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freebsd-dev/sys/vm/vm_page.c
Konstantin Belousov 3abeb8113d In the vm_page_set_invalid() function, do not assert that the page is 
not busy, since its only caller brelse() can legitimately call it on
busy page.  This happens for VOP_PUTPAGES() on filesystems that use
buffers and which VOP_WRITE() method marked the buffer containing page
as non-cacheable.

Reported and tested by:	pho
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2013-07-11 05:38:39 +00:00

2928 lines
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/*-
* Copyright (c) 1991 Regents of the University of California.
* All rights reserved.
* Copyright (c) 1998 Matthew Dillon. 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.
* 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_page.c 7.4 (Berkeley) 5/7/91
*/
/*-
* 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.
*/
/*
* GENERAL RULES ON VM_PAGE MANIPULATION
*
* - A page queue lock is required when adding or removing a page from a
* page queue (vm_pagequeues[]), regardless of other locks or the
* busy state of a page.
*
* * In general, no thread besides the page daemon can acquire or
* hold more than one page queue lock at a time.
*
* * The page daemon can acquire and hold any pair of page queue
* locks in any order.
*
* - The object lock is required when inserting or removing
* pages from an object (vm_page_insert() or vm_page_remove()).
*
*/
/*
* Resident memory management module.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_vm.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/msgbuf.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/rwlock.h>
#include <sys/sysctl.h>
#include <sys/vmmeter.h>
#include <sys/vnode.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_param.h>
#include <vm/vm_kern.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_pager.h>
#include <vm/vm_phys.h>
#include <vm/vm_radix.h>
#include <vm/vm_reserv.h>
#include <vm/vm_extern.h>
#include <vm/uma.h>
#include <vm/uma_int.h>
#include <machine/md_var.h>
/*
* Associated with page of user-allocatable memory is a
* page structure.
*/
struct vm_pagequeue vm_pagequeues[PQ_COUNT] = {
[PQ_INACTIVE] = {
.pq_pl = TAILQ_HEAD_INITIALIZER(
vm_pagequeues[PQ_INACTIVE].pq_pl),
.pq_cnt = &cnt.v_inactive_count,
.pq_name = "vm inactive pagequeue"
},
[PQ_ACTIVE] = {
.pq_pl = TAILQ_HEAD_INITIALIZER(
vm_pagequeues[PQ_ACTIVE].pq_pl),
.pq_cnt = &cnt.v_active_count,
.pq_name = "vm active pagequeue"
}
};
struct mtx_padalign vm_page_queue_free_mtx;
struct mtx_padalign pa_lock[PA_LOCK_COUNT];
vm_page_t vm_page_array;
long vm_page_array_size;
long first_page;
int vm_page_zero_count;
static int boot_pages = UMA_BOOT_PAGES;
TUNABLE_INT("vm.boot_pages", &boot_pages);
SYSCTL_INT(_vm, OID_AUTO, boot_pages, CTLFLAG_RD, &boot_pages, 0,
"number of pages allocated for bootstrapping the VM system");
static int pa_tryrelock_restart;
SYSCTL_INT(_vm, OID_AUTO, tryrelock_restart, CTLFLAG_RD,
&pa_tryrelock_restart, 0, "Number of tryrelock restarts");
static uma_zone_t fakepg_zone;
static struct vnode *vm_page_alloc_init(vm_page_t m);
static void vm_page_clear_dirty_mask(vm_page_t m, vm_page_bits_t pagebits);
static void vm_page_enqueue(int queue, vm_page_t m);
static void vm_page_init_fakepg(void *dummy);
static void vm_page_insert_after(vm_page_t m, vm_object_t object,
vm_pindex_t pindex, vm_page_t mpred);
SYSINIT(vm_page, SI_SUB_VM, SI_ORDER_SECOND, vm_page_init_fakepg, NULL);
static void
vm_page_init_fakepg(void *dummy)
{
fakepg_zone = uma_zcreate("fakepg", sizeof(struct vm_page), NULL, NULL,
NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM);
}
/* Make sure that u_long is at least 64 bits when PAGE_SIZE is 32K. */
#if PAGE_SIZE == 32768
#ifdef CTASSERT
CTASSERT(sizeof(u_long) >= 8);
#endif
#endif
/*
* Try to acquire a physical address lock while a pmap is locked. If we
* fail to trylock we unlock and lock the pmap directly and cache the
* locked pa in *locked. The caller should then restart their loop in case
* the virtual to physical mapping has changed.
*/
int
vm_page_pa_tryrelock(pmap_t pmap, vm_paddr_t pa, vm_paddr_t *locked)
{
vm_paddr_t lockpa;
lockpa = *locked;
*locked = pa;
if (lockpa) {
PA_LOCK_ASSERT(lockpa, MA_OWNED);
if (PA_LOCKPTR(pa) == PA_LOCKPTR(lockpa))
return (0);
PA_UNLOCK(lockpa);
}
if (PA_TRYLOCK(pa))
return (0);
PMAP_UNLOCK(pmap);
atomic_add_int(&pa_tryrelock_restart, 1);
PA_LOCK(pa);
PMAP_LOCK(pmap);
return (EAGAIN);
}
/*
* vm_set_page_size:
*
* Sets the page size, perhaps based upon the memory
* size. Must be called before any use of page-size
* dependent functions.
*/
void
vm_set_page_size(void)
{
if (cnt.v_page_size == 0)
cnt.v_page_size = PAGE_SIZE;
if (((cnt.v_page_size - 1) & cnt.v_page_size) != 0)
panic("vm_set_page_size: page size not a power of two");
}
/*
* vm_page_blacklist_lookup:
*
* See if a physical address in this page has been listed
* in the blacklist tunable. Entries in the tunable are
* separated by spaces or commas. If an invalid integer is
* encountered then the rest of the string is skipped.
*/
static int
vm_page_blacklist_lookup(char *list, vm_paddr_t pa)
{
vm_paddr_t bad;
char *cp, *pos;
for (pos = list; *pos != '\0'; pos = cp) {
bad = strtoq(pos, &cp, 0);
if (*cp != '\0') {
if (*cp == ' ' || *cp == ',') {
cp++;
if (cp == pos)
continue;
} else
break;
}
if (pa == trunc_page(bad))
return (1);
}
return (0);
}
/*
* vm_page_startup:
*
* Initializes the resident memory module.
*
* Allocates memory for the page cells, and
* for the object/offset-to-page hash table headers.
* Each page cell is initialized and placed on the free list.
*/
vm_offset_t
vm_page_startup(vm_offset_t vaddr)
{
vm_offset_t mapped;
vm_paddr_t page_range;
vm_paddr_t new_end;
int i;
vm_paddr_t pa;
vm_paddr_t last_pa;
char *list;
/* the biggest memory array is the second group of pages */
vm_paddr_t end;
vm_paddr_t biggestsize;
vm_paddr_t low_water, high_water;
int biggestone;
biggestsize = 0;
biggestone = 0;
vaddr = round_page(vaddr);
for (i = 0; phys_avail[i + 1]; i += 2) {
phys_avail[i] = round_page(phys_avail[i]);
phys_avail[i + 1] = trunc_page(phys_avail[i + 1]);
}
low_water = phys_avail[0];
high_water = phys_avail[1];
for (i = 0; phys_avail[i + 1]; i += 2) {
vm_paddr_t size = phys_avail[i + 1] - phys_avail[i];
if (size > biggestsize) {
biggestone = i;
biggestsize = size;
}
if (phys_avail[i] < low_water)
low_water = phys_avail[i];
if (phys_avail[i + 1] > high_water)
high_water = phys_avail[i + 1];
}
#ifdef XEN
low_water = 0;
#endif
end = phys_avail[biggestone+1];
/*
* Initialize the page and queue locks.
*/
mtx_init(&vm_page_queue_free_mtx, "vm page free queue", NULL, MTX_DEF);
for (i = 0; i < PA_LOCK_COUNT; i++)
mtx_init(&pa_lock[i], "vm page", NULL, MTX_DEF);
for (i = 0; i < PQ_COUNT; i++)
vm_pagequeue_init_lock(&vm_pagequeues[i]);
/*
* Allocate memory for use when boot strapping the kernel memory
* allocator.
*/
new_end = end - (boot_pages * UMA_SLAB_SIZE);
new_end = trunc_page(new_end);
mapped = pmap_map(&vaddr, new_end, end,
VM_PROT_READ | VM_PROT_WRITE);
bzero((void *)mapped, end - new_end);
uma_startup((void *)mapped, boot_pages);
#if defined(__amd64__) || defined(__i386__) || defined(__arm__) || \
defined(__mips__)
/*
* Allocate a bitmap to indicate that a random physical page
* needs to be included in a minidump.
*
* The amd64 port needs this to indicate which direct map pages
* need to be dumped, via calls to dump_add_page()/dump_drop_page().
*
* However, i386 still needs this workspace internally within the
* minidump code. In theory, they are not needed on i386, but are
* included should the sf_buf code decide to use them.
*/
last_pa = 0;
for (i = 0; dump_avail[i + 1] != 0; i += 2)
if (dump_avail[i + 1] > last_pa)
last_pa = dump_avail[i + 1];
page_range = last_pa / PAGE_SIZE;
vm_page_dump_size = round_page(roundup2(page_range, NBBY) / NBBY);
new_end -= vm_page_dump_size;
vm_page_dump = (void *)(uintptr_t)pmap_map(&vaddr, new_end,
new_end + vm_page_dump_size, VM_PROT_READ | VM_PROT_WRITE);
bzero((void *)vm_page_dump, vm_page_dump_size);
#endif
#ifdef __amd64__
/*
* Request that the physical pages underlying the message buffer be
* included in a crash dump. Since the message buffer is accessed
* through the direct map, they are not automatically included.
*/
pa = DMAP_TO_PHYS((vm_offset_t)msgbufp->msg_ptr);
last_pa = pa + round_page(msgbufsize);
while (pa < last_pa) {
dump_add_page(pa);
pa += PAGE_SIZE;
}
#endif
/*
* Compute the number of pages of memory that will be available for
* use (taking into account the overhead of a page structure per
* page).
*/
first_page = low_water / PAGE_SIZE;
#ifdef VM_PHYSSEG_SPARSE
page_range = 0;
for (i = 0; phys_avail[i + 1] != 0; i += 2)
page_range += atop(phys_avail[i + 1] - phys_avail[i]);
#elif defined(VM_PHYSSEG_DENSE)
page_range = high_water / PAGE_SIZE - first_page;
#else
#error "Either VM_PHYSSEG_DENSE or VM_PHYSSEG_SPARSE must be defined."
#endif
end = new_end;
/*
* Reserve an unmapped guard page to trap access to vm_page_array[-1].
*/
vaddr += PAGE_SIZE;
/*
* Initialize the mem entry structures now, and put them in the free
* queue.
*/
new_end = trunc_page(end - page_range * sizeof(struct vm_page));
mapped = pmap_map(&vaddr, new_end, end,
VM_PROT_READ | VM_PROT_WRITE);
vm_page_array = (vm_page_t) mapped;
#if VM_NRESERVLEVEL > 0
/*
* Allocate memory for the reservation management system's data
* structures.
*/
new_end = vm_reserv_startup(&vaddr, new_end, high_water);
#endif
#if defined(__amd64__) || defined(__mips__)
/*
* pmap_map on amd64 and mips can come out of the direct-map, not kvm
* like i386, so the pages must be tracked for a crashdump to include
* this data. This includes the vm_page_array and the early UMA
* bootstrap pages.
*/
for (pa = new_end; pa < phys_avail[biggestone + 1]; pa += PAGE_SIZE)
dump_add_page(pa);
#endif
phys_avail[biggestone + 1] = new_end;
/*
* Clear all of the page structures
*/
bzero((caddr_t) vm_page_array, page_range * sizeof(struct vm_page));
for (i = 0; i < page_range; i++)
vm_page_array[i].order = VM_NFREEORDER;
vm_page_array_size = page_range;
/*
* Initialize the physical memory allocator.
*/
vm_phys_init();
/*
* Add every available physical page that is not blacklisted to
* the free lists.
*/
cnt.v_page_count = 0;
cnt.v_free_count = 0;
list = getenv("vm.blacklist");
for (i = 0; phys_avail[i + 1] != 0; i += 2) {
pa = phys_avail[i];
last_pa = phys_avail[i + 1];
while (pa < last_pa) {
if (list != NULL &&
vm_page_blacklist_lookup(list, pa))
printf("Skipping page with pa 0x%jx\n",
(uintmax_t)pa);
else
vm_phys_add_page(pa);
pa += PAGE_SIZE;
}
}
freeenv(list);
#if VM_NRESERVLEVEL > 0
/*
* Initialize the reservation management system.
*/
vm_reserv_init();
#endif
return (vaddr);
}
void
vm_page_reference(vm_page_t m)
{
vm_page_aflag_set(m, PGA_REFERENCED);
}
void
vm_page_busy(vm_page_t m)
{
VM_OBJECT_ASSERT_WLOCKED(m->object);
KASSERT((m->oflags & VPO_BUSY) == 0,
("vm_page_busy: page already busy!!!"));
m->oflags |= VPO_BUSY;
}
/*
* vm_page_flash:
*
* wakeup anyone waiting for the page.
*/
void
vm_page_flash(vm_page_t m)
{
VM_OBJECT_ASSERT_WLOCKED(m->object);
if (m->oflags & VPO_WANTED) {
m->oflags &= ~VPO_WANTED;
wakeup(m);
}
}
/*
* vm_page_wakeup:
*
* clear the VPO_BUSY flag and wakeup anyone waiting for the
* page.
*
*/
void
vm_page_wakeup(vm_page_t m)
{
VM_OBJECT_ASSERT_WLOCKED(m->object);
KASSERT(m->oflags & VPO_BUSY, ("vm_page_wakeup: page not busy!!!"));
m->oflags &= ~VPO_BUSY;
vm_page_flash(m);
}
void
vm_page_io_start(vm_page_t m)
{
VM_OBJECT_ASSERT_WLOCKED(m->object);
m->busy++;
}
void
vm_page_io_finish(vm_page_t m)
{
VM_OBJECT_ASSERT_WLOCKED(m->object);
KASSERT(m->busy > 0, ("vm_page_io_finish: page %p is not busy", m));
m->busy--;
if (m->busy == 0)
vm_page_flash(m);
}
/*
* Keep page from being freed by the page daemon
* much of the same effect as wiring, except much lower
* overhead and should be used only for *very* temporary
* holding ("wiring").
*/
void
vm_page_hold(vm_page_t mem)
{
vm_page_lock_assert(mem, MA_OWNED);
mem->hold_count++;
}
void
vm_page_unhold(vm_page_t mem)
{
vm_page_lock_assert(mem, MA_OWNED);
--mem->hold_count;
KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!"));
if (mem->hold_count == 0 && (mem->flags & PG_UNHOLDFREE) != 0)
vm_page_free_toq(mem);
}
/*
* vm_page_unhold_pages:
*
* Unhold each of the pages that is referenced by the given array.
*/
void
vm_page_unhold_pages(vm_page_t *ma, int count)
{
struct mtx *mtx, *new_mtx;
mtx = NULL;
for (; count != 0; count--) {
/*
* Avoid releasing and reacquiring the same page lock.
*/
new_mtx = vm_page_lockptr(*ma);
if (mtx != new_mtx) {
if (mtx != NULL)
mtx_unlock(mtx);
mtx = new_mtx;
mtx_lock(mtx);
}
vm_page_unhold(*ma);
ma++;
}
if (mtx != NULL)
mtx_unlock(mtx);
}
vm_page_t
PHYS_TO_VM_PAGE(vm_paddr_t pa)
{
vm_page_t m;
#ifdef VM_PHYSSEG_SPARSE
m = vm_phys_paddr_to_vm_page(pa);
if (m == NULL)
m = vm_phys_fictitious_to_vm_page(pa);
return (m);
#elif defined(VM_PHYSSEG_DENSE)
long pi;
pi = atop(pa);
if (pi >= first_page && (pi - first_page) < vm_page_array_size) {
m = &vm_page_array[pi - first_page];
return (m);
}
return (vm_phys_fictitious_to_vm_page(pa));
#else
#error "Either VM_PHYSSEG_DENSE or VM_PHYSSEG_SPARSE must be defined."
#endif
}
/*
* vm_page_getfake:
*
* Create a fictitious page with the specified physical address and
* memory attribute. The memory attribute is the only the machine-
* dependent aspect of a fictitious page that must be initialized.
*/
vm_page_t
vm_page_getfake(vm_paddr_t paddr, vm_memattr_t memattr)
{
vm_page_t m;
m = uma_zalloc(fakepg_zone, M_WAITOK | M_ZERO);
vm_page_initfake(m, paddr, memattr);
return (m);
}
void
vm_page_initfake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr)
{
if ((m->flags & PG_FICTITIOUS) != 0) {
/*
* The page's memattr might have changed since the
* previous initialization. Update the pmap to the
* new memattr.
*/
goto memattr;
}
m->phys_addr = paddr;
m->queue = PQ_NONE;
/* Fictitious pages don't use "segind". */
m->flags = PG_FICTITIOUS;
/* Fictitious pages don't use "order" or "pool". */
m->oflags = VPO_BUSY | VPO_UNMANAGED;
m->wire_count = 1;
pmap_page_init(m);
memattr:
pmap_page_set_memattr(m, memattr);
}
/*
* vm_page_putfake:
*
* Release a fictitious page.
*/
void
vm_page_putfake(vm_page_t m)
{
KASSERT((m->oflags & VPO_UNMANAGED) != 0, ("managed %p", m));
KASSERT((m->flags & PG_FICTITIOUS) != 0,
("vm_page_putfake: bad page %p", m));
uma_zfree(fakepg_zone, m);
}
/*
* vm_page_updatefake:
*
* Update the given fictitious page to the specified physical address and
* memory attribute.
*/
void
vm_page_updatefake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr)
{
KASSERT((m->flags & PG_FICTITIOUS) != 0,
("vm_page_updatefake: bad page %p", m));
m->phys_addr = paddr;
pmap_page_set_memattr(m, memattr);
}
/*
* vm_page_free:
*
* Free a page.
*/
void
vm_page_free(vm_page_t m)
{
m->flags &= ~PG_ZERO;
vm_page_free_toq(m);
}
/*
* vm_page_free_zero:
*
* Free a page to the zerod-pages queue
*/
void
vm_page_free_zero(vm_page_t m)
{
m->flags |= PG_ZERO;
vm_page_free_toq(m);
}
/*
* Unbusy and handle the page queueing for a page from the VOP_GETPAGES()
* array which is not the request page.
*/
void
vm_page_readahead_finish(vm_page_t m)
{
if (m->valid != 0) {
/*
* Since the page is not the requested page, whether
* it should be activated or deactivated is not
* obvious. Empirical results have shown that
* deactivating the page is usually the best choice,
* unless the page is wanted by another thread.
*/
if (m->oflags & VPO_WANTED) {
vm_page_lock(m);
vm_page_activate(m);
vm_page_unlock(m);
} else {
vm_page_lock(m);
vm_page_deactivate(m);
vm_page_unlock(m);
}
vm_page_wakeup(m);
} else {
/*
* Free the completely invalid page. Such page state
* occurs due to the short read operation which did
* not covered our page at all, or in case when a read
* error happens.
*/
vm_page_lock(m);
vm_page_free(m);
vm_page_unlock(m);
}
}
/*
* vm_page_sleep:
*
* Sleep and release the page lock.
*
* The object containing the given page must be locked.
*/
void
vm_page_sleep(vm_page_t m, const char *msg)
{
VM_OBJECT_ASSERT_WLOCKED(m->object);
if (mtx_owned(vm_page_lockptr(m)))
vm_page_unlock(m);
/*
* It's possible that while we sleep, the page will get
* unbusied and freed. If we are holding the object
* lock, we will assume we hold a reference to the object
* such that even if m->object changes, we can re-lock
* it.
*/
m->oflags |= VPO_WANTED;
VM_OBJECT_SLEEP(m->object, m, PVM, msg, 0);
}
/*
* vm_page_dirty_KBI: [ internal use only ]
*
* Set all bits in the page's dirty field.
*
* The object containing the specified page must be locked if the
* call is made from the machine-independent layer.
*
* See vm_page_clear_dirty_mask().
*
* This function should only be called by vm_page_dirty().
*/
void
vm_page_dirty_KBI(vm_page_t m)
{
/* These assertions refer to this operation by its public name. */
KASSERT((m->flags & PG_CACHED) == 0,
("vm_page_dirty: page in cache!"));
KASSERT(!VM_PAGE_IS_FREE(m),
("vm_page_dirty: page is free!"));
KASSERT(m->valid == VM_PAGE_BITS_ALL,
("vm_page_dirty: page is invalid!"));
m->dirty = VM_PAGE_BITS_ALL;
}
/*
* vm_page_insert: [ internal use only ]
*
* Inserts the given mem entry into the object and object list.
*
* The object must be locked.
*/
void
vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex)
{
vm_page_t mpred;
VM_OBJECT_ASSERT_WLOCKED(object);
mpred = vm_radix_lookup_le(&object->rtree, pindex);
vm_page_insert_after(m, object, pindex, mpred);
}
/*
* vm_page_insert_after:
*
* Inserts the page "m" into the specified object at offset "pindex".
*
* The page "mpred" must immediately precede the offset "pindex" within
* the specified object.
*
* The object must be locked.
*/
static void
vm_page_insert_after(vm_page_t m, vm_object_t object, vm_pindex_t pindex,
vm_page_t mpred)
{
vm_page_t msucc;
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT(m->object == NULL,
("vm_page_insert_after: page already inserted"));
if (mpred != NULL) {
KASSERT(mpred->object == object ||
(mpred->flags & PG_SLAB) != 0,
("vm_page_insert_after: object doesn't contain mpred"));
KASSERT(mpred->pindex < pindex,
("vm_page_insert_after: mpred doesn't precede pindex"));
msucc = TAILQ_NEXT(mpred, listq);
} else
msucc = TAILQ_FIRST(&object->memq);
if (msucc != NULL)
KASSERT(msucc->pindex > pindex,
("vm_page_insert_after: msucc doesn't succeed pindex"));
/*
* Record the object/offset pair in this page
*/
m->object = object;
m->pindex = pindex;
/*
* Now link into the object's ordered list of backed pages.
*/
if (mpred != NULL)
TAILQ_INSERT_AFTER(&object->memq, mpred, m, listq);
else
TAILQ_INSERT_HEAD(&object->memq, m, listq);
vm_radix_insert(&object->rtree, m);
/*
* Show that the object has one more resident page.
*/
object->resident_page_count++;
/*
* Hold the vnode until the last page is released.
*/
if (object->resident_page_count == 1 && object->type == OBJT_VNODE)
vhold(object->handle);
/*
* Since we are inserting a new and possibly dirty page,
* update the object's OBJ_MIGHTBEDIRTY flag.
*/
if (pmap_page_is_write_mapped(m))
vm_object_set_writeable_dirty(object);
}
/*
* vm_page_remove:
*
* Removes the given mem entry from the object/offset-page
* table and the object page list, but do not invalidate/terminate
* the backing store.
*
* The object must be locked. The page must be locked if it is managed.
*/
void
vm_page_remove(vm_page_t m)
{
vm_object_t object;
if ((m->oflags & VPO_UNMANAGED) == 0)
vm_page_lock_assert(m, MA_OWNED);
if ((object = m->object) == NULL)
return;
VM_OBJECT_ASSERT_WLOCKED(object);
if (m->oflags & VPO_BUSY) {
m->oflags &= ~VPO_BUSY;
vm_page_flash(m);
}
/*
* Now remove from the object's list of backed pages.
*/
vm_radix_remove(&object->rtree, m->pindex);
TAILQ_REMOVE(&object->memq, m, listq);
/*
* And show that the object has one fewer resident page.
*/
object->resident_page_count--;
/*
* The vnode may now be recycled.
*/
if (object->resident_page_count == 0 && object->type == OBJT_VNODE)
vdrop(object->handle);
m->object = NULL;
}
/*
* vm_page_lookup:
*
* Returns the page associated with the object/offset
* pair specified; if none is found, NULL is returned.
*
* The object must be locked.
*/
vm_page_t
vm_page_lookup(vm_object_t object, vm_pindex_t pindex)
{
VM_OBJECT_ASSERT_LOCKED(object);
return (vm_radix_lookup(&object->rtree, pindex));
}
/*
* vm_page_find_least:
*
* Returns the page associated with the object with least pindex
* greater than or equal to the parameter pindex, or NULL.
*
* The object must be locked.
*/
vm_page_t
vm_page_find_least(vm_object_t object, vm_pindex_t pindex)
{
vm_page_t m;
VM_OBJECT_ASSERT_LOCKED(object);
if ((m = TAILQ_FIRST(&object->memq)) != NULL && m->pindex < pindex)
m = vm_radix_lookup_ge(&object->rtree, pindex);
return (m);
}
/*
* Returns the given page's successor (by pindex) within the object if it is
* resident; if none is found, NULL is returned.
*
* The object must be locked.
*/
vm_page_t
vm_page_next(vm_page_t m)
{
vm_page_t next;
VM_OBJECT_ASSERT_WLOCKED(m->object);
if ((next = TAILQ_NEXT(m, listq)) != NULL &&
next->pindex != m->pindex + 1)
next = NULL;
return (next);
}
/*
* Returns the given page's predecessor (by pindex) within the object if it is
* resident; if none is found, NULL is returned.
*
* The object must be locked.
*/
vm_page_t
vm_page_prev(vm_page_t m)
{
vm_page_t prev;
VM_OBJECT_ASSERT_WLOCKED(m->object);
if ((prev = TAILQ_PREV(m, pglist, listq)) != NULL &&
prev->pindex != m->pindex - 1)
prev = NULL;
return (prev);
}
/*
* vm_page_rename:
*
* Move the given memory entry from its
* current object to the specified target object/offset.
*
* Note: swap associated with the page must be invalidated by the move. We
* have to do this for several reasons: (1) we aren't freeing the
* page, (2) we are dirtying the page, (3) the VM system is probably
* moving the page from object A to B, and will then later move
* the backing store from A to B and we can't have a conflict.
*
* Note: we *always* dirty the page. It is necessary both for the
* fact that we moved it, and because we may be invalidating
* swap. If the page is on the cache, we have to deactivate it
* or vm_page_dirty() will panic. Dirty pages are not allowed
* on the cache.
*
* The objects must be locked. The page must be locked if it is managed.
*/
void
vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex)
{
vm_page_remove(m);
vm_page_insert(m, new_object, new_pindex);
vm_page_dirty(m);
}
/*
* Convert all of the given object's cached pages that have a
* pindex within the given range into free pages. If the value
* zero is given for "end", then the range's upper bound is
* infinity. If the given object is backed by a vnode and it
* transitions from having one or more cached pages to none, the
* vnode's hold count is reduced.
*/
void
vm_page_cache_free(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
{
vm_page_t m;
boolean_t empty;
mtx_lock(&vm_page_queue_free_mtx);
if (__predict_false(vm_radix_is_empty(&object->cache))) {
mtx_unlock(&vm_page_queue_free_mtx);
return;
}
while ((m = vm_radix_lookup_ge(&object->cache, start)) != NULL) {
if (end != 0 && m->pindex >= end)
break;
vm_radix_remove(&object->cache, m->pindex);
m->object = NULL;
m->valid = 0;
/* Clear PG_CACHED and set PG_FREE. */
m->flags ^= PG_CACHED | PG_FREE;
KASSERT((m->flags & (PG_CACHED | PG_FREE)) == PG_FREE,
("vm_page_cache_free: page %p has inconsistent flags", m));
cnt.v_cache_count--;
cnt.v_free_count++;
}
empty = vm_radix_is_empty(&object->cache);
mtx_unlock(&vm_page_queue_free_mtx);
if (object->type == OBJT_VNODE && empty)
vdrop(object->handle);
}
/*
* Returns the cached page that is associated with the given
* object and offset. If, however, none exists, returns NULL.
*
* The free page queue must be locked.
*/
static inline vm_page_t
vm_page_cache_lookup(vm_object_t object, vm_pindex_t pindex)
{
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
return (vm_radix_lookup(&object->cache, pindex));
}
/*
* Remove the given cached page from its containing object's
* collection of cached pages.
*
* The free page queue must be locked.
*/
static void
vm_page_cache_remove(vm_page_t m)
{
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
KASSERT((m->flags & PG_CACHED) != 0,
("vm_page_cache_remove: page %p is not cached", m));
vm_radix_remove(&m->object->cache, m->pindex);
m->object = NULL;
cnt.v_cache_count--;
}
/*
* Transfer all of the cached pages with offset greater than or
* equal to 'offidxstart' from the original object's cache to the
* new object's cache. However, any cached pages with offset
* greater than or equal to the new object's size are kept in the
* original object. Initially, the new object's cache must be
* empty. Offset 'offidxstart' in the original object must
* correspond to offset zero in the new object.
*
* The new object must be locked.
*/
void
vm_page_cache_transfer(vm_object_t orig_object, vm_pindex_t offidxstart,
vm_object_t new_object)
{
vm_page_t m;
/*
* Insertion into an object's collection of cached pages
* requires the object to be locked. In contrast, removal does
* not.
*/
VM_OBJECT_ASSERT_WLOCKED(new_object);
KASSERT(vm_radix_is_empty(&new_object->cache),
("vm_page_cache_transfer: object %p has cached pages",
new_object));
mtx_lock(&vm_page_queue_free_mtx);
while ((m = vm_radix_lookup_ge(&orig_object->cache,
offidxstart)) != NULL) {
/*
* Transfer all of the pages with offset greater than or
* equal to 'offidxstart' from the original object's
* cache to the new object's cache.
*/
if ((m->pindex - offidxstart) >= new_object->size)
break;
vm_radix_remove(&orig_object->cache, m->pindex);
/* Update the page's object and offset. */
m->object = new_object;
m->pindex -= offidxstart;
vm_radix_insert(&new_object->cache, m);
}
mtx_unlock(&vm_page_queue_free_mtx);
}
/*
* Returns TRUE if a cached page is associated with the given object and
* offset, and FALSE otherwise.
*
* The object must be locked.
*/
boolean_t
vm_page_is_cached(vm_object_t object, vm_pindex_t pindex)
{
vm_page_t m;
/*
* Insertion into an object's collection of cached pages requires the
* object to be locked. Therefore, if the object is locked and the
* object's collection is empty, there is no need to acquire the free
* page queues lock in order to prove that the specified page doesn't
* exist.
*/
VM_OBJECT_ASSERT_WLOCKED(object);
if (__predict_true(vm_object_cache_is_empty(object)))
return (FALSE);
mtx_lock(&vm_page_queue_free_mtx);
m = vm_page_cache_lookup(object, pindex);
mtx_unlock(&vm_page_queue_free_mtx);
return (m != NULL);
}
/*
* vm_page_alloc:
*
* Allocate and return a page that is associated with the specified
* object and offset pair. By default, this page has the flag VPO_BUSY
* set.
*
* The caller must always specify an allocation class.
*
* allocation classes:
* VM_ALLOC_NORMAL normal process request
* VM_ALLOC_SYSTEM system *really* needs a page
* VM_ALLOC_INTERRUPT interrupt time request
*
* optional allocation flags:
* VM_ALLOC_COUNT(number) the number of additional pages that the caller
* intends to allocate
* VM_ALLOC_IFCACHED return page only if it is cached
* VM_ALLOC_IFNOTCACHED return NULL, do not reactivate if the page
* is cached
* VM_ALLOC_NOBUSY do not set the flag VPO_BUSY on the page
* VM_ALLOC_NODUMP do not include the page in a kernel core dump
* VM_ALLOC_NOOBJ page is not associated with an object and
* should not have the flag VPO_BUSY set
* VM_ALLOC_WIRED wire the allocated page
* VM_ALLOC_ZERO prefer a zeroed page
*
* This routine may not sleep.
*/
vm_page_t
vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req)
{
struct vnode *vp = NULL;
vm_object_t m_object;
vm_page_t m, mpred;
int flags, req_class;
mpred = 0; /* XXX: pacify gcc */
KASSERT((object != NULL) == ((req & VM_ALLOC_NOOBJ) == 0),
("vm_page_alloc: inconsistent object/req"));
if (object != NULL)
VM_OBJECT_ASSERT_WLOCKED(object);
req_class = req & VM_ALLOC_CLASS_MASK;
/*
* The page daemon is allowed to dig deeper into the free page list.
*/
if (curproc == pageproc && req_class != VM_ALLOC_INTERRUPT)
req_class = VM_ALLOC_SYSTEM;
if (object != NULL) {
mpred = vm_radix_lookup_le(&object->rtree, pindex);
KASSERT(mpred == NULL || mpred->pindex != pindex,
("vm_page_alloc: pindex already allocated"));
}
mtx_lock(&vm_page_queue_free_mtx);
if (cnt.v_free_count + cnt.v_cache_count > cnt.v_free_reserved ||
(req_class == VM_ALLOC_SYSTEM &&
cnt.v_free_count + cnt.v_cache_count > cnt.v_interrupt_free_min) ||
(req_class == VM_ALLOC_INTERRUPT &&
cnt.v_free_count + cnt.v_cache_count > 0)) {
/*
* Allocate from the free queue if the number of free pages
* exceeds the minimum for the request class.
*/
if (object != NULL &&
(m = vm_page_cache_lookup(object, pindex)) != NULL) {
if ((req & VM_ALLOC_IFNOTCACHED) != 0) {
mtx_unlock(&vm_page_queue_free_mtx);
return (NULL);
}
if (vm_phys_unfree_page(m))
vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m, 0);
#if VM_NRESERVLEVEL > 0
else if (!vm_reserv_reactivate_page(m))
#else
else
#endif
panic("vm_page_alloc: cache page %p is missing"
" from the free queue", m);
} else if ((req & VM_ALLOC_IFCACHED) != 0) {
mtx_unlock(&vm_page_queue_free_mtx);
return (NULL);
#if VM_NRESERVLEVEL > 0
} else if (object == NULL || (object->flags & (OBJ_COLORED |
OBJ_FICTITIOUS)) != OBJ_COLORED || (m =
vm_reserv_alloc_page(object, pindex, mpred)) == NULL) {
#else
} else {
#endif
m = vm_phys_alloc_pages(object != NULL ?
VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRECT, 0);
#if VM_NRESERVLEVEL > 0
if (m == NULL && vm_reserv_reclaim_inactive()) {
m = vm_phys_alloc_pages(object != NULL ?
VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRECT,
0);
}
#endif
}
} else {
/*
* Not allocatable, give up.
*/
mtx_unlock(&vm_page_queue_free_mtx);
atomic_add_int(&vm_pageout_deficit,
max((u_int)req >> VM_ALLOC_COUNT_SHIFT, 1));
pagedaemon_wakeup();
return (NULL);
}
/*
* At this point we had better have found a good page.
*/
KASSERT(m != NULL, ("vm_page_alloc: missing page"));
KASSERT(m->queue == PQ_NONE,
("vm_page_alloc: page %p has unexpected queue %d", m, m->queue));
KASSERT(m->wire_count == 0, ("vm_page_alloc: page %p is wired", m));
KASSERT(m->hold_count == 0, ("vm_page_alloc: page %p is held", m));
KASSERT(m->busy == 0, ("vm_page_alloc: page %p is busy", m));
KASSERT(m->dirty == 0, ("vm_page_alloc: page %p is dirty", m));
KASSERT(pmap_page_get_memattr(m) == VM_MEMATTR_DEFAULT,
("vm_page_alloc: page %p has unexpected memattr %d", m,
pmap_page_get_memattr(m)));
if ((m->flags & PG_CACHED) != 0) {
KASSERT((m->flags & PG_ZERO) == 0,
("vm_page_alloc: cached page %p is PG_ZERO", m));
KASSERT(m->valid != 0,
("vm_page_alloc: cached page %p is invalid", m));
if (m->object == object && m->pindex == pindex)
cnt.v_reactivated++;
else
m->valid = 0;
m_object = m->object;
vm_page_cache_remove(m);
if (m_object->type == OBJT_VNODE &&
vm_object_cache_is_empty(m_object))
vp = m_object->handle;
} else {
KASSERT(VM_PAGE_IS_FREE(m),
("vm_page_alloc: page %p is not free", m));
KASSERT(m->valid == 0,
("vm_page_alloc: free page %p is valid", m));
cnt.v_free_count--;
}
/*
* Only the PG_ZERO flag is inherited. The PG_CACHED or PG_FREE flag
* must be cleared before the free page queues lock is released.
*/
flags = 0;
if (m->flags & PG_ZERO) {
vm_page_zero_count--;
if (req & VM_ALLOC_ZERO)
flags = PG_ZERO;
}
if (req & VM_ALLOC_NODUMP)
flags |= PG_NODUMP;
m->flags = flags;
mtx_unlock(&vm_page_queue_free_mtx);
m->aflags = 0;
m->oflags = object == NULL || (object->flags & OBJ_UNMANAGED) != 0 ?
VPO_UNMANAGED : 0;
if ((req & (VM_ALLOC_NOBUSY | VM_ALLOC_NOOBJ)) == 0)
m->oflags |= VPO_BUSY;
if (req & VM_ALLOC_WIRED) {
/*
* The page lock is not required for wiring a page until that
* page is inserted into the object.
*/
atomic_add_int(&cnt.v_wire_count, 1);
m->wire_count = 1;
}
m->act_count = 0;
if (object != NULL) {
/* Ignore device objects; the pager sets "memattr" for them. */
if (object->memattr != VM_MEMATTR_DEFAULT &&
(object->flags & OBJ_FICTITIOUS) == 0)
pmap_page_set_memattr(m, object->memattr);
vm_page_insert_after(m, object, pindex, mpred);
} else
m->pindex = pindex;
/*
* The following call to vdrop() must come after the above call
* to vm_page_insert() in case both affect the same object and
* vnode. Otherwise, the affected vnode's hold count could
* temporarily become zero.
*/
if (vp != NULL)
vdrop(vp);
/*
* Don't wakeup too often - wakeup the pageout daemon when
* we would be nearly out of memory.
*/
if (vm_paging_needed())
pagedaemon_wakeup();
return (m);
}
/*
* vm_page_alloc_contig:
*
* Allocate a contiguous set of physical pages of the given size "npages"
* from the free lists. All of the physical pages must be at or above
* the given physical address "low" and below the given physical address
* "high". The given value "alignment" determines the alignment of the
* first physical page in the set. If the given value "boundary" is
* non-zero, then the set of physical pages cannot cross any physical
* address boundary that is a multiple of that value. Both "alignment"
* and "boundary" must be a power of two.
*
* If the specified memory attribute, "memattr", is VM_MEMATTR_DEFAULT,
* then the memory attribute setting for the physical pages is configured
* to the object's memory attribute setting. Otherwise, the memory
* attribute setting for the physical pages is configured to "memattr",
* overriding the object's memory attribute setting. However, if the
* object's memory attribute setting is not VM_MEMATTR_DEFAULT, then the
* memory attribute setting for the physical pages cannot be configured
* to VM_MEMATTR_DEFAULT.
*
* The caller must always specify an allocation class.
*
* allocation classes:
* VM_ALLOC_NORMAL normal process request
* VM_ALLOC_SYSTEM system *really* needs a page
* VM_ALLOC_INTERRUPT interrupt time request
*
* optional allocation flags:
* VM_ALLOC_NOBUSY do not set the flag VPO_BUSY on the page
* VM_ALLOC_NOOBJ page is not associated with an object and
* should not have the flag VPO_BUSY set
* VM_ALLOC_WIRED wire the allocated page
* VM_ALLOC_ZERO prefer a zeroed page
*
* This routine may not sleep.
*/
vm_page_t
vm_page_alloc_contig(vm_object_t object, vm_pindex_t pindex, int req,
u_long npages, vm_paddr_t low, vm_paddr_t high, u_long alignment,
vm_paddr_t boundary, vm_memattr_t memattr)
{
struct vnode *drop;
vm_page_t deferred_vdrop_list, m, m_ret;
u_int flags, oflags;
int req_class;
KASSERT((object != NULL) == ((req & VM_ALLOC_NOOBJ) == 0),
("vm_page_alloc_contig: inconsistent object/req"));
if (object != NULL) {
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT(object->type == OBJT_PHYS,
("vm_page_alloc_contig: object %p isn't OBJT_PHYS",
object));
}
KASSERT(npages > 0, ("vm_page_alloc_contig: npages is zero"));
req_class = req & VM_ALLOC_CLASS_MASK;
/*
* The page daemon is allowed to dig deeper into the free page list.
*/
if (curproc == pageproc && req_class != VM_ALLOC_INTERRUPT)
req_class = VM_ALLOC_SYSTEM;
deferred_vdrop_list = NULL;
mtx_lock(&vm_page_queue_free_mtx);
if (cnt.v_free_count + cnt.v_cache_count >= npages +
cnt.v_free_reserved || (req_class == VM_ALLOC_SYSTEM &&
cnt.v_free_count + cnt.v_cache_count >= npages +
cnt.v_interrupt_free_min) || (req_class == VM_ALLOC_INTERRUPT &&
cnt.v_free_count + cnt.v_cache_count >= npages)) {
#if VM_NRESERVLEVEL > 0
retry:
if (object == NULL || (object->flags & OBJ_COLORED) == 0 ||
(m_ret = vm_reserv_alloc_contig(object, pindex, npages,
low, high, alignment, boundary)) == NULL)
#endif
m_ret = vm_phys_alloc_contig(npages, low, high,
alignment, boundary);
} else {
mtx_unlock(&vm_page_queue_free_mtx);
atomic_add_int(&vm_pageout_deficit, npages);
pagedaemon_wakeup();
return (NULL);
}
if (m_ret != NULL)
for (m = m_ret; m < &m_ret[npages]; m++) {
drop = vm_page_alloc_init(m);
if (drop != NULL) {
/*
* Enqueue the vnode for deferred vdrop().
*
* Once the pages are removed from the free
* page list, "pageq" can be safely abused to
* construct a short-lived list of vnodes.
*/
m->pageq.tqe_prev = (void *)drop;
m->pageq.tqe_next = deferred_vdrop_list;
deferred_vdrop_list = m;
}
}
else {
#if VM_NRESERVLEVEL > 0
if (vm_reserv_reclaim_contig(npages, low, high, alignment,
boundary))
goto retry;
#endif
}
mtx_unlock(&vm_page_queue_free_mtx);
if (m_ret == NULL)
return (NULL);
/*
* Initialize the pages. Only the PG_ZERO flag is inherited.
*/
flags = 0;
if ((req & VM_ALLOC_ZERO) != 0)
flags = PG_ZERO;
if ((req & VM_ALLOC_NODUMP) != 0)
flags |= PG_NODUMP;
if ((req & VM_ALLOC_WIRED) != 0)
atomic_add_int(&cnt.v_wire_count, npages);
oflags = VPO_UNMANAGED;
if (object != NULL) {
if ((req & VM_ALLOC_NOBUSY) == 0)
oflags |= VPO_BUSY;
if (object->memattr != VM_MEMATTR_DEFAULT &&
memattr == VM_MEMATTR_DEFAULT)
memattr = object->memattr;
}
for (m = m_ret; m < &m_ret[npages]; m++) {
m->aflags = 0;
m->flags = (m->flags | PG_NODUMP) & flags;
if ((req & VM_ALLOC_WIRED) != 0)
m->wire_count = 1;
/* Unmanaged pages don't use "act_count". */
m->oflags = oflags;
if (memattr != VM_MEMATTR_DEFAULT)
pmap_page_set_memattr(m, memattr);
if (object != NULL)
vm_page_insert(m, object, pindex);
else
m->pindex = pindex;
pindex++;
}
while (deferred_vdrop_list != NULL) {
vdrop((struct vnode *)deferred_vdrop_list->pageq.tqe_prev);
deferred_vdrop_list = deferred_vdrop_list->pageq.tqe_next;
}
if (vm_paging_needed())
pagedaemon_wakeup();
return (m_ret);
}
/*
* Initialize a page that has been freshly dequeued from a freelist.
* The caller has to drop the vnode returned, if it is not NULL.
*
* This function may only be used to initialize unmanaged pages.
*
* To be called with vm_page_queue_free_mtx held.
*/
static struct vnode *
vm_page_alloc_init(vm_page_t m)
{
struct vnode *drop;
vm_object_t m_object;
KASSERT(m->queue == PQ_NONE,
("vm_page_alloc_init: page %p has unexpected queue %d",
m, m->queue));
KASSERT(m->wire_count == 0,
("vm_page_alloc_init: page %p is wired", m));
KASSERT(m->hold_count == 0,
("vm_page_alloc_init: page %p is held", m));
KASSERT(m->busy == 0,
("vm_page_alloc_init: page %p is busy", m));
KASSERT(m->dirty == 0,
("vm_page_alloc_init: page %p is dirty", m));
KASSERT(pmap_page_get_memattr(m) == VM_MEMATTR_DEFAULT,
("vm_page_alloc_init: page %p has unexpected memattr %d",
m, pmap_page_get_memattr(m)));
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
drop = NULL;
if ((m->flags & PG_CACHED) != 0) {
KASSERT((m->flags & PG_ZERO) == 0,
("vm_page_alloc_init: cached page %p is PG_ZERO", m));
m->valid = 0;
m_object = m->object;
vm_page_cache_remove(m);
if (m_object->type == OBJT_VNODE &&
vm_object_cache_is_empty(m_object))
drop = m_object->handle;
} else {
KASSERT(VM_PAGE_IS_FREE(m),
("vm_page_alloc_init: page %p is not free", m));
KASSERT(m->valid == 0,
("vm_page_alloc_init: free page %p is valid", m));
cnt.v_free_count--;
if ((m->flags & PG_ZERO) != 0)
vm_page_zero_count--;
}
/* Don't clear the PG_ZERO flag; we'll need it later. */
m->flags &= PG_ZERO;
return (drop);
}
/*
* vm_page_alloc_freelist:
*
* Allocate a physical page from the specified free page list.
*
* The caller must always specify an allocation class.
*
* allocation classes:
* VM_ALLOC_NORMAL normal process request
* VM_ALLOC_SYSTEM system *really* needs a page
* VM_ALLOC_INTERRUPT interrupt time request
*
* optional allocation flags:
* VM_ALLOC_COUNT(number) the number of additional pages that the caller
* intends to allocate
* VM_ALLOC_WIRED wire the allocated page
* VM_ALLOC_ZERO prefer a zeroed page
*
* This routine may not sleep.
*/
vm_page_t
vm_page_alloc_freelist(int flind, int req)
{
struct vnode *drop;
vm_page_t m;
u_int flags;
int req_class;
req_class = req & VM_ALLOC_CLASS_MASK;
/*
* The page daemon is allowed to dig deeper into the free page list.
*/
if (curproc == pageproc && req_class != VM_ALLOC_INTERRUPT)
req_class = VM_ALLOC_SYSTEM;
/*
* Do not allocate reserved pages unless the req has asked for it.
*/
mtx_lock(&vm_page_queue_free_mtx);
if (cnt.v_free_count + cnt.v_cache_count > cnt.v_free_reserved ||
(req_class == VM_ALLOC_SYSTEM &&
cnt.v_free_count + cnt.v_cache_count > cnt.v_interrupt_free_min) ||
(req_class == VM_ALLOC_INTERRUPT &&
cnt.v_free_count + cnt.v_cache_count > 0))
m = vm_phys_alloc_freelist_pages(flind, VM_FREEPOOL_DIRECT, 0);
else {
mtx_unlock(&vm_page_queue_free_mtx);
atomic_add_int(&vm_pageout_deficit,
max((u_int)req >> VM_ALLOC_COUNT_SHIFT, 1));
pagedaemon_wakeup();
return (NULL);
}
if (m == NULL) {
mtx_unlock(&vm_page_queue_free_mtx);
return (NULL);
}
drop = vm_page_alloc_init(m);
mtx_unlock(&vm_page_queue_free_mtx);
/*
* Initialize the page. Only the PG_ZERO flag is inherited.
*/
m->aflags = 0;
flags = 0;
if ((req & VM_ALLOC_ZERO) != 0)
flags = PG_ZERO;
m->flags &= flags;
if ((req & VM_ALLOC_WIRED) != 0) {
/*
* The page lock is not required for wiring a page that does
* not belong to an object.
*/
atomic_add_int(&cnt.v_wire_count, 1);
m->wire_count = 1;
}
/* Unmanaged pages don't use "act_count". */
m->oflags = VPO_UNMANAGED;
if (drop != NULL)
vdrop(drop);
if (vm_paging_needed())
pagedaemon_wakeup();
return (m);
}
/*
* vm_wait: (also see VM_WAIT macro)
*
* Sleep until free pages are available for allocation.
* - Called in various places before memory allocations.
*/
void
vm_wait(void)
{
mtx_lock(&vm_page_queue_free_mtx);
if (curproc == pageproc) {
vm_pageout_pages_needed = 1;
msleep(&vm_pageout_pages_needed, &vm_page_queue_free_mtx,
PDROP | PSWP, "VMWait", 0);
} else {
if (!vm_pages_needed) {
vm_pages_needed = 1;
wakeup(&vm_pages_needed);
}
msleep(&cnt.v_free_count, &vm_page_queue_free_mtx, PDROP | PVM,
"vmwait", 0);
}
}
/*
* vm_waitpfault: (also see VM_WAITPFAULT macro)
*
* Sleep until free pages are available for allocation.
* - Called only in vm_fault so that processes page faulting
* can be easily tracked.
* - Sleeps at a lower priority than vm_wait() so that vm_wait()ing
* processes will be able to grab memory first. Do not change
* this balance without careful testing first.
*/
void
vm_waitpfault(void)
{
mtx_lock(&vm_page_queue_free_mtx);
if (!vm_pages_needed) {
vm_pages_needed = 1;
wakeup(&vm_pages_needed);
}
msleep(&cnt.v_free_count, &vm_page_queue_free_mtx, PDROP | PUSER,
"pfault", 0);
}
/*
* vm_page_dequeue:
*
* Remove the given page from its current page queue.
*
* The page must be locked.
*/
void
vm_page_dequeue(vm_page_t m)
{
struct vm_pagequeue *pq;
vm_page_lock_assert(m, MA_OWNED);
KASSERT(m->queue != PQ_NONE,
("vm_page_dequeue: page %p is not queued", m));
pq = &vm_pagequeues[m->queue];
vm_pagequeue_lock(pq);
m->queue = PQ_NONE;
TAILQ_REMOVE(&pq->pq_pl, m, pageq);
(*pq->pq_cnt)--;
vm_pagequeue_unlock(pq);
}
/*
* vm_page_dequeue_locked:
*
* Remove the given page from its current page queue.
*
* The page and page queue must be locked.
*/
void
vm_page_dequeue_locked(vm_page_t m)
{
struct vm_pagequeue *pq;
vm_page_lock_assert(m, MA_OWNED);
pq = &vm_pagequeues[m->queue];
vm_pagequeue_assert_locked(pq);
m->queue = PQ_NONE;
TAILQ_REMOVE(&pq->pq_pl, m, pageq);
(*pq->pq_cnt)--;
}
/*
* vm_page_enqueue:
*
* Add the given page to the specified page queue.
*
* The page must be locked.
*/
static void
vm_page_enqueue(int queue, vm_page_t m)
{
struct vm_pagequeue *pq;
vm_page_lock_assert(m, MA_OWNED);
pq = &vm_pagequeues[queue];
vm_pagequeue_lock(pq);
m->queue = queue;
TAILQ_INSERT_TAIL(&pq->pq_pl, m, pageq);
++*pq->pq_cnt;
vm_pagequeue_unlock(pq);
}
/*
* vm_page_requeue:
*
* Move the given page to the tail of its current page queue.
*
* The page must be locked.
*/
void
vm_page_requeue(vm_page_t m)
{
struct vm_pagequeue *pq;
vm_page_lock_assert(m, MA_OWNED);
KASSERT(m->queue != PQ_NONE,
("vm_page_requeue: page %p is not queued", m));
pq = &vm_pagequeues[m->queue];
vm_pagequeue_lock(pq);
TAILQ_REMOVE(&pq->pq_pl, m, pageq);
TAILQ_INSERT_TAIL(&pq->pq_pl, m, pageq);
vm_pagequeue_unlock(pq);
}
/*
* vm_page_requeue_locked:
*
* Move the given page to the tail of its current page queue.
*
* The page queue must be locked.
*/
void
vm_page_requeue_locked(vm_page_t m)
{
struct vm_pagequeue *pq;
KASSERT(m->queue != PQ_NONE,
("vm_page_requeue_locked: page %p is not queued", m));
pq = &vm_pagequeues[m->queue];
vm_pagequeue_assert_locked(pq);
TAILQ_REMOVE(&pq->pq_pl, m, pageq);
TAILQ_INSERT_TAIL(&pq->pq_pl, m, pageq);
}
/*
* vm_page_activate:
*
* Put the specified page on the active list (if appropriate).
* Ensure that act_count is at least ACT_INIT but do not otherwise
* mess with it.
*
* The page must be locked.
*/
void
vm_page_activate(vm_page_t m)
{
int queue;
vm_page_lock_assert(m, MA_OWNED);
if ((queue = m->queue) != PQ_ACTIVE) {
if (m->wire_count == 0 && (m->oflags & VPO_UNMANAGED) == 0) {
if (m->act_count < ACT_INIT)
m->act_count = ACT_INIT;
if (queue != PQ_NONE)
vm_page_dequeue(m);
vm_page_enqueue(PQ_ACTIVE, m);
} else
KASSERT(queue == PQ_NONE,
("vm_page_activate: wired page %p is queued", m));
} else {
if (m->act_count < ACT_INIT)
m->act_count = ACT_INIT;
}
}
/*
* vm_page_free_wakeup:
*
* Helper routine for vm_page_free_toq() and vm_page_cache(). This
* routine is called when a page has been added to the cache or free
* queues.
*
* The page queues must be locked.
*/
static inline void
vm_page_free_wakeup(void)
{
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
/*
* if pageout daemon needs pages, then tell it that there are
* some free.
*/
if (vm_pageout_pages_needed &&
cnt.v_cache_count + cnt.v_free_count >= cnt.v_pageout_free_min) {
wakeup(&vm_pageout_pages_needed);
vm_pageout_pages_needed = 0;
}
/*
* wakeup processes that are waiting on memory if we hit a
* high water mark. And wakeup scheduler process if we have
* lots of memory. this process will swapin processes.
*/
if (vm_pages_needed && !vm_page_count_min()) {
vm_pages_needed = 0;
wakeup(&cnt.v_free_count);
}
}
/*
* vm_page_free_toq:
*
* Returns the given page to the free list,
* disassociating it with any VM object.
*
* The object must be locked. The page must be locked if it is managed.
*/
void
vm_page_free_toq(vm_page_t m)
{
if ((m->oflags & VPO_UNMANAGED) == 0) {
vm_page_lock_assert(m, MA_OWNED);
KASSERT(!pmap_page_is_mapped(m),
("vm_page_free_toq: freeing mapped page %p", m));
} else
KASSERT(m->queue == PQ_NONE,
("vm_page_free_toq: unmanaged page %p is queued", m));
PCPU_INC(cnt.v_tfree);
if (VM_PAGE_IS_FREE(m))
panic("vm_page_free: freeing free page %p", m);
else if (m->busy != 0)
panic("vm_page_free: freeing busy page %p", m);
/*
* Unqueue, then remove page. Note that we cannot destroy
* the page here because we do not want to call the pager's
* callback routine until after we've put the page on the
* appropriate free queue.
*/
vm_page_remque(m);
vm_page_remove(m);
/*
* If fictitious remove object association and
* return, otherwise delay object association removal.
*/
if ((m->flags & PG_FICTITIOUS) != 0) {
return;
}
m->valid = 0;
vm_page_undirty(m);
if (m->wire_count != 0)
panic("vm_page_free: freeing wired page %p", m);
if (m->hold_count != 0) {
m->flags &= ~PG_ZERO;
KASSERT((m->flags & PG_UNHOLDFREE) == 0,
("vm_page_free: freeing PG_UNHOLDFREE page %p", m));
m->flags |= PG_UNHOLDFREE;
} else {
/*
* Restore the default memory attribute to the page.
*/
if (pmap_page_get_memattr(m) != VM_MEMATTR_DEFAULT)
pmap_page_set_memattr(m, VM_MEMATTR_DEFAULT);
/*
* Insert the page into the physical memory allocator's
* cache/free page queues.
*/
mtx_lock(&vm_page_queue_free_mtx);
m->flags |= PG_FREE;
cnt.v_free_count++;
#if VM_NRESERVLEVEL > 0
if (!vm_reserv_free_page(m))
#else
if (TRUE)
#endif
vm_phys_free_pages(m, 0);
if ((m->flags & PG_ZERO) != 0)
++vm_page_zero_count;
else
vm_page_zero_idle_wakeup();
vm_page_free_wakeup();
mtx_unlock(&vm_page_queue_free_mtx);
}
}
/*
* vm_page_wire:
*
* Mark this page as wired down by yet
* another map, removing it from paging queues
* as necessary.
*
* If the page is fictitious, then its wire count must remain one.
*
* The page must be locked.
*/
void
vm_page_wire(vm_page_t m)
{
/*
* Only bump the wire statistics if the page is not already wired,
* and only unqueue the page if it is on some queue (if it is unmanaged
* it is already off the queues).
*/
vm_page_lock_assert(m, MA_OWNED);
if ((m->flags & PG_FICTITIOUS) != 0) {
KASSERT(m->wire_count == 1,
("vm_page_wire: fictitious page %p's wire count isn't one",
m));
return;
}
if (m->wire_count == 0) {
KASSERT((m->oflags & VPO_UNMANAGED) == 0 ||
m->queue == PQ_NONE,
("vm_page_wire: unmanaged page %p is queued", m));
vm_page_remque(m);
atomic_add_int(&cnt.v_wire_count, 1);
}
m->wire_count++;
KASSERT(m->wire_count != 0, ("vm_page_wire: wire_count overflow m=%p", m));
}
/*
* vm_page_unwire:
*
* Release one wiring of the specified page, potentially enabling it to be
* paged again. If paging is enabled, then the value of the parameter
* "activate" determines to which queue the page is added. If "activate" is
* non-zero, then the page is added to the active queue. Otherwise, it is
* added to the inactive queue.
*
* However, unless the page belongs to an object, it is not enqueued because
* it cannot be paged out.
*
* If a page is fictitious, then its wire count must always be one.
*
* A managed page must be locked.
*/
void
vm_page_unwire(vm_page_t m, int activate)
{
if ((m->oflags & VPO_UNMANAGED) == 0)
vm_page_lock_assert(m, MA_OWNED);
if ((m->flags & PG_FICTITIOUS) != 0) {
KASSERT(m->wire_count == 1,
("vm_page_unwire: fictitious page %p's wire count isn't one", m));
return;
}
if (m->wire_count > 0) {
m->wire_count--;
if (m->wire_count == 0) {
atomic_subtract_int(&cnt.v_wire_count, 1);
if ((m->oflags & VPO_UNMANAGED) != 0 ||
m->object == NULL)
return;
if (!activate)
m->flags &= ~PG_WINATCFLS;
vm_page_enqueue(activate ? PQ_ACTIVE : PQ_INACTIVE, m);
}
} else
panic("vm_page_unwire: page %p's wire count is zero", m);
}
/*
* Move the specified page to the inactive queue.
*
* Many pages placed on the inactive queue should actually go
* into the cache, but it is difficult to figure out which. What
* we do instead, if the inactive target is well met, is to put
* clean pages at the head of the inactive queue instead of the tail.
* This will cause them to be moved to the cache more quickly and
* if not actively re-referenced, reclaimed more quickly. If we just
* stick these pages at the end of the inactive queue, heavy filesystem
* meta-data accesses can cause an unnecessary paging load on memory bound
* processes. This optimization causes one-time-use metadata to be
* reused more quickly.
*
* Normally athead is 0 resulting in LRU operation. athead is set
* to 1 if we want this page to be 'as if it were placed in the cache',
* except without unmapping it from the process address space.
*
* The page must be locked.
*/
static inline void
_vm_page_deactivate(vm_page_t m, int athead)
{
struct vm_pagequeue *pq;
int queue;
vm_page_lock_assert(m, MA_OWNED);
/*
* Ignore if already inactive.
*/
if ((queue = m->queue) == PQ_INACTIVE)
return;
if (m->wire_count == 0 && (m->oflags & VPO_UNMANAGED) == 0) {
if (queue != PQ_NONE)
vm_page_dequeue(m);
m->flags &= ~PG_WINATCFLS;
pq = &vm_pagequeues[PQ_INACTIVE];
vm_pagequeue_lock(pq);
m->queue = PQ_INACTIVE;
if (athead)
TAILQ_INSERT_HEAD(&pq->pq_pl, m, pageq);
else
TAILQ_INSERT_TAIL(&pq->pq_pl, m, pageq);
cnt.v_inactive_count++;
vm_pagequeue_unlock(pq);
}
}
/*
* Move the specified page to the inactive queue.
*
* The page must be locked.
*/
void
vm_page_deactivate(vm_page_t m)
{
_vm_page_deactivate(m, 0);
}
/*
* vm_page_try_to_cache:
*
* Returns 0 on failure, 1 on success
*/
int
vm_page_try_to_cache(vm_page_t m)
{
vm_page_lock_assert(m, MA_OWNED);
VM_OBJECT_ASSERT_WLOCKED(m->object);
if (m->dirty || m->hold_count || m->busy || m->wire_count ||
(m->oflags & (VPO_BUSY | VPO_UNMANAGED)) != 0)
return (0);
pmap_remove_all(m);
if (m->dirty)
return (0);
vm_page_cache(m);
return (1);
}
/*
* vm_page_try_to_free()
*
* Attempt to free the page. If we cannot free it, we do nothing.
* 1 is returned on success, 0 on failure.
*/
int
vm_page_try_to_free(vm_page_t m)
{
vm_page_lock_assert(m, MA_OWNED);
if (m->object != NULL)
VM_OBJECT_ASSERT_WLOCKED(m->object);
if (m->dirty || m->hold_count || m->busy || m->wire_count ||
(m->oflags & (VPO_BUSY | VPO_UNMANAGED)) != 0)
return (0);
pmap_remove_all(m);
if (m->dirty)
return (0);
vm_page_free(m);
return (1);
}
/*
* vm_page_cache
*
* Put the specified page onto the page cache queue (if appropriate).
*
* The object and page must be locked.
*/
void
vm_page_cache(vm_page_t m)
{
vm_object_t object;
boolean_t cache_was_empty;
vm_page_lock_assert(m, MA_OWNED);
object = m->object;
VM_OBJECT_ASSERT_WLOCKED(object);
if ((m->oflags & (VPO_UNMANAGED | VPO_BUSY)) || m->busy ||
m->hold_count || m->wire_count)
panic("vm_page_cache: attempting to cache busy page");
KASSERT(!pmap_page_is_mapped(m),
("vm_page_cache: page %p is mapped", m));
KASSERT(m->dirty == 0, ("vm_page_cache: page %p is dirty", m));
if (m->valid == 0 || object->type == OBJT_DEFAULT ||
(object->type == OBJT_SWAP &&
!vm_pager_has_page(object, m->pindex, NULL, NULL))) {
/*
* Hypothesis: A cache-elgible page belonging to a
* default object or swap object but without a backing
* store must be zero filled.
*/
vm_page_free(m);
return;
}
KASSERT((m->flags & PG_CACHED) == 0,
("vm_page_cache: page %p is already cached", m));
PCPU_INC(cnt.v_tcached);
/*
* Remove the page from the paging queues.
*/
vm_page_remque(m);
/*
* Remove the page from the object's collection of resident
* pages.
*/
vm_radix_remove(&object->rtree, m->pindex);
TAILQ_REMOVE(&object->memq, m, listq);
object->resident_page_count--;
/*
* Restore the default memory attribute to the page.
*/
if (pmap_page_get_memattr(m) != VM_MEMATTR_DEFAULT)
pmap_page_set_memattr(m, VM_MEMATTR_DEFAULT);
/*
* Insert the page into the object's collection of cached pages
* and the physical memory allocator's cache/free page queues.
*/
m->flags &= ~PG_ZERO;
mtx_lock(&vm_page_queue_free_mtx);
m->flags |= PG_CACHED;
cnt.v_cache_count++;
cache_was_empty = vm_radix_is_empty(&object->cache);
vm_radix_insert(&object->cache, m);
#if VM_NRESERVLEVEL > 0
if (!vm_reserv_free_page(m)) {
#else
if (TRUE) {
#endif
vm_phys_set_pool(VM_FREEPOOL_CACHE, m, 0);
vm_phys_free_pages(m, 0);
}
vm_page_free_wakeup();
mtx_unlock(&vm_page_queue_free_mtx);
/*
* Increment the vnode's hold count if this is the object's only
* cached page. Decrement the vnode's hold count if this was
* the object's only resident page.
*/
if (object->type == OBJT_VNODE) {
if (cache_was_empty && object->resident_page_count != 0)
vhold(object->handle);
else if (!cache_was_empty && object->resident_page_count == 0)
vdrop(object->handle);
}
}
/*
* vm_page_advise
*
* Cache, deactivate, or do nothing as appropriate. This routine
* is used by madvise().
*
* Generally speaking we want to move the page into the cache so
* it gets reused quickly. However, this can result in a silly syndrome
* due to the page recycling too quickly. Small objects will not be
* fully cached. On the other hand, if we move the page to the inactive
* queue we wind up with a problem whereby very large objects
* unnecessarily blow away our inactive and cache queues.
*
* The solution is to move the pages based on a fixed weighting. We
* either leave them alone, deactivate them, or move them to the cache,
* where moving them to the cache has the highest weighting.
* By forcing some pages into other queues we eventually force the
* system to balance the queues, potentially recovering other unrelated
* space from active. The idea is to not force this to happen too
* often.
*
* The object and page must be locked.
*/
void
vm_page_advise(vm_page_t m, int advice)
{
int dnw, head;
vm_page_assert_locked(m);
VM_OBJECT_ASSERT_WLOCKED(m->object);
if (advice == MADV_FREE) {
/*
* Mark the page clean. This will allow the page to be freed
* up by the system. However, such pages are often reused
* quickly by malloc() so we do not do anything that would
* cause a page fault if we can help it.
*
* Specifically, we do not try to actually free the page now
* nor do we try to put it in the cache (which would cause a
* page fault on reuse).
*
* But we do make the page is freeable as we can without
* actually taking the step of unmapping it.
*/
pmap_clear_modify(m);
m->dirty = 0;
m->act_count = 0;
} else if (advice != MADV_DONTNEED)
return;
dnw = PCPU_GET(dnweight);
PCPU_INC(dnweight);
/*
* Occasionally leave the page alone.
*/
if ((dnw & 0x01F0) == 0 || m->queue == PQ_INACTIVE) {
if (m->act_count >= ACT_INIT)
--m->act_count;
return;
}
/*
* Clear any references to the page. Otherwise, the page daemon will
* immediately reactivate the page.
*
* Perform the pmap_clear_reference() first. Otherwise, a concurrent
* pmap operation, such as pmap_remove(), could clear a reference in
* the pmap and set PGA_REFERENCED on the page before the
* pmap_clear_reference() had completed. Consequently, the page would
* appear referenced based upon an old reference that occurred before
* this function ran.
*/
pmap_clear_reference(m);
vm_page_aflag_clear(m, PGA_REFERENCED);
if (advice != MADV_FREE && m->dirty == 0 && pmap_is_modified(m))
vm_page_dirty(m);
if (m->dirty || (dnw & 0x0070) == 0) {
/*
* Deactivate the page 3 times out of 32.
*/
head = 0;
} else {
/*
* Cache the page 28 times out of every 32. Note that
* the page is deactivated instead of cached, but placed
* at the head of the queue instead of the tail.
*/
head = 1;
}
_vm_page_deactivate(m, head);
}
/*
* Grab a page, waiting until we are waken up due to the page
* changing state. We keep on waiting, if the page continues
* to be in the object. If the page doesn't exist, first allocate it
* and then conditionally zero it.
*
* The caller must always specify the VM_ALLOC_RETRY flag. This is intended
* to facilitate its eventual removal.
*
* This routine may sleep.
*
* The object must be locked on entry. The lock will, however, be released
* and reacquired if the routine sleeps.
*/
vm_page_t
vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags)
{
vm_page_t m;
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT((allocflags & VM_ALLOC_RETRY) != 0,
("vm_page_grab: VM_ALLOC_RETRY is required"));
retrylookup:
if ((m = vm_page_lookup(object, pindex)) != NULL) {
if ((m->oflags & VPO_BUSY) != 0 ||
((allocflags & VM_ALLOC_IGN_SBUSY) == 0 && m->busy != 0)) {
/*
* Reference the page before unlocking and
* sleeping so that the page daemon is less
* likely to reclaim it.
*/
vm_page_aflag_set(m, PGA_REFERENCED);
vm_page_sleep(m, "pgrbwt");
goto retrylookup;
} else {
if ((allocflags & VM_ALLOC_WIRED) != 0) {
vm_page_lock(m);
vm_page_wire(m);
vm_page_unlock(m);
}
if ((allocflags & VM_ALLOC_NOBUSY) == 0)
vm_page_busy(m);
return (m);
}
}
m = vm_page_alloc(object, pindex, allocflags & ~(VM_ALLOC_RETRY |
VM_ALLOC_IGN_SBUSY));
if (m == NULL) {
VM_OBJECT_WUNLOCK(object);
VM_WAIT;
VM_OBJECT_WLOCK(object);
goto retrylookup;
} else if (m->valid != 0)
return (m);
if (allocflags & VM_ALLOC_ZERO && (m->flags & PG_ZERO) == 0)
pmap_zero_page(m);
return (m);
}
/*
* Mapping function for valid or dirty bits in a page.
*
* Inputs are required to range within a page.
*/
vm_page_bits_t
vm_page_bits(int base, int size)
{
int first_bit;
int last_bit;
KASSERT(
base + size <= PAGE_SIZE,
("vm_page_bits: illegal base/size %d/%d", base, size)
);
if (size == 0) /* handle degenerate case */
return (0);
first_bit = base >> DEV_BSHIFT;
last_bit = (base + size - 1) >> DEV_BSHIFT;
return (((vm_page_bits_t)2 << last_bit) -
((vm_page_bits_t)1 << first_bit));
}
/*
* vm_page_set_valid_range:
*
* Sets portions of a page valid. The arguments are expected
* to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive
* of any partial chunks touched by the range. The invalid portion of
* such chunks will be zeroed.
*
* (base + size) must be less then or equal to PAGE_SIZE.
*/
void
vm_page_set_valid_range(vm_page_t m, int base, int size)
{
int endoff, frag;
VM_OBJECT_ASSERT_WLOCKED(m->object);
if (size == 0) /* handle degenerate case */
return;
/*
* If the base is not DEV_BSIZE aligned and the valid
* bit is clear, we have to zero out a portion of the
* first block.
*/
if ((frag = base & ~(DEV_BSIZE - 1)) != base &&
(m->valid & (1 << (base >> DEV_BSHIFT))) == 0)
pmap_zero_page_area(m, frag, base - frag);
/*
* If the ending offset is not DEV_BSIZE aligned and the
* valid bit is clear, we have to zero out a portion of
* the last block.
*/
endoff = base + size;
if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff &&
(m->valid & (1 << (endoff >> DEV_BSHIFT))) == 0)
pmap_zero_page_area(m, endoff,
DEV_BSIZE - (endoff & (DEV_BSIZE - 1)));
/*
* Assert that no previously invalid block that is now being validated
* is already dirty.
*/
KASSERT((~m->valid & vm_page_bits(base, size) & m->dirty) == 0,
("vm_page_set_valid_range: page %p is dirty", m));
/*
* Set valid bits inclusive of any overlap.
*/
m->valid |= vm_page_bits(base, size);
}
/*
* Clear the given bits from the specified page's dirty field.
*/
static __inline void
vm_page_clear_dirty_mask(vm_page_t m, vm_page_bits_t pagebits)
{
uintptr_t addr;
#if PAGE_SIZE < 16384
int shift;
#endif
/*
* If the object is locked and the page is neither VPO_BUSY nor
* write mapped, then the page's dirty field cannot possibly be
* set by a concurrent pmap operation.
*/
VM_OBJECT_ASSERT_WLOCKED(m->object);
if ((m->oflags & VPO_BUSY) == 0 && !pmap_page_is_write_mapped(m))
m->dirty &= ~pagebits;
else {
/*
* The pmap layer can call vm_page_dirty() without
* holding a distinguished lock. The combination of
* the object's lock and an atomic operation suffice
* to guarantee consistency of the page dirty field.
*
* For PAGE_SIZE == 32768 case, compiler already
* properly aligns the dirty field, so no forcible
* alignment is needed. Only require existence of
* atomic_clear_64 when page size is 32768.
*/
addr = (uintptr_t)&m->dirty;
#if PAGE_SIZE == 32768
atomic_clear_64((uint64_t *)addr, pagebits);
#elif PAGE_SIZE == 16384
atomic_clear_32((uint32_t *)addr, pagebits);
#else /* PAGE_SIZE <= 8192 */
/*
* Use a trick to perform a 32-bit atomic on the
* containing aligned word, to not depend on the existence
* of atomic_clear_{8, 16}.
*/
shift = addr & (sizeof(uint32_t) - 1);
#if BYTE_ORDER == BIG_ENDIAN
shift = (sizeof(uint32_t) - sizeof(m->dirty) - shift) * NBBY;
#else
shift *= NBBY;
#endif
addr &= ~(sizeof(uint32_t) - 1);
atomic_clear_32((uint32_t *)addr, pagebits << shift);
#endif /* PAGE_SIZE */
}
}
/*
* vm_page_set_validclean:
*
* Sets portions of a page valid and clean. The arguments are expected
* to be DEV_BSIZE aligned but if they aren't the bitmap is inclusive
* of any partial chunks touched by the range. The invalid portion of
* such chunks will be zero'd.
*
* (base + size) must be less then or equal to PAGE_SIZE.
*/
void
vm_page_set_validclean(vm_page_t m, int base, int size)
{
vm_page_bits_t oldvalid, pagebits;
int endoff, frag;
VM_OBJECT_ASSERT_WLOCKED(m->object);
if (size == 0) /* handle degenerate case */
return;
/*
* If the base is not DEV_BSIZE aligned and the valid
* bit is clear, we have to zero out a portion of the
* first block.
*/
if ((frag = base & ~(DEV_BSIZE - 1)) != base &&
(m->valid & ((vm_page_bits_t)1 << (base >> DEV_BSHIFT))) == 0)
pmap_zero_page_area(m, frag, base - frag);
/*
* If the ending offset is not DEV_BSIZE aligned and the
* valid bit is clear, we have to zero out a portion of
* the last block.
*/
endoff = base + size;
if ((frag = endoff & ~(DEV_BSIZE - 1)) != endoff &&
(m->valid & ((vm_page_bits_t)1 << (endoff >> DEV_BSHIFT))) == 0)
pmap_zero_page_area(m, endoff,
DEV_BSIZE - (endoff & (DEV_BSIZE - 1)));
/*
* Set valid, clear dirty bits. If validating the entire
* page we can safely clear the pmap modify bit. We also
* use this opportunity to clear the VPO_NOSYNC flag. If a process
* takes a write fault on a MAP_NOSYNC memory area the flag will
* be set again.
*
* We set valid bits inclusive of any overlap, but we can only
* clear dirty bits for DEV_BSIZE chunks that are fully within
* the range.
*/
oldvalid = m->valid;
pagebits = vm_page_bits(base, size);
m->valid |= pagebits;
#if 0 /* NOT YET */
if ((frag = base & (DEV_BSIZE - 1)) != 0) {
frag = DEV_BSIZE - frag;
base += frag;
size -= frag;
if (size < 0)
size = 0;
}
pagebits = vm_page_bits(base, size & (DEV_BSIZE - 1));
#endif
if (base == 0 && size == PAGE_SIZE) {
/*
* The page can only be modified within the pmap if it is
* mapped, and it can only be mapped if it was previously
* fully valid.
*/
if (oldvalid == VM_PAGE_BITS_ALL)
/*
* Perform the pmap_clear_modify() first. Otherwise,
* a concurrent pmap operation, such as
* pmap_protect(), could clear a modification in the
* pmap and set the dirty field on the page before
* pmap_clear_modify() had begun and after the dirty
* field was cleared here.
*/
pmap_clear_modify(m);
m->dirty = 0;
m->oflags &= ~VPO_NOSYNC;
} else if (oldvalid != VM_PAGE_BITS_ALL)
m->dirty &= ~pagebits;
else
vm_page_clear_dirty_mask(m, pagebits);
}
void
vm_page_clear_dirty(vm_page_t m, int base, int size)
{
vm_page_clear_dirty_mask(m, vm_page_bits(base, size));
}
/*
* vm_page_set_invalid:
*
* Invalidates DEV_BSIZE'd chunks within a page. Both the
* valid and dirty bits for the effected areas are cleared.
*/
void
vm_page_set_invalid(vm_page_t m, int base, int size)
{
vm_page_bits_t bits;
VM_OBJECT_ASSERT_WLOCKED(m->object);
bits = vm_page_bits(base, size);
if (m->valid == VM_PAGE_BITS_ALL && bits != 0)
pmap_remove_all(m);
KASSERT(!pmap_page_is_mapped(m),
("vm_page_set_invalid: page %p is mapped", m));
m->valid &= ~bits;
m->dirty &= ~bits;
}
/*
* vm_page_zero_invalid()
*
* The kernel assumes that the invalid portions of a page contain
* garbage, but such pages can be mapped into memory by user code.
* When this occurs, we must zero out the non-valid portions of the
* page so user code sees what it expects.
*
* Pages are most often semi-valid when the end of a file is mapped
* into memory and the file's size is not page aligned.
*/
void
vm_page_zero_invalid(vm_page_t m, boolean_t setvalid)
{
int b;
int i;
VM_OBJECT_ASSERT_WLOCKED(m->object);
/*
* Scan the valid bits looking for invalid sections that
* must be zerod. Invalid sub-DEV_BSIZE'd areas ( where the
* valid bit may be set ) have already been zerod by
* vm_page_set_validclean().
*/
for (b = i = 0; i <= PAGE_SIZE / DEV_BSIZE; ++i) {
if (i == (PAGE_SIZE / DEV_BSIZE) ||
(m->valid & ((vm_page_bits_t)1 << i))) {
if (i > b) {
pmap_zero_page_area(m,
b << DEV_BSHIFT, (i - b) << DEV_BSHIFT);
}
b = i + 1;
}
}
/*
* setvalid is TRUE when we can safely set the zero'd areas
* as being valid. We can do this if there are no cache consistancy
* issues. e.g. it is ok to do with UFS, but not ok to do with NFS.
*/
if (setvalid)
m->valid = VM_PAGE_BITS_ALL;
}
/*
* vm_page_is_valid:
*
* Is (partial) page valid? Note that the case where size == 0
* will return FALSE in the degenerate case where the page is
* entirely invalid, and TRUE otherwise.
*/
int
vm_page_is_valid(vm_page_t m, int base, int size)
{
vm_page_bits_t bits;
VM_OBJECT_ASSERT_WLOCKED(m->object);
bits = vm_page_bits(base, size);
return (m->valid != 0 && (m->valid & bits) == bits);
}
/*
* Set the page's dirty bits if the page is modified.
*/
void
vm_page_test_dirty(vm_page_t m)
{
VM_OBJECT_ASSERT_WLOCKED(m->object);
if (m->dirty != VM_PAGE_BITS_ALL && pmap_is_modified(m))
vm_page_dirty(m);
}
void
vm_page_lock_KBI(vm_page_t m, const char *file, int line)
{
mtx_lock_flags_(vm_page_lockptr(m), 0, file, line);
}
void
vm_page_unlock_KBI(vm_page_t m, const char *file, int line)
{
mtx_unlock_flags_(vm_page_lockptr(m), 0, file, line);
}
int
vm_page_trylock_KBI(vm_page_t m, const char *file, int line)
{
return (mtx_trylock_flags_(vm_page_lockptr(m), 0, file, line));
}
#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
void
vm_page_assert_locked_KBI(vm_page_t m, const char *file, int line)
{
vm_page_lock_assert_KBI(m, MA_OWNED, file, line);
}
void
vm_page_lock_assert_KBI(vm_page_t m, int a, const char *file, int line)
{
mtx_assert_(vm_page_lockptr(m), a, file, line);
}
#endif
int so_zerocp_fullpage = 0;
/*
* Replace the given page with a copy. The copied page assumes
* the portion of the given page's "wire_count" that is not the
* responsibility of this copy-on-write mechanism.
*
* The object containing the given page must have a non-zero
* paging-in-progress count and be locked.
*/
void
vm_page_cowfault(vm_page_t m)
{
vm_page_t mnew;
vm_object_t object;
vm_pindex_t pindex;
vm_page_lock_assert(m, MA_OWNED);
object = m->object;
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT(object->paging_in_progress != 0,
("vm_page_cowfault: object %p's paging-in-progress count is zero.",
object));
pindex = m->pindex;
retry_alloc:
pmap_remove_all(m);
vm_page_remove(m);
mnew = vm_page_alloc(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
if (mnew == NULL) {
vm_page_insert(m, object, pindex);
vm_page_unlock(m);
VM_OBJECT_WUNLOCK(object);
VM_WAIT;
VM_OBJECT_WLOCK(object);
if (m == vm_page_lookup(object, pindex)) {
vm_page_lock(m);
goto retry_alloc;
} else {
/*
* Page disappeared during the wait.
*/
return;
}
}
if (m->cow == 0) {
/*
* check to see if we raced with an xmit complete when
* waiting to allocate a page. If so, put things back
* the way they were
*/
vm_page_unlock(m);
vm_page_lock(mnew);
vm_page_free(mnew);
vm_page_unlock(mnew);
vm_page_insert(m, object, pindex);
} else { /* clear COW & copy page */
if (!so_zerocp_fullpage)
pmap_copy_page(m, mnew);
mnew->valid = VM_PAGE_BITS_ALL;
vm_page_dirty(mnew);
mnew->wire_count = m->wire_count - m->cow;
m->wire_count = m->cow;
vm_page_unlock(m);
}
}
void
vm_page_cowclear(vm_page_t m)
{
vm_page_lock_assert(m, MA_OWNED);
if (m->cow) {
m->cow--;
/*
* let vm_fault add back write permission lazily
*/
}
/*
* sf_buf_free() will free the page, so we needn't do it here
*/
}
int
vm_page_cowsetup(vm_page_t m)
{
vm_page_lock_assert(m, MA_OWNED);
if ((m->flags & PG_FICTITIOUS) != 0 ||
(m->oflags & VPO_UNMANAGED) != 0 ||
m->cow == USHRT_MAX - 1 || !VM_OBJECT_TRYWLOCK(m->object))
return (EBUSY);
m->cow++;
pmap_remove_write(m);
VM_OBJECT_WUNLOCK(m->object);
return (0);
}
#ifdef INVARIANTS
void
vm_page_object_lock_assert(vm_page_t m)
{
/*
* Certain of the page's fields may only be modified by the
* holder of the containing object's lock or the setter of the
* page's VPO_BUSY flag. Unfortunately, the setter of the
* VPO_BUSY flag is not recorded, and thus cannot be checked
* here.
*/
if (m->object != NULL && (m->oflags & VPO_BUSY) == 0)
VM_OBJECT_ASSERT_WLOCKED(m->object);
}
#endif
#include "opt_ddb.h"
#ifdef DDB
#include <sys/kernel.h>
#include <ddb/ddb.h>
DB_SHOW_COMMAND(page, vm_page_print_page_info)
{
db_printf("cnt.v_free_count: %d\n", cnt.v_free_count);
db_printf("cnt.v_cache_count: %d\n", cnt.v_cache_count);
db_printf("cnt.v_inactive_count: %d\n", cnt.v_inactive_count);
db_printf("cnt.v_active_count: %d\n", cnt.v_active_count);
db_printf("cnt.v_wire_count: %d\n", cnt.v_wire_count);
db_printf("cnt.v_free_reserved: %d\n", cnt.v_free_reserved);
db_printf("cnt.v_free_min: %d\n", cnt.v_free_min);
db_printf("cnt.v_free_target: %d\n", cnt.v_free_target);
db_printf("cnt.v_cache_min: %d\n", cnt.v_cache_min);
db_printf("cnt.v_inactive_target: %d\n", cnt.v_inactive_target);
}
DB_SHOW_COMMAND(pageq, vm_page_print_pageq_info)
{
db_printf("PQ_FREE:");
db_printf(" %d", cnt.v_free_count);
db_printf("\n");
db_printf("PQ_CACHE:");
db_printf(" %d", cnt.v_cache_count);
db_printf("\n");
db_printf("PQ_ACTIVE: %d, PQ_INACTIVE: %d\n",
*vm_pagequeues[PQ_ACTIVE].pq_cnt,
*vm_pagequeues[PQ_INACTIVE].pq_cnt);
}
DB_SHOW_COMMAND(pginfo, vm_page_print_pginfo)
{
vm_page_t m;
boolean_t phys;
if (!have_addr) {
db_printf("show pginfo addr\n");
return;
}
phys = strchr(modif, 'p') != NULL;
if (phys)
m = PHYS_TO_VM_PAGE(addr);
else
m = (vm_page_t)addr;
db_printf(
"page %p obj %p pidx 0x%jx phys 0x%jx q %d hold %d wire %d\n"
" af 0x%x of 0x%x f 0x%x act %d busy %d valid 0x%x dirty 0x%x\n",
m, m->object, (uintmax_t)m->pindex, (uintmax_t)m->phys_addr,
m->queue, m->hold_count, m->wire_count, m->aflags, m->oflags,
m->flags, m->act_count, m->busy, m->valid, m->dirty);
}
#endif /* DDB */
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