Date: Fri, 22 Jan 1999 04:10:22 -0500 (EST) From: "John S. Dyson" <dyson@iquest.net> To: dillon@apollo.backplane.com (Matthew Dillon) Cc: dyson@iquest.net, hackers@FreeBSD.ORG Subject: Re: Error in vm_fault change (correct fix for problem posed) Message-ID: <199901220910.EAA00340@y.dyson.net> In-Reply-To: <199901220656.WAA48081@apollo.backplane.com> from Matthew Dillon at "Jan 21, 99 10:56:49 pm"
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Matthew Dillon said:
>
> The problem is that in a heavy paging situation, which can be
> brought about by a single memory-hogging process, OTHER
> process's pages can wind up in the cache very easily.
>
Attached is a rough copy of my current vm_fault (it is relative to earlier
this month in FreeBSD.) Note that it isn't optimum, but is CORRECT regarding
the problem that you posed (a hogging process.) It eats CPU, so needs some
work -- but should not be brain surgery. I don't have time to perfect it,
and this has too hard a limit, but works really well (under X especially :-)).
--
John | Never try to teach a pig to sing,
dyson@iquest.net | it makes one look stupid
jdyson@nc.com | and it irritates the pig.
--ELM916996222-326-0_
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/*
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
* Copyright (c) 1994 John S. Dyson
* All rights reserved.
* Copyright (c) 1994 David Greenman
* All rights reserved.
*
*
* This code is derived from software contributed to Berkeley by
* The Mach Operating System project at Carnegie-Mellon University.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94
*
*
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
* All rights reserved.
*
* Authors: Avadis Tevanian, Jr., Michael Wayne Young
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $Id: vm_fault.c,v 1.91 1998/11/25 07:40:49 dg Exp $
*/
/*
* Page fault handling module.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/resourcevar.h>
#include <sys/vmmeter.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_prot.h>
#include <sys/lock.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_kern.h>
#include <vm/vm_pager.h>
#include <vm/vnode_pager.h>
#include <vm/vm_extern.h>
static int vm_fault_additional_pages __P((vm_page_t, int,
int, vm_page_t *, int *));
#define VM_FAULT_READ_AHEAD 8
#define VM_FAULT_READ_BEHIND 7
#define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1)
struct faultstate {
vm_page_t m;
vm_object_t object;
vm_pindex_t pindex;
vm_page_t first_m;
vm_object_t first_object;
vm_pindex_t first_pindex;
vm_map_t map;
vm_map_entry_t entry;
int lookup_still_valid;
struct vnode *vp;
};
static void
release_page(struct faultstate *fs)
{
vm_page_wakeup(fs->m);
vm_page_deactivate(fs->m);
fs->m = NULL;
}
static void
unlock_map(struct faultstate *fs)
{
if (fs->lookup_still_valid) {
vm_map_lookup_done(fs->map, fs->entry);
fs->lookup_still_valid = FALSE;
}
}
static void
_unlock_things(struct faultstate *fs, int dealloc)
{
vm_object_pip_wakeup(fs->object);
if (fs->object != fs->first_object) {
vm_page_free(fs->first_m);
vm_object_pip_wakeup(fs->first_object);
fs->first_m = NULL;
}
if (dealloc) {
vm_object_deallocate(fs->first_object);
}
unlock_map(fs);
if (fs->vp != NULL) {
vput(fs->vp);
fs->vp = NULL;
}
}
#define unlock_things(fs) _unlock_things(fs, 0)
#define unlock_and_deallocate(fs) _unlock_things(fs, 1)
static void
_vm_page_limit(void)
{
struct proc *p = curproc;
quad_t limit, size;
if ((p->p_vmspace == NULL) || (p->p_flag & P_SYSTEM))
return;
#if 0
limit = qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur,
p->p_rlimit[RLIMIT_RSS].rlim_max);
#endif
limit = p->p_rlimit[RLIMIT_RSS].rlim_max;
size = p->p_vmspace->vm_pmap.pm_stats.resident_count * PAGE_SIZE;
if (limit >= 0 && size >= limit) {
vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map,
(vm_pindex_t)(limit >> PAGE_SHIFT) );
}
}
/*
* vm_fault:
*
* Handle a page fault occuring 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(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, int fault_flags)
{
vm_prot_t prot;
int result;
boolean_t wired;
int map_generation;
vm_page_t old_m;
vm_object_t next_object;
vm_page_t marray[VM_FAULT_READ];
int hardfault;
int faultcount;
struct faultstate fs;
cnt.v_vm_faults++; /* needs lock XXX */
hardfault = 0;
RetryFault:;
if ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min) {
_vm_page_limit();
}
fs.map = map;
/*
* Find the backing store object and offset into it to begin the
* search.
*/
if ((result = vm_map_lookup(&fs.map, vaddr,
fault_type, &fs.entry, &fs.first_object,
&fs.first_pindex, &prot, &wired)) != KERN_SUCCESS) {
if ((result != KERN_PROTECTION_FAILURE) ||
((fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE)) {
return result;
}
/*
* If we are user-wiring a r/w segment, and it is COW, then
* we need to do the COW operation. Note that we don't COW
* currently RO sections now, because it is NOT desirable
* to COW .text. We simply keep .text from ever being COW'ed
* and take the heat that one cannot debug wired .text sections.
*/
result = vm_map_lookup(&fs.map, vaddr,
VM_PROT_READ|VM_PROT_WRITE|VM_PROT_OVERRIDE_WRITE,
&fs.entry, &fs.first_object, &fs.first_pindex, &prot, &wired);
if (result != KERN_SUCCESS) {
return result;
}
/*
* If we don't COW now, on a user wire, the user will never
* be able to write to the mapping. If we don't make this
* restriction, the bookkeeping would be nearly impossible.
*/
if ((fs.entry->protection & VM_PROT_WRITE) == 0)
fs.entry->max_protection &= ~VM_PROT_WRITE;
}
map_generation = fs.map->timestamp;
if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
panic("vm_fault: fault on nofault entry, addr: %lx",
(u_long)vaddr);
}
/*
* 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.
*/
vm_object_reference(fs.first_object);
vm_object_pip_add(fs.first_object, 1);
fs.vp = vnode_pager_lock(fs.first_object);
if ((fault_type & VM_PROT_WRITE) &&
(fs.first_object->type == OBJT_VNODE)) {
vm_freeze_copyopts(fs.first_object,
fs.first_pindex, fs.first_pindex + 1);
}
fs.lookup_still_valid = TRUE;
if (wired)
fault_type = prot;
fs.first_m = NULL;
/*
* Search for the page at object/offset.
*/
fs.object = fs.first_object;
fs.pindex = fs.first_pindex;
/*
* See whether this page is resident
*/
while (TRUE) {
if (fs.object->flags & OBJ_DEAD) {
unlock_and_deallocate(&fs);
return (KERN_PROTECTION_FAILURE);
}
fs.m = vm_page_lookup(fs.object, fs.pindex);
if (fs.m != NULL) {
int queue, s;
/*
* If the page is being brought in, wait for it and
* then retry.
*/
if ((fs.m->flags & PG_BUSY) ||
(fs.m->busy &&
(fs.m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL)) {
unlock_things(&fs);
s = splvm();
if ((fs.m->flags & PG_BUSY) ||
(fs.m->busy &&
(fs.m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL)) {
vm_page_flag_set(fs.m, PG_WANTED | PG_REFERENCED);
cnt.v_intrans++;
tsleep(fs.m, PSWP, "vmpfw", 0);
}
splx(s);
vm_object_deallocate(fs.first_object);
goto RetryFault;
}
queue = fs.m->queue;
s = splvm();
vm_page_unqueue_nowakeup(fs.m);
splx(s);
/*
* Mark page busy for other processes, and the pagedaemon.
*/
if (((queue - fs.m->pc) == PQ_CACHE) &&
(cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min) {
vm_page_activate(fs.m);
unlock_and_deallocate(&fs);
VM_WAIT;
goto RetryFault;
}
vm_page_busy(fs.m);
if (((fs.m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) &&
fs.m->object != kernel_object && fs.m->object != kmem_object) {
goto readrest;
}
break;
}
if (((fs.object->type != OBJT_DEFAULT) &&
(((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired))
|| (fs.object == fs.first_object)) {
if (fs.pindex >= fs.object->size) {
unlock_and_deallocate(&fs);
return (KERN_PROTECTION_FAILURE);
}
/*
* Allocate a new page for this object/offset pair.
*/
fs.m = vm_page_alloc(fs.object, fs.pindex,
(fs.vp || fs.object->backing_object)? VM_ALLOC_NORMAL: VM_ALLOC_ZERO);
if (fs.m == NULL) {
unlock_and_deallocate(&fs);
VM_WAIT;
goto RetryFault;
}
}
readrest:
if (fs.object->type != OBJT_DEFAULT &&
(((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired)) {
int rv;
int reqpage;
int ahead, behind;
if (fs.first_object->behavior == OBJ_RANDOM) {
ahead = 0;
behind = 0;
} else {
behind = (vaddr - fs.entry->start) >> PAGE_SHIFT;
if (behind > VM_FAULT_READ_BEHIND)
behind = VM_FAULT_READ_BEHIND;
ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1;
if (ahead > VM_FAULT_READ_AHEAD)
ahead = VM_FAULT_READ_AHEAD;
}
if ((fs.first_object->type != OBJT_DEVICE) &&
(fs.first_object->behavior == OBJ_SEQUENTIAL)) {
vm_pindex_t firstpindex, tmppindex;
if (fs.first_pindex <
2*(VM_FAULT_READ_BEHIND + VM_FAULT_READ_AHEAD + 1))
firstpindex = 0;
else
firstpindex = fs.first_pindex -
2*(VM_FAULT_READ_BEHIND + VM_FAULT_READ_AHEAD + 1);
for(tmppindex = fs.first_pindex - 1;
tmppindex >= firstpindex;
--tmppindex) {
vm_page_t mt;
mt = vm_page_lookup( fs.first_object, tmppindex);
if (mt == NULL || (mt->valid != VM_PAGE_BITS_ALL))
break;
if (mt->busy ||
(mt->flags & (PG_BUSY | PG_FICTITIOUS)) ||
mt->hold_count ||
mt->wire_count)
continue;
if (mt->dirty == 0)
vm_page_test_dirty(mt);
if (mt->dirty) {
vm_page_protect(mt, VM_PROT_NONE);
vm_page_deactivate(mt);
} else {
vm_page_cache(mt);
}
}
ahead += behind;
behind = 0;
}
/*
* 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.
*/
faultcount = vm_fault_additional_pages(
fs.m, behind, ahead, marray, &reqpage);
/*
* Call the pager to retrieve the data, if any, after
* releasing the lock on the map.
*/
unlock_map(&fs);
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;
}
/*
* 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_free(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_free(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);
fs.object = fs.first_object;
fs.pindex = fs.first_pindex;
fs.m = fs.first_m;
}
fs.first_m = NULL;
if ((fs.m->flags & PG_ZERO) == 0) {
vm_page_zero_fill(fs.m);
cnt.v_ozfod++;
}
cnt.v_zfod++;
break;
} else {
if (fs.object != fs.first_object) {
vm_object_pip_wakeup(fs.object);
}
fs.object = next_object;
vm_object_pip_add(fs.object, 1);
}
}
#if defined(DIAGNOSTIC)
if ((fs.m->flags & PG_BUSY) == 0)
panic("vm_fault: not busy after main loop");
#endif
/*
* PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
* is held.]
*/
old_m = fs.m; /* save page that would be copied */
/*
* 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_WRITE) {
/*
* 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.
*/
if (map_generation == fs.map->timestamp &&
/*
* Only one shadow object
*/
(fs.object->shadow_count == 1) &&
/*
* No COW refs, except us
*/
(fs.object->ref_count == 1) &&
/*
* Noone 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)) &&
/*
* We don't chase down the shadow chain
*/
(fs.object == fs.first_object->backing_object) &&
/*
* grab the lock if we need to
*/
(fs.lookup_still_valid ||
(((fs.entry->eflags & MAP_ENTRY_IS_A_MAP) == 0) &&
lockmgr(&fs.map->lock,
LK_EXCLUSIVE|LK_NOWAIT, (void *)0, curproc) == 0))) {
fs.lookup_still_valid = 1;
/*
* get rid of the unnecessary page
*/
vm_page_protect(fs.first_m, VM_PROT_NONE);
vm_page_free(fs.first_m);
fs.first_m = NULL;
/*
* grab the page and put it into the process'es object
*/
vm_page_rename(fs.m, fs.first_object, fs.first_pindex);
fs.first_m = fs.m;
fs.first_m->dirty = VM_PAGE_BITS_ALL;
vm_page_busy(fs.first_m);
fs.m = NULL;
cnt.v_cow_optim++;
} else {
/*
* Oh, well, lets copy it.
*/
vm_page_copy(fs.m, fs.first_m);
}
if (fs.m) {
/*
* We no longer need the old page or object.
*/
release_page(&fs);
}
vm_object_pip_wakeup(fs.object);
/*
* Only use the new page below...
*/
cnt.v_cow_faults++;
fs.m = fs.first_m;
fs.object = fs.first_object;
fs.pindex = fs.first_pindex;
} else {
prot &= ~VM_PROT_WRITE;
}
}
/*
* We must verify that the maps have not changed since our last
* lookup.
*/
if (!fs.lookup_still_valid &&
(fs.map->timestamp != map_generation)) {
vm_object_t retry_object;
vm_pindex_t retry_pindex;
vm_prot_t retry_prot;
/*
* Since map entries may be pageable, make sure we can take a
* page fault on them.
*/
/*
* To avoid trying to write_lock the map while another process
* has it read_locked (in vm_map_pageable), we do not try for
* write permission. If the page is still writable, we will
* get write permission. If it is not, or has been marked
* needs_copy, we enter the mapping without write permission,
* and will merely take another fault.
*/
result = vm_map_lookup(&fs.map, vaddr, fault_type & ~VM_PROT_WRITE,
&fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired);
map_generation = fs.map->timestamp;
/*
* If we don't need the page any longer, put it on the active
* 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);
return (result);
}
fs.lookup_still_valid = TRUE;
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;
}
/*
* Put this page into the physical map. We had to do the unlock above
* because pmap_enter may cause other faults. We don't put the page
* back on the active queue until later so that the page-out daemon
* won't find us (yet).
*/
if (prot & VM_PROT_WRITE) {
vm_page_flag_set(fs.m, PG_WRITEABLE);
vm_object_set_flag(fs.m->object,
OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
/*
* If the fault is a write, we know that this page is being
* written NOW. This will save on the pmap_is_modified() calls
* later.
*/
if (fault_flags & VM_FAULT_DIRTY) {
fs.m->dirty = VM_PAGE_BITS_ALL;
}
}
unlock_things(&fs);
fs.m->valid = VM_PAGE_BITS_ALL;
vm_page_flag_clear(fs.m, PG_ZERO);
pmap_enter(fs.map->pmap, vaddr, VM_PAGE_TO_PHYS(fs.m), prot, wired);
if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) {
pmap_prefault(fs.map->pmap, vaddr, fs.entry);
}
vm_page_flag_set(fs.m, PG_MAPPED|PG_REFERENCED);
if (fault_flags & VM_FAULT_HOLD)
vm_page_hold(fs.m);
/*
* If the page is not wired down, then put it where the pageout daemon
* can find it.
*/
if (fault_flags & VM_FAULT_WIRE_MASK) {
if (wired)
vm_page_wire(fs.m);
else
vm_page_unwire(fs.m, 1);
} else {
vm_page_activate(fs.m);
}
if (curproc && (curproc->p_flag & P_INMEM) && curproc->p_stats) {
if (hardfault) {
curproc->p_stats->p_ru.ru_majflt++;
} else {
curproc->p_stats->p_ru.ru_minflt++;
}
}
/*
* Unlock everything, and return
*/
vm_page_wakeup(fs.m);
vm_object_deallocate(fs.first_object);
return (KERN_SUCCESS);
}
/*
* vm_fault_wire:
*
* Wire down a range of virtual addresses in a map.
*/
int
vm_fault_wire(map, start, end)
vm_map_t map;
vm_offset_t start, end;
{
register vm_offset_t va;
register pmap_t pmap;
int rv;
pmap = vm_map_pmap(map);
/*
* Inform the physical mapping system that the range of addresses may
* not fault, so that page tables and such can be locked down as well.
*/
pmap_pageable(pmap, start, end, FALSE);
/*
* We simulate a fault to get the page and enter it in the physical
* map.
*/
for (va = start; va < end; va += PAGE_SIZE) {
rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE,
VM_FAULT_CHANGE_WIRING);
if (rv) {
if (va != start)
vm_fault_unwire(map, start, va);
return (rv);
}
}
return (KERN_SUCCESS);
}
/*
* vm_fault_user_wire:
*
* Wire down a range of virtual addresses in a map. This
* is for user mode though, so we only ask for read access
* on currently read only sections.
*/
int
vm_fault_user_wire(map, start, end)
vm_map_t map;
vm_offset_t start, end;
{
register vm_offset_t va;
register pmap_t pmap;
int rv;
pmap = vm_map_pmap(map);
/*
* Inform the physical mapping system that the range of addresses may
* not fault, so that page tables and such can be locked down as well.
*/
pmap_pageable(pmap, start, end, FALSE);
/*
* We simulate a fault to get the page and enter it in the physical
* map.
*/
for (va = start; va < end; va += PAGE_SIZE) {
rv = vm_fault(map, va, VM_PROT_READ, VM_FAULT_USER_WIRE);
if (rv) {
if (va != start)
vm_fault_unwire(map, start, va);
return (rv);
}
}
return (KERN_SUCCESS);
}
/*
* vm_fault_unwire:
*
* Unwire a range of virtual addresses in a map.
*/
void
vm_fault_unwire(map, start, end)
vm_map_t map;
vm_offset_t start, end;
{
register vm_offset_t va, pa;
register pmap_t pmap;
pmap = vm_map_pmap(map);
/*
* Since the pages are wired down, we must be able to get their
* mappings from the physical map system.
*/
for (va = start; va < end; va += PAGE_SIZE) {
pa = pmap_extract(pmap, va);
if (pa != (vm_offset_t) 0) {
pmap_change_wiring(pmap, va, FALSE);
vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1);
}
}
/*
* Inform the physical mapping system that the range of addresses may
* fault, so that page tables and such may be unwired themselves.
*/
pmap_pageable(pmap, start, end, TRUE);
}
/*
* Routine:
* vm_fault_copy_entry
* Function:
* Copy all of the pages from a wired-down map entry to another.
*
* 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(dst_map, src_map, dst_entry, src_entry)
vm_map_t dst_map;
vm_map_t src_map;
vm_map_entry_t dst_entry;
vm_map_entry_t src_entry;
{
vm_object_t dst_object;
vm_object_t src_object;
vm_ooffset_t dst_offset;
vm_ooffset_t src_offset;
vm_prot_t prot;
vm_offset_t vaddr;
vm_page_t dst_m;
vm_page_t src_m;
#ifdef lint
src_map++;
#endif /* lint */
src_object = src_entry->object.vm_object;
src_offset = src_entry->offset;
/*
* 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,
(vm_size_t) OFF_TO_IDX(dst_entry->end - dst_entry->start));
dst_entry->object.vm_object = dst_object;
dst_entry->offset = 0;
prot = dst_entry->max_protection;
/*
* Loop through all of the pages in the entry's range, copying each
* one from the source object (it should be there) to the destination
* object.
*/
for (vaddr = dst_entry->start, dst_offset = 0;
vaddr < dst_entry->end;
vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) {
/*
* Allocate a page in the destination object
*/
do {
dst_m = vm_page_alloc(dst_object,
OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL);
if (dst_m == NULL) {
VM_WAIT;
}
} while (dst_m == NULL);
/*
* Find the page in the source object, and copy it in.
* (Because the source is wired down, the page will be in
* memory.)
*/
src_m = vm_page_lookup(src_object,
OFF_TO_IDX(dst_offset + src_offset));
if (src_m == NULL)
panic("vm_fault_copy_wired: page missing");
vm_page_copy(src_m, dst_m);
/*
* Enter it in the pmap...
*/
vm_page_flag_clear(dst_m, PG_ZERO);
pmap_enter(dst_map->pmap, vaddr, VM_PAGE_TO_PHYS(dst_m),
prot, FALSE);
vm_page_flag_set(dst_m, PG_WRITEABLE|PG_MAPPED);
/*
* Mark it no longer busy, and put it on the active list.
*/
vm_page_activate(dst_m);
vm_page_wakeup(dst_m);
}
}
/*
* 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;
object = m->object;
pindex = m->pindex;
/*
* we don't fault-ahead for device pager
*/
if (object->type == OBJT_DEVICE) {
*reqpage = 0;
marray[0] = m;
return 1;
}
/*
* if the requested page is not available, then give up now
*/
if (!vm_pager_has_page(object,
OFF_TO_IDX(object->paging_offset) + 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;
}
/*
* try to do any readahead that we might have free pages for.
*/
if ((rahead + rbehind) >
((cnt.v_free_count + cnt.v_cache_count) - cnt.v_free_reserved)) {
vm_pageout_deficit += rahead + rbehind;
pagedaemon_wakeup();
marray[0] = m;
*reqpage = 0;
return 1;
}
/*
* scan backward for the read behind pages -- in memory
*/
if (pindex > 0) {
if (rbehind > pindex) {
rbehind = pindex;
startpindex = 0;
} else {
startpindex = pindex - rbehind;
}
for ( tpindex = pindex - 1; tpindex >= startpindex; tpindex -= 1) {
if (vm_page_lookup( object, tpindex)) {
startpindex = tpindex + 1;
break;
}
if (tpindex == 0)
break;
}
for(i = 0, tpindex = startpindex; tpindex < pindex; i++, tpindex++) {
rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
if (rtm == NULL) {
for (j = 0; j < i; j++) {
vm_page_free(marray[j]);
}
marray[0] = m;
*reqpage = 0;
return 1;
}
marray[i] = 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 (endpindex > object->size)
endpindex = object->size;
for( ; tpindex < endpindex; i++, tpindex++) {
if (vm_page_lookup(object, tpindex)) {
break;
}
rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
if (rtm == NULL) {
break;
}
marray[i] = rtm;
}
/* return number of bytes of pages */
return i;
}
--ELM916996222-326-0_--
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