->protection;
|
|
|
|
src_object = src_entry->object.vm_object;
|
|
src_pindex = OFF_TO_IDX(src_entry->offset);
|
|
|
|
if (upgrade && (dst_entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) {
|
|
dst_object = src_object;
|
|
vm_object_reference(dst_object);
|
|
} else {
|
|
/*
|
|
* Create the top-level object for the destination entry. (Doesn't
|
|
* actually shadow anything - we copy the pages directly.)
|
|
*/
|
|
dst_object = vm_object_allocate(OBJT_DEFAULT,
|
|
OFF_TO_IDX(dst_entry->end - dst_entry->start));
|
|
#if VM_NRESERVLEVEL > 0
|
|
dst_object->flags |= OBJ_COLORED;
|
|
dst_object->pg_color = atop(dst_entry->start);
|
|
#endif
|
|
}
|
|
|
|
VM_OBJECT_WLOCK(dst_object);
|
|
KASSERT(upgrade || dst_entry->object.vm_object == NULL,
|
|
("vm_fault_copy_entry: vm_object not NULL"));
|
|
if (src_object != dst_object) {
|
|
dst_entry->object.vm_object = dst_object;
|
|
dst_entry->offset = 0;
|
|
dst_object->charge = dst_entry->end - dst_entry->start;
|
|
}
|
|
if (fork_charge != NULL) {
|
|
KASSERT(dst_entry->cred == NULL,
|
|
("vm_fault_copy_entry: leaked swp charge"));
|
|
dst_object->cred = curthread->td_ucred;
|
|
crhold(dst_object->cred);
|
|
*fork_charge += dst_object->charge;
|
|
} else if (dst_object->cred == NULL) {
|
|
KASSERT(dst_entry->cred != NULL, ("no cred for entry %p",
|
|
dst_entry));
|
|
dst_object->cred = dst_entry->cred;
|
|
dst_entry->cred = NULL;
|
|
}
|
|
|
|
/*
|
|
* If not an upgrade, then enter the mappings in the pmap as
|
|
* read and/or execute accesses. Otherwise, enter them as
|
|
* write accesses.
|
|
*
|
|
* A writeable large page mapping is only created if all of
|
|
* the constituent small page mappings are modified. Marking
|
|
* PTEs as modified on inception allows promotion to happen
|
|
* without taking potentially large number of soft faults.
|
|
*/
|
|
if (!upgrade)
|
|
access &= ~VM_PROT_WRITE;
|
|
|
|
/*
|
|
* Loop through all of the virtual pages within the entry's
|
|
* range, copying each page from the source object to the
|
|
* destination object. Since the source is wired, those pages
|
|
* must exist. In contrast, the destination is pageable.
|
|
* Since the destination object does share any backing storage
|
|
* with the source object, all of its pages must be dirtied,
|
|
* regardless of whether they can be written.
|
|
*/
|
|
for (vaddr = dst_entry->start, dst_pindex = 0;
|
|
vaddr < dst_entry->end;
|
|
vaddr += PAGE_SIZE, dst_pindex++) {
|
|
again:
|
|
/*
|
|
* Find the page in the source object, and copy it in.
|
|
* Because the source is wired down, the page will be
|
|
* in memory.
|
|
*/
|
|
if (src_object != dst_object)
|
|
VM_OBJECT_RLOCK(src_object);
|
|
object = src_object;
|
|
pindex = src_pindex + dst_pindex;
|
|
while ((src_m = vm_page_lookup(object, pindex)) == NULL &&
|
|
(backing_object = object->backing_object) != NULL) {
|
|
/*
|
|
* Unless the source mapping is read-only or
|
|
* it is presently being upgraded from
|
|
* read-only, the first object in the shadow
|
|
* chain should provide all of the pages. In
|
|
* other words, this loop body should never be
|
|
* executed when the source mapping is already
|
|
* read/write.
|
|
*/
|
|
KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 ||
|
|
upgrade,
|
|
("vm_fault_copy_entry: main object missing page"));
|
|
|
|
VM_OBJECT_RLOCK(backing_object);
|
|
pindex += OFF_TO_IDX(object->backing_object_offset);
|
|
if (object != dst_object)
|
|
VM_OBJECT_RUNLOCK(object);
|
|
object = backing_object;
|
|
}
|
|
KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing"));
|
|
|
|
if (object != dst_object) {
|
|
/*
|
|
* Allocate a page in the destination object.
|
|
*/
|
|
dst_m = vm_page_alloc(dst_object, (src_object ==
|
|
dst_object ? src_pindex : 0) + dst_pindex,
|
|
VM_ALLOC_NORMAL);
|
|
if (dst_m == NULL) {
|
|
VM_OBJECT_WUNLOCK(dst_object);
|
|
VM_OBJECT_RUNLOCK(object);
|
|
VM_WAIT;
|
|
VM_OBJECT_WLOCK(dst_object);
|
|
goto again;
|
|
}
|
|
pmap_copy_page(src_m, dst_m);
|
|
VM_OBJECT_RUNLOCK(object);
|
|
dst_m->valid = VM_PAGE_BITS_ALL;
|
|
dst_m->dirty = VM_PAGE_BITS_ALL;
|
|
} else {
|
|
dst_m = src_m;
|
|
if (vm_page_sleep_if_busy(dst_m, "fltupg"))
|
|
goto again;
|
|
vm_page_xbusy(dst_m);
|
|
KASSERT(dst_m->valid == VM_PAGE_BITS_ALL,
|
|
("invalid dst page %p", dst_m));
|
|
}
|
|
VM_OBJECT_WUNLOCK(dst_object);
|
|
|
|
/*
|
|
* Enter it in the pmap. If a wired, copy-on-write
|
|
* mapping is being replaced by a write-enabled
|
|
* mapping, then wire that new mapping.
|
|
*/
|
|
pmap_enter(dst_map->pmap, vaddr, access, dst_m, prot, upgrade);
|
|
|
|
/*
|
|
* Mark it no longer busy, and put it on the active list.
|
|
*/
|
|
VM_OBJECT_WLOCK(dst_object);
|
|
|
|
if (upgrade) {
|
|
if (src_m != dst_m) {
|
|
vm_page_lock(src_m);
|
|
vm_page_unwire(src_m, PQ_INACTIVE);
|
|
vm_page_unlock(src_m);
|
|
vm_page_lock(dst_m);
|
|
vm_page_wire(dst_m);
|
|
vm_page_unlock(dst_m);
|
|
} else {
|
|
KASSERT(dst_m->wire_count > 0,
|
|
("dst_m %p is not wired", dst_m));
|
|
}
|
|
} else {
|
|
vm_page_lock(dst_m);
|
|
vm_page_activate(dst_m);
|
|
vm_page_unlock(dst_m);
|
|
}
|
|
vm_page_xunbusy(dst_m);
|
|
}
|
|
VM_OBJECT_WUNLOCK(dst_object);
|
|
if (upgrade) {
|
|
dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY);
|
|
vm_object_deallocate(src_object);
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* This routine checks around the requested page for other pages that
|
|
* might be able to be faulted in. This routine brackets the viable
|
|
* pages for the pages to be paged in.
|
|
*
|
|
* Inputs:
|
|
* m, rbehind, rahead
|
|
*
|
|
* Outputs:
|
|
* marray (array of vm_page_t), reqpage (index of requested page)
|
|
*
|
|
* Return value:
|
|
* number of pages in marray
|
|
*/
|
|
static int
|
|
vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage)
|
|
vm_page_t m;
|
|
int rbehind;
|
|
int rahead;
|
|
vm_page_t *marray;
|
|
int *reqpage;
|
|
{
|
|
int i,j;
|
|
vm_object_t object;
|
|
vm_pindex_t pindex, startpindex, endpindex, tpindex;
|
|
vm_page_t rtm;
|
|
int cbehind, cahead;
|
|
|
|
VM_OBJECT_ASSERT_WLOCKED(m->object);
|
|
|
|
object = m->object;
|
|
pindex = m->pindex;
|
|
cbehind = cahead = 0;
|
|
|
|
/*
|
|
* if the requested page is not available, then give up now
|
|
*/
|
|
if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) {
|
|
return 0;
|
|
}
|
|
|
|
if ((cbehind == 0) && (cahead == 0)) {
|
|
*reqpage = 0;
|
|
marray[0] = m;
|
|
return 1;
|
|
}
|
|
|
|
if (rahead > cahead) {
|
|
rahead = cahead;
|
|
}
|
|
|
|
if (rbehind > cbehind) {
|
|
rbehind = cbehind;
|
|
}
|
|
|
|
/*
|
|
* scan backward for the read behind pages -- in memory
|
|
*/
|
|
if (pindex > 0) {
|
|
if (rbehind > pindex) {
|
|
rbehind = pindex;
|
|
startpindex = 0;
|
|
} else {
|
|
startpindex = pindex - rbehind;
|
|
}
|
|
|
|
if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL &&
|
|
rtm->pindex >= startpindex)
|
|
startpindex = rtm->pindex + 1;
|
|
|
|
/* tpindex is unsigned; beware of numeric underflow. */
|
|
for (i = 0, tpindex = pindex - 1; tpindex >= startpindex &&
|
|
tpindex < pindex; i++, tpindex--) {
|
|
|
|
rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL |
|
|
VM_ALLOC_IFNOTCACHED);
|
|
if (rtm == NULL) {
|
|
/*
|
|
* Shift the allocated pages to the
|
|
* beginning of the array.
|
|
*/
|
|
for (j = 0; j < i; j++) {
|
|
marray[j] = marray[j + tpindex + 1 -
|
|
startpindex];
|
|
}
|
|
break;
|
|
}
|
|
|
|
marray[tpindex - startpindex] = rtm;
|
|
}
|
|
} else {
|
|
startpindex = 0;
|
|
i = 0;
|
|
}
|
|
|
|
marray[i] = m;
|
|
/* page offset of the required page */
|
|
*reqpage = i;
|
|
|
|
tpindex = pindex + 1;
|
|
i++;
|
|
|
|
/*
|
|
* scan forward for the read ahead pages
|
|
*/
|
|
endpindex = tpindex + rahead;
|
|
if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex)
|
|
endpindex = rtm->pindex;
|
|
if (endpindex > object->size)
|
|
endpindex = object->size;
|
|
|
|
for (; tpindex < endpindex; i++, tpindex++) {
|
|
|
|
rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL |
|
|
VM_ALLOC_IFNOTCACHED);
|
|
if (rtm == NULL) {
|
|
break;
|
|
}
|
|
|
|
marray[i] = rtm;
|
|
}
|
|
|
|
/* return number of pages */
|
|
return i;
|
|
}
|
|
|
|
/*
|
|
* Block entry into the machine-independent layer's page fault handler by
|
|
* the calling thread. Subsequent calls to vm_fault() by that thread will
|
|
* return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of
|
|
* spurious page faults.
|
|
*/
|
|
int
|
|
vm_fault_disable_pagefaults(void)
|
|
{
|
|
|
|
return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR));
|
|
}
|
|
|
|
void
|
|
vm_fault_enable_pagefaults(int save)
|
|
{
|
|
|
|
curthread_pflags_restore(save);
|
|
}
|