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freebsd-dev/sys/vm/vm_object.c
Ed Maste c3821149f4 Drop space in "vm object" lock name to improve wchan 
Lock names are shown in top as a `*` followed by the first five
characters of the name.  `*vmobj` a little more obvious and easier to
search for than `*vm ob`.

Differential Revision:	https://reviews.freebsd.org/D36264
2023-02-15 08:31:17 -05:00

2873 lines
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/*-
* SPDX-License-Identifier: (BSD-3-Clause AND MIT-CMU)
*
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* The Mach Operating System project at Carnegie-Mellon University.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. 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_object.c 8.5 (Berkeley) 3/22/94
*
*
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
* All rights reserved.
*
* Authors: Avadis Tevanian, Jr., Michael Wayne Young
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
/*
* Virtual memory object module.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_vm.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/blockcount.h>
#include <sys/cpuset.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/kernel.h>
#include <sys/pctrie.h>
#include <sys/sysctl.h>
#include <sys/mutex.h>
#include <sys/proc.h> /* for curproc, pageproc */
#include <sys/refcount.h>
#include <sys/socket.h>
#include <sys/resourcevar.h>
#include <sys/refcount.h>
#include <sys/rwlock.h>
#include <sys/user.h>
#include <sys/vnode.h>
#include <sys/vmmeter.h>
#include <sys/sx.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_pager.h>
#include <vm/vm_phys.h>
#include <vm/vm_pagequeue.h>
#include <vm/swap_pager.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/vm_radix.h>
#include <vm/vm_reserv.h>
#include <vm/uma.h>
static int old_msync;
SYSCTL_INT(_vm, OID_AUTO, old_msync, CTLFLAG_RW, &old_msync, 0,
"Use old (insecure) msync behavior");
static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p,
int pagerflags, int flags, boolean_t *allclean,
boolean_t *eio);
static boolean_t vm_object_page_remove_write(vm_page_t p, int flags,
boolean_t *allclean);
static void vm_object_backing_remove(vm_object_t object);
/*
* Virtual memory objects maintain the actual data
* associated with allocated virtual memory. A given
* page of memory exists within exactly one object.
*
* An object is only deallocated when all "references"
* are given up. Only one "reference" to a given
* region of an object should be writeable.
*
* Associated with each object is a list of all resident
* memory pages belonging to that object; this list is
* maintained by the "vm_page" module, and locked by the object's
* lock.
*
* Each object also records a "pager" routine which is
* used to retrieve (and store) pages to the proper backing
* storage. In addition, objects may be backed by other
* objects from which they were virtual-copied.
*
* The only items within the object structure which are
* modified after time of creation are:
* reference count locked by object's lock
* pager routine locked by object's lock
*
*/
struct object_q vm_object_list;
struct mtx vm_object_list_mtx; /* lock for object list and count */
struct vm_object kernel_object_store;
static SYSCTL_NODE(_vm_stats, OID_AUTO, object, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
"VM object stats");
static COUNTER_U64_DEFINE_EARLY(object_collapses);
SYSCTL_COUNTER_U64(_vm_stats_object, OID_AUTO, collapses, CTLFLAG_RD,
&object_collapses,
"VM object collapses");
static COUNTER_U64_DEFINE_EARLY(object_bypasses);
SYSCTL_COUNTER_U64(_vm_stats_object, OID_AUTO, bypasses, CTLFLAG_RD,
&object_bypasses,
"VM object bypasses");
static COUNTER_U64_DEFINE_EARLY(object_collapse_waits);
SYSCTL_COUNTER_U64(_vm_stats_object, OID_AUTO, collapse_waits, CTLFLAG_RD,
&object_collapse_waits,
"Number of sleeps for collapse");
static uma_zone_t obj_zone;
static int vm_object_zinit(void *mem, int size, int flags);
#ifdef INVARIANTS
static void vm_object_zdtor(void *mem, int size, void *arg);
static void
vm_object_zdtor(void *mem, int size, void *arg)
{
vm_object_t object;
object = (vm_object_t)mem;
KASSERT(object->ref_count == 0,
("object %p ref_count = %d", object, object->ref_count));
KASSERT(TAILQ_EMPTY(&object->memq),
("object %p has resident pages in its memq", object));
KASSERT(vm_radix_is_empty(&object->rtree),
("object %p has resident pages in its trie", object));
#if VM_NRESERVLEVEL > 0
KASSERT(LIST_EMPTY(&object->rvq),
("object %p has reservations",
object));
#endif
KASSERT(!vm_object_busied(object),
("object %p busy = %d", object, blockcount_read(&object->busy)));
KASSERT(object->resident_page_count == 0,
("object %p resident_page_count = %d",
object, object->resident_page_count));
KASSERT(atomic_load_int(&object->shadow_count) == 0,
("object %p shadow_count = %d",
object, atomic_load_int(&object->shadow_count)));
KASSERT(object->type == OBJT_DEAD,
("object %p has non-dead type %d",
object, object->type));
KASSERT(object->charge == 0 && object->cred == NULL,
("object %p has non-zero charge %ju (%p)",
object, (uintmax_t)object->charge, object->cred));
}
#endif
static int
vm_object_zinit(void *mem, int size, int flags)
{
vm_object_t object;
object = (vm_object_t)mem;
rw_init_flags(&object->lock, "vmobject", RW_DUPOK | RW_NEW);
/* These are true for any object that has been freed */
object->type = OBJT_DEAD;
vm_radix_init(&object->rtree);
refcount_init(&object->ref_count, 0);
blockcount_init(&object->paging_in_progress);
blockcount_init(&object->busy);
object->resident_page_count = 0;
atomic_store_int(&object->shadow_count, 0);
object->flags = OBJ_DEAD;
mtx_lock(&vm_object_list_mtx);
TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
mtx_unlock(&vm_object_list_mtx);
return (0);
}
static void
_vm_object_allocate(objtype_t type, vm_pindex_t size, u_short flags,
vm_object_t object, void *handle)
{
TAILQ_INIT(&object->memq);
LIST_INIT(&object->shadow_head);
object->type = type;
object->flags = flags;
if ((flags & OBJ_SWAP) != 0) {
pctrie_init(&object->un_pager.swp.swp_blks);
object->un_pager.swp.writemappings = 0;
}
/*
* Ensure that swap_pager_swapoff() iteration over object_list
* sees up to date type and pctrie head if it observed
* non-dead object.
*/
atomic_thread_fence_rel();
object->pg_color = 0;
object->size = size;
object->domain.dr_policy = NULL;
object->generation = 1;
object->cleangeneration = 1;
refcount_init(&object->ref_count, 1);
object->memattr = VM_MEMATTR_DEFAULT;
object->cred = NULL;
object->charge = 0;
object->handle = handle;
object->backing_object = NULL;
object->backing_object_offset = (vm_ooffset_t) 0;
#if VM_NRESERVLEVEL > 0
LIST_INIT(&object->rvq);
#endif
umtx_shm_object_init(object);
}
/*
* vm_object_init:
*
* Initialize the VM objects module.
*/
void
vm_object_init(void)
{
TAILQ_INIT(&vm_object_list);
mtx_init(&vm_object_list_mtx, "vm object_list", NULL, MTX_DEF);
rw_init(&kernel_object->lock, "kernel vm object");
_vm_object_allocate(OBJT_PHYS, atop(VM_MAX_KERNEL_ADDRESS -
VM_MIN_KERNEL_ADDRESS), OBJ_UNMANAGED, kernel_object, NULL);
#if VM_NRESERVLEVEL > 0
kernel_object->flags |= OBJ_COLORED;
kernel_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
#endif
kernel_object->un_pager.phys.ops = &default_phys_pg_ops;
/*
* The lock portion of struct vm_object must be type stable due
* to vm_pageout_fallback_object_lock locking a vm object
* without holding any references to it.
*
* paging_in_progress is valid always. Lockless references to
* the objects may acquire pip and then check OBJ_DEAD.
*/
obj_zone = uma_zcreate("VM OBJECT", sizeof (struct vm_object), NULL,
#ifdef INVARIANTS
vm_object_zdtor,
#else
NULL,
#endif
vm_object_zinit, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
vm_radix_zinit();
}
void
vm_object_clear_flag(vm_object_t object, u_short bits)
{
VM_OBJECT_ASSERT_WLOCKED(object);
object->flags &= ~bits;
}
/*
* Sets the default memory attribute for the specified object. Pages
* that are allocated to this object are by default assigned this memory
* attribute.
*
* Presently, this function must be called before any pages are allocated
* to the object. In the future, this requirement may be relaxed for
* "default" and "swap" objects.
*/
int
vm_object_set_memattr(vm_object_t object, vm_memattr_t memattr)
{
VM_OBJECT_ASSERT_WLOCKED(object);
if (object->type == OBJT_DEAD)
return (KERN_INVALID_ARGUMENT);
if (!TAILQ_EMPTY(&object->memq))
return (KERN_FAILURE);
object->memattr = memattr;
return (KERN_SUCCESS);
}
void
vm_object_pip_add(vm_object_t object, short i)
{
if (i > 0)
blockcount_acquire(&object->paging_in_progress, i);
}
void
vm_object_pip_wakeup(vm_object_t object)
{
vm_object_pip_wakeupn(object, 1);
}
void
vm_object_pip_wakeupn(vm_object_t object, short i)
{
if (i > 0)
blockcount_release(&object->paging_in_progress, i);
}
/*
* Atomically drop the object lock and wait for pip to drain. This protects
* from sleep/wakeup races due to identity changes. The lock is not re-acquired
* on return.
*/
static void
vm_object_pip_sleep(vm_object_t object, const char *waitid)
{
(void)blockcount_sleep(&object->paging_in_progress, &object->lock,
waitid, PVM | PDROP);
}
void
vm_object_pip_wait(vm_object_t object, const char *waitid)
{
VM_OBJECT_ASSERT_WLOCKED(object);
blockcount_wait(&object->paging_in_progress, &object->lock, waitid,
PVM);
}
void
vm_object_pip_wait_unlocked(vm_object_t object, const char *waitid)
{
VM_OBJECT_ASSERT_UNLOCKED(object);
blockcount_wait(&object->paging_in_progress, NULL, waitid, PVM);
}
/*
* vm_object_allocate:
*
* Returns a new object with the given size.
*/
vm_object_t
vm_object_allocate(objtype_t type, vm_pindex_t size)
{
vm_object_t object;
u_short flags;
switch (type) {
case OBJT_DEAD:
panic("vm_object_allocate: can't create OBJT_DEAD");
case OBJT_SWAP:
flags = OBJ_COLORED | OBJ_SWAP;
break;
case OBJT_DEVICE:
case OBJT_SG:
flags = OBJ_FICTITIOUS | OBJ_UNMANAGED;
break;
case OBJT_MGTDEVICE:
flags = OBJ_FICTITIOUS;
break;
case OBJT_PHYS:
flags = OBJ_UNMANAGED;
break;
case OBJT_VNODE:
flags = 0;
break;
default:
panic("vm_object_allocate: type %d is undefined or dynamic",
type);
}
object = (vm_object_t)uma_zalloc(obj_zone, M_WAITOK);
_vm_object_allocate(type, size, flags, object, NULL);
return (object);
}
vm_object_t
vm_object_allocate_dyn(objtype_t dyntype, vm_pindex_t size, u_short flags)
{
vm_object_t object;
MPASS(dyntype >= OBJT_FIRST_DYN /* && dyntype < nitems(pagertab) */);
object = (vm_object_t)uma_zalloc(obj_zone, M_WAITOK);
_vm_object_allocate(dyntype, size, flags, object, NULL);
return (object);
}
/*
* vm_object_allocate_anon:
*
* Returns a new default object of the given size and marked as
* anonymous memory for special split/collapse handling. Color
* to be initialized by the caller.
*/
vm_object_t
vm_object_allocate_anon(vm_pindex_t size, vm_object_t backing_object,
struct ucred *cred, vm_size_t charge)
{
vm_object_t handle, object;
if (backing_object == NULL)
handle = NULL;
else if ((backing_object->flags & OBJ_ANON) != 0)
handle = backing_object->handle;
else
handle = backing_object;
object = uma_zalloc(obj_zone, M_WAITOK);
_vm_object_allocate(OBJT_SWAP, size,
OBJ_ANON | OBJ_ONEMAPPING | OBJ_SWAP, object, handle);
object->cred = cred;
object->charge = cred != NULL ? charge : 0;
return (object);
}
static void
vm_object_reference_vnode(vm_object_t object)
{
u_int old;
/*
* vnode objects need the lock for the first reference
* to serialize with vnode_object_deallocate().
*/
if (!refcount_acquire_if_gt(&object->ref_count, 0)) {
VM_OBJECT_RLOCK(object);
old = refcount_acquire(&object->ref_count);
if (object->type == OBJT_VNODE && old == 0)
vref(object->handle);
VM_OBJECT_RUNLOCK(object);
}
}
/*
* vm_object_reference:
*
* Acquires a reference to the given object.
*/
void
vm_object_reference(vm_object_t object)
{
if (object == NULL)
return;
if (object->type == OBJT_VNODE)
vm_object_reference_vnode(object);
else
refcount_acquire(&object->ref_count);
KASSERT((object->flags & OBJ_DEAD) == 0,
("vm_object_reference: Referenced dead object."));
}
/*
* vm_object_reference_locked:
*
* Gets another reference to the given object.
*
* The object must be locked.
*/
void
vm_object_reference_locked(vm_object_t object)
{
u_int old;
VM_OBJECT_ASSERT_LOCKED(object);
old = refcount_acquire(&object->ref_count);
if (object->type == OBJT_VNODE && old == 0)
vref(object->handle);
KASSERT((object->flags & OBJ_DEAD) == 0,
("vm_object_reference: Referenced dead object."));
}
/*
* Handle deallocating an object of type OBJT_VNODE.
*/
static void
vm_object_deallocate_vnode(vm_object_t object)
{
struct vnode *vp = (struct vnode *) object->handle;
bool last;
KASSERT(object->type == OBJT_VNODE,
("vm_object_deallocate_vnode: not a vnode object"));
KASSERT(vp != NULL, ("vm_object_deallocate_vnode: missing vp"));
/* Object lock to protect handle lookup. */
last = refcount_release(&object->ref_count);
VM_OBJECT_RUNLOCK(object);
if (!last)
return;
if (!umtx_shm_vnobj_persistent)
umtx_shm_object_terminated(object);
/* vrele may need the vnode lock. */
vrele(vp);
}
/*
* We dropped a reference on an object and discovered that it had a
* single remaining shadow. This is a sibling of the reference we
* dropped. Attempt to collapse the sibling and backing object.
*/
static vm_object_t
vm_object_deallocate_anon(vm_object_t backing_object)
{
vm_object_t object;
/* Fetch the final shadow. */
object = LIST_FIRST(&backing_object->shadow_head);
KASSERT(object != NULL &&
atomic_load_int(&backing_object->shadow_count) == 1,
("vm_object_anon_deallocate: ref_count: %d, shadow_count: %d",
backing_object->ref_count,
atomic_load_int(&backing_object->shadow_count)));
KASSERT((object->flags & OBJ_ANON) != 0,
("invalid shadow object %p", object));
if (!VM_OBJECT_TRYWLOCK(object)) {
/*
* Prevent object from disappearing since we do not have a
* reference.
*/
vm_object_pip_add(object, 1);
VM_OBJECT_WUNLOCK(backing_object);
VM_OBJECT_WLOCK(object);
vm_object_pip_wakeup(object);
} else
VM_OBJECT_WUNLOCK(backing_object);
/*
* Check for a collapse/terminate race with the last reference holder.
*/
if ((object->flags & (OBJ_DEAD | OBJ_COLLAPSING)) != 0 ||
!refcount_acquire_if_not_zero(&object->ref_count)) {
VM_OBJECT_WUNLOCK(object);
return (NULL);
}
backing_object = object->backing_object;
if (backing_object != NULL && (backing_object->flags & OBJ_ANON) != 0)
vm_object_collapse(object);
VM_OBJECT_WUNLOCK(object);
return (object);
}
/*
* vm_object_deallocate:
*
* Release a reference to the specified object,
* gained either through a vm_object_allocate
* or a vm_object_reference call. When all references
* are gone, storage associated with this object
* may be relinquished.
*
* No object may be locked.
*/
void
vm_object_deallocate(vm_object_t object)
{
vm_object_t temp;
bool released;
while (object != NULL) {
/*
* If the reference count goes to 0 we start calling
* vm_object_terminate() on the object chain. A ref count
* of 1 may be a special case depending on the shadow count
* being 0 or 1. These cases require a write lock on the
* object.
*/
if ((object->flags & OBJ_ANON) == 0)
released = refcount_release_if_gt(&object->ref_count, 1);
else
released = refcount_release_if_gt(&object->ref_count, 2);
if (released)
return;
if (object->type == OBJT_VNODE) {
VM_OBJECT_RLOCK(object);
if (object->type == OBJT_VNODE) {
vm_object_deallocate_vnode(object);
return;
}
VM_OBJECT_RUNLOCK(object);
}
VM_OBJECT_WLOCK(object);
KASSERT(object->ref_count > 0,
("vm_object_deallocate: object deallocated too many times: %d",
object->type));
/*
* If this is not the final reference to an anonymous
* object we may need to collapse the shadow chain.
*/
if (!refcount_release(&object->ref_count)) {
if (object->ref_count > 1 ||
atomic_load_int(&object->shadow_count) == 0) {
if ((object->flags & OBJ_ANON) != 0 &&
object->ref_count == 1)
vm_object_set_flag(object,
OBJ_ONEMAPPING);
VM_OBJECT_WUNLOCK(object);
return;
}
/* Handle collapsing last ref on anonymous objects. */
object = vm_object_deallocate_anon(object);
continue;
}
/*
* Handle the final reference to an object. We restart
* the loop with the backing object to avoid recursion.
*/
umtx_shm_object_terminated(object);
temp = object->backing_object;
if (temp != NULL) {
KASSERT(object->type == OBJT_SWAP,
("shadowed tmpfs v_object 2 %p", object));
vm_object_backing_remove(object);
}
KASSERT((object->flags & OBJ_DEAD) == 0,
("vm_object_deallocate: Terminating dead object."));
vm_object_set_flag(object, OBJ_DEAD);
vm_object_terminate(object);
object = temp;
}
}
void
vm_object_destroy(vm_object_t object)
{
uma_zfree(obj_zone, object);
}
static void
vm_object_sub_shadow(vm_object_t object)
{
KASSERT(object->shadow_count >= 1,
("object %p sub_shadow count zero", object));
atomic_subtract_int(&object->shadow_count, 1);
}
static void
vm_object_backing_remove_locked(vm_object_t object)
{
vm_object_t backing_object;
backing_object = object->backing_object;
VM_OBJECT_ASSERT_WLOCKED(object);
VM_OBJECT_ASSERT_WLOCKED(backing_object);
KASSERT((object->flags & OBJ_COLLAPSING) == 0,
("vm_object_backing_remove: Removing collapsing object."));
vm_object_sub_shadow(backing_object);
if ((object->flags & OBJ_SHADOWLIST) != 0) {
LIST_REMOVE(object, shadow_list);
vm_object_clear_flag(object, OBJ_SHADOWLIST);
}
object->backing_object = NULL;
}
static void
vm_object_backing_remove(vm_object_t object)
{
vm_object_t backing_object;
VM_OBJECT_ASSERT_WLOCKED(object);
backing_object = object->backing_object;
if ((object->flags & OBJ_SHADOWLIST) != 0) {
VM_OBJECT_WLOCK(backing_object);
vm_object_backing_remove_locked(object);
VM_OBJECT_WUNLOCK(backing_object);
} else {
object->backing_object = NULL;
vm_object_sub_shadow(backing_object);
}
}
static void
vm_object_backing_insert_locked(vm_object_t object, vm_object_t backing_object)
{
VM_OBJECT_ASSERT_WLOCKED(object);
atomic_add_int(&backing_object->shadow_count, 1);
if ((backing_object->flags & OBJ_ANON) != 0) {
VM_OBJECT_ASSERT_WLOCKED(backing_object);
LIST_INSERT_HEAD(&backing_object->shadow_head, object,
shadow_list);
vm_object_set_flag(object, OBJ_SHADOWLIST);
}
object->backing_object = backing_object;
}
static void
vm_object_backing_insert(vm_object_t object, vm_object_t backing_object)
{
VM_OBJECT_ASSERT_WLOCKED(object);
if ((backing_object->flags & OBJ_ANON) != 0) {
VM_OBJECT_WLOCK(backing_object);
vm_object_backing_insert_locked(object, backing_object);
VM_OBJECT_WUNLOCK(backing_object);
} else {
object->backing_object = backing_object;
atomic_add_int(&backing_object->shadow_count, 1);
}
}
/*
* Insert an object into a backing_object's shadow list with an additional
* reference to the backing_object added.
*/
static void
vm_object_backing_insert_ref(vm_object_t object, vm_object_t backing_object)
{
VM_OBJECT_ASSERT_WLOCKED(object);
if ((backing_object->flags & OBJ_ANON) != 0) {
VM_OBJECT_WLOCK(backing_object);
KASSERT((backing_object->flags & OBJ_DEAD) == 0,
("shadowing dead anonymous object"));
vm_object_reference_locked(backing_object);
vm_object_backing_insert_locked(object, backing_object);
vm_object_clear_flag(backing_object, OBJ_ONEMAPPING);
VM_OBJECT_WUNLOCK(backing_object);
} else {
vm_object_reference(backing_object);
atomic_add_int(&backing_object->shadow_count, 1);
object->backing_object = backing_object;
}
}
/*
* Transfer a backing reference from backing_object to object.
*/
static void
vm_object_backing_transfer(vm_object_t object, vm_object_t backing_object)
{
vm_object_t new_backing_object;
/*
* Note that the reference to backing_object->backing_object
* moves from within backing_object to within object.
*/
vm_object_backing_remove_locked(object);
new_backing_object = backing_object->backing_object;
if (new_backing_object == NULL)
return;
if ((new_backing_object->flags & OBJ_ANON) != 0) {
VM_OBJECT_WLOCK(new_backing_object);
vm_object_backing_remove_locked(backing_object);
vm_object_backing_insert_locked(object, new_backing_object);
VM_OBJECT_WUNLOCK(new_backing_object);
} else {
/*
* shadow_count for new_backing_object is left
* unchanged, its reference provided by backing_object
* is replaced by object.
*/
object->backing_object = new_backing_object;
backing_object->backing_object = NULL;
}
}
/*
* Wait for a concurrent collapse to settle.
*/
static void
vm_object_collapse_wait(vm_object_t object)
{
VM_OBJECT_ASSERT_WLOCKED(object);
while ((object->flags & OBJ_COLLAPSING) != 0) {
vm_object_pip_wait(object, "vmcolwait");
counter_u64_add(object_collapse_waits, 1);
}
}
/*
* Waits for a backing object to clear a pending collapse and returns
* it locked if it is an ANON object.
*/
static vm_object_t
vm_object_backing_collapse_wait(vm_object_t object)
{
vm_object_t backing_object;
VM_OBJECT_ASSERT_WLOCKED(object);
for (;;) {
backing_object = object->backing_object;
if (backing_object == NULL ||
(backing_object->flags & OBJ_ANON) == 0)
return (NULL);
VM_OBJECT_WLOCK(backing_object);
if ((backing_object->flags & (OBJ_DEAD | OBJ_COLLAPSING)) == 0)
break;
VM_OBJECT_WUNLOCK(object);
vm_object_pip_sleep(backing_object, "vmbckwait");
counter_u64_add(object_collapse_waits, 1);
VM_OBJECT_WLOCK(object);
}
return (backing_object);
}
/*
* vm_object_terminate_pages removes any remaining pageable pages
* from the object and resets the object to an empty state.
*/
static void
vm_object_terminate_pages(vm_object_t object)
{
vm_page_t p, p_next;
VM_OBJECT_ASSERT_WLOCKED(object);
/*
* Free any remaining pageable pages. This also removes them from the
* paging queues. However, don't free wired pages, just remove them
* from the object. Rather than incrementally removing each page from
* the object, the page and object are reset to any empty state.
*/
TAILQ_FOREACH_SAFE(p, &object->memq, listq, p_next) {
vm_page_assert_unbusied(p);
KASSERT(p->object == object &&
(p->ref_count & VPRC_OBJREF) != 0,
("vm_object_terminate_pages: page %p is inconsistent", p));
p->object = NULL;
if (vm_page_drop(p, VPRC_OBJREF) == VPRC_OBJREF) {
VM_CNT_INC(v_pfree);
vm_page_free(p);
}
}
/*
* If the object contained any pages, then reset it to an empty state.
* None of the object's fields, including "resident_page_count", were
* modified by the preceding loop.
*/
if (object->resident_page_count != 0) {
vm_radix_reclaim_allnodes(&object->rtree);
TAILQ_INIT(&object->memq);
object->resident_page_count = 0;
if (object->type == OBJT_VNODE)
vdrop(object->handle);
}
}
/*
* vm_object_terminate actually destroys the specified object, freeing
* up all previously used resources.
*
* The object must be locked.
* This routine may block.
*/
void
vm_object_terminate(vm_object_t object)
{
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT((object->flags & OBJ_DEAD) != 0,
("terminating non-dead obj %p", object));
KASSERT((object->flags & OBJ_COLLAPSING) == 0,
("terminating collapsing obj %p", object));
KASSERT(object->backing_object == NULL,
("terminating shadow obj %p", object));
/*
* Wait for the pageout daemon and other current users to be
* done with the object. Note that new paging_in_progress
* users can come after this wait, but they must check
* OBJ_DEAD flag set (without unlocking the object), and avoid
* the object being terminated.
*/
vm_object_pip_wait(object, "objtrm");
KASSERT(object->ref_count == 0,
("vm_object_terminate: object with references, ref_count=%d",
object->ref_count));
if ((object->flags & OBJ_PG_DTOR) == 0)
vm_object_terminate_pages(object);
#if VM_NRESERVLEVEL > 0
if (__predict_false(!LIST_EMPTY(&object->rvq)))
vm_reserv_break_all(object);
#endif
KASSERT(object->cred == NULL || (object->flags & OBJ_SWAP) != 0,
("%s: non-swap obj %p has cred", __func__, object));
/*
* Let the pager know object is dead.
*/
vm_pager_deallocate(object);
VM_OBJECT_WUNLOCK(object);
vm_object_destroy(object);
}
/*
* Make the page read-only so that we can clear the object flags. However, if
* this is a nosync mmap then the object is likely to stay dirty so do not
* mess with the page and do not clear the object flags. Returns TRUE if the
* page should be flushed, and FALSE otherwise.
*/
static boolean_t
vm_object_page_remove_write(vm_page_t p, int flags, boolean_t *allclean)
{
vm_page_assert_busied(p);
/*
* If we have been asked to skip nosync pages and this is a
* nosync page, skip it. Note that the object flags were not
* cleared in this case so we do not have to set them.
*/
if ((flags & OBJPC_NOSYNC) != 0 && (p->a.flags & PGA_NOSYNC) != 0) {
*allclean = FALSE;
return (FALSE);
} else {
pmap_remove_write(p);
return (p->dirty != 0);
}
}
/*
* vm_object_page_clean
*
* Clean all dirty pages in the specified range of object. Leaves page
* on whatever queue it is currently on. If NOSYNC is set then do not
* write out pages with PGA_NOSYNC set (originally comes from MAP_NOSYNC),
* leaving the object dirty.
*
* For swap objects backing tmpfs regular files, do not flush anything,
* but remove write protection on the mapped pages to update mtime through
* mmaped writes.
*
* When stuffing pages asynchronously, allow clustering. XXX we need a
* synchronous clustering mode implementation.
*
* Odd semantics: if start == end, we clean everything.
*
* The object must be locked.
*
* Returns FALSE if some page from the range was not written, as
* reported by the pager, and TRUE otherwise.
*/
boolean_t
vm_object_page_clean(vm_object_t object, vm_ooffset_t start, vm_ooffset_t end,
int flags)
{
vm_page_t np, p;
vm_pindex_t pi, tend, tstart;
int curgeneration, n, pagerflags;
boolean_t eio, res, allclean;
VM_OBJECT_ASSERT_WLOCKED(object);
if (!vm_object_mightbedirty(object) || object->resident_page_count == 0)
return (TRUE);
pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) != 0 ?
VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK;
pagerflags |= (flags & OBJPC_INVAL) != 0 ? VM_PAGER_PUT_INVAL : 0;
tstart = OFF_TO_IDX(start);
tend = (end == 0) ? object->size : OFF_TO_IDX(end + PAGE_MASK);
allclean = tstart == 0 && tend >= object->size;
res = TRUE;
rescan:
curgeneration = object->generation;
for (p = vm_page_find_least(object, tstart); p != NULL; p = np) {
pi = p->pindex;
if (pi >= tend)
break;
np = TAILQ_NEXT(p, listq);
if (vm_page_none_valid(p))
continue;
if (vm_page_busy_acquire(p, VM_ALLOC_WAITFAIL) == 0) {
if (object->generation != curgeneration &&
(flags & OBJPC_SYNC) != 0)
goto rescan;
np = vm_page_find_least(object, pi);
continue;
}
if (!vm_object_page_remove_write(p, flags, &allclean)) {
vm_page_xunbusy(p);
continue;
}
if (object->type == OBJT_VNODE) {
n = vm_object_page_collect_flush(object, p, pagerflags,
flags, &allclean, &eio);
if (eio) {
res = FALSE;
allclean = FALSE;
}
if (object->generation != curgeneration &&
(flags & OBJPC_SYNC) != 0)
goto rescan;
/*
* If the VOP_PUTPAGES() did a truncated write, so
* that even the first page of the run is not fully
* written, vm_pageout_flush() returns 0 as the run
* length. Since the condition that caused truncated
* write may be permanent, e.g. exhausted free space,
* accepting n == 0 would cause an infinite loop.
*
* Forwarding the iterator leaves the unwritten page
* behind, but there is not much we can do there if
* filesystem refuses to write it.
*/
if (n == 0) {
n = 1;
allclean = FALSE;
}
} else {
n = 1;
vm_page_xunbusy(p);
}
np = vm_page_find_least(object, pi + n);
}
#if 0
VOP_FSYNC(vp, (pagerflags & VM_PAGER_PUT_SYNC) ? MNT_WAIT : 0);
#endif
/*
* Leave updating cleangeneration for tmpfs objects to tmpfs
* scan. It needs to update mtime, which happens for other
* filesystems during page writeouts.
*/
if (allclean && object->type == OBJT_VNODE)
object->cleangeneration = curgeneration;
return (res);
}
static int
vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags,
int flags, boolean_t *allclean, boolean_t *eio)
{
vm_page_t ma[vm_pageout_page_count], p_first, tp;
int count, i, mreq, runlen;
vm_page_lock_assert(p, MA_NOTOWNED);
vm_page_assert_xbusied(p);
VM_OBJECT_ASSERT_WLOCKED(object);
count = 1;
mreq = 0;
for (tp = p; count < vm_pageout_page_count; count++) {
tp = vm_page_next(tp);
if (tp == NULL || vm_page_tryxbusy(tp) == 0)
break;
if (!vm_object_page_remove_write(tp, flags, allclean)) {
vm_page_xunbusy(tp);
break;
}
}
for (p_first = p; count < vm_pageout_page_count; count++) {
tp = vm_page_prev(p_first);
if (tp == NULL || vm_page_tryxbusy(tp) == 0)
break;
if (!vm_object_page_remove_write(tp, flags, allclean)) {
vm_page_xunbusy(tp);
break;
}
p_first = tp;
mreq++;
}
for (tp = p_first, i = 0; i < count; tp = TAILQ_NEXT(tp, listq), i++)
ma[i] = tp;
vm_pageout_flush(ma, count, pagerflags, mreq, &runlen, eio);
return (runlen);
}
/*
* Note that there is absolutely no sense in writing out
* anonymous objects, so we track down the vnode object
* to write out.
* We invalidate (remove) all pages from the address space
* for semantic correctness.
*
* If the backing object is a device object with unmanaged pages, then any
* mappings to the specified range of pages must be removed before this
* function is called.
*
* Note: certain anonymous maps, such as MAP_NOSYNC maps,
* may start out with a NULL object.
*/
boolean_t
vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
boolean_t syncio, boolean_t invalidate)
{
vm_object_t backing_object;
struct vnode *vp;
struct mount *mp;
int error, flags, fsync_after;
boolean_t res;
if (object == NULL)
return (TRUE);
res = TRUE;
error = 0;
VM_OBJECT_WLOCK(object);
while ((backing_object = object->backing_object) != NULL) {
VM_OBJECT_WLOCK(backing_object);
offset += object->backing_object_offset;
VM_OBJECT_WUNLOCK(object);
object = backing_object;
if (object->size < OFF_TO_IDX(offset + size))
size = IDX_TO_OFF(object->size) - offset;
}
/*
* Flush pages if writing is allowed, invalidate them
* if invalidation requested. Pages undergoing I/O
* will be ignored by vm_object_page_remove().
*
* We cannot lock the vnode and then wait for paging
* to complete without deadlocking against vm_fault.
* Instead we simply call vm_object_page_remove() and
* allow it to block internally on a page-by-page
* basis when it encounters pages undergoing async
* I/O.
*/
if (object->type == OBJT_VNODE &&
vm_object_mightbedirty(object) != 0 &&
((vp = object->handle)->v_vflag & VV_NOSYNC) == 0) {
VM_OBJECT_WUNLOCK(object);
(void)vn_start_write(vp, &mp, V_WAIT);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
if (syncio && !invalidate && offset == 0 &&
atop(size) == object->size) {
/*
* If syncing the whole mapping of the file,
* it is faster to schedule all the writes in
* async mode, also allowing the clustering,
* and then wait for i/o to complete.
*/
flags = 0;
fsync_after = TRUE;
} else {
flags = (syncio || invalidate) ? OBJPC_SYNC : 0;
flags |= invalidate ? (OBJPC_SYNC | OBJPC_INVAL) : 0;
fsync_after = FALSE;
}
VM_OBJECT_WLOCK(object);
res = vm_object_page_clean(object, offset, offset + size,
flags);
VM_OBJECT_WUNLOCK(object);
if (fsync_after) {
for (;;) {
error = VOP_FSYNC(vp, MNT_WAIT, curthread);
if (error != ERELOOKUP)
break;
/*
* Allow SU/bufdaemon to handle more
* dependencies in the meantime.
*/
VOP_UNLOCK(vp);
vn_finished_write(mp);
(void)vn_start_write(vp, &mp, V_WAIT);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
}
}
VOP_UNLOCK(vp);
vn_finished_write(mp);
if (error != 0)
res = FALSE;
VM_OBJECT_WLOCK(object);
}
if ((object->type == OBJT_VNODE ||
object->type == OBJT_DEVICE) && invalidate) {
if (object->type == OBJT_DEVICE)
/*
* The option OBJPR_NOTMAPPED must be passed here
* because vm_object_page_remove() cannot remove
* unmanaged mappings.
*/
flags = OBJPR_NOTMAPPED;
else if (old_msync)
flags = 0;
else
flags = OBJPR_CLEANONLY;
vm_object_page_remove(object, OFF_TO_IDX(offset),
OFF_TO_IDX(offset + size + PAGE_MASK), flags);
}
VM_OBJECT_WUNLOCK(object);
return (res);
}
/*
* Determine whether the given advice can be applied to the object. Advice is
* not applied to unmanaged pages since they never belong to page queues, and
* since MADV_FREE is destructive, it can apply only to anonymous pages that
* have been mapped at most once.
*/
static bool
vm_object_advice_applies(vm_object_t object, int advice)
{
if ((object->flags & OBJ_UNMANAGED) != 0)
return (false);
if (advice != MADV_FREE)
return (true);
return ((object->flags & (OBJ_ONEMAPPING | OBJ_ANON)) ==
(OBJ_ONEMAPPING | OBJ_ANON));
}
static void
vm_object_madvise_freespace(vm_object_t object, int advice, vm_pindex_t pindex,
vm_size_t size)
{
if (advice == MADV_FREE)
vm_pager_freespace(object, pindex, size);
}
/*
* vm_object_madvise:
*
* Implements the madvise function at the object/page level.
*
* MADV_WILLNEED (any object)
*
* Activate the specified pages if they are resident.
*
* MADV_DONTNEED (any object)
*
* Deactivate the specified pages if they are resident.
*
* MADV_FREE (OBJT_SWAP objects, OBJ_ONEMAPPING only)
*
* Deactivate and clean the specified pages if they are
* resident. This permits the process to reuse the pages
* without faulting or the kernel to reclaim the pages
* without I/O.
*/
void
vm_object_madvise(vm_object_t object, vm_pindex_t pindex, vm_pindex_t end,
int advice)
{
vm_pindex_t tpindex;
vm_object_t backing_object, tobject;
vm_page_t m, tm;
if (object == NULL)
return;
relookup:
VM_OBJECT_WLOCK(object);
if (!vm_object_advice_applies(object, advice)) {
VM_OBJECT_WUNLOCK(object);
return;
}
for (m = vm_page_find_least(object, pindex); pindex < end; pindex++) {
tobject = object;
/*
* If the next page isn't resident in the top-level object, we
* need to search the shadow chain. When applying MADV_FREE, we
* take care to release any swap space used to store
* non-resident pages.
*/
if (m == NULL || pindex < m->pindex) {
/*
* Optimize a common case: if the top-level object has
* no backing object, we can skip over the non-resident
* range in constant time.
*/
if (object->backing_object == NULL) {
tpindex = (m != NULL && m->pindex < end) ?
m->pindex : end;
vm_object_madvise_freespace(object, advice,
pindex, tpindex - pindex);
if ((pindex = tpindex) == end)
break;
goto next_page;
}
tpindex = pindex;
do {
vm_object_madvise_freespace(tobject, advice,
tpindex, 1);
/*
* Prepare to search the next object in the
* chain.
*/
backing_object = tobject->backing_object;
if (backing_object == NULL)
goto next_pindex;
VM_OBJECT_WLOCK(backing_object);
tpindex +=
OFF_TO_IDX(tobject->backing_object_offset);
if (tobject != object)
VM_OBJECT_WUNLOCK(tobject);
tobject = backing_object;
if (!vm_object_advice_applies(tobject, advice))
goto next_pindex;
} while ((tm = vm_page_lookup(tobject, tpindex)) ==
NULL);
} else {
next_page:
tm = m;
m = TAILQ_NEXT(m, listq);
}
/*
* If the page is not in a normal state, skip it. The page
* can not be invalidated while the object lock is held.
*/
if (!vm_page_all_valid(tm) || vm_page_wired(tm))
goto next_pindex;
KASSERT((tm->flags & PG_FICTITIOUS) == 0,
("vm_object_madvise: page %p is fictitious", tm));
KASSERT((tm->oflags & VPO_UNMANAGED) == 0,
("vm_object_madvise: page %p is not managed", tm));
if (vm_page_tryxbusy(tm) == 0) {
if (object != tobject)
VM_OBJECT_WUNLOCK(object);
if (advice == MADV_WILLNEED) {
/*
* Reference the page before unlocking and
* sleeping so that the page daemon is less
* likely to reclaim it.
*/
vm_page_aflag_set(tm, PGA_REFERENCED);
}
if (!vm_page_busy_sleep(tm, "madvpo", 0))
VM_OBJECT_WUNLOCK(tobject);
goto relookup;
}
vm_page_advise(tm, advice);
vm_page_xunbusy(tm);
vm_object_madvise_freespace(tobject, advice, tm->pindex, 1);
next_pindex:
if (tobject != object)
VM_OBJECT_WUNLOCK(tobject);
}
VM_OBJECT_WUNLOCK(object);
}
/*
* vm_object_shadow:
*
* Create a new object which is backed by the
* specified existing object range. The source
* object reference is deallocated.
*
* The new object and offset into that object
* are returned in the source parameters.
*/
void
vm_object_shadow(vm_object_t *object, vm_ooffset_t *offset, vm_size_t length,
struct ucred *cred, bool shared)
{
vm_object_t source;
vm_object_t result;
source = *object;
/*
* Don't create the new object if the old object isn't shared.
*
* If we hold the only reference we can guarantee that it won't
* increase while we have the map locked. Otherwise the race is
* harmless and we will end up with an extra shadow object that
* will be collapsed later.
*/
if (source != NULL && source->ref_count == 1 &&
(source->flags & OBJ_ANON) != 0)
return;
/*
* Allocate a new object with the given length.
*/
result = vm_object_allocate_anon(atop(length), source, cred, length);
/*
* Store the offset into the source object, and fix up the offset into
* the new object.
*/
result->backing_object_offset = *offset;
if (shared || source != NULL) {
VM_OBJECT_WLOCK(result);
/*
* The new object shadows the source object, adding a
* reference to it. Our caller changes his reference
* to point to the new object, removing a reference to
* the source object. Net result: no change of
* reference count, unless the caller needs to add one
* more reference due to forking a shared map entry.
*/
if (shared) {
vm_object_reference_locked(result);
vm_object_clear_flag(result, OBJ_ONEMAPPING);
}
/*
* Try to optimize the result object's page color when
* shadowing in order to maintain page coloring
* consistency in the combined shadowed object.
*/
if (source != NULL) {
vm_object_backing_insert(result, source);
result->domain = source->domain;
#if VM_NRESERVLEVEL > 0
vm_object_set_flag(result,
(source->flags & OBJ_COLORED));
result->pg_color = (source->pg_color +
OFF_TO_IDX(*offset)) & ((1 << (VM_NFREEORDER -
1)) - 1);
#endif
}
VM_OBJECT_WUNLOCK(result);
}
/*
* Return the new things
*/
*offset = 0;
*object = result;
}
/*
* vm_object_split:
*
* Split the pages in a map entry into a new object. This affords
* easier removal of unused pages, and keeps object inheritance from
* being a negative impact on memory usage.
*/
void
vm_object_split(vm_map_entry_t entry)
{
vm_page_t m, m_next;
vm_object_t orig_object, new_object, backing_object;
vm_pindex_t idx, offidxstart;
vm_size_t size;
orig_object = entry->object.vm_object;
KASSERT((orig_object->flags & OBJ_ONEMAPPING) != 0,
("vm_object_split: Splitting object with multiple mappings."));
if ((orig_object->flags & OBJ_ANON) == 0)
return;
if (orig_object->ref_count <= 1)
return;
VM_OBJECT_WUNLOCK(orig_object);
offidxstart = OFF_TO_IDX(entry->offset);
size = atop(entry->end - entry->start);
new_object = vm_object_allocate_anon(size, orig_object,
orig_object->cred, ptoa(size));
/*
* We must wait for the orig_object to complete any in-progress
* collapse so that the swap blocks are stable below. The
* additional reference on backing_object by new object will
* prevent further collapse operations until split completes.
*/
VM_OBJECT_WLOCK(orig_object);
vm_object_collapse_wait(orig_object);
/*
* At this point, the new object is still private, so the order in
* which the original and new objects are locked does not matter.
*/
VM_OBJECT_WLOCK(new_object);
new_object->domain = orig_object->domain;
backing_object = orig_object->backing_object;
if (backing_object != NULL) {
vm_object_backing_insert_ref(new_object, backing_object);
new_object->backing_object_offset =
orig_object->backing_object_offset + entry->offset;
}
if (orig_object->cred != NULL) {
crhold(orig_object->cred);
KASSERT(orig_object->charge >= ptoa(size),
("orig_object->charge < 0"));
orig_object->charge -= ptoa(size);
}
/*
* Mark the split operation so that swap_pager_getpages() knows
* that the object is in transition.
*/
vm_object_set_flag(orig_object, OBJ_SPLIT);
#ifdef INVARIANTS
idx = 0;
#endif
retry:
m = vm_page_find_least(orig_object, offidxstart);
KASSERT(m == NULL || idx <= m->pindex - offidxstart,
("%s: object %p was repopulated", __func__, orig_object));
for (; m != NULL && (idx = m->pindex - offidxstart) < size;
m = m_next) {
m_next = TAILQ_NEXT(m, listq);
/*
* We must wait for pending I/O to complete before we can
* rename the page.
*
* We do not have to VM_PROT_NONE the page as mappings should
* not be changed by this operation.
*/
if (vm_page_tryxbusy(m) == 0) {
VM_OBJECT_WUNLOCK(new_object);
if (vm_page_busy_sleep(m, "spltwt", 0))
VM_OBJECT_WLOCK(orig_object);
VM_OBJECT_WLOCK(new_object);
goto retry;
}
/*
* The page was left invalid. Likely placed there by
* an incomplete fault. Just remove and ignore.
*/
if (vm_page_none_valid(m)) {
if (vm_page_remove(m))
vm_page_free(m);
continue;
}
/* vm_page_rename() will dirty the page. */
if (vm_page_rename(m, new_object, idx)) {
vm_page_xunbusy(m);
VM_OBJECT_WUNLOCK(new_object);
VM_OBJECT_WUNLOCK(orig_object);
vm_radix_wait();
VM_OBJECT_WLOCK(orig_object);
VM_OBJECT_WLOCK(new_object);
goto retry;
}
#if VM_NRESERVLEVEL > 0
/*
* If some of the reservation's allocated pages remain with
* the original object, then transferring the reservation to
* the new object is neither particularly beneficial nor
* particularly harmful as compared to leaving the reservation
* with the original object. If, however, all of the
* reservation's allocated pages are transferred to the new
* object, then transferring the reservation is typically
* beneficial. Determining which of these two cases applies
* would be more costly than unconditionally renaming the
* reservation.
*/
vm_reserv_rename(m, new_object, orig_object, offidxstart);
#endif
}
/*
* swap_pager_copy() can sleep, in which case the orig_object's
* and new_object's locks are released and reacquired.
*/
swap_pager_copy(orig_object, new_object, offidxstart, 0);
TAILQ_FOREACH(m, &new_object->memq, listq)
vm_page_xunbusy(m);
vm_object_clear_flag(orig_object, OBJ_SPLIT);
VM_OBJECT_WUNLOCK(orig_object);
VM_OBJECT_WUNLOCK(new_object);
entry->object.vm_object = new_object;
entry->offset = 0LL;
vm_object_deallocate(orig_object);
VM_OBJECT_WLOCK(new_object);
}
static vm_page_t
vm_object_collapse_scan_wait(vm_object_t object, vm_page_t p)
{
vm_object_t backing_object;
VM_OBJECT_ASSERT_WLOCKED(object);
backing_object = object->backing_object;
VM_OBJECT_ASSERT_WLOCKED(backing_object);
KASSERT(p == NULL || p->object == object || p->object == backing_object,
("invalid ownership %p %p %p", p, object, backing_object));
/* The page is only NULL when rename fails. */
if (p == NULL) {
VM_OBJECT_WUNLOCK(object);
VM_OBJECT_WUNLOCK(backing_object);
vm_radix_wait();
VM_OBJECT_WLOCK(object);
} else if (p->object == object) {
VM_OBJECT_WUNLOCK(backing_object);
if (vm_page_busy_sleep(p, "vmocol", 0))
VM_OBJECT_WLOCK(object);
} else {
VM_OBJECT_WUNLOCK(object);
if (!vm_page_busy_sleep(p, "vmocol", 0))
VM_OBJECT_WUNLOCK(backing_object);
VM_OBJECT_WLOCK(object);
}
VM_OBJECT_WLOCK(backing_object);
return (TAILQ_FIRST(&backing_object->memq));
}
static bool
vm_object_scan_all_shadowed(vm_object_t object)
{
vm_object_t backing_object;
vm_page_t p, pp;
vm_pindex_t backing_offset_index, new_pindex, pi, ps;
VM_OBJECT_ASSERT_WLOCKED(object);
VM_OBJECT_ASSERT_WLOCKED(object->backing_object);
backing_object = object->backing_object;
if ((backing_object->flags & OBJ_ANON) == 0)
return (false);
pi = backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
p = vm_page_find_least(backing_object, pi);
ps = swap_pager_find_least(backing_object, pi);
/*
* Only check pages inside the parent object's range and
* inside the parent object's mapping of the backing object.
*/
for (;; pi++) {
if (p != NULL && p->pindex < pi)
p = TAILQ_NEXT(p, listq);
if (ps < pi)
ps = swap_pager_find_least(backing_object, pi);
if (p == NULL && ps >= backing_object->size)
break;
else if (p == NULL)
pi = ps;
else
pi = MIN(p->pindex, ps);
new_pindex = pi - backing_offset_index;
if (new_pindex >= object->size)
break;
if (p != NULL) {
/*
* If the backing object page is busy a
* grandparent or older page may still be
* undergoing CoW. It is not safe to collapse
* the backing object until it is quiesced.
*/
if (vm_page_tryxbusy(p) == 0)
return (false);
/*
* We raced with the fault handler that left
* newly allocated invalid page on the object
* queue and retried.
*/
if (!vm_page_all_valid(p))
goto unbusy_ret;
}
/*
* See if the parent has the page or if the parent's object
* pager has the page. If the parent has the page but the page
* is not valid, the parent's object pager must have the page.
*
* If this fails, the parent does not completely shadow the
* object and we might as well give up now.
*/
pp = vm_page_lookup(object, new_pindex);
/*
* The valid check here is stable due to object lock
* being required to clear valid and initiate paging.
* Busy of p disallows fault handler to validate pp.
*/
if ((pp == NULL || vm_page_none_valid(pp)) &&
!vm_pager_has_page(object, new_pindex, NULL, NULL))
goto unbusy_ret;
if (p != NULL)
vm_page_xunbusy(p);
}
return (true);
unbusy_ret:
if (p != NULL)
vm_page_xunbusy(p);
return (false);
}
static void
vm_object_collapse_scan(vm_object_t object)
{
vm_object_t backing_object;
vm_page_t next, p, pp;
vm_pindex_t backing_offset_index, new_pindex;
VM_OBJECT_ASSERT_WLOCKED(object);
VM_OBJECT_ASSERT_WLOCKED(object->backing_object);
backing_object = object->backing_object;
backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
/*
* Our scan
*/
for (p = TAILQ_FIRST(&backing_object->memq); p != NULL; p = next) {
next = TAILQ_NEXT(p, listq);
new_pindex = p->pindex - backing_offset_index;
/*
* Check for busy page
*/
if (vm_page_tryxbusy(p) == 0) {
next = vm_object_collapse_scan_wait(object, p);
continue;
}
KASSERT(object->backing_object == backing_object,
("vm_object_collapse_scan: backing object mismatch %p != %p",
object->backing_object, backing_object));
KASSERT(p->object == backing_object,
("vm_object_collapse_scan: object mismatch %p != %p",
p->object, backing_object));
if (p->pindex < backing_offset_index ||
new_pindex >= object->size) {
vm_pager_freespace(backing_object, p->pindex, 1);
KASSERT(!pmap_page_is_mapped(p),
("freeing mapped page %p", p));
if (vm_page_remove(p))
vm_page_free(p);
continue;
}
if (!vm_page_all_valid(p)) {
KASSERT(!pmap_page_is_mapped(p),
("freeing mapped page %p", p));
if (vm_page_remove(p))
vm_page_free(p);
continue;
}
pp = vm_page_lookup(object, new_pindex);
if (pp != NULL && vm_page_tryxbusy(pp) == 0) {
vm_page_xunbusy(p);
/*
* The page in the parent is busy and possibly not
* (yet) valid. Until its state is finalized by the
* busy bit owner, we can't tell whether it shadows the
* original page.
*/
next = vm_object_collapse_scan_wait(object, pp);
continue;
}
if (pp != NULL && vm_page_none_valid(pp)) {
/*
* The page was invalid in the parent. Likely placed
* there by an incomplete fault. Just remove and
* ignore. p can replace it.
*/
if (vm_page_remove(pp))
vm_page_free(pp);
pp = NULL;
}
if (pp != NULL || vm_pager_has_page(object, new_pindex, NULL,
NULL)) {
/*
* The page already exists in the parent OR swap exists
* for this location in the parent. Leave the parent's
* page alone. Destroy the original page from the
* backing object.
*/
vm_pager_freespace(backing_object, p->pindex, 1);
KASSERT(!pmap_page_is_mapped(p),
("freeing mapped page %p", p));
if (vm_page_remove(p))
vm_page_free(p);
if (pp != NULL)
vm_page_xunbusy(pp);
continue;
}
/*
* Page does not exist in parent, rename the page from the
* backing object to the main object.
*
* If the page was mapped to a process, it can remain mapped
* through the rename. vm_page_rename() will dirty the page.
*/
if (vm_page_rename(p, object, new_pindex)) {
vm_page_xunbusy(p);
next = vm_object_collapse_scan_wait(object, NULL);
continue;
}
/* Use the old pindex to free the right page. */
vm_pager_freespace(backing_object, new_pindex +
backing_offset_index, 1);
#if VM_NRESERVLEVEL > 0
/*
* Rename the reservation.
*/
vm_reserv_rename(p, object, backing_object,
backing_offset_index);
#endif
vm_page_xunbusy(p);
}
return;
}
/*
* vm_object_collapse:
*
* Collapse an object with the object backing it.
* Pages in the backing object are moved into the
* parent, and the backing object is deallocated.
*/
void
vm_object_collapse(vm_object_t object)
{
vm_object_t backing_object, new_backing_object;
VM_OBJECT_ASSERT_WLOCKED(object);
while (TRUE) {
KASSERT((object->flags & (OBJ_DEAD | OBJ_ANON)) == OBJ_ANON,
("collapsing invalid object"));
/*
* Wait for the backing_object to finish any pending
* collapse so that the caller sees the shortest possible
* shadow chain.
*/
backing_object = vm_object_backing_collapse_wait(object);
if (backing_object == NULL)
return;
KASSERT(object->ref_count > 0 &&
object->ref_count > atomic_load_int(&object->shadow_count),
("collapse with invalid ref %d or shadow %d count.",
object->ref_count, atomic_load_int(&object->shadow_count)));
KASSERT((backing_object->flags &
(OBJ_COLLAPSING | OBJ_DEAD)) == 0,
("vm_object_collapse: Backing object already collapsing."));
KASSERT((object->flags & (OBJ_COLLAPSING | OBJ_DEAD)) == 0,
("vm_object_collapse: object is already collapsing."));
/*
* We know that we can either collapse the backing object if
* the parent is the only reference to it, or (perhaps) have
* the parent bypass the object if the parent happens to shadow
* all the resident pages in the entire backing object.
*/
if (backing_object->ref_count == 1) {
KASSERT(atomic_load_int(&backing_object->shadow_count)
== 1,
("vm_object_collapse: shadow_count: %d",
atomic_load_int(&backing_object->shadow_count)));
vm_object_pip_add(object, 1);
vm_object_set_flag(object, OBJ_COLLAPSING);
vm_object_pip_add(backing_object, 1);
vm_object_set_flag(backing_object, OBJ_DEAD);
/*
* If there is exactly one reference to the backing
* object, we can collapse it into the parent.
*/
vm_object_collapse_scan(object);
#if VM_NRESERVLEVEL > 0
/*
* Break any reservations from backing_object.
*/
if (__predict_false(!LIST_EMPTY(&backing_object->rvq)))
vm_reserv_break_all(backing_object);
#endif
/*
* Move the pager from backing_object to object.
*
* swap_pager_copy() can sleep, in which case the
* backing_object's and object's locks are released and
* reacquired.
*/
swap_pager_copy(backing_object, object,
OFF_TO_IDX(object->backing_object_offset), TRUE);
/*
* Object now shadows whatever backing_object did.
*/
vm_object_clear_flag(object, OBJ_COLLAPSING);
vm_object_backing_transfer(object, backing_object);
object->backing_object_offset +=
backing_object->backing_object_offset;
VM_OBJECT_WUNLOCK(object);
vm_object_pip_wakeup(object);
/*
* Discard backing_object.
*
* Since the backing object has no pages, no pager left,
* and no object references within it, all that is
* necessary is to dispose of it.
*/
KASSERT(backing_object->ref_count == 1, (
"backing_object %p was somehow re-referenced during collapse!",
backing_object));
vm_object_pip_wakeup(backing_object);
(void)refcount_release(&backing_object->ref_count);
vm_object_terminate(backing_object);
counter_u64_add(object_collapses, 1);
VM_OBJECT_WLOCK(object);
} else {
/*
* If we do not entirely shadow the backing object,
* there is nothing we can do so we give up.
*
* The object lock and backing_object lock must not
* be dropped during this sequence.
*/
if (!vm_object_scan_all_shadowed(object)) {
VM_OBJECT_WUNLOCK(backing_object);
break;
}
/*
* Make the parent shadow the next object in the
* chain. Deallocating backing_object will not remove
* it, since its reference count is at least 2.
*/
vm_object_backing_remove_locked(object);
new_backing_object = backing_object->backing_object;
if (new_backing_object != NULL) {
vm_object_backing_insert_ref(object,
new_backing_object);
object->backing_object_offset +=
backing_object->backing_object_offset;
}
/*
* Drop the reference count on backing_object. Since
* its ref_count was at least 2, it will not vanish.
*/
(void)refcount_release(&backing_object->ref_count);
KASSERT(backing_object->ref_count >= 1, (
"backing_object %p was somehow dereferenced during collapse!",
backing_object));
VM_OBJECT_WUNLOCK(backing_object);
counter_u64_add(object_bypasses, 1);
}
/*
* Try again with this object's new backing object.
*/
}
}
/*
* vm_object_page_remove:
*
* For the given object, either frees or invalidates each of the
* specified pages. In general, a page is freed. However, if a page is
* wired for any reason other than the existence of a managed, wired
* mapping, then it may be invalidated but not removed from the object.
* Pages are specified by the given range ["start", "end") and the option
* OBJPR_CLEANONLY. As a special case, if "end" is zero, then the range
* extends from "start" to the end of the object. If the option
* OBJPR_CLEANONLY is specified, then only the non-dirty pages within the
* specified range are affected. If the option OBJPR_NOTMAPPED is
* specified, then the pages within the specified range must have no
* mappings. Otherwise, if this option is not specified, any mappings to
* the specified pages are removed before the pages are freed or
* invalidated.
*
* In general, this operation should only be performed on objects that
* contain managed pages. There are, however, two exceptions. First, it
* is performed on the kernel and kmem objects by vm_map_entry_delete().
* Second, it is used by msync(..., MS_INVALIDATE) to invalidate device-
* backed pages. In both of these cases, the option OBJPR_CLEANONLY must
* not be specified and the option OBJPR_NOTMAPPED must be specified.
*
* The object must be locked.
*/
void
vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
int options)
{
vm_page_t p, next;
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT((object->flags & OBJ_UNMANAGED) == 0 ||
(options & (OBJPR_CLEANONLY | OBJPR_NOTMAPPED)) == OBJPR_NOTMAPPED,
("vm_object_page_remove: illegal options for object %p", object));
if (object->resident_page_count == 0)
return;
vm_object_pip_add(object, 1);
again:
p = vm_page_find_least(object, start);
/*
* Here, the variable "p" is either (1) the page with the least pindex
* greater than or equal to the parameter "start" or (2) NULL.
*/
for (; p != NULL && (p->pindex < end || end == 0); p = next) {
next = TAILQ_NEXT(p, listq);
/*
* Skip invalid pages if asked to do so. Try to avoid acquiring
* the busy lock, as some consumers rely on this to avoid
* deadlocks.
*
* A thread may concurrently transition the page from invalid to
* valid using only the busy lock, so the result of this check
* is immediately stale. It is up to consumers to handle this,
* for instance by ensuring that all invalid->valid transitions
* happen with a mutex held, as may be possible for a
* filesystem.
*/
if ((options & OBJPR_VALIDONLY) != 0 && vm_page_none_valid(p))
continue;
/*
* If the page is wired for any reason besides the existence
* of managed, wired mappings, then it cannot be freed. For
* example, fictitious pages, which represent device memory,
* are inherently wired and cannot be freed. They can,
* however, be invalidated if the option OBJPR_CLEANONLY is
* not specified.
*/
if (vm_page_tryxbusy(p) == 0) {
if (vm_page_busy_sleep(p, "vmopar", 0))
VM_OBJECT_WLOCK(object);
goto again;
}
if ((options & OBJPR_VALIDONLY) != 0 && vm_page_none_valid(p)) {
vm_page_xunbusy(p);
continue;
}
if (vm_page_wired(p)) {
wired:
if ((options & OBJPR_NOTMAPPED) == 0 &&
object->ref_count != 0)
pmap_remove_all(p);
if ((options & OBJPR_CLEANONLY) == 0) {
vm_page_invalid(p);
vm_page_undirty(p);
}
vm_page_xunbusy(p);
continue;
}
KASSERT((p->flags & PG_FICTITIOUS) == 0,
("vm_object_page_remove: page %p is fictitious", p));
if ((options & OBJPR_CLEANONLY) != 0 &&
!vm_page_none_valid(p)) {
if ((options & OBJPR_NOTMAPPED) == 0 &&
object->ref_count != 0 &&
!vm_page_try_remove_write(p))
goto wired;
if (p->dirty != 0) {
vm_page_xunbusy(p);
continue;
}
}
if ((options & OBJPR_NOTMAPPED) == 0 &&
object->ref_count != 0 && !vm_page_try_remove_all(p))
goto wired;
vm_page_free(p);
}
vm_object_pip_wakeup(object);
vm_pager_freespace(object, start, (end == 0 ? object->size : end) -
start);
}
/*
* vm_object_page_noreuse:
*
* For the given object, attempt to move the specified pages to
* the head of the inactive queue. This bypasses regular LRU
* operation and allows the pages to be reused quickly under memory
* pressure. If a page is wired for any reason, then it will not
* be queued. Pages are specified by the range ["start", "end").
* As a special case, if "end" is zero, then the range extends from
* "start" to the end of the object.
*
* This operation should only be performed on objects that
* contain non-fictitious, managed pages.
*
* The object must be locked.
*/
void
vm_object_page_noreuse(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
{
vm_page_t p, next;
VM_OBJECT_ASSERT_LOCKED(object);
KASSERT((object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0,
("vm_object_page_noreuse: illegal object %p", object));
if (object->resident_page_count == 0)
return;
p = vm_page_find_least(object, start);
/*
* Here, the variable "p" is either (1) the page with the least pindex
* greater than or equal to the parameter "start" or (2) NULL.
*/
for (; p != NULL && (p->pindex < end || end == 0); p = next) {
next = TAILQ_NEXT(p, listq);
vm_page_deactivate_noreuse(p);
}
}
/*
* Populate the specified range of the object with valid pages. Returns
* TRUE if the range is successfully populated and FALSE otherwise.
*
* Note: This function should be optimized to pass a larger array of
* pages to vm_pager_get_pages() before it is applied to a non-
* OBJT_DEVICE object.
*
* The object must be locked.
*/
boolean_t
vm_object_populate(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
{
vm_page_t m;
vm_pindex_t pindex;
int rv;
VM_OBJECT_ASSERT_WLOCKED(object);
for (pindex = start; pindex < end; pindex++) {
rv = vm_page_grab_valid(&m, object, pindex, VM_ALLOC_NORMAL);
if (rv != VM_PAGER_OK)
break;
/*
* Keep "m" busy because a subsequent iteration may unlock
* the object.
*/
}
if (pindex > start) {
m = vm_page_lookup(object, start);
while (m != NULL && m->pindex < pindex) {
vm_page_xunbusy(m);
m = TAILQ_NEXT(m, listq);
}
}
return (pindex == end);
}
/*
* Routine: vm_object_coalesce
* Function: Coalesces two objects backing up adjoining
* regions of memory into a single object.
*
* returns TRUE if objects were combined.
*
* NOTE: Only works at the moment if the second object is NULL -
* if it's not, which object do we lock first?
*
* Parameters:
* prev_object First object to coalesce
* prev_offset Offset into prev_object
* prev_size Size of reference to prev_object
* next_size Size of reference to the second object
* reserved Indicator that extension region has
* swap accounted for
*
* Conditions:
* The object must *not* be locked.
*/
boolean_t
vm_object_coalesce(vm_object_t prev_object, vm_ooffset_t prev_offset,
vm_size_t prev_size, vm_size_t next_size, boolean_t reserved)
{
vm_pindex_t next_pindex;
if (prev_object == NULL)
return (TRUE);
if ((prev_object->flags & OBJ_ANON) == 0)
return (FALSE);
VM_OBJECT_WLOCK(prev_object);
/*
* Try to collapse the object first.
*/
vm_object_collapse(prev_object);
/*
* Can't coalesce if: . more than one reference . paged out . shadows
* another object . has a copy elsewhere (any of which mean that the
* pages not mapped to prev_entry may be in use anyway)
*/
if (prev_object->backing_object != NULL) {
VM_OBJECT_WUNLOCK(prev_object);
return (FALSE);
}
prev_size >>= PAGE_SHIFT;
next_size >>= PAGE_SHIFT;
next_pindex = OFF_TO_IDX(prev_offset) + prev_size;
if (prev_object->ref_count > 1 &&
prev_object->size != next_pindex &&
(prev_object->flags & OBJ_ONEMAPPING) == 0) {
VM_OBJECT_WUNLOCK(prev_object);
return (FALSE);
}
/*
* Account for the charge.
*/
if (prev_object->cred != NULL) {
/*
* If prev_object was charged, then this mapping,
* although not charged now, may become writable
* later. Non-NULL cred in the object would prevent
* swap reservation during enabling of the write
* access, so reserve swap now. Failed reservation
* cause allocation of the separate object for the map
* entry, and swap reservation for this entry is
* managed in appropriate time.
*/
if (!reserved && !swap_reserve_by_cred(ptoa(next_size),
prev_object->cred)) {
VM_OBJECT_WUNLOCK(prev_object);
return (FALSE);
}
prev_object->charge += ptoa(next_size);
}
/*
* Remove any pages that may still be in the object from a previous
* deallocation.
*/
if (next_pindex < prev_object->size) {
vm_object_page_remove(prev_object, next_pindex, next_pindex +
next_size, 0);
#if 0
if (prev_object->cred != NULL) {
KASSERT(prev_object->charge >=
ptoa(prev_object->size - next_pindex),
("object %p overcharged 1 %jx %jx", prev_object,
(uintmax_t)next_pindex, (uintmax_t)next_size));
prev_object->charge -= ptoa(prev_object->size -
next_pindex);
}
#endif
}
/*
* Extend the object if necessary.
*/
if (next_pindex + next_size > prev_object->size)
prev_object->size = next_pindex + next_size;
VM_OBJECT_WUNLOCK(prev_object);
return (TRUE);
}
void
vm_object_set_writeable_dirty_(vm_object_t object)
{
atomic_add_int(&object->generation, 1);
}
bool
vm_object_mightbedirty_(vm_object_t object)
{
return (object->generation != object->cleangeneration);
}
/*
* vm_object_unwire:
*
* For each page offset within the specified range of the given object,
* find the highest-level page in the shadow chain and unwire it. A page
* must exist at every page offset, and the highest-level page must be
* wired.
*/
void
vm_object_unwire(vm_object_t object, vm_ooffset_t offset, vm_size_t length,
uint8_t queue)
{
vm_object_t tobject, t1object;
vm_page_t m, tm;
vm_pindex_t end_pindex, pindex, tpindex;
int depth, locked_depth;
KASSERT((offset & PAGE_MASK) == 0,
("vm_object_unwire: offset is not page aligned"));
KASSERT((length & PAGE_MASK) == 0,
("vm_object_unwire: length is not a multiple of PAGE_SIZE"));
/* The wired count of a fictitious page never changes. */
if ((object->flags & OBJ_FICTITIOUS) != 0)
return;
pindex = OFF_TO_IDX(offset);
end_pindex = pindex + atop(length);
again:
locked_depth = 1;
VM_OBJECT_RLOCK(object);
m = vm_page_find_least(object, pindex);
while (pindex < end_pindex) {
if (m == NULL || pindex < m->pindex) {
/*
* The first object in the shadow chain doesn't
* contain a page at the current index. Therefore,
* the page must exist in a backing object.
*/
tobject = object;
tpindex = pindex;
depth = 0;
do {
tpindex +=
OFF_TO_IDX(tobject->backing_object_offset);
tobject = tobject->backing_object;
KASSERT(tobject != NULL,
("vm_object_unwire: missing page"));
if ((tobject->flags & OBJ_FICTITIOUS) != 0)
goto next_page;
depth++;
if (depth == locked_depth) {
locked_depth++;
VM_OBJECT_RLOCK(tobject);
}
} while ((tm = vm_page_lookup(tobject, tpindex)) ==
NULL);
} else {
tm = m;
m = TAILQ_NEXT(m, listq);
}
if (vm_page_trysbusy(tm) == 0) {
for (tobject = object; locked_depth >= 1;
locked_depth--) {
t1object = tobject->backing_object;
if (tm->object != tobject)
VM_OBJECT_RUNLOCK(tobject);
tobject = t1object;
}
tobject = tm->object;
if (!vm_page_busy_sleep(tm, "unwbo",
VM_ALLOC_IGN_SBUSY))
VM_OBJECT_RUNLOCK(tobject);
goto again;
}
vm_page_unwire(tm, queue);
vm_page_sunbusy(tm);
next_page:
pindex++;
}
/* Release the accumulated object locks. */
for (tobject = object; locked_depth >= 1; locked_depth--) {
t1object = tobject->backing_object;
VM_OBJECT_RUNLOCK(tobject);
tobject = t1object;
}
}
/*
* Return the vnode for the given object, or NULL if none exists.
* For tmpfs objects, the function may return NULL if there is
* no vnode allocated at the time of the call.
*/
struct vnode *
vm_object_vnode(vm_object_t object)
{
struct vnode *vp;
VM_OBJECT_ASSERT_LOCKED(object);
vm_pager_getvp(object, &vp, NULL);
return (vp);
}
/*
* Busy the vm object. This prevents new pages belonging to the object from
* becoming busy. Existing pages persist as busy. Callers are responsible
* for checking page state before proceeding.
*/
void
vm_object_busy(vm_object_t obj)
{
VM_OBJECT_ASSERT_LOCKED(obj);
blockcount_acquire(&obj->busy, 1);
/* The fence is required to order loads of page busy. */
atomic_thread_fence_acq_rel();
}
void
vm_object_unbusy(vm_object_t obj)
{
blockcount_release(&obj->busy, 1);
}
void
vm_object_busy_wait(vm_object_t obj, const char *wmesg)
{
VM_OBJECT_ASSERT_UNLOCKED(obj);
(void)blockcount_sleep(&obj->busy, NULL, wmesg, PVM);
}
/*
* This function aims to determine if the object is mapped,
* specifically, if it is referenced by a vm_map_entry. Because
* objects occasionally acquire transient references that do not
* represent a mapping, the method used here is inexact. However, it
* has very low overhead and is good enough for the advisory
* vm.vmtotal sysctl.
*/
bool
vm_object_is_active(vm_object_t obj)
{
return (obj->ref_count > atomic_load_int(&obj->shadow_count));
}
static int
vm_object_list_handler(struct sysctl_req *req, bool swap_only)
{
struct kinfo_vmobject *kvo;
char *fullpath, *freepath;
struct vnode *vp;
struct vattr va;
vm_object_t obj;
vm_page_t m;
u_long sp;
int count, error;
if (req->oldptr == NULL) {
/*
* If an old buffer has not been provided, generate an
* estimate of the space needed for a subsequent call.
*/
mtx_lock(&vm_object_list_mtx);
count = 0;
TAILQ_FOREACH(obj, &vm_object_list, object_list) {
if (obj->type == OBJT_DEAD)
continue;
count++;
}
mtx_unlock(&vm_object_list_mtx);
return (SYSCTL_OUT(req, NULL, sizeof(struct kinfo_vmobject) *
count * 11 / 10));
}
kvo = malloc(sizeof(*kvo), M_TEMP, M_WAITOK | M_ZERO);
error = 0;
/*
* VM objects are type stable and are never removed from the
* list once added. This allows us to safely read obj->object_list
* after reacquiring the VM object lock.
*/
mtx_lock(&vm_object_list_mtx);
TAILQ_FOREACH(obj, &vm_object_list, object_list) {
if (obj->type == OBJT_DEAD ||
(swap_only && (obj->flags & (OBJ_ANON | OBJ_SWAP)) == 0))
continue;
VM_OBJECT_RLOCK(obj);
if (obj->type == OBJT_DEAD ||
(swap_only && (obj->flags & (OBJ_ANON | OBJ_SWAP)) == 0)) {
VM_OBJECT_RUNLOCK(obj);
continue;
}
mtx_unlock(&vm_object_list_mtx);
kvo->kvo_size = ptoa(obj->size);
kvo->kvo_resident = obj->resident_page_count;
kvo->kvo_ref_count = obj->ref_count;
kvo->kvo_shadow_count = atomic_load_int(&obj->shadow_count);
kvo->kvo_memattr = obj->memattr;
kvo->kvo_active = 0;
kvo->kvo_inactive = 0;
if (!swap_only) {
TAILQ_FOREACH(m, &obj->memq, listq) {
/*
* A page may belong to the object but be
* dequeued and set to PQ_NONE while the
* object lock is not held. This makes the
* reads of m->queue below racy, and we do not
* count pages set to PQ_NONE. However, this
* sysctl is only meant to give an
* approximation of the system anyway.
*/
if (m->a.queue == PQ_ACTIVE)
kvo->kvo_active++;
else if (m->a.queue == PQ_INACTIVE)
kvo->kvo_inactive++;
}
}
kvo->kvo_vn_fileid = 0;
kvo->kvo_vn_fsid = 0;
kvo->kvo_vn_fsid_freebsd11 = 0;
freepath = NULL;
fullpath = "";
vp = NULL;
kvo->kvo_type = vm_object_kvme_type(obj, swap_only ? NULL : &vp);
if (vp != NULL) {
vref(vp);
} else if ((obj->flags & OBJ_ANON) != 0) {
MPASS(kvo->kvo_type == KVME_TYPE_SWAP);
kvo->kvo_me = (uintptr_t)obj;
/* tmpfs objs are reported as vnodes */
kvo->kvo_backing_obj = (uintptr_t)obj->backing_object;
sp = swap_pager_swapped_pages(obj);
kvo->kvo_swapped = sp > UINT32_MAX ? UINT32_MAX : sp;
}
VM_OBJECT_RUNLOCK(obj);
if (vp != NULL) {
vn_fullpath(vp, &fullpath, &freepath);
vn_lock(vp, LK_SHARED | LK_RETRY);
if (VOP_GETATTR(vp, &va, curthread->td_ucred) == 0) {
kvo->kvo_vn_fileid = va.va_fileid;
kvo->kvo_vn_fsid = va.va_fsid;
kvo->kvo_vn_fsid_freebsd11 = va.va_fsid;
/* truncate */
}
vput(vp);
}
strlcpy(kvo->kvo_path, fullpath, sizeof(kvo->kvo_path));
if (freepath != NULL)
free(freepath, M_TEMP);
/* Pack record size down */
kvo->kvo_structsize = offsetof(struct kinfo_vmobject, kvo_path)
+ strlen(kvo->kvo_path) + 1;
kvo->kvo_structsize = roundup(kvo->kvo_structsize,
sizeof(uint64_t));
error = SYSCTL_OUT(req, kvo, kvo->kvo_structsize);
maybe_yield();
mtx_lock(&vm_object_list_mtx);
if (error)
break;
}
mtx_unlock(&vm_object_list_mtx);
free(kvo, M_TEMP);
return (error);
}
static int
sysctl_vm_object_list(SYSCTL_HANDLER_ARGS)
{
return (vm_object_list_handler(req, false));
}
SYSCTL_PROC(_vm, OID_AUTO, objects, CTLTYPE_STRUCT | CTLFLAG_RW | CTLFLAG_SKIP |
CTLFLAG_MPSAFE, NULL, 0, sysctl_vm_object_list, "S,kinfo_vmobject",
"List of VM objects");
static int
sysctl_vm_object_list_swap(SYSCTL_HANDLER_ARGS)
{
return (vm_object_list_handler(req, true));
}
/*
* This sysctl returns list of the anonymous or swap objects. Intent
* is to provide stripped optimized list useful to analyze swap use.
* Since technically non-swap (default) objects participate in the
* shadow chains, and are converted to swap type as needed by swap
* pager, we must report them.
*/
SYSCTL_PROC(_vm, OID_AUTO, swap_objects,
CTLTYPE_STRUCT | CTLFLAG_RW | CTLFLAG_SKIP | CTLFLAG_MPSAFE, NULL, 0,
sysctl_vm_object_list_swap, "S,kinfo_vmobject",
"List of swap VM objects");
#include "opt_ddb.h"
#ifdef DDB
#include <sys/kernel.h>
#include <sys/cons.h>
#include <ddb/ddb.h>
static int
_vm_object_in_map(vm_map_t map, vm_object_t object, vm_map_entry_t entry)
{
vm_map_t tmpm;
vm_map_entry_t tmpe;
vm_object_t obj;
if (map == 0)
return 0;
if (entry == 0) {
VM_MAP_ENTRY_FOREACH(tmpe, map) {
if (_vm_object_in_map(map, object, tmpe)) {
return 1;
}
}
} else if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) {
tmpm = entry->object.sub_map;
VM_MAP_ENTRY_FOREACH(tmpe, tmpm) {
if (_vm_object_in_map(tmpm, object, tmpe)) {
return 1;
}
}
} else if ((obj = entry->object.vm_object) != NULL) {
for (; obj; obj = obj->backing_object)
if (obj == object) {
return 1;
}
}
return 0;
}
static int
vm_object_in_map(vm_object_t object)
{
struct proc *p;
/* sx_slock(&allproc_lock); */
FOREACH_PROC_IN_SYSTEM(p) {
if (!p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */)
continue;
if (_vm_object_in_map(&p->p_vmspace->vm_map, object, 0)) {
/* sx_sunlock(&allproc_lock); */
return 1;
}
}
/* sx_sunlock(&allproc_lock); */
if (_vm_object_in_map(kernel_map, object, 0))
return 1;
return 0;
}
DB_SHOW_COMMAND_FLAGS(vmochk, vm_object_check, DB_CMD_MEMSAFE)
{
vm_object_t object;
/*
* make sure that internal objs are in a map somewhere
* and none have zero ref counts.
*/
TAILQ_FOREACH(object, &vm_object_list, object_list) {
if ((object->flags & OBJ_ANON) != 0) {
if (object->ref_count == 0) {
db_printf("vmochk: internal obj has zero ref count: %ld\n",
(long)object->size);
}
if (!vm_object_in_map(object)) {
db_printf(
"vmochk: internal obj is not in a map: "
"ref: %d, size: %lu: 0x%lx, backing_object: %p\n",
object->ref_count, (u_long)object->size,
(u_long)object->size,
(void *)object->backing_object);
}
}
if (db_pager_quit)
return;
}
}
/*
* vm_object_print: [ debug ]
*/
DB_SHOW_COMMAND(object, vm_object_print_static)
{
/* XXX convert args. */
vm_object_t object = (vm_object_t)addr;
boolean_t full = have_addr;
vm_page_t p;
/* XXX count is an (unused) arg. Avoid shadowing it. */
#define count was_count
int count;
if (object == NULL)
return;
db_iprintf(
"Object %p: type=%d, size=0x%jx, res=%d, ref=%d, flags=0x%x ruid %d charge %jx\n",
object, (int)object->type, (uintmax_t)object->size,
object->resident_page_count, object->ref_count, object->flags,
object->cred ? object->cred->cr_ruid : -1, (uintmax_t)object->charge);
db_iprintf(" sref=%d, backing_object(%d)=(%p)+0x%jx\n",
atomic_load_int(&object->shadow_count),
object->backing_object ? object->backing_object->ref_count : 0,
object->backing_object, (uintmax_t)object->backing_object_offset);
if (!full)
return;
db_indent += 2;
count = 0;
TAILQ_FOREACH(p, &object->memq, listq) {
if (count == 0)
db_iprintf("memory:=");
else if (count == 6) {
db_printf("\n");
db_iprintf(" ...");
count = 0;
} else
db_printf(",");
count++;
db_printf("(off=0x%jx,page=0x%jx)",
(uintmax_t)p->pindex, (uintmax_t)VM_PAGE_TO_PHYS(p));
if (db_pager_quit)
break;
}
if (count != 0)
db_printf("\n");
db_indent -= 2;
}
/* XXX. */
#undef count
/* XXX need this non-static entry for calling from vm_map_print. */
void
vm_object_print(
/* db_expr_t */ long addr,
boolean_t have_addr,
/* db_expr_t */ long count,
char *modif)
{
vm_object_print_static(addr, have_addr, count, modif);
}
DB_SHOW_COMMAND_FLAGS(vmopag, vm_object_print_pages, DB_CMD_MEMSAFE)
{
vm_object_t object;
vm_pindex_t fidx;
vm_paddr_t pa;
vm_page_t m, prev_m;
int rcount;
TAILQ_FOREACH(object, &vm_object_list, object_list) {
db_printf("new object: %p\n", (void *)object);
if (db_pager_quit)
return;
rcount = 0;
fidx = 0;
pa = -1;
TAILQ_FOREACH(m, &object->memq, listq) {
if ((prev_m = TAILQ_PREV(m, pglist, listq)) != NULL &&
prev_m->pindex + 1 != m->pindex) {
if (rcount) {
db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
(long)fidx, rcount, (long)pa);
if (db_pager_quit)
return;
rcount = 0;
}
}
if (rcount &&
(VM_PAGE_TO_PHYS(m) == pa + rcount * PAGE_SIZE)) {
++rcount;
continue;
}
if (rcount) {
db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
(long)fidx, rcount, (long)pa);
if (db_pager_quit)
return;
}
fidx = m->pindex;
pa = VM_PAGE_TO_PHYS(m);
rcount = 1;
}
if (rcount) {
db_printf(" index(%ld)run(%d)pa(0x%lx)\n",
(long)fidx, rcount, (long)pa);
if (db_pager_quit)
return;
}
}
}
#endif /* DDB */
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