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freebsd-nq/sys/vm/vm_object.c
Mark Johnston d28af1abf0 vm: Add a mode to vm_object_page_remove() which skips invalid pages 
This will be used to break a deadlock in ZFS between the per-mountpoint
teardown lock and page busy locks.  In particular, when purging data
from the page cache during dataset rollback, we want to avoid blocking
on the busy state of invalid pages since the busying thread may be
blocked on the teardown lock in zfs_getpages().

Add a helper, vn_pages_remove_valid(), for use by filesystems.  Bump
__FreeBSD_version so that the OpenZFS port can make use of the new
helper.

PR:		258208
Reviewed by:	avg, kib, sef
Tested by:	pho (part of a larger patch)
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D32931
2021-11-15 13:01:30 -05:00

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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(object->shadow_count == 0,
("object %p shadow_count = %d",
object, object->shadow_count));
KASSERT(object->type == OBJT_DEAD,
("object %p has non-dead type %d",
object, object->type));
}
#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, "vm object", 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;
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);
/*
* 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_DEFAULT:
flags = OBJ_COLORED;
break;
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_DEFAULT, size, OBJ_ANON | OBJ_ONEMAPPING,
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 && backing_object->shadow_count == 1,
("vm_object_anon_deallocate: ref_count: %d, shadow_count: %d",
backing_object->ref_count, 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 ||
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_DEFAULT ||
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;
}
}
/*
* vm_object_destroy removes the object from the global object list
* and frees the space for the object.
*/
void
vm_object_destroy(vm_object_t object)
{
/*
* Release the allocation charge.
*/
if (object->cred != NULL) {
swap_release_by_cred(object->charge, object->cred);
object->charge = 0;
crfree(object->cred);
object->cred = NULL;
}
/*
* Free the space for the object.
*/
uma_zfree(obj_zone, object);
}
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."));
if ((object->flags & OBJ_SHADOWLIST) != 0) {
LIST_REMOVE(object, shadow_list);
backing_object->shadow_count--;
object->flags &= ~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);
if ((object->flags & OBJ_SHADOWLIST) != 0) {
backing_object = object->backing_object;
VM_OBJECT_WLOCK(backing_object);
vm_object_backing_remove_locked(object);
VM_OBJECT_WUNLOCK(backing_object);
} else
object->backing_object = NULL;
}
static void
vm_object_backing_insert_locked(vm_object_t object, vm_object_t backing_object)
{
VM_OBJECT_ASSERT_WLOCKED(object);
if ((backing_object->flags & OBJ_ANON) != 0) {
VM_OBJECT_ASSERT_WLOCKED(backing_object);
LIST_INSERT_HEAD(&backing_object->shadow_head, object,
shadow_list);
backing_object->shadow_count++;
object->flags |= 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;
}
/*
* 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);
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 {
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->type == OBJT_DEFAULT ||
(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)
error = VOP_FSYNC(vp, MNT_WAIT, curthread);
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_DEFAULT/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
result->flags |= 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_busy, 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);
/*
* If swap_pager_copy() is later called, it will convert new_object
* into a swap object.
*/
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);
m_busy = NULL;
#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
/*
* orig_object's type may change while sleeping, so keep track
* of the beginning of the busied range.
*/
if (orig_object->type != OBJT_SWAP)
vm_page_xunbusy(m);
else if (m_busy == NULL)
m_busy = m;
}
if ((orig_object->flags & OBJ_SWAP) != 0) {
/*
* 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);
if (m_busy != NULL)
TAILQ_FOREACH_FROM(m_busy, &new_object->memq, listq)
vm_page_xunbusy(m_busy);
}
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 > object->shadow_count,
("collapse with invalid ref %d or shadow %d count.",
object->ref_count, 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(backing_object->shadow_count == 1,
("vm_object_collapse: shadow_count: %d",
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.
*/
if ((backing_object->flags & OBJ_SWAP) != 0) {
/*
* swap_pager_copy() can sleep, in which case
* the backing_object's and object's locks are
* released and reacquired.
* Since swap_pager_copy() is being asked to
* destroy backing_object, it will change the
* type to OBJT_DEFAULT.
*/
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);
}
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);
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 = 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_DEFAULT ||
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(vmochk, vm_object_check)
{
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",
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(vmopag, vm_object_print_pages)
{
vm_object_t object;
vm_pindex_t fidx;
vm_paddr_t pa;
vm_page_t m, prev_m;
int rcount, nl, c;
nl = 0;
TAILQ_FOREACH(object, &vm_object_list, object_list) {
db_printf("new object: %p\n", (void *)object);
if (nl > 18) {
c = cngetc();
if (c != ' ')
return;
nl = 0;
}
nl++;
rcount = 0;
fidx = 0;
pa = -1;
TAILQ_FOREACH(m, &object->memq, listq) {
if (m->pindex > 128)
break;
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 (nl > 18) {
c = cngetc();
if (c != ' ')
return;
nl = 0;
}
nl++;
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 (nl > 18) {
c = cngetc();
if (c != ' ')
return;
nl = 0;
}
nl++;
}
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 (nl > 18) {
c = cngetc();
if (c != ' ')
return;
nl = 0;
}
nl++;
}
}
}
#endif /* DDB */
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