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freebsd-skq/sys/vm/vm_page.c
Alan Cox 2863482058 In the past four years, we've added two new vm object types. Each time, 
similar changes had to be made in various places throughout the machine-
independent virtual memory layer to support the new vm object type.
However, in most of these places, it's actually not the type of the vm
object that matters to us but instead certain attributes of its pages.
For example, OBJT_DEVICE, OBJT_MGTDEVICE, and OBJT_SG objects contain
fictitious pages.  In other words, in most of these places, we were
testing the vm object's type to determine if it contained fictitious (or
unmanaged) pages.

To both simplify the code in these places and make the addition of future
vm object types easier, this change introduces two new vm object flags
that describe attributes of the vm object's pages, specifically, whether
they are fictitious or unmanaged.

Reviewed and tested by:	kib
2012-12-09 00:32:38 +00:00

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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 mutex is held 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/msgbuf.h>
#include <sys/mutex.h>
#include <sys/proc.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_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);
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_LOCK_ASSERT(m->object, MA_OWNED);
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_LOCK_ASSERT(m->object, MA_OWNED);
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_LOCK_ASSERT(m->object, MA_OWNED);
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_LOCK_ASSERT(m->object, MA_OWNED);
m->busy++;
}
void
vm_page_io_finish(vm_page_t m)
{
VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
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;
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_LOCK_ASSERT(m->object, MA_OWNED);
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;
msleep(m, VM_OBJECT_MTX(m->object), 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_splay:
*
* Implements Sleator and Tarjan's top-down splay algorithm. Returns
* the vm_page containing the given pindex. If, however, that
* pindex is not found in the vm_object, returns a vm_page that is
* adjacent to the pindex, coming before or after it.
*/
vm_page_t
vm_page_splay(vm_pindex_t pindex, vm_page_t root)
{
struct vm_page dummy;
vm_page_t lefttreemax, righttreemin, y;
if (root == NULL)
return (root);
lefttreemax = righttreemin = &dummy;
for (;; root = y) {
if (pindex < root->pindex) {
if ((y = root->left) == NULL)
break;
if (pindex < y->pindex) {
/* Rotate right. */
root->left = y->right;
y->right = root;
root = y;
if ((y = root->left) == NULL)
break;
}
/* Link into the new root's right tree. */
righttreemin->left = root;
righttreemin = root;
} else if (pindex > root->pindex) {
if ((y = root->right) == NULL)
break;
if (pindex > y->pindex) {
/* Rotate left. */
root->right = y->left;
y->left = root;
root = y;
if ((y = root->right) == NULL)
break;
}
/* Link into the new root's left tree. */
lefttreemax->right = root;
lefttreemax = root;
} else
break;
}
/* Assemble the new root. */
lefttreemax->right = root->left;
righttreemin->left = root->right;
root->left = dummy.right;
root->right = dummy.left;
return (root);
}
/*
* vm_page_insert: [ internal use only ]
*
* Inserts the given mem entry into the object and object list.
*
* The pagetables are not updated but will presumably fault the page
* in if necessary, or if a kernel page the caller will at some point
* enter the page into the kernel's pmap. We are not allowed to sleep
* here so we *can't* do this anyway.
*
* The object must be locked.
*/
void
vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex)
{
vm_page_t root;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
if (m->object != NULL)
panic("vm_page_insert: page already inserted");
/*
* 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.
*/
root = object->root;
if (root == NULL) {
m->left = NULL;
m->right = NULL;
TAILQ_INSERT_TAIL(&object->memq, m, listq);
} else {
root = vm_page_splay(pindex, root);
if (pindex < root->pindex) {
m->left = root->left;
m->right = root;
root->left = NULL;
TAILQ_INSERT_BEFORE(root, m, listq);
} else if (pindex == root->pindex)
panic("vm_page_insert: offset already allocated");
else {
m->right = root->right;
m->left = root;
root->right = NULL;
TAILQ_INSERT_AFTER(&object->memq, root, m, listq);
}
}
object->root = 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 underlying pmap entry (if any) is NOT removed here.
*
* 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;
vm_page_t next, prev, root;
if ((m->oflags & VPO_UNMANAGED) == 0)
vm_page_lock_assert(m, MA_OWNED);
if ((object = m->object) == NULL)
return;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
if (m->oflags & VPO_BUSY) {
m->oflags &= ~VPO_BUSY;
vm_page_flash(m);
}
/*
* Now remove from the object's list of backed pages.
*/
if ((next = TAILQ_NEXT(m, listq)) != NULL && next->left == m) {
/*
* Since the page's successor in the list is also its parent
* in the tree, its right subtree must be empty.
*/
next->left = m->left;
KASSERT(m->right == NULL,
("vm_page_remove: page %p has right child", m));
} else if ((prev = TAILQ_PREV(m, pglist, listq)) != NULL &&
prev->right == m) {
/*
* Since the page's predecessor in the list is also its parent
* in the tree, its left subtree must be empty.
*/
KASSERT(m->left == NULL,
("vm_page_remove: page %p has left child", m));
prev->right = m->right;
} else {
if (m != object->root)
vm_page_splay(m->pindex, object->root);
if (m->left == NULL)
root = m->right;
else if (m->right == NULL)
root = m->left;
else {
/*
* Move the page's successor to the root, because
* pages are usually removed in ascending order.
*/
if (m->right != next)
vm_page_splay(m->pindex, m->right);
next->left = m->left;
root = next;
}
object->root = root;
}
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_page_t m;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
if ((m = object->root) != NULL && m->pindex != pindex) {
m = vm_page_splay(pindex, m);
if ((object->root = m)->pindex != pindex)
m = NULL;
}
return (m);
}
/*
* 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_LOCK_ASSERT(object, MA_OWNED);
if ((m = TAILQ_FIRST(&object->memq)) != NULL) {
if (m->pindex < pindex) {
m = vm_page_splay(pindex, object->root);
if ((object->root = m)->pindex < pindex)
m = TAILQ_NEXT(m, listq);
}
}
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_LOCK_ASSERT(m->object, MA_OWNED);
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_LOCK_ASSERT(m->object, MA_OWNED);
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, m_next;
boolean_t empty;
mtx_lock(&vm_page_queue_free_mtx);
if (__predict_false(object->cache == NULL)) {
mtx_unlock(&vm_page_queue_free_mtx);
return;
}
m = object->cache = vm_page_splay(start, object->cache);
if (m->pindex < start) {
if (m->right == NULL)
m = NULL;
else {
m_next = vm_page_splay(start, m->right);
m_next->left = m;
m->right = NULL;
m = object->cache = m_next;
}
}
/*
* At this point, "m" is either (1) a reference to the page
* with the least pindex that is greater than or equal to
* "start" or (2) NULL.
*/
for (; m != NULL && (m->pindex < end || end == 0); m = m_next) {
/*
* Find "m"'s successor and remove "m" from the
* object's cache.
*/
if (m->right == NULL) {
object->cache = m->left;
m_next = NULL;
} else {
m_next = vm_page_splay(start, m->right);
m_next->left = m->left;
object->cache = m_next;
}
/* Convert "m" to a free page. */
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 = object->cache == NULL;
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)
{
vm_page_t m;
mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
if ((m = object->cache) != NULL && m->pindex != pindex) {
m = vm_page_splay(pindex, m);
if ((object->cache = m)->pindex != pindex)
m = NULL;
}
return (m);
}
/*
* 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)
{
vm_object_t object;
vm_page_t root;
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));
object = m->object;
if (m != object->cache) {
root = vm_page_splay(m->pindex, object->cache);
KASSERT(root == m,
("vm_page_cache_remove: page %p is not cached in object %p",
m, object));
}
if (m->left == NULL)
root = m->right;
else if (m->right == NULL)
root = m->left;
else {
root = vm_page_splay(m->pindex, m->left);
root->right = m->right;
}
object->cache = root;
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, m_next;
/*
* Insertion into an object's collection of cached pages
* requires the object to be locked. In contrast, removal does
* not.
*/
VM_OBJECT_LOCK_ASSERT(new_object, MA_OWNED);
KASSERT(new_object->cache == NULL,
("vm_page_cache_transfer: object %p has cached pages",
new_object));
mtx_lock(&vm_page_queue_free_mtx);
if ((m = orig_object->cache) != 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.
*/
m = vm_page_splay(offidxstart, m);
if (m->pindex < offidxstart) {
orig_object->cache = m;
new_object->cache = m->right;
m->right = NULL;
} else {
orig_object->cache = m->left;
new_object->cache = m;
m->left = NULL;
}
while ((m = new_object->cache) != NULL) {
if ((m->pindex - offidxstart) >= new_object->size) {
/*
* Return all of the cached pages with
* offset greater than or equal to the
* new object's size to the original
* object's cache.
*/
new_object->cache = m->left;
m->left = orig_object->cache;
orig_object->cache = m;
break;
}
m_next = vm_page_splay(m->pindex, m->right);
/* Update the page's object and offset. */
m->object = new_object;
m->pindex -= offidxstart;
if (m_next == NULL)
break;
m->right = NULL;
m_next->left = m;
new_object->cache = m_next;
}
KASSERT(new_object->cache == NULL ||
new_object->type == OBJT_SWAP,
("vm_page_cache_transfer: object %p's type is incompatible"
" with cached pages", new_object));
}
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_LOCK_ASSERT(object, MA_OWNED);
if (__predict_true(object->cache == NULL))
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;
int flags, req_class;
KASSERT((object != NULL) == ((req & VM_ALLOC_NOOBJ) == 0),
("vm_page_alloc: inconsistent object/req"));
if (object != NULL)
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
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;
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)) == 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 && m_object->cache == NULL)
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(m, object, pindex);
} 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_LOCK_ASSERT(object, MA_OWNED);
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 && m_object->cache == NULL)
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);
VM_OBJECT_LOCK_ASSERT(m->object, 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 alway 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_LOCK_ASSERT(m->object, MA_OWNED);
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_LOCK_ASSERT(m->object, MA_OWNED);
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;
vm_page_t next, prev, root;
vm_page_lock_assert(m, MA_OWNED);
object = m->object;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
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.
*/
if ((next = TAILQ_NEXT(m, listq)) != NULL && next->left == m) {
/*
* Since the page's successor in the list is also its parent
* in the tree, its right subtree must be empty.
*/
next->left = m->left;
KASSERT(m->right == NULL,
("vm_page_cache: page %p has right child", m));
} else if ((prev = TAILQ_PREV(m, pglist, listq)) != NULL &&
prev->right == m) {
/*
* Since the page's predecessor in the list is also its parent
* in the tree, its left subtree must be empty.
*/
KASSERT(m->left == NULL,
("vm_page_cache: page %p has left child", m));
prev->right = m->right;
} else {
if (m != object->root)
vm_page_splay(m->pindex, object->root);
if (m->left == NULL)
root = m->right;
else if (m->right == NULL)
root = m->left;
else {
/*
* Move the page's successor to the root, because
* pages are usually removed in ascending order.
*/
if (m->right != next)
vm_page_splay(m->pindex, m->right);
next->left = m->left;
root = next;
}
object->root = root;
}
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++;
root = object->cache;
if (root == NULL) {
m->left = NULL;
m->right = NULL;
} else {
root = vm_page_splay(m->pindex, root);
if (m->pindex < root->pindex) {
m->left = root->left;
m->right = root;
root->left = NULL;
} else if (__predict_false(m->pindex == root->pindex))
panic("vm_page_cache: offset already cached");
else {
m->right = root->right;
m->left = root;
root->right = NULL;
}
}
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 (root == NULL && object->resident_page_count != 0)
vhold(object->handle);
else if (root != NULL && object->resident_page_count == 0)
vdrop(object->handle);
}
}
/*
* vm_page_dontneed
*
* Cache, deactivate, or do nothing as appropriate. This routine
* is typically used by madvise() MADV_DONTNEED.
*
* 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 otherhand, 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_dontneed(vm_page_t m)
{
int dnw;
int head;
vm_page_lock_assert(m, MA_OWNED);
VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
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 (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_LOCK_ASSERT(object, MA_OWNED);
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_UNLOCK(object);
VM_WAIT;
VM_OBJECT_LOCK(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_LOCK_ASSERT(m->object, MA_OWNED);
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_LOCK_ASSERT(m->object, MA_OWNED);
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_LOCK_ASSERT(m->object, MA_OWNED);
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_LOCK_ASSERT(m->object, MA_OWNED);
KASSERT((m->oflags & VPO_BUSY) == 0,
("vm_page_set_invalid: page %p is busy", m));
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_LOCK_ASSERT(m->object, MA_OWNED);
/*
* 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_LOCK_ASSERT(m->object, MA_OWNED);
bits = vm_page_bits(base, size);
if (m->valid && ((m->valid & bits) == bits))
return 1;
else
return 0;
}
/*
* Set the page's dirty bits if the page is modified.
*/
void
vm_page_test_dirty(vm_page_t m)
{
VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
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_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_LOCK_ASSERT(object, MA_OWNED);
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_UNLOCK(object);
VM_WAIT;
VM_OBJECT_LOCK(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_TRYLOCK(m->object))
return (EBUSY);
m->cow++;
pmap_remove_write(m);
VM_OBJECT_UNLOCK(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_LOCK_ASSERT(m->object, MA_OWNED);
}
#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);
}
#endif /* DDB */
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