2281 lines
64 KiB
C
2281 lines
64 KiB
C
/*-
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* SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU)
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*
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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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#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/mman.h>
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#include <sys/mutex.h>
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#include <sys/pctrie.h>
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#include <sys/proc.h>
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#include <sys/racct.h>
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#include <sys/refcount.h>
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#include <sys/resourcevar.h>
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#include <sys/rwlock.h>
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#include <sys/signalvar.h>
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#include <sys/sysctl.h>
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#include <sys/sysent.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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#include <vm/vm_reserv.h>
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#define PFBAK 4
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#define PFFOR 4
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#define VM_FAULT_READ_DEFAULT (1 + VM_FAULT_READ_AHEAD_INIT)
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#define VM_FAULT_DONTNEED_MIN 1048576
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struct faultstate {
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/* Fault parameters. */
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vm_offset_t vaddr;
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vm_page_t *m_hold;
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vm_prot_t fault_type;
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vm_prot_t prot;
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int fault_flags;
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boolean_t wired;
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/* Control state. */
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struct timeval oom_start_time;
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bool oom_started;
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int nera;
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bool can_read_lock;
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/* Page reference for cow. */
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vm_page_t m_cow;
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/* Current object. */
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vm_object_t object;
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vm_pindex_t pindex;
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vm_page_t m;
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/* Top-level map object. */
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vm_object_t first_object;
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vm_pindex_t first_pindex;
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vm_page_t first_m;
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/* Map state. */
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vm_map_t map;
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vm_map_entry_t entry;
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int map_generation;
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bool lookup_still_valid;
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/* Vnode if locked. */
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struct vnode *vp;
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};
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/*
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* Return codes for internal fault routines.
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*/
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enum fault_status {
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FAULT_SUCCESS = 10000, /* Return success to user. */
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FAULT_FAILURE, /* Return failure to user. */
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FAULT_CONTINUE, /* Continue faulting. */
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FAULT_RESTART, /* Restart fault. */
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FAULT_OUT_OF_BOUNDS, /* Invalid address for pager. */
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FAULT_HARD, /* Performed I/O. */
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FAULT_SOFT, /* Found valid page. */
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FAULT_PROTECTION_FAILURE, /* Invalid access. */
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};
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enum fault_next_status {
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FAULT_NEXT_GOTOBJ = 1,
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FAULT_NEXT_NOOBJ,
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FAULT_NEXT_RESTART,
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};
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static void vm_fault_dontneed(const struct faultstate *fs, vm_offset_t vaddr,
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int ahead);
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static void vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra,
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int backward, int forward, bool obj_locked);
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static int vm_pfault_oom_attempts = 3;
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SYSCTL_INT(_vm, OID_AUTO, pfault_oom_attempts, CTLFLAG_RWTUN,
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&vm_pfault_oom_attempts, 0,
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"Number of page allocation attempts in page fault handler before it "
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"triggers OOM handling");
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static int vm_pfault_oom_wait = 10;
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SYSCTL_INT(_vm, OID_AUTO, pfault_oom_wait, CTLFLAG_RWTUN,
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&vm_pfault_oom_wait, 0,
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"Number of seconds to wait for free pages before retrying "
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"the page fault handler");
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static inline void
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vm_fault_page_release(vm_page_t *mp)
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{
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vm_page_t m;
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m = *mp;
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if (m != NULL) {
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/*
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* We are likely to loop around again and attempt to busy
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* this page. Deactivating it leaves it available for
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* pageout while optimizing fault restarts.
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*/
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vm_page_deactivate(m);
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vm_page_xunbusy(m);
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*mp = NULL;
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}
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}
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static inline void
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vm_fault_page_free(vm_page_t *mp)
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{
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vm_page_t m;
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m = *mp;
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if (m != NULL) {
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VM_OBJECT_ASSERT_WLOCKED(m->object);
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if (!vm_page_wired(m))
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vm_page_free(m);
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else
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vm_page_xunbusy(m);
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*mp = NULL;
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}
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}
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/*
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* Return true if a vm_pager_get_pages() call is needed in order to check
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* whether the pager might have a particular page, false if it can be determined
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* immediately that the pager can not have a copy. For swap objects, this can
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* be checked quickly.
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*/
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static inline bool
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vm_fault_object_needs_getpages(vm_object_t object)
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{
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VM_OBJECT_ASSERT_LOCKED(object);
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return ((object->flags & OBJ_SWAP) == 0 ||
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!pctrie_is_empty(&object->un_pager.swp.swp_blks));
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}
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static inline void
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vm_fault_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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vm_fault_unlock_vp(struct faultstate *fs)
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{
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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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static void
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vm_fault_deallocate(struct faultstate *fs)
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{
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vm_fault_page_release(&fs->m_cow);
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vm_fault_page_release(&fs->m);
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vm_object_pip_wakeup(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_fault_page_free(&fs->first_m);
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VM_OBJECT_WUNLOCK(fs->first_object);
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vm_object_pip_wakeup(fs->first_object);
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}
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vm_object_deallocate(fs->first_object);
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vm_fault_unlock_map(fs);
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vm_fault_unlock_vp(fs);
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}
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static void
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vm_fault_unlock_and_deallocate(struct faultstate *fs)
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{
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VM_OBJECT_UNLOCK(fs->object);
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vm_fault_deallocate(fs);
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}
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static void
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vm_fault_dirty(struct faultstate *fs, vm_page_t m)
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{
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bool need_dirty;
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if (((fs->prot & VM_PROT_WRITE) == 0 &&
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(fs->fault_flags & VM_FAULT_DIRTY) == 0) ||
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(m->oflags & VPO_UNMANAGED) != 0)
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return;
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VM_PAGE_OBJECT_BUSY_ASSERT(m);
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need_dirty = ((fs->fault_type & VM_PROT_WRITE) != 0 &&
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(fs->fault_flags & VM_FAULT_WIRE) == 0) ||
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(fs->fault_flags & VM_FAULT_DIRTY) != 0;
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vm_object_set_writeable_dirty(m->object);
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/*
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* If the fault is a write, we know that this page is being
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* written NOW so dirty it explicitly to save on
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* pmap_is_modified() calls later.
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*
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* Also, since the page is now dirty, we can possibly tell
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* the pager to release any swap backing the page.
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*/
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if (need_dirty && vm_page_set_dirty(m) == 0) {
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/*
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* If this is a NOSYNC mmap we do not want to set PGA_NOSYNC
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* if the page is already dirty to prevent data written with
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* the expectation of being synced from not being synced.
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* Likewise if this entry does not request NOSYNC then make
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* sure the page isn't marked NOSYNC. Applications sharing
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* data should use the same flags to avoid ping ponging.
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*/
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if ((fs->entry->eflags & MAP_ENTRY_NOSYNC) != 0)
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vm_page_aflag_set(m, PGA_NOSYNC);
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else
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vm_page_aflag_clear(m, PGA_NOSYNC);
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}
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}
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/*
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* Unlocks fs.first_object and fs.map on success.
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*/
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static enum fault_status
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vm_fault_soft_fast(struct faultstate *fs)
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{
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vm_page_t m, m_map;
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#if VM_NRESERVLEVEL > 0
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vm_page_t m_super;
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int flags;
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#endif
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int psind;
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vm_offset_t vaddr;
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MPASS(fs->vp == NULL);
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/*
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* If we fail, vast majority of the time it is because the page is not
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* there to begin with. Opportunistically perform the lookup and
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* subsequent checks without the object lock, revalidate later.
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*
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* Note: a busy page can be mapped for read|execute access.
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*/
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m = vm_page_lookup_unlocked(fs->first_object, fs->first_pindex);
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if (m == NULL || !vm_page_all_valid(m) ||
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((fs->prot & VM_PROT_WRITE) != 0 && vm_page_busied(m))) {
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VM_OBJECT_WLOCK(fs->first_object);
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return (FAULT_FAILURE);
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}
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vaddr = fs->vaddr;
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VM_OBJECT_RLOCK(fs->first_object);
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/*
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* Now that we stabilized the state, revalidate the page is in the shape
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* we encountered above.
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*/
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if (m->object != fs->first_object || m->pindex != fs->first_pindex)
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goto fail;
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vm_object_busy(fs->first_object);
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if (!vm_page_all_valid(m) ||
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((fs->prot & VM_PROT_WRITE) != 0 && vm_page_busied(m)))
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goto fail_busy;
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m_map = m;
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psind = 0;
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#if VM_NRESERVLEVEL > 0
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if ((m->flags & PG_FICTITIOUS) == 0 &&
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(m_super = vm_reserv_to_superpage(m)) != NULL &&
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rounddown2(vaddr, pagesizes[m_super->psind]) >= fs->entry->start &&
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roundup2(vaddr + 1, pagesizes[m_super->psind]) <= fs->entry->end &&
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(vaddr & (pagesizes[m_super->psind] - 1)) == (VM_PAGE_TO_PHYS(m) &
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(pagesizes[m_super->psind] - 1)) && !fs->wired &&
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pmap_ps_enabled(fs->map->pmap)) {
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flags = PS_ALL_VALID;
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if ((fs->prot & VM_PROT_WRITE) != 0) {
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/*
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* Create a superpage mapping allowing write access
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* only if none of the constituent pages are busy and
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* all of them are already dirty (except possibly for
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* the page that was faulted on).
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*/
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flags |= PS_NONE_BUSY;
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if ((fs->first_object->flags & OBJ_UNMANAGED) == 0)
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flags |= PS_ALL_DIRTY;
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}
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if (vm_page_ps_test(m_super, flags, m)) {
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m_map = m_super;
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psind = m_super->psind;
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vaddr = rounddown2(vaddr, pagesizes[psind]);
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/* Preset the modified bit for dirty superpages. */
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if ((flags & PS_ALL_DIRTY) != 0)
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fs->fault_type |= VM_PROT_WRITE;
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}
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}
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#endif
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if (pmap_enter(fs->map->pmap, vaddr, m_map, fs->prot, fs->fault_type |
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PMAP_ENTER_NOSLEEP | (fs->wired ? PMAP_ENTER_WIRED : 0), psind) !=
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KERN_SUCCESS)
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goto fail_busy;
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if (fs->m_hold != NULL) {
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(*fs->m_hold) = m;
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vm_page_wire(m);
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}
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if (psind == 0 && !fs->wired)
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vm_fault_prefault(fs, vaddr, PFBAK, PFFOR, true);
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VM_OBJECT_RUNLOCK(fs->first_object);
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vm_fault_dirty(fs, m);
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vm_object_unbusy(fs->first_object);
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vm_map_lookup_done(fs->map, fs->entry);
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curthread->td_ru.ru_minflt++;
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return (FAULT_SUCCESS);
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fail_busy:
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vm_object_unbusy(fs->first_object);
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fail:
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if (!VM_OBJECT_TRYUPGRADE(fs->first_object)) {
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VM_OBJECT_RUNLOCK(fs->first_object);
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VM_OBJECT_WLOCK(fs->first_object);
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}
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return (FAULT_FAILURE);
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}
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|
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static void
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vm_fault_restore_map_lock(struct faultstate *fs)
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{
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|
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VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
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MPASS(blockcount_read(&fs->first_object->paging_in_progress) > 0);
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|
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if (!vm_map_trylock_read(fs->map)) {
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VM_OBJECT_WUNLOCK(fs->first_object);
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vm_map_lock_read(fs->map);
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VM_OBJECT_WLOCK(fs->first_object);
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}
|
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fs->lookup_still_valid = true;
|
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}
|
|
|
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static void
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vm_fault_populate_check_page(vm_page_t m)
|
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{
|
|
|
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/*
|
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* Check each page to ensure that the pager is obeying the
|
|
* interface: the page must be installed in the object, fully
|
|
* valid, and exclusively busied.
|
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*/
|
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MPASS(m != NULL);
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MPASS(vm_page_all_valid(m));
|
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MPASS(vm_page_xbusied(m));
|
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}
|
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|
|
static void
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vm_fault_populate_cleanup(vm_object_t object, vm_pindex_t first,
|
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vm_pindex_t last)
|
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{
|
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vm_page_t m;
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vm_pindex_t pidx;
|
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|
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VM_OBJECT_ASSERT_WLOCKED(object);
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MPASS(first <= last);
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for (pidx = first, m = vm_page_lookup(object, pidx);
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pidx <= last; pidx++, m = vm_page_next(m)) {
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vm_fault_populate_check_page(m);
|
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vm_page_deactivate(m);
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vm_page_xunbusy(m);
|
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}
|
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}
|
|
|
|
static enum fault_status
|
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vm_fault_populate(struct faultstate *fs)
|
|
{
|
|
vm_offset_t vaddr;
|
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vm_page_t m;
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vm_pindex_t map_first, map_last, pager_first, pager_last, pidx;
|
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int bdry_idx, i, npages, psind, rv;
|
|
enum fault_status res;
|
|
|
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MPASS(fs->object == fs->first_object);
|
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VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
|
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MPASS(blockcount_read(&fs->first_object->paging_in_progress) > 0);
|
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MPASS(fs->first_object->backing_object == NULL);
|
|
MPASS(fs->lookup_still_valid);
|
|
|
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pager_first = OFF_TO_IDX(fs->entry->offset);
|
|
pager_last = pager_first + atop(fs->entry->end - fs->entry->start) - 1;
|
|
vm_fault_unlock_map(fs);
|
|
vm_fault_unlock_vp(fs);
|
|
|
|
res = FAULT_SUCCESS;
|
|
|
|
/*
|
|
* Call the pager (driver) populate() method.
|
|
*
|
|
* There is no guarantee that the method will be called again
|
|
* if the current fault is for read, and a future fault is
|
|
* for write. Report the entry's maximum allowed protection
|
|
* to the driver.
|
|
*/
|
|
rv = vm_pager_populate(fs->first_object, fs->first_pindex,
|
|
fs->fault_type, fs->entry->max_protection, &pager_first,
|
|
&pager_last);
|
|
|
|
VM_OBJECT_ASSERT_WLOCKED(fs->first_object);
|
|
if (rv == VM_PAGER_BAD) {
|
|
/*
|
|
* VM_PAGER_BAD is the backdoor for a pager to request
|
|
* normal fault handling.
|
|
*/
|
|
vm_fault_restore_map_lock(fs);
|
|
if (fs->map->timestamp != fs->map_generation)
|
|
return (FAULT_RESTART);
|
|
return (FAULT_CONTINUE);
|
|
}
|
|
if (rv != VM_PAGER_OK)
|
|
return (FAULT_FAILURE); /* AKA SIGSEGV */
|
|
|
|
/* Ensure that the driver is obeying the interface. */
|
|
MPASS(pager_first <= pager_last);
|
|
MPASS(fs->first_pindex <= pager_last);
|
|
MPASS(fs->first_pindex >= pager_first);
|
|
MPASS(pager_last < fs->first_object->size);
|
|
|
|
vm_fault_restore_map_lock(fs);
|
|
bdry_idx = MAP_ENTRY_SPLIT_BOUNDARY_INDEX(fs->entry);
|
|
if (fs->map->timestamp != fs->map_generation) {
|
|
if (bdry_idx == 0) {
|
|
vm_fault_populate_cleanup(fs->first_object, pager_first,
|
|
pager_last);
|
|
} else {
|
|
m = vm_page_lookup(fs->first_object, pager_first);
|
|
if (m != fs->m)
|
|
vm_page_xunbusy(m);
|
|
}
|
|
return (FAULT_RESTART);
|
|
}
|
|
|
|
/*
|
|
* The map is unchanged after our last unlock. Process the fault.
|
|
*
|
|
* First, the special case of largepage mappings, where
|
|
* populate only busies the first page in superpage run.
|
|
*/
|
|
if (bdry_idx != 0) {
|
|
KASSERT(PMAP_HAS_LARGEPAGES,
|
|
("missing pmap support for large pages"));
|
|
m = vm_page_lookup(fs->first_object, pager_first);
|
|
vm_fault_populate_check_page(m);
|
|
VM_OBJECT_WUNLOCK(fs->first_object);
|
|
vaddr = fs->entry->start + IDX_TO_OFF(pager_first) -
|
|
fs->entry->offset;
|
|
/* assert alignment for entry */
|
|
KASSERT((vaddr & (pagesizes[bdry_idx] - 1)) == 0,
|
|
("unaligned superpage start %#jx pager_first %#jx offset %#jx vaddr %#jx",
|
|
(uintmax_t)fs->entry->start, (uintmax_t)pager_first,
|
|
(uintmax_t)fs->entry->offset, (uintmax_t)vaddr));
|
|
KASSERT((VM_PAGE_TO_PHYS(m) & (pagesizes[bdry_idx] - 1)) == 0,
|
|
("unaligned superpage m %p %#jx", m,
|
|
(uintmax_t)VM_PAGE_TO_PHYS(m)));
|
|
rv = pmap_enter(fs->map->pmap, vaddr, m, fs->prot,
|
|
fs->fault_type | (fs->wired ? PMAP_ENTER_WIRED : 0) |
|
|
PMAP_ENTER_LARGEPAGE, bdry_idx);
|
|
VM_OBJECT_WLOCK(fs->first_object);
|
|
vm_page_xunbusy(m);
|
|
if (rv != KERN_SUCCESS) {
|
|
res = FAULT_FAILURE;
|
|
goto out;
|
|
}
|
|
if ((fs->fault_flags & VM_FAULT_WIRE) != 0) {
|
|
for (i = 0; i < atop(pagesizes[bdry_idx]); i++)
|
|
vm_page_wire(m + i);
|
|
}
|
|
if (fs->m_hold != NULL) {
|
|
*fs->m_hold = m + (fs->first_pindex - pager_first);
|
|
vm_page_wire(*fs->m_hold);
|
|
}
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* The range [pager_first, pager_last] that is given to the
|
|
* pager is only a hint. The pager may populate any range
|
|
* within the object that includes the requested page index.
|
|
* In case the pager expanded the range, clip it to fit into
|
|
* the map entry.
|
|
*/
|
|
map_first = OFF_TO_IDX(fs->entry->offset);
|
|
if (map_first > pager_first) {
|
|
vm_fault_populate_cleanup(fs->first_object, pager_first,
|
|
map_first - 1);
|
|
pager_first = map_first;
|
|
}
|
|
map_last = map_first + atop(fs->entry->end - fs->entry->start) - 1;
|
|
if (map_last < pager_last) {
|
|
vm_fault_populate_cleanup(fs->first_object, map_last + 1,
|
|
pager_last);
|
|
pager_last = map_last;
|
|
}
|
|
for (pidx = pager_first, m = vm_page_lookup(fs->first_object, pidx);
|
|
pidx <= pager_last;
|
|
pidx += npages, m = vm_page_next(&m[npages - 1])) {
|
|
vaddr = fs->entry->start + IDX_TO_OFF(pidx) - fs->entry->offset;
|
|
|
|
psind = m->psind;
|
|
if (psind > 0 && ((vaddr & (pagesizes[psind] - 1)) != 0 ||
|
|
pidx + OFF_TO_IDX(pagesizes[psind]) - 1 > pager_last ||
|
|
!pmap_ps_enabled(fs->map->pmap) || fs->wired))
|
|
psind = 0;
|
|
|
|
npages = atop(pagesizes[psind]);
|
|
for (i = 0; i < npages; i++) {
|
|
vm_fault_populate_check_page(&m[i]);
|
|
vm_fault_dirty(fs, &m[i]);
|
|
}
|
|
VM_OBJECT_WUNLOCK(fs->first_object);
|
|
rv = pmap_enter(fs->map->pmap, vaddr, m, fs->prot, fs->fault_type |
|
|
(fs->wired ? PMAP_ENTER_WIRED : 0), psind);
|
|
|
|
/*
|
|
* pmap_enter() may fail for a superpage mapping if additional
|
|
* protection policies prevent the full mapping.
|
|
* For example, this will happen on amd64 if the entire
|
|
* address range does not share the same userspace protection
|
|
* key. Revert to single-page mappings if this happens.
|
|
*/
|
|
MPASS(rv == KERN_SUCCESS ||
|
|
(psind > 0 && rv == KERN_PROTECTION_FAILURE));
|
|
if (__predict_false(psind > 0 &&
|
|
rv == KERN_PROTECTION_FAILURE)) {
|
|
MPASS(!fs->wired);
|
|
for (i = 0; i < npages; i++) {
|
|
rv = pmap_enter(fs->map->pmap, vaddr + ptoa(i),
|
|
&m[i], fs->prot, fs->fault_type, 0);
|
|
MPASS(rv == KERN_SUCCESS);
|
|
}
|
|
}
|
|
|
|
VM_OBJECT_WLOCK(fs->first_object);
|
|
for (i = 0; i < npages; i++) {
|
|
if ((fs->fault_flags & VM_FAULT_WIRE) != 0 &&
|
|
m[i].pindex == fs->first_pindex)
|
|
vm_page_wire(&m[i]);
|
|
else
|
|
vm_page_activate(&m[i]);
|
|
if (fs->m_hold != NULL &&
|
|
m[i].pindex == fs->first_pindex) {
|
|
(*fs->m_hold) = &m[i];
|
|
vm_page_wire(&m[i]);
|
|
}
|
|
vm_page_xunbusy(&m[i]);
|
|
}
|
|
}
|
|
out:
|
|
curthread->td_ru.ru_majflt++;
|
|
return (res);
|
|
}
|
|
|
|
static int prot_fault_translation;
|
|
SYSCTL_INT(_machdep, OID_AUTO, prot_fault_translation, CTLFLAG_RWTUN,
|
|
&prot_fault_translation, 0,
|
|
"Control signal to deliver on protection fault");
|
|
|
|
/* compat definition to keep common code for signal translation */
|
|
#define UCODE_PAGEFLT 12
|
|
#ifdef T_PAGEFLT
|
|
_Static_assert(UCODE_PAGEFLT == T_PAGEFLT, "T_PAGEFLT");
|
|
#endif
|
|
|
|
/*
|
|
* vm_fault_trap:
|
|
*
|
|
* Handle a page fault occurring at the given address,
|
|
* requiring the given permissions, in the map specified.
|
|
* If successful, the page is inserted into the
|
|
* associated physical map.
|
|
*
|
|
* NOTE: the given address should be truncated to the
|
|
* proper page address.
|
|
*
|
|
* KERN_SUCCESS is returned if the page fault is handled; otherwise,
|
|
* a standard error specifying why the fault is fatal is returned.
|
|
*
|
|
* The map in question must be referenced, and remains so.
|
|
* Caller may hold no locks.
|
|
*/
|
|
int
|
|
vm_fault_trap(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
|
|
int fault_flags, int *signo, int *ucode)
|
|
{
|
|
int result;
|
|
|
|
MPASS(signo == NULL || ucode != NULL);
|
|
#ifdef KTRACE
|
|
if (map != kernel_map && KTRPOINT(curthread, KTR_FAULT))
|
|
ktrfault(vaddr, fault_type);
|
|
#endif
|
|
result = vm_fault(map, trunc_page(vaddr), fault_type, fault_flags,
|
|
NULL);
|
|
KASSERT(result == KERN_SUCCESS || result == KERN_FAILURE ||
|
|
result == KERN_INVALID_ADDRESS ||
|
|
result == KERN_RESOURCE_SHORTAGE ||
|
|
result == KERN_PROTECTION_FAILURE ||
|
|
result == KERN_OUT_OF_BOUNDS,
|
|
("Unexpected Mach error %d from vm_fault()", result));
|
|
#ifdef KTRACE
|
|
if (map != kernel_map && KTRPOINT(curthread, KTR_FAULTEND))
|
|
ktrfaultend(result);
|
|
#endif
|
|
if (result != KERN_SUCCESS && signo != NULL) {
|
|
switch (result) {
|
|
case KERN_FAILURE:
|
|
case KERN_INVALID_ADDRESS:
|
|
*signo = SIGSEGV;
|
|
*ucode = SEGV_MAPERR;
|
|
break;
|
|
case KERN_RESOURCE_SHORTAGE:
|
|
*signo = SIGBUS;
|
|
*ucode = BUS_OOMERR;
|
|
break;
|
|
case KERN_OUT_OF_BOUNDS:
|
|
*signo = SIGBUS;
|
|
*ucode = BUS_OBJERR;
|
|
break;
|
|
case KERN_PROTECTION_FAILURE:
|
|
if (prot_fault_translation == 0) {
|
|
/*
|
|
* Autodetect. This check also covers
|
|
* the images without the ABI-tag ELF
|
|
* note.
|
|
*/
|
|
if (SV_CURPROC_ABI() == SV_ABI_FREEBSD &&
|
|
curproc->p_osrel >= P_OSREL_SIGSEGV) {
|
|
*signo = SIGSEGV;
|
|
*ucode = SEGV_ACCERR;
|
|
} else {
|
|
*signo = SIGBUS;
|
|
*ucode = UCODE_PAGEFLT;
|
|
}
|
|
} else if (prot_fault_translation == 1) {
|
|
/* Always compat mode. */
|
|
*signo = SIGBUS;
|
|
*ucode = UCODE_PAGEFLT;
|
|
} else {
|
|
/* Always SIGSEGV mode. */
|
|
*signo = SIGSEGV;
|
|
*ucode = SEGV_ACCERR;
|
|
}
|
|
break;
|
|
default:
|
|
KASSERT(0, ("Unexpected Mach error %d from vm_fault()",
|
|
result));
|
|
break;
|
|
}
|
|
}
|
|
return (result);
|
|
}
|
|
|
|
static bool
|
|
vm_fault_object_ensure_wlocked(struct faultstate *fs)
|
|
{
|
|
if (fs->object == fs->first_object)
|
|
VM_OBJECT_ASSERT_WLOCKED(fs->object);
|
|
|
|
if (!fs->can_read_lock) {
|
|
VM_OBJECT_ASSERT_WLOCKED(fs->object);
|
|
return (true);
|
|
}
|
|
|
|
if (VM_OBJECT_WOWNED(fs->object))
|
|
return (true);
|
|
|
|
if (VM_OBJECT_TRYUPGRADE(fs->object))
|
|
return (true);
|
|
|
|
return (false);
|
|
}
|
|
|
|
static enum fault_status
|
|
vm_fault_lock_vnode(struct faultstate *fs, bool objlocked)
|
|
{
|
|
struct vnode *vp;
|
|
int error, locked;
|
|
|
|
if (fs->object->type != OBJT_VNODE)
|
|
return (FAULT_CONTINUE);
|
|
vp = fs->object->handle;
|
|
if (vp == fs->vp) {
|
|
ASSERT_VOP_LOCKED(vp, "saved vnode is not locked");
|
|
return (FAULT_CONTINUE);
|
|
}
|
|
|
|
/*
|
|
* Perform an unlock in case the desired vnode changed while
|
|
* the map was unlocked during a retry.
|
|
*/
|
|
vm_fault_unlock_vp(fs);
|
|
|
|
locked = VOP_ISLOCKED(vp);
|
|
if (locked != LK_EXCLUSIVE)
|
|
locked = LK_SHARED;
|
|
|
|
/*
|
|
* We must not sleep acquiring the vnode lock while we have
|
|
* the page exclusive busied or the object's
|
|
* paging-in-progress count incremented. Otherwise, we could
|
|
* deadlock.
|
|
*/
|
|
error = vget(vp, locked | LK_CANRECURSE | LK_NOWAIT);
|
|
if (error == 0) {
|
|
fs->vp = vp;
|
|
return (FAULT_CONTINUE);
|
|
}
|
|
|
|
vhold(vp);
|
|
if (objlocked)
|
|
vm_fault_unlock_and_deallocate(fs);
|
|
else
|
|
vm_fault_deallocate(fs);
|
|
error = vget(vp, locked | LK_RETRY | LK_CANRECURSE);
|
|
vdrop(vp);
|
|
fs->vp = vp;
|
|
KASSERT(error == 0, ("vm_fault: vget failed %d", error));
|
|
return (FAULT_RESTART);
|
|
}
|
|
|
|
/*
|
|
* Calculate the desired readahead. Handle drop-behind.
|
|
*
|
|
* Returns the number of readahead blocks to pass to the pager.
|
|
*/
|
|
static int
|
|
vm_fault_readahead(struct faultstate *fs)
|
|
{
|
|
int era, nera;
|
|
u_char behavior;
|
|
|
|
KASSERT(fs->lookup_still_valid, ("map unlocked"));
|
|
era = fs->entry->read_ahead;
|
|
behavior = vm_map_entry_behavior(fs->entry);
|
|
if (behavior == MAP_ENTRY_BEHAV_RANDOM) {
|
|
nera = 0;
|
|
} else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) {
|
|
nera = VM_FAULT_READ_AHEAD_MAX;
|
|
if (fs->vaddr == fs->entry->next_read)
|
|
vm_fault_dontneed(fs, fs->vaddr, nera);
|
|
} else if (fs->vaddr == fs->entry->next_read) {
|
|
/*
|
|
* This is a sequential fault. Arithmetically
|
|
* increase the requested number of pages in
|
|
* the read-ahead window. The requested
|
|
* number of pages is "# of sequential faults
|
|
* x (read ahead min + 1) + read ahead min"
|
|
*/
|
|
nera = VM_FAULT_READ_AHEAD_MIN;
|
|
if (era > 0) {
|
|
nera += era + 1;
|
|
if (nera > VM_FAULT_READ_AHEAD_MAX)
|
|
nera = VM_FAULT_READ_AHEAD_MAX;
|
|
}
|
|
if (era == VM_FAULT_READ_AHEAD_MAX)
|
|
vm_fault_dontneed(fs, fs->vaddr, nera);
|
|
} else {
|
|
/*
|
|
* This is a non-sequential fault.
|
|
*/
|
|
nera = 0;
|
|
}
|
|
if (era != nera) {
|
|
/*
|
|
* A read lock on the map suffices to update
|
|
* the read ahead count safely.
|
|
*/
|
|
fs->entry->read_ahead = nera;
|
|
}
|
|
|
|
return (nera);
|
|
}
|
|
|
|
static int
|
|
vm_fault_lookup(struct faultstate *fs)
|
|
{
|
|
int result;
|
|
|
|
KASSERT(!fs->lookup_still_valid,
|
|
("vm_fault_lookup: Map already locked."));
|
|
result = vm_map_lookup(&fs->map, fs->vaddr, fs->fault_type |
|
|
VM_PROT_FAULT_LOOKUP, &fs->entry, &fs->first_object,
|
|
&fs->first_pindex, &fs->prot, &fs->wired);
|
|
if (result != KERN_SUCCESS) {
|
|
vm_fault_unlock_vp(fs);
|
|
return (result);
|
|
}
|
|
|
|
fs->map_generation = fs->map->timestamp;
|
|
|
|
if (fs->entry->eflags & MAP_ENTRY_NOFAULT) {
|
|
panic("%s: fault on nofault entry, addr: %#lx",
|
|
__func__, (u_long)fs->vaddr);
|
|
}
|
|
|
|
if (fs->entry->eflags & MAP_ENTRY_IN_TRANSITION &&
|
|
fs->entry->wiring_thread != curthread) {
|
|
vm_map_unlock_read(fs->map);
|
|
vm_map_lock(fs->map);
|
|
if (vm_map_lookup_entry(fs->map, fs->vaddr, &fs->entry) &&
|
|
(fs->entry->eflags & MAP_ENTRY_IN_TRANSITION)) {
|
|
vm_fault_unlock_vp(fs);
|
|
fs->entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP;
|
|
vm_map_unlock_and_wait(fs->map, 0);
|
|
} else
|
|
vm_map_unlock(fs->map);
|
|
return (KERN_RESOURCE_SHORTAGE);
|
|
}
|
|
|
|
MPASS((fs->entry->eflags & MAP_ENTRY_GUARD) == 0);
|
|
|
|
if (fs->wired)
|
|
fs->fault_type = fs->prot | (fs->fault_type & VM_PROT_COPY);
|
|
else
|
|
KASSERT((fs->fault_flags & VM_FAULT_WIRE) == 0,
|
|
("!fs->wired && VM_FAULT_WIRE"));
|
|
fs->lookup_still_valid = true;
|
|
|
|
return (KERN_SUCCESS);
|
|
}
|
|
|
|
static int
|
|
vm_fault_relookup(struct faultstate *fs)
|
|
{
|
|
vm_object_t retry_object;
|
|
vm_pindex_t retry_pindex;
|
|
vm_prot_t retry_prot;
|
|
int result;
|
|
|
|
if (!vm_map_trylock_read(fs->map))
|
|
return (KERN_RESTART);
|
|
|
|
fs->lookup_still_valid = true;
|
|
if (fs->map->timestamp == fs->map_generation)
|
|
return (KERN_SUCCESS);
|
|
|
|
result = vm_map_lookup_locked(&fs->map, fs->vaddr, fs->fault_type,
|
|
&fs->entry, &retry_object, &retry_pindex, &retry_prot,
|
|
&fs->wired);
|
|
if (result != KERN_SUCCESS) {
|
|
/*
|
|
* If retry of map lookup would have blocked then
|
|
* retry fault from start.
|
|
*/
|
|
if (result == KERN_FAILURE)
|
|
return (KERN_RESTART);
|
|
return (result);
|
|
}
|
|
if (retry_object != fs->first_object ||
|
|
retry_pindex != fs->first_pindex)
|
|
return (KERN_RESTART);
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
fs->prot &= retry_prot;
|
|
fs->fault_type &= retry_prot;
|
|
if (fs->prot == 0)
|
|
return (KERN_RESTART);
|
|
|
|
/* Reassert because wired may have changed. */
|
|
KASSERT(fs->wired || (fs->fault_flags & VM_FAULT_WIRE) == 0,
|
|
("!wired && VM_FAULT_WIRE"));
|
|
|
|
return (KERN_SUCCESS);
|
|
}
|
|
|
|
static void
|
|
vm_fault_cow(struct faultstate *fs)
|
|
{
|
|
bool is_first_object_locked;
|
|
|
|
KASSERT(fs->object != fs->first_object,
|
|
("source and target COW objects are identical"));
|
|
|
|
/*
|
|
* 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 and no other refs.
|
|
*/
|
|
fs->object->shadow_count == 1 && fs->object->ref_count == 1 &&
|
|
/*
|
|
* No other ways to look the object up
|
|
*/
|
|
fs->object->handle == NULL && (fs->object->flags & OBJ_ANON) != 0 &&
|
|
/*
|
|
* We don't chase down the shadow chain and we can acquire locks.
|
|
*/
|
|
(is_first_object_locked = VM_OBJECT_TRYWLOCK(fs->first_object)) &&
|
|
fs->object == fs->first_object->backing_object &&
|
|
VM_OBJECT_TRYWLOCK(fs->object)) {
|
|
/*
|
|
* Remove but keep xbusy for replace. fs->m is moved into
|
|
* fs->first_object and left busy while fs->first_m is
|
|
* conditionally freed.
|
|
*/
|
|
vm_page_remove_xbusy(fs->m);
|
|
vm_page_replace(fs->m, fs->first_object, fs->first_pindex,
|
|
fs->first_m);
|
|
vm_page_dirty(fs->m);
|
|
#if VM_NRESERVLEVEL > 0
|
|
/*
|
|
* Rename the reservation.
|
|
*/
|
|
vm_reserv_rename(fs->m, fs->first_object, fs->object,
|
|
OFF_TO_IDX(fs->first_object->backing_object_offset));
|
|
#endif
|
|
VM_OBJECT_WUNLOCK(fs->object);
|
|
VM_OBJECT_WUNLOCK(fs->first_object);
|
|
fs->first_m = fs->m;
|
|
fs->m = NULL;
|
|
VM_CNT_INC(v_cow_optim);
|
|
} else {
|
|
if (is_first_object_locked)
|
|
VM_OBJECT_WUNLOCK(fs->first_object);
|
|
/*
|
|
* Oh, well, lets copy it.
|
|
*/
|
|
pmap_copy_page(fs->m, fs->first_m);
|
|
vm_page_valid(fs->first_m);
|
|
if (fs->wired && (fs->fault_flags & VM_FAULT_WIRE) == 0) {
|
|
vm_page_wire(fs->first_m);
|
|
vm_page_unwire(fs->m, PQ_INACTIVE);
|
|
}
|
|
/*
|
|
* Save the cow page to be released after
|
|
* pmap_enter is complete.
|
|
*/
|
|
fs->m_cow = fs->m;
|
|
fs->m = NULL;
|
|
|
|
/*
|
|
* Typically, the shadow object is either private to this
|
|
* address space (OBJ_ONEMAPPING) or its pages are read only.
|
|
* In the highly unusual case where the pages of a shadow object
|
|
* are read/write shared between this and other address spaces,
|
|
* we need to ensure that any pmap-level mappings to the
|
|
* original, copy-on-write page from the backing object are
|
|
* removed from those other address spaces.
|
|
*
|
|
* The flag check is racy, but this is tolerable: if
|
|
* OBJ_ONEMAPPING is cleared after the check, the busy state
|
|
* ensures that new mappings of m_cow can't be created.
|
|
* pmap_enter() will replace an existing mapping in the current
|
|
* address space. If OBJ_ONEMAPPING is set after the check,
|
|
* removing mappings will at worse trigger some unnecessary page
|
|
* faults.
|
|
*/
|
|
vm_page_assert_xbusied(fs->m_cow);
|
|
if ((fs->first_object->flags & OBJ_ONEMAPPING) == 0)
|
|
pmap_remove_all(fs->m_cow);
|
|
}
|
|
|
|
vm_object_pip_wakeup(fs->object);
|
|
|
|
/*
|
|
* Only use the new page below...
|
|
*/
|
|
fs->object = fs->first_object;
|
|
fs->pindex = fs->first_pindex;
|
|
fs->m = fs->first_m;
|
|
VM_CNT_INC(v_cow_faults);
|
|
curthread->td_cow++;
|
|
}
|
|
|
|
static enum fault_next_status
|
|
vm_fault_next(struct faultstate *fs)
|
|
{
|
|
vm_object_t next_object;
|
|
|
|
if (fs->object == fs->first_object || !fs->can_read_lock)
|
|
VM_OBJECT_ASSERT_WLOCKED(fs->object);
|
|
else
|
|
VM_OBJECT_ASSERT_LOCKED(fs->object);
|
|
|
|
/*
|
|
* The requested page does not exist at this object/
|
|
* offset. Remove the invalid page from the object,
|
|
* waking up anyone waiting for it, and continue on to
|
|
* the next object. However, if this is the top-level
|
|
* object, we must leave the busy page in place to
|
|
* prevent another process from rushing past us, and
|
|
* inserting the page in that object at the same time
|
|
* that we are.
|
|
*/
|
|
if (fs->object == fs->first_object) {
|
|
fs->first_m = fs->m;
|
|
fs->m = NULL;
|
|
} else if (fs->m != NULL) {
|
|
if (!vm_fault_object_ensure_wlocked(fs)) {
|
|
fs->can_read_lock = false;
|
|
vm_fault_unlock_and_deallocate(fs);
|
|
return (FAULT_NEXT_RESTART);
|
|
}
|
|
vm_fault_page_free(&fs->m);
|
|
}
|
|
|
|
/*
|
|
* Move on to the next object. Lock the next object before
|
|
* unlocking the current one.
|
|
*/
|
|
next_object = fs->object->backing_object;
|
|
if (next_object == NULL)
|
|
return (FAULT_NEXT_NOOBJ);
|
|
MPASS(fs->first_m != NULL);
|
|
KASSERT(fs->object != next_object, ("object loop %p", next_object));
|
|
if (fs->can_read_lock)
|
|
VM_OBJECT_RLOCK(next_object);
|
|
else
|
|
VM_OBJECT_WLOCK(next_object);
|
|
vm_object_pip_add(next_object, 1);
|
|
if (fs->object != fs->first_object)
|
|
vm_object_pip_wakeup(fs->object);
|
|
fs->pindex += OFF_TO_IDX(fs->object->backing_object_offset);
|
|
VM_OBJECT_UNLOCK(fs->object);
|
|
fs->object = next_object;
|
|
|
|
return (FAULT_NEXT_GOTOBJ);
|
|
}
|
|
|
|
static void
|
|
vm_fault_zerofill(struct faultstate *fs)
|
|
{
|
|
|
|
/*
|
|
* 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);
|
|
fs->object = fs->first_object;
|
|
fs->pindex = fs->first_pindex;
|
|
}
|
|
MPASS(fs->first_m != NULL);
|
|
MPASS(fs->m == NULL);
|
|
fs->m = fs->first_m;
|
|
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 {
|
|
VM_CNT_INC(v_ozfod);
|
|
}
|
|
VM_CNT_INC(v_zfod);
|
|
vm_page_valid(fs->m);
|
|
}
|
|
|
|
/*
|
|
* Initiate page fault after timeout. Returns true if caller should
|
|
* do vm_waitpfault() after the call.
|
|
*/
|
|
static bool
|
|
vm_fault_allocate_oom(struct faultstate *fs)
|
|
{
|
|
struct timeval now;
|
|
|
|
vm_fault_unlock_and_deallocate(fs);
|
|
if (vm_pfault_oom_attempts < 0)
|
|
return (true);
|
|
if (!fs->oom_started) {
|
|
fs->oom_started = true;
|
|
getmicrotime(&fs->oom_start_time);
|
|
return (true);
|
|
}
|
|
|
|
getmicrotime(&now);
|
|
timevalsub(&now, &fs->oom_start_time);
|
|
if (now.tv_sec < vm_pfault_oom_attempts * vm_pfault_oom_wait)
|
|
return (true);
|
|
|
|
if (bootverbose)
|
|
printf(
|
|
"proc %d (%s) failed to alloc page on fault, starting OOM\n",
|
|
curproc->p_pid, curproc->p_comm);
|
|
vm_pageout_oom(VM_OOM_MEM_PF);
|
|
fs->oom_started = false;
|
|
return (false);
|
|
}
|
|
|
|
/*
|
|
* Allocate a page directly or via the object populate method.
|
|
*/
|
|
static enum fault_status
|
|
vm_fault_allocate(struct faultstate *fs)
|
|
{
|
|
struct domainset *dset;
|
|
enum fault_status res;
|
|
|
|
if ((fs->object->flags & OBJ_SIZEVNLOCK) != 0) {
|
|
res = vm_fault_lock_vnode(fs, true);
|
|
MPASS(res == FAULT_CONTINUE || res == FAULT_RESTART);
|
|
if (res == FAULT_RESTART)
|
|
return (res);
|
|
}
|
|
|
|
if (fs->pindex >= fs->object->size) {
|
|
vm_fault_unlock_and_deallocate(fs);
|
|
return (FAULT_OUT_OF_BOUNDS);
|
|
}
|
|
|
|
if (fs->object == fs->first_object &&
|
|
(fs->first_object->flags & OBJ_POPULATE) != 0 &&
|
|
fs->first_object->shadow_count == 0) {
|
|
res = vm_fault_populate(fs);
|
|
switch (res) {
|
|
case FAULT_SUCCESS:
|
|
case FAULT_FAILURE:
|
|
case FAULT_RESTART:
|
|
vm_fault_unlock_and_deallocate(fs);
|
|
return (res);
|
|
case FAULT_CONTINUE:
|
|
/*
|
|
* Pager's populate() method
|
|
* returned VM_PAGER_BAD.
|
|
*/
|
|
break;
|
|
default:
|
|
panic("inconsistent return codes");
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate a new page for this object/offset pair.
|
|
*
|
|
* If the process has a fatal signal pending, prioritize the allocation
|
|
* with the expectation that the process will exit shortly and free some
|
|
* pages. In particular, the signal may have been posted by the page
|
|
* daemon in an attempt to resolve an out-of-memory condition.
|
|
*
|
|
* The unlocked read of the p_flag is harmless. At worst, the P_KILLED
|
|
* might be not observed here, and allocation fails, causing a restart
|
|
* and new reading of the p_flag.
|
|
*/
|
|
dset = fs->object->domain.dr_policy;
|
|
if (dset == NULL)
|
|
dset = curthread->td_domain.dr_policy;
|
|
if (!vm_page_count_severe_set(&dset->ds_mask) || P_KILLED(curproc)) {
|
|
#if VM_NRESERVLEVEL > 0
|
|
vm_object_color(fs->object, atop(fs->vaddr) - fs->pindex);
|
|
#endif
|
|
if (!vm_pager_can_alloc_page(fs->object, fs->pindex)) {
|
|
vm_fault_unlock_and_deallocate(fs);
|
|
return (FAULT_FAILURE);
|
|
}
|
|
fs->m = vm_page_alloc(fs->object, fs->pindex,
|
|
P_KILLED(curproc) ? VM_ALLOC_SYSTEM : 0);
|
|
}
|
|
if (fs->m == NULL) {
|
|
if (vm_fault_allocate_oom(fs))
|
|
vm_waitpfault(dset, vm_pfault_oom_wait * hz);
|
|
return (FAULT_RESTART);
|
|
}
|
|
fs->oom_started = false;
|
|
|
|
return (FAULT_CONTINUE);
|
|
}
|
|
|
|
/*
|
|
* Call the pager to retrieve the page if there is a chance
|
|
* that the pager has it, and potentially retrieve additional
|
|
* pages at the same time.
|
|
*/
|
|
static enum fault_status
|
|
vm_fault_getpages(struct faultstate *fs, int *behindp, int *aheadp)
|
|
{
|
|
vm_offset_t e_end, e_start;
|
|
int ahead, behind, cluster_offset, rv;
|
|
enum fault_status status;
|
|
u_char behavior;
|
|
|
|
/*
|
|
* Prepare for unlocking the map. Save the map
|
|
* entry's start and end addresses, which are used to
|
|
* optimize the size of the pager operation below.
|
|
* Even if the map entry's addresses change after
|
|
* unlocking the map, using the saved addresses is
|
|
* safe.
|
|
*/
|
|
e_start = fs->entry->start;
|
|
e_end = fs->entry->end;
|
|
behavior = vm_map_entry_behavior(fs->entry);
|
|
|
|
/*
|
|
* If the pager for the current object might have
|
|
* the page, then determine the number of additional
|
|
* pages to read and potentially reprioritize
|
|
* previously read pages for earlier reclamation.
|
|
* These operations should only be performed once per
|
|
* page fault. Even if the current pager doesn't
|
|
* have the page, the number of additional pages to
|
|
* read will apply to subsequent objects in the
|
|
* shadow chain.
|
|
*/
|
|
if (fs->nera == -1 && !P_KILLED(curproc))
|
|
fs->nera = vm_fault_readahead(fs);
|
|
|
|
/*
|
|
* Release the map lock before locking the vnode or
|
|
* sleeping in the pager. (If the current object has
|
|
* a shadow, then an earlier iteration of this loop
|
|
* may have already unlocked the map.)
|
|
*/
|
|
vm_fault_unlock_map(fs);
|
|
|
|
status = vm_fault_lock_vnode(fs, false);
|
|
MPASS(status == FAULT_CONTINUE || status == FAULT_RESTART);
|
|
if (status == FAULT_RESTART)
|
|
return (status);
|
|
KASSERT(fs->vp == NULL || !fs->map->system_map,
|
|
("vm_fault: vnode-backed object mapped by system map"));
|
|
|
|
/*
|
|
* Page in the requested page and hint the pager,
|
|
* that it may bring up surrounding pages.
|
|
*/
|
|
if (fs->nera == -1 || behavior == MAP_ENTRY_BEHAV_RANDOM ||
|
|
P_KILLED(curproc)) {
|
|
behind = 0;
|
|
ahead = 0;
|
|
} else {
|
|
/* Is this a sequential fault? */
|
|
if (fs->nera > 0) {
|
|
behind = 0;
|
|
ahead = fs->nera;
|
|
} else {
|
|
/*
|
|
* Request a cluster of pages that is
|
|
* aligned to a VM_FAULT_READ_DEFAULT
|
|
* page offset boundary within the
|
|
* object. Alignment to a page offset
|
|
* boundary is more likely to coincide
|
|
* with the underlying file system
|
|
* block than alignment to a virtual
|
|
* address boundary.
|
|
*/
|
|
cluster_offset = fs->pindex % VM_FAULT_READ_DEFAULT;
|
|
behind = ulmin(cluster_offset,
|
|
atop(fs->vaddr - e_start));
|
|
ahead = VM_FAULT_READ_DEFAULT - 1 - cluster_offset;
|
|
}
|
|
ahead = ulmin(ahead, atop(e_end - fs->vaddr) - 1);
|
|
}
|
|
*behindp = behind;
|
|
*aheadp = ahead;
|
|
rv = vm_pager_get_pages(fs->object, &fs->m, 1, behindp, aheadp);
|
|
if (rv == VM_PAGER_OK)
|
|
return (FAULT_HARD);
|
|
if (rv == VM_PAGER_ERROR)
|
|
printf("vm_fault: pager read error, pid %d (%s)\n",
|
|
curproc->p_pid, curproc->p_comm);
|
|
/*
|
|
* If an I/O error occurred or the requested page was
|
|
* outside the range of the pager, clean up and return
|
|
* an error.
|
|
*/
|
|
if (rv == VM_PAGER_ERROR || rv == VM_PAGER_BAD) {
|
|
VM_OBJECT_WLOCK(fs->object);
|
|
vm_fault_page_free(&fs->m);
|
|
vm_fault_unlock_and_deallocate(fs);
|
|
return (FAULT_OUT_OF_BOUNDS);
|
|
}
|
|
KASSERT(rv == VM_PAGER_FAIL,
|
|
("%s: unexpected pager error %d", __func__, rv));
|
|
return (FAULT_CONTINUE);
|
|
}
|
|
|
|
/*
|
|
* Wait/Retry if the page is busy. We have to do this if the page is
|
|
* either exclusive or shared busy because the vm_pager may be using
|
|
* read busy for pageouts (and even pageins if it is the vnode pager),
|
|
* and we could end up trying to pagein and pageout the same page
|
|
* simultaneously.
|
|
*
|
|
* We can theoretically allow the busy case on a read fault if the page
|
|
* is marked valid, but since such pages are typically already pmap'd,
|
|
* putting that special case in might be more effort then it is worth.
|
|
* We cannot under any circumstances mess around with a shared busied
|
|
* page except, perhaps, to pmap it.
|
|
*/
|
|
static void
|
|
vm_fault_busy_sleep(struct faultstate *fs)
|
|
{
|
|
/*
|
|
* Reference the page before unlocking and
|
|
* sleeping so that the page daemon is less
|
|
* likely to reclaim it.
|
|
*/
|
|
vm_page_aflag_set(fs->m, PGA_REFERENCED);
|
|
if (fs->object != fs->first_object) {
|
|
vm_fault_page_release(&fs->first_m);
|
|
vm_object_pip_wakeup(fs->first_object);
|
|
}
|
|
vm_object_pip_wakeup(fs->object);
|
|
vm_fault_unlock_map(fs);
|
|
if (fs->m != vm_page_lookup(fs->object, fs->pindex) ||
|
|
!vm_page_busy_sleep(fs->m, "vmpfw", 0))
|
|
VM_OBJECT_UNLOCK(fs->object);
|
|
VM_CNT_INC(v_intrans);
|
|
vm_object_deallocate(fs->first_object);
|
|
}
|
|
|
|
/*
|
|
* Handle page lookup, populate, allocate, page-in for the current
|
|
* object.
|
|
*
|
|
* The object is locked on entry and will remain locked with a return
|
|
* code of FAULT_CONTINUE so that fault may follow the shadow chain.
|
|
* Otherwise, the object will be unlocked upon return.
|
|
*/
|
|
static enum fault_status
|
|
vm_fault_object(struct faultstate *fs, int *behindp, int *aheadp)
|
|
{
|
|
enum fault_status res;
|
|
bool dead;
|
|
|
|
if (fs->object == fs->first_object || !fs->can_read_lock)
|
|
VM_OBJECT_ASSERT_WLOCKED(fs->object);
|
|
else
|
|
VM_OBJECT_ASSERT_LOCKED(fs->object);
|
|
|
|
/*
|
|
* If the object is marked for imminent termination, we retry
|
|
* here, since the collapse pass has raced with us. Otherwise,
|
|
* if we see terminally dead object, return fail.
|
|
*/
|
|
if ((fs->object->flags & OBJ_DEAD) != 0) {
|
|
dead = fs->object->type == OBJT_DEAD;
|
|
vm_fault_unlock_and_deallocate(fs);
|
|
if (dead)
|
|
return (FAULT_PROTECTION_FAILURE);
|
|
pause("vmf_de", 1);
|
|
return (FAULT_RESTART);
|
|
}
|
|
|
|
/*
|
|
* See if the page is resident.
|
|
*/
|
|
fs->m = vm_page_lookup(fs->object, fs->pindex);
|
|
if (fs->m != NULL) {
|
|
if (!vm_page_tryxbusy(fs->m)) {
|
|
vm_fault_busy_sleep(fs);
|
|
return (FAULT_RESTART);
|
|
}
|
|
|
|
/*
|
|
* The page is marked busy for other processes and the
|
|
* pagedaemon. If it is still completely valid we are
|
|
* done.
|
|
*/
|
|
if (vm_page_all_valid(fs->m)) {
|
|
VM_OBJECT_UNLOCK(fs->object);
|
|
return (FAULT_SOFT);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Page is not resident. If the pager might contain the page
|
|
* or this is the beginning of the search, allocate a new
|
|
* page.
|
|
*/
|
|
if (fs->m == NULL && (vm_fault_object_needs_getpages(fs->object) ||
|
|
fs->object == fs->first_object)) {
|
|
if (!vm_fault_object_ensure_wlocked(fs)) {
|
|
fs->can_read_lock = false;
|
|
vm_fault_unlock_and_deallocate(fs);
|
|
return (FAULT_RESTART);
|
|
}
|
|
res = vm_fault_allocate(fs);
|
|
if (res != FAULT_CONTINUE)
|
|
return (res);
|
|
}
|
|
|
|
/*
|
|
* Check to see if the pager can possibly satisfy this fault.
|
|
* If not, skip to the next object without dropping the lock to
|
|
* preserve atomicity of shadow faults.
|
|
*/
|
|
if (vm_fault_object_needs_getpages(fs->object)) {
|
|
/*
|
|
* At this point, we have either allocated a new page
|
|
* or found an existing page that is only partially
|
|
* valid.
|
|
*
|
|
* We hold a reference on the current object and the
|
|
* page is exclusive busied. The exclusive busy
|
|
* prevents simultaneous faults and collapses while
|
|
* the object lock is dropped.
|
|
*/
|
|
VM_OBJECT_UNLOCK(fs->object);
|
|
res = vm_fault_getpages(fs, behindp, aheadp);
|
|
if (res == FAULT_CONTINUE)
|
|
VM_OBJECT_WLOCK(fs->object);
|
|
} else {
|
|
res = FAULT_CONTINUE;
|
|
}
|
|
return (res);
|
|
}
|
|
|
|
int
|
|
vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
|
|
int fault_flags, vm_page_t *m_hold)
|
|
{
|
|
struct faultstate fs;
|
|
int ahead, behind, faultcount, rv;
|
|
enum fault_status res;
|
|
enum fault_next_status res_next;
|
|
bool hardfault;
|
|
|
|
VM_CNT_INC(v_vm_faults);
|
|
|
|
if ((curthread->td_pflags & TDP_NOFAULTING) != 0)
|
|
return (KERN_PROTECTION_FAILURE);
|
|
|
|
fs.vp = NULL;
|
|
fs.vaddr = vaddr;
|
|
fs.m_hold = m_hold;
|
|
fs.fault_flags = fault_flags;
|
|
fs.map = map;
|
|
fs.lookup_still_valid = false;
|
|
fs.oom_started = false;
|
|
fs.nera = -1;
|
|
fs.can_read_lock = true;
|
|
faultcount = 0;
|
|
hardfault = false;
|
|
|
|
RetryFault:
|
|
fs.fault_type = fault_type;
|
|
|
|
/*
|
|
* Find the backing store object and offset into it to begin the
|
|
* search.
|
|
*/
|
|
rv = vm_fault_lookup(&fs);
|
|
if (rv != KERN_SUCCESS) {
|
|
if (rv == KERN_RESOURCE_SHORTAGE)
|
|
goto RetryFault;
|
|
return (rv);
|
|
}
|
|
|
|
/*
|
|
* Try to avoid lock contention on the top-level object through
|
|
* special-case handling of some types of page faults, specifically,
|
|
* those that are mapping an existing page from the top-level object.
|
|
* Under this condition, a read lock on the object suffices, allowing
|
|
* multiple page faults of a similar type to run in parallel.
|
|
*/
|
|
if (fs.vp == NULL /* avoid locked vnode leak */ &&
|
|
(fs.entry->eflags & MAP_ENTRY_SPLIT_BOUNDARY_MASK) == 0 &&
|
|
(fs.fault_flags & (VM_FAULT_WIRE | VM_FAULT_DIRTY)) == 0) {
|
|
res = vm_fault_soft_fast(&fs);
|
|
if (res == FAULT_SUCCESS) {
|
|
VM_OBJECT_ASSERT_UNLOCKED(fs.first_object);
|
|
return (KERN_SUCCESS);
|
|
}
|
|
VM_OBJECT_ASSERT_WLOCKED(fs.first_object);
|
|
} else {
|
|
VM_OBJECT_WLOCK(fs.first_object);
|
|
}
|
|
|
|
/*
|
|
* Make a reference to this object to prevent its disposal while we
|
|
* are messing with it. Once we have the reference, the map is free
|
|
* to be diddled. Since objects reference their shadows (and copies),
|
|
* they will stay around as well.
|
|
*
|
|
* Bump the paging-in-progress count to prevent size changes (e.g.
|
|
* truncation operations) during I/O.
|
|
*/
|
|
vm_object_reference_locked(fs.first_object);
|
|
vm_object_pip_add(fs.first_object, 1);
|
|
|
|
fs.m_cow = fs.m = fs.first_m = NULL;
|
|
|
|
/*
|
|
* Search for the page at object/offset.
|
|
*/
|
|
fs.object = fs.first_object;
|
|
fs.pindex = fs.first_pindex;
|
|
|
|
if ((fs.entry->eflags & MAP_ENTRY_SPLIT_BOUNDARY_MASK) != 0) {
|
|
res = vm_fault_allocate(&fs);
|
|
switch (res) {
|
|
case FAULT_RESTART:
|
|
goto RetryFault;
|
|
case FAULT_SUCCESS:
|
|
return (KERN_SUCCESS);
|
|
case FAULT_FAILURE:
|
|
return (KERN_FAILURE);
|
|
case FAULT_OUT_OF_BOUNDS:
|
|
return (KERN_OUT_OF_BOUNDS);
|
|
case FAULT_CONTINUE:
|
|
break;
|
|
default:
|
|
panic("vm_fault: Unhandled status %d", res);
|
|
}
|
|
}
|
|
|
|
while (TRUE) {
|
|
KASSERT(fs.m == NULL,
|
|
("page still set %p at loop start", fs.m));
|
|
|
|
res = vm_fault_object(&fs, &behind, &ahead);
|
|
switch (res) {
|
|
case FAULT_SOFT:
|
|
goto found;
|
|
case FAULT_HARD:
|
|
faultcount = behind + 1 + ahead;
|
|
hardfault = true;
|
|
goto found;
|
|
case FAULT_RESTART:
|
|
goto RetryFault;
|
|
case FAULT_SUCCESS:
|
|
return (KERN_SUCCESS);
|
|
case FAULT_FAILURE:
|
|
return (KERN_FAILURE);
|
|
case FAULT_OUT_OF_BOUNDS:
|
|
return (KERN_OUT_OF_BOUNDS);
|
|
case FAULT_PROTECTION_FAILURE:
|
|
return (KERN_PROTECTION_FAILURE);
|
|
case FAULT_CONTINUE:
|
|
break;
|
|
default:
|
|
panic("vm_fault: Unhandled status %d", res);
|
|
}
|
|
|
|
/*
|
|
* The page was not found in the current object. Try to
|
|
* traverse into a backing object or zero fill if none is
|
|
* found.
|
|
*/
|
|
res_next = vm_fault_next(&fs);
|
|
if (res_next == FAULT_NEXT_RESTART)
|
|
goto RetryFault;
|
|
else if (res_next == FAULT_NEXT_GOTOBJ)
|
|
continue;
|
|
MPASS(res_next == FAULT_NEXT_NOOBJ);
|
|
if ((fs.fault_flags & VM_FAULT_NOFILL) != 0) {
|
|
if (fs.first_object == fs.object)
|
|
vm_fault_page_free(&fs.first_m);
|
|
vm_fault_unlock_and_deallocate(&fs);
|
|
return (KERN_OUT_OF_BOUNDS);
|
|
}
|
|
VM_OBJECT_UNLOCK(fs.object);
|
|
vm_fault_zerofill(&fs);
|
|
/* Don't try to prefault neighboring pages. */
|
|
faultcount = 1;
|
|
break;
|
|
}
|
|
|
|
found:
|
|
/*
|
|
* A valid page has been found and exclusively busied. The
|
|
* object lock must no longer be held.
|
|
*/
|
|
vm_page_assert_xbusied(fs.m);
|
|
VM_OBJECT_ASSERT_UNLOCKED(fs.object);
|
|
|
|
/*
|
|
* 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 ((fs.fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) {
|
|
vm_fault_cow(&fs);
|
|
/*
|
|
* We only try to prefault read-only mappings to the
|
|
* neighboring pages when this copy-on-write fault is
|
|
* a hard fault. In other cases, trying to prefault
|
|
* is typically wasted effort.
|
|
*/
|
|
if (faultcount == 0)
|
|
faultcount = 1;
|
|
|
|
} else {
|
|
fs.prot &= ~VM_PROT_WRITE;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We must verify that the maps have not changed since our last
|
|
* lookup.
|
|
*/
|
|
if (!fs.lookup_still_valid) {
|
|
rv = vm_fault_relookup(&fs);
|
|
if (rv != KERN_SUCCESS) {
|
|
vm_fault_deallocate(&fs);
|
|
if (rv == KERN_RESTART)
|
|
goto RetryFault;
|
|
return (rv);
|
|
}
|
|
}
|
|
VM_OBJECT_ASSERT_UNLOCKED(fs.object);
|
|
|
|
/*
|
|
* If the page was filled by a pager, save the virtual address that
|
|
* should be faulted on next under a sequential access pattern to the
|
|
* map entry. A read lock on the map suffices to update this address
|
|
* safely.
|
|
*/
|
|
if (hardfault)
|
|
fs.entry->next_read = vaddr + ptoa(ahead) + PAGE_SIZE;
|
|
|
|
/*
|
|
* Page must be completely valid or it is not fit to
|
|
* map into user space. vm_pager_get_pages() ensures this.
|
|
*/
|
|
vm_page_assert_xbusied(fs.m);
|
|
KASSERT(vm_page_all_valid(fs.m),
|
|
("vm_fault: page %p partially invalid", fs.m));
|
|
|
|
vm_fault_dirty(&fs, fs.m);
|
|
|
|
/*
|
|
* 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, fs.m, fs.prot,
|
|
fs.fault_type | (fs.wired ? PMAP_ENTER_WIRED : 0), 0);
|
|
if (faultcount != 1 && (fs.fault_flags & VM_FAULT_WIRE) == 0 &&
|
|
fs.wired == 0)
|
|
vm_fault_prefault(&fs, vaddr,
|
|
faultcount > 0 ? behind : PFBAK,
|
|
faultcount > 0 ? ahead : PFFOR, false);
|
|
|
|
/*
|
|
* If the page is not wired down, then put it where the pageout daemon
|
|
* can find it.
|
|
*/
|
|
if ((fs.fault_flags & VM_FAULT_WIRE) != 0)
|
|
vm_page_wire(fs.m);
|
|
else
|
|
vm_page_activate(fs.m);
|
|
if (fs.m_hold != NULL) {
|
|
(*fs.m_hold) = fs.m;
|
|
vm_page_wire(fs.m);
|
|
}
|
|
vm_page_xunbusy(fs.m);
|
|
fs.m = NULL;
|
|
|
|
/*
|
|
* Unlock everything, and return
|
|
*/
|
|
vm_fault_deallocate(&fs);
|
|
if (hardfault) {
|
|
VM_CNT_INC(v_io_faults);
|
|
curthread->td_ru.ru_majflt++;
|
|
#ifdef RACCT
|
|
if (racct_enable && fs.object->type == OBJT_VNODE) {
|
|
PROC_LOCK(curproc);
|
|
if ((fs.fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) {
|
|
racct_add_force(curproc, RACCT_WRITEBPS,
|
|
PAGE_SIZE + behind * PAGE_SIZE);
|
|
racct_add_force(curproc, RACCT_WRITEIOPS, 1);
|
|
} else {
|
|
racct_add_force(curproc, RACCT_READBPS,
|
|
PAGE_SIZE + ahead * PAGE_SIZE);
|
|
racct_add_force(curproc, RACCT_READIOPS, 1);
|
|
}
|
|
PROC_UNLOCK(curproc);
|
|
}
|
|
#endif
|
|
} else
|
|
curthread->td_ru.ru_minflt++;
|
|
|
|
return (KERN_SUCCESS);
|
|
}
|
|
|
|
/*
|
|
* Speed up the reclamation of pages that precede the faulting pindex within
|
|
* the first object of the shadow chain. Essentially, perform the equivalent
|
|
* to madvise(..., MADV_DONTNEED) on a large cluster of pages that precedes
|
|
* the faulting pindex by the cluster size when the pages read by vm_fault()
|
|
* cross a cluster-size boundary. The cluster size is the greater of the
|
|
* smallest superpage size and VM_FAULT_DONTNEED_MIN.
|
|
*
|
|
* When "fs->first_object" is a shadow object, the pages in the backing object
|
|
* that precede the faulting pindex are deactivated by vm_fault(). So, this
|
|
* function must only be concerned with pages in the first object.
|
|
*/
|
|
static void
|
|
vm_fault_dontneed(const struct faultstate *fs, vm_offset_t vaddr, int ahead)
|
|
{
|
|
vm_map_entry_t entry;
|
|
vm_object_t first_object;
|
|
vm_offset_t end, start;
|
|
vm_page_t m, m_next;
|
|
vm_pindex_t pend, pstart;
|
|
vm_size_t size;
|
|
|
|
VM_OBJECT_ASSERT_UNLOCKED(fs->object);
|
|
first_object = fs->first_object;
|
|
/* Neither fictitious nor unmanaged pages can be reclaimed. */
|
|
if ((first_object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0) {
|
|
VM_OBJECT_RLOCK(first_object);
|
|
size = VM_FAULT_DONTNEED_MIN;
|
|
if (MAXPAGESIZES > 1 && size < pagesizes[1])
|
|
size = pagesizes[1];
|
|
end = rounddown2(vaddr, size);
|
|
if (vaddr - end >= size - PAGE_SIZE - ptoa(ahead) &&
|
|
(entry = fs->entry)->start < end) {
|
|
if (end - entry->start < size)
|
|
start = entry->start;
|
|
else
|
|
start = end - size;
|
|
pmap_advise(fs->map->pmap, start, end, MADV_DONTNEED);
|
|
pstart = OFF_TO_IDX(entry->offset) + atop(start -
|
|
entry->start);
|
|
m_next = vm_page_find_least(first_object, pstart);
|
|
pend = OFF_TO_IDX(entry->offset) + atop(end -
|
|
entry->start);
|
|
while ((m = m_next) != NULL && m->pindex < pend) {
|
|
m_next = TAILQ_NEXT(m, listq);
|
|
if (!vm_page_all_valid(m) ||
|
|
vm_page_busied(m))
|
|
continue;
|
|
|
|
/*
|
|
* Don't clear PGA_REFERENCED, since it would
|
|
* likely represent a reference by a different
|
|
* process.
|
|
*
|
|
* Typically, at this point, prefetched pages
|
|
* are still in the inactive queue. Only
|
|
* pages that triggered page faults are in the
|
|
* active queue. The test for whether the page
|
|
* is in the inactive queue is racy; in the
|
|
* worst case we will requeue the page
|
|
* unnecessarily.
|
|
*/
|
|
if (!vm_page_inactive(m))
|
|
vm_page_deactivate(m);
|
|
}
|
|
}
|
|
VM_OBJECT_RUNLOCK(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 backward, int forward, bool obj_locked)
|
|
{
|
|
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 i;
|
|
|
|
pmap = fs->map->pmap;
|
|
if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace))
|
|
return;
|
|
|
|
entry = fs->entry;
|
|
|
|
if (addra < backward * PAGE_SIZE) {
|
|
starta = entry->start;
|
|
} else {
|
|
starta = addra - backward * PAGE_SIZE;
|
|
if (starta < entry->start)
|
|
starta = entry->start;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
if (!obj_locked)
|
|
VM_OBJECT_RLOCK(lobject);
|
|
while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
|
|
!vm_fault_object_needs_getpages(lobject) &&
|
|
(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);
|
|
if (!obj_locked || lobject != entry->object.vm_object)
|
|
VM_OBJECT_RUNLOCK(lobject);
|
|
lobject = backing_object;
|
|
}
|
|
if (m == NULL) {
|
|
if (!obj_locked || lobject != entry->object.vm_object)
|
|
VM_OBJECT_RUNLOCK(lobject);
|
|
break;
|
|
}
|
|
if (vm_page_all_valid(m) &&
|
|
(m->flags & PG_FICTITIOUS) == 0)
|
|
pmap_enter_quick(pmap, addr, m, entry->protection);
|
|
if (!obj_locked || lobject != entry->object.vm_object)
|
|
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);
|
|
|
|
if (!vm_map_range_valid(map, addr, end))
|
|
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.
|
|
*
|
|
* If vm_fault_disable_pagefaults() was called,
|
|
* i.e., TDP_NOFAULTING is set, we must not sleep nor
|
|
* acquire MD VM locks, which means we must not call
|
|
* vm_fault(). Some (out of tree) callers mark
|
|
* too wide a code area with vm_fault_disable_pagefaults()
|
|
* already, use the VM_PROT_QUICK_NOFAULT flag to request
|
|
* the proper behaviour explicitly.
|
|
*/
|
|
if ((prot & VM_PROT_QUICK_NOFAULT) != 0 &&
|
|
(curthread->td_pflags & TDP_NOFAULTING) != 0)
|
|
goto error;
|
|
for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE)
|
|
if (*mp == NULL && vm_fault(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_unwire(*mp, PQ_INACTIVE);
|
|
return (-1);
|
|
}
|
|
|
|
/*
|
|
* Routine:
|
|
* vm_fault_copy_entry
|
|
* Function:
|
|
* Create new 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 __unused,
|
|
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;
|
|
bool upgrade;
|
|
|
|
upgrade = src_entry == dst_entry;
|
|
KASSERT(upgrade || dst_entry->object.vm_object == NULL,
|
|
("vm_fault_copy_entry: vm_object not 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.
|
|
*/
|
|
access = prot = dst_entry->protection;
|
|
if (!upgrade)
|
|
access &= ~VM_PROT_WRITE;
|
|
|
|
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_anon(atop(dst_entry->end -
|
|
dst_entry->start), NULL, NULL, 0);
|
|
#if VM_NRESERVLEVEL > 0
|
|
dst_object->flags |= OBJ_COLORED;
|
|
dst_object->pg_color = atop(dst_entry->start);
|
|
#endif
|
|
dst_object->domain = src_object->domain;
|
|
dst_object->charge = dst_entry->end - dst_entry->start;
|
|
|
|
dst_entry->object.vm_object = dst_object;
|
|
dst_entry->offset = 0;
|
|
dst_entry->eflags &= ~MAP_ENTRY_VN_EXEC;
|
|
}
|
|
|
|
VM_OBJECT_WLOCK(dst_object);
|
|
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->flags & OBJ_SWAP) != 0 &&
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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 doesn't 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(dst_object);
|
|
VM_OBJECT_WLOCK(dst_object);
|
|
goto again;
|
|
}
|
|
|
|
/*
|
|
* See the comment in vm_fault_cow().
|
|
*/
|
|
if (src_object == dst_object &&
|
|
(object->flags & OBJ_ONEMAPPING) == 0)
|
|
pmap_remove_all(src_m);
|
|
pmap_copy_page(src_m, dst_m);
|
|
|
|
/*
|
|
* The object lock does not guarantee that "src_m" will
|
|
* transition from invalid to valid, but it does ensure
|
|
* that "src_m" will not transition from valid to
|
|
* invalid.
|
|
*/
|
|
dst_m->dirty = dst_m->valid = src_m->valid;
|
|
VM_OBJECT_RUNLOCK(object);
|
|
} else {
|
|
dst_m = src_m;
|
|
if (vm_page_busy_acquire(dst_m, VM_ALLOC_WAITFAIL) == 0)
|
|
goto again;
|
|
if (dst_m->pindex >= dst_object->size) {
|
|
/*
|
|
* We are upgrading. Index can occur
|
|
* out of bounds if the object type is
|
|
* vnode and the file was truncated.
|
|
*/
|
|
vm_page_xunbusy(dst_m);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*
|
|
* The page can be invalid if the user called
|
|
* msync(MS_INVALIDATE) or truncated the backing vnode
|
|
* or shared memory object. In this case, do not
|
|
* insert it into pmap, but still do the copy so that
|
|
* all copies of the wired map entry have similar
|
|
* backing pages.
|
|
*/
|
|
if (vm_page_all_valid(dst_m)) {
|
|
VM_OBJECT_WUNLOCK(dst_object);
|
|
pmap_enter(dst_map->pmap, vaddr, dst_m, prot,
|
|
access | (upgrade ? PMAP_ENTER_WIRED : 0), 0);
|
|
VM_OBJECT_WLOCK(dst_object);
|
|
}
|
|
|
|
/*
|
|
* Mark it no longer busy, and put it on the active list.
|
|
*/
|
|
if (upgrade) {
|
|
if (src_m != dst_m) {
|
|
vm_page_unwire(src_m, PQ_INACTIVE);
|
|
vm_page_wire(dst_m);
|
|
} else {
|
|
KASSERT(vm_page_wired(dst_m),
|
|
("dst_m %p is not wired", dst_m));
|
|
}
|
|
} else {
|
|
vm_page_activate(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);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|