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freebsd-skq/sys/vm/vm_fault.c
David Greenman a1f6d91cc2 swap_pager.c: 
Fixed long standing bug in freeing swap space during object collapses.
Fixed 'out of space' messages from printing out too often.
Modified to use new kmem_malloc() calling convention.
Implemented an additional stat in the swap pager struct to count the
amount of space allocated to that pager. This may be removed at some
point in the future.
Minimized unnecessary wakeups.

vm_fault.c:
Don't try to collect fault stats on 'swapped' processes - there aren't
any upages to store the stats in.
Changed read-ahead policy (again!).

vm_glue.c:
Be sure to gain a reference to the process's map before swapping.
Be sure to lose it when done.

kern_malloc.c:
Added the ability to specify if allocations are at interrupt time or
are 'safe'; this affects what types of pages can be allocated.

vm_map.c:
Fixed a variety of map lock problems; there's still a lurking bug that
will eventually bite.

vm_object.c:
Explicitly initialize the object fields rather than bzeroing the struct.
Eliminated the 'rcollapse' code and folded it's functionality into the
"real" collapse routine.
Moved an object_unlock() so that the backing_object is protected in
the qcollapse routine.
Make sure nobody fools with the backing_object when we're destroying it.
Added some diagnostic code which can be called from the debugger that
looks through all the internal objects and makes certain that they
all belong to someone.

vm_page.c:
Fixed a rather serious logic bug that would result in random system
crashes. Changed pagedaemon wakeup policy (again!).

vm_pageout.c:
Removed unnecessary page rotations on the inactive queue.
Changed the number of pages to explicitly free to just free_reserved
level.

Submitted by:	John Dyson
1995-02-02 09:09:15 +00:00

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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 1.17 1995/01/26 01:40:04 davidg Exp $
*/
/*
* Page fault handling module.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/resource.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_kern.h>
int vm_fault_additional_pages __P((vm_object_t, vm_offset_t, vm_page_t, int, int, vm_page_t *, int *));
#define VM_FAULT_READ_AHEAD 4
#define VM_FAULT_READ_AHEAD_MIN 1
#define VM_FAULT_READ_BEHIND 3
#define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1)
extern int swap_pager_full;
extern int vm_pageout_proc_limit;
/*
* 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(map, vaddr, fault_type, change_wiring)
vm_map_t map;
vm_offset_t vaddr;
vm_prot_t fault_type;
boolean_t change_wiring;
{
vm_object_t first_object;
vm_offset_t first_offset;
vm_map_entry_t entry;
register vm_object_t object;
register vm_offset_t offset;
vm_page_t m;
vm_page_t first_m;
vm_prot_t prot;
int result;
boolean_t wired;
boolean_t su;
boolean_t lookup_still_valid;
boolean_t page_exists;
vm_page_t old_m;
vm_object_t next_object;
vm_page_t marray[VM_FAULT_READ];
int spl;
int hardfault = 0;
cnt.v_vm_faults++; /* needs lock XXX */
/*
* Recovery actions
*/
#define FREE_PAGE(m) { \
PAGE_WAKEUP(m); \
vm_page_lock_queues(); \
vm_page_free(m); \
vm_page_unlock_queues(); \
}
#define RELEASE_PAGE(m) { \
PAGE_WAKEUP(m); \
vm_page_lock_queues(); \
vm_page_activate(m); \
vm_page_unlock_queues(); \
}
#define UNLOCK_MAP { \
if (lookup_still_valid) { \
vm_map_lookup_done(map, entry); \
lookup_still_valid = FALSE; \
} \
}
#define UNLOCK_THINGS { \
object->paging_in_progress--; \
if (object->paging_in_progress == 0) \
wakeup((caddr_t)object); \
vm_object_unlock(object); \
if (object != first_object) { \
vm_object_lock(first_object); \
FREE_PAGE(first_m); \
first_object->paging_in_progress--; \
if (first_object->paging_in_progress == 0) \
wakeup((caddr_t)first_object); \
vm_object_unlock(first_object); \
} \
UNLOCK_MAP; \
}
#define UNLOCK_AND_DEALLOCATE { \
UNLOCK_THINGS; \
vm_object_deallocate(first_object); \
}
RetryFault:;
/*
* Find the backing store object and offset into it to begin the
* search.
*/
if ((result = vm_map_lookup(&map, vaddr, fault_type, &entry, &first_object,
&first_offset, &prot, &wired, &su)) != KERN_SUCCESS) {
return (result);
}
lookup_still_valid = TRUE;
if (wired)
fault_type = prot;
first_m = NULL;
/*
* 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_lock(first_object);
first_object->ref_count++;
first_object->paging_in_progress++;
/*
* INVARIANTS (through entire routine):
*
* 1) At all times, we must either have the object lock or a busy
* page in some object to prevent some other thread from trying to
* bring in the same page.
*
* Note that we cannot hold any locks during the pager access or when
* waiting for memory, so we use a busy page then.
*
* Note also that we aren't as concerned about more than one thead
* attempting to pager_data_unlock the same page at once, so we don't
* hold the page as busy then, but do record the highest unlock value
* so far. [Unlock requests may also be delivered out of order.]
*
* 2) Once we have a busy page, we must remove it from the pageout
* queues, so that the pageout daemon will not grab it away.
*
* 3) To prevent another thread from racing us down the shadow chain
* and entering a new page in the top object before we do, we must
* keep a busy page in the top object while following the shadow
* chain.
*
* 4) We must increment paging_in_progress on any object for which
* we have a busy page, to prevent vm_object_collapse from removing
* the busy page without our noticing.
*/
/*
* Search for the page at object/offset.
*/
object = first_object;
offset = first_offset;
/*
* See whether this page is resident
*/
while (TRUE) {
m = vm_page_lookup(object, offset);
if (m != NULL) {
/*
* If the page is being brought in, wait for it and
* then retry.
*/
if ((m->flags & PG_BUSY) || m->busy) {
int s;
UNLOCK_THINGS;
s = splhigh();
if ((m->flags & PG_BUSY) || m->busy) {
m->flags |= PG_WANTED | PG_REFERENCED;
cnt.v_intrans++;
tsleep((caddr_t) m, PSWP, "vmpfw", 0);
}
splx(s);
vm_object_deallocate(first_object);
goto RetryFault;
}
if ((m->flags & PG_CACHE) &&
(cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_reserved) {
UNLOCK_AND_DEALLOCATE;
VM_WAIT;
goto RetryFault;
}
/*
* Remove the page from the pageout daemon's reach
* while we play with it.
*/
vm_page_lock_queues();
vm_page_unqueue(m);
vm_page_unlock_queues();
/*
* Mark page busy for other threads.
*/
m->flags |= PG_BUSY;
if (m->object != kernel_object && m->object != kmem_object &&
m->valid && ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL)) {
goto readrest;
}
break;
}
if (((object->pager != NULL) && (!change_wiring || wired))
|| (object == first_object)) {
if (swap_pager_full && !object->shadow && (!object->pager ||
(object->pager && object->pager->pg_type == PG_SWAP &&
!vm_pager_has_page(object->pager, offset + object->paging_offset)))) {
if (vaddr < VM_MAXUSER_ADDRESS && curproc && curproc->p_pid >= 48) { /* XXX */
printf("Process %lu killed by vm_fault -- out of swap\n", (u_long) curproc->p_pid);
psignal(curproc, SIGKILL);
curproc->p_estcpu = 0;
curproc->p_nice = PRIO_MIN;
resetpriority(curproc);
}
}
/*
* Allocate a new page for this object/offset pair.
*/
m = vm_page_alloc(object, offset, VM_ALLOC_NORMAL);
if (m == NULL) {
UNLOCK_AND_DEALLOCATE;
VM_WAIT;
goto RetryFault;
}
}
readrest:
if (object->pager != NULL && (!change_wiring || wired)) {
int rv;
int faultcount;
int reqpage;
/*
* Now that we have a busy page, we can release the
* object lock.
*/
vm_object_unlock(object);
/*
* 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(
first_object, first_offset,
m, VM_FAULT_READ_BEHIND, VM_FAULT_READ_AHEAD,
marray, &reqpage);
/*
* Call the pager to retrieve the data, if any, after
* releasing the lock on the map.
*/
UNLOCK_MAP;
rv = faultcount ?
vm_pager_get_pages(object->pager,
marray, faultcount, reqpage, TRUE) : VM_PAGER_FAIL;
if (rv == VM_PAGER_OK) {
/*
* Found the page. Leave it busy while we play
* with it.
*/
vm_object_lock(object);
/*
* Relookup in case pager changed page. Pager
* is responsible for disposition of old page
* if moved.
*/
m = vm_page_lookup(object, offset);
m->valid = VM_PAGE_BITS_ALL;
pmap_clear_modify(VM_PAGE_TO_PHYS(m));
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 thread that may want to bring
* in this page.
*
* If this is the top-level object, we must leave the
* busy page to prevent another thread 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 input (probably hardware) error, PID %d failure\n",
curproc->p_pid);
vm_object_lock(object);
/*
* 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 (((map != kernel_map) && (rv == VM_PAGER_ERROR)) || (rv == VM_PAGER_BAD)) {
FREE_PAGE(m);
UNLOCK_AND_DEALLOCATE;
return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE);
}
if (object != first_object) {
FREE_PAGE(m);
/*
* XXX - we cannot just fall out at this
* point, m has been freed and is invalid!
*/
}
}
/*
* We get here if the object has no pager (or unwiring) or the
* pager doesn't have the page.
*/
if (object == first_object)
first_m = m;
/*
* Move on to the next object. Lock the next object before
* unlocking the current one.
*/
offset += object->shadow_offset;
next_object = object->shadow;
if (next_object == NULL) {
/*
* If there's no object left, fill the page in the top
* object with zeros.
*/
if (object != first_object) {
object->paging_in_progress--;
if (object->paging_in_progress == 0)
wakeup((caddr_t) object);
vm_object_unlock(object);
object = first_object;
offset = first_offset;
m = first_m;
vm_object_lock(object);
}
first_m = NULL;
vm_page_zero_fill(m);
m->valid = VM_PAGE_BITS_ALL;
cnt.v_zfod++;
break;
} else {
vm_object_lock(next_object);
if (object != first_object) {
object->paging_in_progress--;
if (object->paging_in_progress == 0)
wakeup((caddr_t) object);
}
vm_object_unlock(object);
object = next_object;
object->paging_in_progress++;
}
}
if ((m->flags & (PG_ACTIVE | PG_INACTIVE | PG_CACHE) != 0) ||
(m->flags & PG_BUSY) == 0)
panic("vm_fault: absent or active or inactive or not busy after main loop");
/*
* PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
* is held.]
*/
old_m = 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 (object != first_object) {
/*
* We only really need to copy if we want to write it.
*/
if (fault_type & VM_PROT_WRITE) {
/*
* If we try to collapse first_object at this point,
* we may deadlock when we try to get the lock on an
* intermediate object (since we have the bottom
* object locked). We can't unlock the bottom object,
* because the page we found may move (by collapse) if
* we do.
*
* Instead, we first copy the page. Then, when we have
* no more use for the bottom object, we unlock it and
* try to collapse.
*
* Note that we copy the page even if we didn't need
* to... that's the breaks.
*/
/*
* We already have an empty page in first_object - use
* it.
*/
vm_page_copy(m, first_m);
first_m->valid = VM_PAGE_BITS_ALL;
/*
* If another map is truly sharing this page with us,
* we have to flush all uses of the original page,
* since we can't distinguish those which want the
* original from those which need the new copy.
*
* XXX If we know that only one map has access to this
* page, then we could avoid the pmap_page_protect()
* call.
*/
vm_page_lock_queues();
vm_page_activate(m);
pmap_page_protect(VM_PAGE_TO_PHYS(m), VM_PROT_NONE);
vm_page_unlock_queues();
/*
* We no longer need the old page or object.
*/
PAGE_WAKEUP(m);
object->paging_in_progress--;
if (object->paging_in_progress == 0)
wakeup((caddr_t) object);
vm_object_unlock(object);
/*
* Only use the new page below...
*/
cnt.v_cow_faults++;
m = first_m;
object = first_object;
offset = first_offset;
/*
* Now that we've gotten the copy out of the way,
* let's try to collapse the top object.
*/
vm_object_lock(object);
/*
* But we have to play ugly games with
* paging_in_progress to do that...
*/
object->paging_in_progress--;
if (object->paging_in_progress == 0)
wakeup((caddr_t) object);
vm_object_collapse(object);
object->paging_in_progress++;
} else {
prot &= ~VM_PROT_WRITE;
m->flags |= PG_COPYONWRITE;
}
}
if (m->flags & (PG_ACTIVE | PG_INACTIVE | PG_CACHE))
panic("vm_fault: active or inactive before copy object handling");
/*
* If the page is being written, but hasn't been copied to the
* copy-object, we have to copy it there.
*/
RetryCopy:
if (first_object->copy != NULL) {
vm_object_t copy_object = first_object->copy;
vm_offset_t copy_offset;
vm_page_t copy_m;
/*
* We only need to copy if we want to write it.
*/
if ((fault_type & VM_PROT_WRITE) == 0) {
prot &= ~VM_PROT_WRITE;
m->flags |= PG_COPYONWRITE;
} else {
/*
* Try to get the lock on the copy_object.
*/
if (!vm_object_lock_try(copy_object)) {
vm_object_unlock(object);
/* should spin a bit here... */
vm_object_lock(object);
goto RetryCopy;
}
/*
* Make another reference to the copy-object, to keep
* it from disappearing during the copy.
*/
copy_object->ref_count++;
/*
* Does the page exist in the copy?
*/
copy_offset = first_offset
- copy_object->shadow_offset;
copy_m = vm_page_lookup(copy_object, copy_offset);
page_exists = (copy_m != NULL);
if (page_exists) {
if ((copy_m->flags & PG_BUSY) || copy_m->busy) {
/*
* If the page is being brought in,
* wait for it and then retry.
*/
RELEASE_PAGE(m);
copy_object->ref_count--;
vm_object_unlock(copy_object);
UNLOCK_THINGS;
spl = splhigh();
if ((copy_m->flags & PG_BUSY) || copy_m->busy) {
copy_m->flags |= PG_WANTED | PG_REFERENCED;
tsleep((caddr_t) copy_m, PSWP, "vmpfwc", 0);
}
splx(spl);
vm_object_deallocate(first_object);
goto RetryFault;
}
}
/*
* If the page is not in memory (in the object) and
* the object has a pager, we have to check if the
* pager has the data in secondary storage.
*/
if (!page_exists) {
/*
* If we don't allocate a (blank) page here...
* another thread could try to page it in,
* allocate a page, and then block on the busy
* page in its shadow (first_object). Then
* we'd trip over the busy page after we found
* that the copy_object's pager doesn't have
* the page...
*/
copy_m = vm_page_alloc(copy_object, copy_offset, VM_ALLOC_NORMAL);
if (copy_m == NULL) {
/*
* Wait for a page, then retry.
*/
RELEASE_PAGE(m);
copy_object->ref_count--;
vm_object_unlock(copy_object);
UNLOCK_AND_DEALLOCATE;
VM_WAIT;
goto RetryFault;
}
if (copy_object->pager != NULL) {
vm_object_unlock(object);
vm_object_unlock(copy_object);
UNLOCK_MAP;
page_exists = vm_pager_has_page(
copy_object->pager,
(copy_offset + copy_object->paging_offset));
vm_object_lock(copy_object);
/*
* Since the map is unlocked, someone
* else could have copied this object
* and put a different copy_object
* between the two. Or, the last
* reference to the copy-object (other
* than the one we have) may have
* disappeared - if that has happened,
* we don't need to make the copy.
*/
if (copy_object->shadow != object ||
copy_object->ref_count == 1) {
/*
* Gaah... start over!
*/
FREE_PAGE(copy_m);
vm_object_unlock(copy_object);
vm_object_deallocate(copy_object);
/* may block */
vm_object_lock(object);
goto RetryCopy;
}
vm_object_lock(object);
if (page_exists) {
/*
* We didn't need the page
*/
FREE_PAGE(copy_m);
}
}
}
if (!page_exists) {
/*
* Must copy page into copy-object.
*/
vm_page_copy(m, copy_m);
copy_m->valid = VM_PAGE_BITS_ALL;
/*
* Things to remember: 1. The copied page must
* be marked 'dirty' so it will be paged out
* to the copy object. 2. If the old page was
* in use by any users of the copy-object, it
* must be removed from all pmaps. (We can't
* know which pmaps use it.)
*/
vm_page_lock_queues();
vm_page_activate(old_m);
pmap_page_protect(VM_PAGE_TO_PHYS(old_m),
VM_PROT_NONE);
copy_m->dirty = VM_PAGE_BITS_ALL;
vm_page_activate(copy_m);
vm_page_unlock_queues();
PAGE_WAKEUP(copy_m);
}
/*
* The reference count on copy_object must be at least
* 2: one for our extra reference, and at least one
* from the outside world (we checked that when we
* last locked copy_object).
*/
copy_object->ref_count--;
vm_object_unlock(copy_object);
m->flags &= ~PG_COPYONWRITE;
}
}
if (m->flags & (PG_ACTIVE | PG_INACTIVE | PG_CACHE))
panic("vm_fault: active or inactive before retrying lookup");
/*
* We must verify that the maps have not changed since our last
* lookup.
*/
if (!lookup_still_valid) {
vm_object_t retry_object;
vm_offset_t retry_offset;
vm_prot_t retry_prot;
/*
* Since map entries may be pageable, make sure we can take a
* page fault on them.
*/
vm_object_unlock(object);
/*
* To avoid trying to write_lock the map while another thread
* 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(&map, vaddr, fault_type & ~VM_PROT_WRITE,
&entry, &retry_object, &retry_offset, &retry_prot, &wired, &su);
vm_object_lock(object);
/*
* 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(m);
UNLOCK_AND_DEALLOCATE;
return (result);
}
lookup_still_valid = TRUE;
if ((retry_object != first_object) ||
(retry_offset != first_offset)) {
RELEASE_PAGE(m);
UNLOCK_AND_DEALLOCATE;
goto RetryFault;
}
/*
* Check whether the protection has changed or the object has
* been copied while we left the map unlocked. Changing from
* read to write permission is OK - we leave the page
* write-protected, and catch the write fault. Changing from
* write to read permission means that we can't mark the page
* write-enabled after all.
*/
prot &= retry_prot;
if (m->flags & PG_COPYONWRITE)
prot &= ~VM_PROT_WRITE;
}
/*
* (the various bits we're fiddling with here are locked by the
* object's lock)
*/
/* XXX This distorts the meaning of the copy_on_write bit */
if (prot & VM_PROT_WRITE)
m->flags &= ~PG_COPYONWRITE;
/*
* It's critically important that a wired-down page be faulted only
* once in each map for which it is wired.
*/
if (m->flags & (PG_ACTIVE | PG_INACTIVE | PG_CACHE))
panic("vm_fault: active or inactive before pmap_enter");
vm_object_unlock(object);
/*
* 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).
*/
pmap_enter(map->pmap, vaddr, VM_PAGE_TO_PHYS(m), prot, wired);
#if 0
if( ((prot & VM_PROT_WRITE) == 0) && change_wiring == 0 && wired == 0)
pmap_prefault(map->pmap, vaddr, entry, first_object);
#endif
/*
* If the page is not wired down, then put it where the pageout daemon
* can find it.
*/
vm_object_lock(object);
vm_page_lock_queues();
if (change_wiring) {
if (wired)
vm_page_wire(m);
else
vm_page_unwire(m);
} else {
vm_page_activate(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++;
}
}
vm_page_unlock_queues();
/*
* Unlock everything, and return
*/
PAGE_WAKEUP(m);
UNLOCK_AND_DEALLOCATE;
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) {
while( curproc != pageproc &&
(cnt.v_free_count <= cnt.v_pageout_free_min))
VM_WAIT;
rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE, TRUE);
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.
*/
vm_page_lock_queues();
for (va = start; va < end; va += PAGE_SIZE) {
pa = pmap_extract(pmap, va);
if (pa == (vm_offset_t) 0) {
panic("unwire: page not in pmap");
}
pmap_change_wiring(pmap, va, FALSE);
vm_page_unwire(PHYS_TO_VM_PAGE(pa));
}
vm_page_unlock_queues();
/*
* 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_offset_t dst_offset;
vm_offset_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(
(vm_size_t) (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
*/
vm_object_lock(dst_object);
do {
dst_m = vm_page_alloc(dst_object, dst_offset, VM_ALLOC_NORMAL);
if (dst_m == NULL) {
vm_object_unlock(dst_object);
VM_WAIT;
vm_object_lock(dst_object);
}
} 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.)
*/
vm_object_lock(src_object);
src_m = vm_page_lookup(src_object, 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_object_unlock(src_object);
vm_object_unlock(dst_object);
pmap_enter(dst_map->pmap, vaddr, VM_PAGE_TO_PHYS(dst_m),
prot, FALSE);
/*
* Mark it no longer busy, and put it on the active list.
*/
vm_object_lock(dst_object);
vm_page_lock_queues();
vm_page_activate(dst_m);
vm_page_unlock_queues();
PAGE_WAKEUP(dst_m);
vm_object_unlock(dst_object);
}
}
/*
* looks page up in shadow chain
*/
int
vm_fault_page_lookup(object, offset, rtobject, rtoffset, rtm)
vm_object_t object;
vm_offset_t offset;
vm_object_t *rtobject;
vm_offset_t *rtoffset;
vm_page_t *rtm;
{
vm_page_t m;
*rtm = 0;
*rtobject = 0;
*rtoffset = 0;
while (!(m = vm_page_lookup(object, offset))) {
if (object->pager) {
if (vm_pager_has_page(object->pager, object->paging_offset + offset)) {
*rtobject = object;
*rtoffset = offset;
return 1;
}
}
if (!object->shadow)
return 0;
else {
offset += object->shadow_offset;
object = object->shadow;
}
}
*rtobject = object;
*rtoffset = offset;
*rtm = m;
return 1;
}
/*
* This routine checks around the requested page for other pages that
* might be able to be faulted in.
*
* Inputs:
* first_object, first_offset, m, rbehind, rahead
*
* Outputs:
* marray (array of vm_page_t), reqpage (index of requested page)
*
* Return value:
* number of pages in marray
*/
int
vm_fault_additional_pages(first_object, first_offset, m, rbehind, raheada, marray, reqpage)
vm_object_t first_object;
vm_offset_t first_offset;
vm_page_t m;
int rbehind;
int raheada;
vm_page_t *marray;
int *reqpage;
{
int i;
vm_object_t object;
vm_offset_t offset, startoffset, endoffset, toffset, size;
vm_object_t rtobject;
vm_page_t rtm;
vm_offset_t rtoffset;
vm_offset_t offsetdiff;
int rahead;
int treqpage;
object = m->object;
offset = m->offset;
offsetdiff = offset - first_offset;
/*
* if the requested page is not available, then give up now
*/
if (!vm_pager_has_page(object->pager, object->paging_offset + offset))
return 0;
/*
* try to do any readahead that we might have free pages for.
*/
rahead = raheada;
if ((rahead + rbehind) > ((cnt.v_free_count + cnt.v_cache_count) - 2*cnt.v_free_reserved)) {
rahead = ((cnt.v_free_count + cnt.v_cache_count) - 2*cnt.v_free_reserved) / 2;
rbehind = rahead;
if (!rahead)
wakeup((caddr_t) &vm_pages_needed);
}
/*
* if we don't have any free pages, then just read one page.
*/
if (rahead <= 0) {
*reqpage = 0;
marray[0] = m;
return 1;
}
/*
* scan backward for the read behind pages -- in memory or on disk not
* in same object
*/
toffset = offset - NBPG;
if (toffset < offset) {
if (rbehind * NBPG > offset)
rbehind = offset / NBPG;
startoffset = offset - rbehind * NBPG;
while (toffset >= startoffset) {
if (!vm_fault_page_lookup(first_object, toffset - offsetdiff, &rtobject, &rtoffset, &rtm) ||
rtm != 0 || rtobject != object) {
startoffset = toffset + NBPG;
break;
}
if (toffset == 0)
break;
toffset -= NBPG;
}
} else {
startoffset = offset;
}
/*
* scan forward for the read ahead pages -- in memory or on disk not
* in same object
*/
toffset = offset + NBPG;
endoffset = offset + (rahead + 1) * NBPG;
while (toffset < object->size && toffset < endoffset) {
if (!vm_fault_page_lookup(first_object, toffset - offsetdiff, &rtobject, &rtoffset, &rtm) ||
rtm != 0 || rtobject != object) {
break;
}
toffset += NBPG;
}
endoffset = toffset;
/* calculate number of bytes of pages */
size = (endoffset - startoffset) / NBPG;
/* calculate the page offset of the required page */
treqpage = (offset - startoffset) / NBPG;
/* see if we have space (again) */
if ((cnt.v_free_count + cnt.v_cache_count) > (cnt.v_free_reserved + size)) {
bzero(marray, (rahead + rbehind + 1) * sizeof(vm_page_t));
/*
* get our pages and don't block for them
*/
for (i = 0; i < size; i++) {
if (i != treqpage)
rtm = vm_page_alloc(object, startoffset + i * NBPG, VM_ALLOC_NORMAL);
else
rtm = m;
marray[i] = rtm;
}
for (i = 0; i < size; i++) {
if (marray[i] == 0)
break;
}
/*
* if we could not get our block of pages, then free the
* readahead/readbehind pages.
*/
if (i < size) {
for (i = 0; i < size; i++) {
if (i != treqpage && marray[i])
FREE_PAGE(marray[i]);
}
*reqpage = 0;
marray[0] = m;
return 1;
}
*reqpage = treqpage;
return size;
}
*reqpage = 0;
marray[0] = m;
return 1;
}
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