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e18cc7bf3e
freebsd-skq/sys/vm/vm_object.c
Max Laier e18cc7bf3e Another long standing vm bug found at Isilon: 
Fix a race between vm_object_collapse and vm_fault.

Reviewed by:	alc@
MFC after:	3 days
2011-05-09 20:27:49 +00:00

2260 lines
59 KiB
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/*-
* 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)vm_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/lock.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/mutex.h>
#include <sys/proc.h> /* for curproc, pageproc */
#include <sys/socket.h>
#include <sys/resourcevar.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/swap_pager.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.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, int *clearobjflags);
static boolean_t vm_object_page_remove_write(vm_page_t p, int flags,
int *clearobjflags);
static void vm_object_qcollapse(vm_object_t object);
static void vm_object_vndeallocate(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;
struct vm_object kmem_object_store;
SYSCTL_NODE(_vm_stats, OID_AUTO, object, CTLFLAG_RD, 0, "VM object stats");
static long object_collapses;
SYSCTL_LONG(_vm_stats_object, OID_AUTO, collapses, CTLFLAG_RD,
&object_collapses, 0, "VM object collapses");
static long object_bypasses;
SYSCTL_LONG(_vm_stats_object, OID_AUTO, bypasses, CTLFLAG_RD,
&object_bypasses, 0, "VM object bypasses");
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(TAILQ_EMPTY(&object->memq),
("object %p has resident pages",
object));
#if VM_NRESERVLEVEL > 0
KASSERT(LIST_EMPTY(&object->rvq),
("object %p has reservations",
object));
#endif
KASSERT(object->cache == NULL,
("object %p has cached pages",
object));
KASSERT(object->paging_in_progress == 0,
("object %p paging_in_progress = %d",
object, object->paging_in_progress));
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));
}
#endif
static int
vm_object_zinit(void *mem, int size, int flags)
{
vm_object_t object;
object = (vm_object_t)mem;
bzero(&object->mtx, sizeof(object->mtx));
VM_OBJECT_LOCK_INIT(object, "standard object");
/* These are true for any object that has been freed */
object->paging_in_progress = 0;
object->resident_page_count = 0;
object->shadow_count = 0;
return (0);
}
void
_vm_object_allocate(objtype_t type, vm_pindex_t size, vm_object_t object)
{
TAILQ_INIT(&object->memq);
LIST_INIT(&object->shadow_head);
object->root = NULL;
object->type = type;
object->size = size;
object->generation = 1;
object->ref_count = 1;
object->memattr = VM_MEMATTR_DEFAULT;
object->flags = 0;
object->cred = NULL;
object->charge = 0;
if ((object->type == OBJT_DEFAULT) || (object->type == OBJT_SWAP))
object->flags = OBJ_ONEMAPPING;
object->pg_color = 0;
object->handle = NULL;
object->backing_object = NULL;
object->backing_object_offset = (vm_ooffset_t) 0;
#if VM_NRESERVLEVEL > 0
LIST_INIT(&object->rvq);
#endif
object->cache = NULL;
mtx_lock(&vm_object_list_mtx);
TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
mtx_unlock(&vm_object_list_mtx);
}
/*
* 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);
VM_OBJECT_LOCK_INIT(kernel_object, "kernel object");
_vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
kernel_object);
#if VM_NRESERVLEVEL > 0
kernel_object->flags |= OBJ_COLORED;
kernel_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
#endif
VM_OBJECT_LOCK_INIT(kmem_object, "kmem object");
_vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
kmem_object);
#if VM_NRESERVLEVEL > 0
kmem_object->flags |= OBJ_COLORED;
kmem_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
#endif
/*
* 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.
*/
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_VM|UMA_ZONE_NOFREE);
}
void
vm_object_clear_flag(vm_object_t object, u_short bits)
{
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
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_LOCK_ASSERT(object, MA_OWNED);
switch (object->type) {
case OBJT_DEFAULT:
case OBJT_DEVICE:
case OBJT_PHYS:
case OBJT_SG:
case OBJT_SWAP:
case OBJT_VNODE:
if (!TAILQ_EMPTY(&object->memq))
return (KERN_FAILURE);
break;
case OBJT_DEAD:
return (KERN_INVALID_ARGUMENT);
}
object->memattr = memattr;
return (KERN_SUCCESS);
}
void
vm_object_pip_add(vm_object_t object, short i)
{
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
object->paging_in_progress += i;
}
void
vm_object_pip_subtract(vm_object_t object, short i)
{
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
object->paging_in_progress -= i;
}
void
vm_object_pip_wakeup(vm_object_t object)
{
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
object->paging_in_progress--;
if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
vm_object_clear_flag(object, OBJ_PIPWNT);
wakeup(object);
}
}
void
vm_object_pip_wakeupn(vm_object_t object, short i)
{
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
if (i)
object->paging_in_progress -= i;
if ((object->flags & OBJ_PIPWNT) && object->paging_in_progress == 0) {
vm_object_clear_flag(object, OBJ_PIPWNT);
wakeup(object);
}
}
void
vm_object_pip_wait(vm_object_t object, char *waitid)
{
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
while (object->paging_in_progress) {
object->flags |= OBJ_PIPWNT;
msleep(object, VM_OBJECT_MTX(object), PVM, waitid, 0);
}
}
/*
* 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;
object = (vm_object_t)uma_zalloc(obj_zone, M_WAITOK);
_vm_object_allocate(type, size, object);
return (object);
}
/*
* vm_object_reference:
*
* Gets another reference to the given object. Note: OBJ_DEAD
* objects can be referenced during final cleaning.
*/
void
vm_object_reference(vm_object_t object)
{
if (object == NULL)
return;
VM_OBJECT_LOCK(object);
vm_object_reference_locked(object);
VM_OBJECT_UNLOCK(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)
{
struct vnode *vp;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
object->ref_count++;
if (object->type == OBJT_VNODE) {
vp = object->handle;
vref(vp);
}
}
/*
* Handle deallocating an object of type OBJT_VNODE.
*/
static void
vm_object_vndeallocate(vm_object_t object)
{
struct vnode *vp = (struct vnode *) object->handle;
VFS_ASSERT_GIANT(vp->v_mount);
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
KASSERT(object->type == OBJT_VNODE,
("vm_object_vndeallocate: not a vnode object"));
KASSERT(vp != NULL, ("vm_object_vndeallocate: missing vp"));
#ifdef INVARIANTS
if (object->ref_count == 0) {
vprint("vm_object_vndeallocate", vp);
panic("vm_object_vndeallocate: bad object reference count");
}
#endif
if (object->ref_count > 1) {
object->ref_count--;
VM_OBJECT_UNLOCK(object);
/* vrele may need the vnode lock. */
vrele(vp);
} else {
vhold(vp);
VM_OBJECT_UNLOCK(object);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
vdrop(vp);
VM_OBJECT_LOCK(object);
object->ref_count--;
if (object->type == OBJT_DEAD) {
VM_OBJECT_UNLOCK(object);
VOP_UNLOCK(vp, 0);
} else {
if (object->ref_count == 0)
vp->v_vflag &= ~VV_TEXT;
VM_OBJECT_UNLOCK(object);
vput(vp);
}
}
}
/*
* 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;
while (object != NULL) {
int vfslocked;
vfslocked = 0;
restart:
VM_OBJECT_LOCK(object);
if (object->type == OBJT_VNODE) {
struct vnode *vp = (struct vnode *) object->handle;
/*
* Conditionally acquire Giant for a vnode-backed
* object. We have to be careful since the type of
* a vnode object can change while the object is
* unlocked.
*/
if (VFS_NEEDSGIANT(vp->v_mount) && !vfslocked) {
vfslocked = 1;
if (!mtx_trylock(&Giant)) {
VM_OBJECT_UNLOCK(object);
mtx_lock(&Giant);
goto restart;
}
}
vm_object_vndeallocate(object);
VFS_UNLOCK_GIANT(vfslocked);
return;
} else
/*
* This is to handle the case that the object
* changed type while we dropped its lock to
* obtain Giant.
*/
VFS_UNLOCK_GIANT(vfslocked);
KASSERT(object->ref_count != 0,
("vm_object_deallocate: object deallocated too many times: %d", object->type));
/*
* 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.
*/
object->ref_count--;
if (object->ref_count > 1) {
VM_OBJECT_UNLOCK(object);
return;
} else if (object->ref_count == 1) {
if (object->shadow_count == 0 &&
object->handle == NULL &&
(object->type == OBJT_DEFAULT ||
object->type == OBJT_SWAP)) {
vm_object_set_flag(object, OBJ_ONEMAPPING);
} else if ((object->shadow_count == 1) &&
(object->handle == NULL) &&
(object->type == OBJT_DEFAULT ||
object->type == OBJT_SWAP)) {
vm_object_t robject;
robject = LIST_FIRST(&object->shadow_head);
KASSERT(robject != NULL,
("vm_object_deallocate: ref_count: %d, shadow_count: %d",
object->ref_count,
object->shadow_count));
if (!VM_OBJECT_TRYLOCK(robject)) {
/*
* Avoid a potential deadlock.
*/
object->ref_count++;
VM_OBJECT_UNLOCK(object);
/*
* More likely than not the thread
* holding robject's lock has lower
* priority than the current thread.
* Let the lower priority thread run.
*/
pause("vmo_de", 1);
continue;
}
/*
* Collapse object into its shadow unless its
* shadow is dead. In that case, object will
* be deallocated by the thread that is
* deallocating its shadow.
*/
if ((robject->flags & OBJ_DEAD) == 0 &&
(robject->handle == NULL) &&
(robject->type == OBJT_DEFAULT ||
robject->type == OBJT_SWAP)) {
robject->ref_count++;
retry:
if (robject->paging_in_progress) {
VM_OBJECT_UNLOCK(object);
vm_object_pip_wait(robject,
"objde1");
temp = robject->backing_object;
if (object == temp) {
VM_OBJECT_LOCK(object);
goto retry;
}
} else if (object->paging_in_progress) {
VM_OBJECT_UNLOCK(robject);
object->flags |= OBJ_PIPWNT;
msleep(object,
VM_OBJECT_MTX(object),
PDROP | PVM, "objde2", 0);
VM_OBJECT_LOCK(robject);
temp = robject->backing_object;
if (object == temp) {
VM_OBJECT_LOCK(object);
goto retry;
}
} else
VM_OBJECT_UNLOCK(object);
if (robject->ref_count == 1) {
robject->ref_count--;
object = robject;
goto doterm;
}
object = robject;
vm_object_collapse(object);
VM_OBJECT_UNLOCK(object);
continue;
}
VM_OBJECT_UNLOCK(robject);
}
VM_OBJECT_UNLOCK(object);
return;
}
doterm:
temp = object->backing_object;
if (temp != NULL) {
VM_OBJECT_LOCK(temp);
LIST_REMOVE(object, shadow_list);
temp->shadow_count--;
VM_OBJECT_UNLOCK(temp);
object->backing_object = NULL;
}
/*
* Don't double-terminate, we could be in a termination
* recursion due to the terminate having to sync data
* to disk.
*/
if ((object->flags & OBJ_DEAD) == 0)
vm_object_terminate(object);
else
VM_OBJECT_UNLOCK(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)
{
/*
* Remove the object from the global object list.
*/
mtx_lock(&vm_object_list_mtx);
TAILQ_REMOVE(&vm_object_list, object, object_list);
mtx_unlock(&vm_object_list_mtx);
/*
* Release the allocation charge.
*/
if (object->cred != NULL) {
KASSERT(object->type == OBJT_DEFAULT ||
object->type == OBJT_SWAP,
("vm_object_terminate: non-swap obj %p has cred",
object));
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);
}
/*
* 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_page_t p, p_next;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
/*
* Make sure no one uses us.
*/
vm_object_set_flag(object, OBJ_DEAD);
/*
* wait for the pageout daemon to be done with the object
*/
vm_object_pip_wait(object, "objtrm");
KASSERT(!object->paging_in_progress,
("vm_object_terminate: pageout in progress"));
/*
* Clean and free the pages, as appropriate. All references to the
* object are gone, so we don't need to lock it.
*/
if (object->type == OBJT_VNODE) {
struct vnode *vp = (struct vnode *)object->handle;
/*
* Clean pages and flush buffers.
*/
vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
VM_OBJECT_UNLOCK(object);
vinvalbuf(vp, V_SAVE, 0, 0);
VM_OBJECT_LOCK(object);
}
KASSERT(object->ref_count == 0,
("vm_object_terminate: object with references, ref_count=%d",
object->ref_count));
/*
* 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) {
KASSERT(!p->busy && (p->oflags & VPO_BUSY) == 0,
("vm_object_terminate: freeing busy page %p", p));
vm_page_lock(p);
/*
* Optimize the page's removal from the object by resetting
* its "object" field. Specifically, if the page is not
* wired, then the effect of this assignment is that
* vm_page_free()'s call to vm_page_remove() will return
* immediately without modifying the page or the object.
*/
p->object = NULL;
if (p->wire_count == 0) {
vm_page_free(p);
PCPU_INC(cnt.v_pfree);
}
vm_page_unlock(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) {
object->root = NULL;
TAILQ_INIT(&object->memq);
object->resident_page_count = 0;
if (object->type == OBJT_VNODE)
vdrop(object->handle);
}
#if VM_NRESERVLEVEL > 0
if (__predict_false(!LIST_EMPTY(&object->rvq)))
vm_reserv_break_all(object);
#endif
if (__predict_false(object->cache != NULL))
vm_page_cache_free(object, 0, 0);
/*
* Let the pager know object is dead.
*/
vm_pager_deallocate(object);
VM_OBJECT_UNLOCK(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, int *clearobjflags)
{
/*
* 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->oflags & VPO_NOSYNC) != 0) {
*clearobjflags = 0;
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 VPO_NOSYNC set (originally comes from MAP_NOSYNC),
* leaving the object dirty.
*
* 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.
*/
void
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 clearobjflags, curgeneration, n, pagerflags;
mtx_assert(&vm_page_queue_mtx, MA_NOTOWNED);
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
KASSERT(object->type == OBJT_VNODE, ("Not a vnode object"));
if ((object->flags & OBJ_MIGHTBEDIRTY) == 0 ||
object->resident_page_count == 0)
return;
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);
clearobjflags = tstart == 0 && tend >= object->size;
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 (p->valid == 0)
continue;
if (vm_page_sleep_if_busy(p, TRUE, "vpcwai")) {
if (object->generation != curgeneration)
goto rescan;
np = vm_page_find_least(object, pi);
continue;
}
if (!vm_object_page_remove_write(p, flags, &clearobjflags))
continue;
n = vm_object_page_collect_flush(object, p, pagerflags,
flags, &clearobjflags);
if (object->generation != curgeneration)
goto rescan;
np = vm_page_find_least(object, pi + n);
}
#if 0
VOP_FSYNC(vp, (pagerflags & VM_PAGER_PUT_SYNC) ? MNT_WAIT : 0);
#endif
if (clearobjflags)
vm_object_clear_flag(object, OBJ_MIGHTBEDIRTY);
}
static int
vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags,
int flags, int *clearobjflags)
{
vm_page_t ma[vm_pageout_page_count], p_first, tp;
int count, i, mreq, runlen;
mtx_assert(&vm_page_queue_mtx, MA_NOTOWNED);
vm_page_lock_assert(p, MA_NOTOWNED);
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
count = 1;
mreq = 0;
for (tp = p; count < vm_pageout_page_count; count++) {
tp = vm_page_next(tp);
if (tp == NULL || tp->busy != 0 || (tp->oflags & VPO_BUSY) != 0)
break;
if (!vm_object_page_remove_write(tp, flags, clearobjflags))
break;
}
for (p_first = p; count < vm_pageout_page_count; count++) {
tp = vm_page_prev(p_first);
if (tp == NULL || tp->busy != 0 || (tp->oflags & VPO_BUSY) != 0)
break;
if (!vm_object_page_remove_write(tp, flags, clearobjflags))
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);
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.
*
* Note: certain anonymous maps, such as MAP_NOSYNC maps,
* may start out with a NULL object.
*/
void
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 flags;
if (object == NULL)
return;
VM_OBJECT_LOCK(object);
while ((backing_object = object->backing_object) != NULL) {
VM_OBJECT_LOCK(backing_object);
offset += object->backing_object_offset;
VM_OBJECT_UNLOCK(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 &&
(object->flags & OBJ_MIGHTBEDIRTY) != 0) {
int vfslocked;
vp = object->handle;
VM_OBJECT_UNLOCK(object);
(void) vn_start_write(vp, &mp, V_WAIT);
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
flags = (syncio || invalidate) ? OBJPC_SYNC : 0;
flags |= invalidate ? OBJPC_INVAL : 0;
VM_OBJECT_LOCK(object);
vm_object_page_clean(object, offset, offset + size, flags);
VM_OBJECT_UNLOCK(object);
VOP_UNLOCK(vp, 0);
VFS_UNLOCK_GIANT(vfslocked);
vn_finished_write(mp);
VM_OBJECT_LOCK(object);
}
if ((object->type == OBJT_VNODE ||
object->type == OBJT_DEVICE) && invalidate) {
boolean_t purge;
purge = old_msync || (object->type == OBJT_DEVICE);
vm_object_page_remove(object,
OFF_TO_IDX(offset),
OFF_TO_IDX(offset + size + PAGE_MASK),
purge ? FALSE : TRUE);
}
VM_OBJECT_UNLOCK(object);
}
/*
* 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, int count, int advise)
{
vm_pindex_t end, tpindex;
vm_object_t backing_object, tobject;
vm_page_t m;
if (object == NULL)
return;
VM_OBJECT_LOCK(object);
end = pindex + count;
/*
* Locate and adjust resident pages
*/
for (; pindex < end; pindex += 1) {
relookup:
tobject = object;
tpindex = pindex;
shadowlookup:
/*
* MADV_FREE only operates on OBJT_DEFAULT or OBJT_SWAP pages
* and those pages must be OBJ_ONEMAPPING.
*/
if (advise == MADV_FREE) {
if ((tobject->type != OBJT_DEFAULT &&
tobject->type != OBJT_SWAP) ||
(tobject->flags & OBJ_ONEMAPPING) == 0) {
goto unlock_tobject;
}
} else if (tobject->type == OBJT_PHYS)
goto unlock_tobject;
m = vm_page_lookup(tobject, tpindex);
if (m == NULL && advise == MADV_WILLNEED) {
/*
* If the page is cached, reactivate it.
*/
m = vm_page_alloc(tobject, tpindex, VM_ALLOC_IFCACHED |
VM_ALLOC_NOBUSY);
}
if (m == NULL) {
/*
* There may be swap even if there is no backing page
*/
if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
swap_pager_freespace(tobject, tpindex, 1);
/*
* next object
*/
backing_object = tobject->backing_object;
if (backing_object == NULL)
goto unlock_tobject;
VM_OBJECT_LOCK(backing_object);
tpindex += OFF_TO_IDX(tobject->backing_object_offset);
if (tobject != object)
VM_OBJECT_UNLOCK(tobject);
tobject = backing_object;
goto shadowlookup;
} else if (m->valid != VM_PAGE_BITS_ALL)
goto unlock_tobject;
/*
* If the page is not in a normal state, skip it.
*/
vm_page_lock(m);
if (m->hold_count != 0 || m->wire_count != 0) {
vm_page_unlock(m);
goto unlock_tobject;
}
KASSERT((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0,
("vm_object_madvise: page %p is not managed", m));
if ((m->oflags & VPO_BUSY) || m->busy) {
if (advise == MADV_WILLNEED) {
/*
* Reference the page before unlocking and
* sleeping so that the page daemon is less
* likely to reclaim it.
*/
vm_page_lock_queues();
vm_page_flag_set(m, PG_REFERENCED);
vm_page_unlock_queues();
}
vm_page_unlock(m);
if (object != tobject)
VM_OBJECT_UNLOCK(object);
m->oflags |= VPO_WANTED;
msleep(m, VM_OBJECT_MTX(tobject), PDROP | PVM, "madvpo",
0);
VM_OBJECT_LOCK(object);
goto relookup;
}
if (advise == MADV_WILLNEED) {
vm_page_activate(m);
} else if (advise == MADV_DONTNEED) {
vm_page_dontneed(m);
} else if (advise == MADV_FREE) {
/*
* Mark the page clean. This will allow the page
* to be freed up by the system. However, such pages
* are often reused quickly by malloc()/free()
* so we do not do anything that would cause
* a page fault if we can help it.
*
* Specifically, we do not try to actually free
* the page now nor do we try to put it in the
* cache (which would cause a page fault on reuse).
*
* But we do make the page is freeable as we
* can without actually taking the step of unmapping
* it.
*/
pmap_clear_modify(m);
m->dirty = 0;
m->act_count = 0;
vm_page_dontneed(m);
}
vm_page_unlock(m);
if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
swap_pager_freespace(tobject, tpindex, 1);
unlock_tobject:
if (tobject != object)
VM_OBJECT_UNLOCK(tobject);
}
VM_OBJECT_UNLOCK(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, /* IN/OUT */
vm_ooffset_t *offset, /* IN/OUT */
vm_size_t length)
{
vm_object_t source;
vm_object_t result;
source = *object;
/*
* Don't create the new object if the old object isn't shared.
*/
if (source != NULL) {
VM_OBJECT_LOCK(source);
if (source->ref_count == 1 &&
source->handle == NULL &&
(source->type == OBJT_DEFAULT ||
source->type == OBJT_SWAP)) {
VM_OBJECT_UNLOCK(source);
return;
}
VM_OBJECT_UNLOCK(source);
}
/*
* Allocate a new object with the given length.
*/
result = vm_object_allocate(OBJT_DEFAULT, atop(length));
/*
* 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.
*
* Try to optimize the result object's page color when shadowing
* in order to maintain page coloring consistency in the combined
* shadowed object.
*/
result->backing_object = source;
/*
* Store the offset into the source object, and fix up the offset into
* the new object.
*/
result->backing_object_offset = *offset;
if (source != NULL) {
VM_OBJECT_LOCK(source);
LIST_INSERT_HEAD(&source->shadow_head, result, shadow_list);
source->shadow_count++;
#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_UNLOCK(source);
}
/*
* 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, source;
vm_pindex_t idx, offidxstart;
vm_size_t size;
orig_object = entry->object.vm_object;
if (orig_object->type != OBJT_DEFAULT && orig_object->type != OBJT_SWAP)
return;
if (orig_object->ref_count <= 1)
return;
VM_OBJECT_UNLOCK(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(OBJT_DEFAULT, size);
/*
* 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_LOCK(new_object);
VM_OBJECT_LOCK(orig_object);
source = orig_object->backing_object;
if (source != NULL) {
VM_OBJECT_LOCK(source);
if ((source->flags & OBJ_DEAD) != 0) {
VM_OBJECT_UNLOCK(source);
VM_OBJECT_UNLOCK(orig_object);
VM_OBJECT_UNLOCK(new_object);
vm_object_deallocate(new_object);
VM_OBJECT_LOCK(orig_object);
return;
}
LIST_INSERT_HEAD(&source->shadow_head,
new_object, shadow_list);
source->shadow_count++;
vm_object_reference_locked(source); /* for new_object */
vm_object_clear_flag(source, OBJ_ONEMAPPING);
VM_OBJECT_UNLOCK(source);
new_object->backing_object_offset =
orig_object->backing_object_offset + entry->offset;
new_object->backing_object = source;
}
if (orig_object->cred != NULL) {
new_object->cred = orig_object->cred;
crhold(orig_object->cred);
new_object->charge = ptoa(size);
KASSERT(orig_object->charge >= ptoa(size),
("orig_object->charge < 0"));
orig_object->charge -= ptoa(size);
}
retry:
m = vm_page_find_least(orig_object, offidxstart);
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 ((m->oflags & VPO_BUSY) || m->busy) {
VM_OBJECT_UNLOCK(new_object);
m->oflags |= VPO_WANTED;
msleep(m, VM_OBJECT_MTX(orig_object), PVM, "spltwt", 0);
VM_OBJECT_LOCK(new_object);
goto retry;
}
vm_page_lock(m);
vm_page_rename(m, new_object, idx);
vm_page_unlock(m);
/* page automatically made dirty by rename and cache handled */
vm_page_busy(m);
}
if (orig_object->type == OBJT_SWAP) {
/*
* 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);
/*
* Transfer any cached pages from orig_object to new_object.
*/
if (__predict_false(orig_object->cache != NULL))
vm_page_cache_transfer(orig_object, offidxstart,
new_object);
}
VM_OBJECT_UNLOCK(orig_object);
TAILQ_FOREACH(m, &new_object->memq, listq)
vm_page_wakeup(m);
VM_OBJECT_UNLOCK(new_object);
entry->object.vm_object = new_object;
entry->offset = 0LL;
vm_object_deallocate(orig_object);
VM_OBJECT_LOCK(new_object);
}
#define OBSC_TEST_ALL_SHADOWED 0x0001
#define OBSC_COLLAPSE_NOWAIT 0x0002
#define OBSC_COLLAPSE_WAIT 0x0004
static int
vm_object_backing_scan(vm_object_t object, int op)
{
int r = 1;
vm_page_t p;
vm_object_t backing_object;
vm_pindex_t backing_offset_index;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
VM_OBJECT_LOCK_ASSERT(object->backing_object, MA_OWNED);
backing_object = object->backing_object;
backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
/*
* Initial conditions
*/
if (op & OBSC_TEST_ALL_SHADOWED) {
/*
* We do not want to have to test for the existence of cache
* or swap pages in the backing object. XXX but with the
* new swapper this would be pretty easy to do.
*
* XXX what about anonymous MAP_SHARED memory that hasn't
* been ZFOD faulted yet? If we do not test for this, the
* shadow test may succeed! XXX
*/
if (backing_object->type != OBJT_DEFAULT) {
return (0);
}
}
if (op & OBSC_COLLAPSE_WAIT) {
vm_object_set_flag(backing_object, OBJ_DEAD);
}
/*
* Our scan
*/
p = TAILQ_FIRST(&backing_object->memq);
while (p) {
vm_page_t next = TAILQ_NEXT(p, listq);
vm_pindex_t new_pindex = p->pindex - backing_offset_index;
if (op & OBSC_TEST_ALL_SHADOWED) {
vm_page_t pp;
/*
* Ignore pages outside the parent object's range
* and outside the parent object's mapping of the
* backing object.
*
* note that we do not busy the backing object's
* page.
*/
if (
p->pindex < backing_offset_index ||
new_pindex >= object->size
) {
p = next;
continue;
}
/*
* 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);
if (
(pp == NULL || pp->valid == 0) &&
!vm_pager_has_page(object, new_pindex, NULL, NULL)
) {
r = 0;
break;
}
}
/*
* Check for busy page
*/
if (op & (OBSC_COLLAPSE_WAIT | OBSC_COLLAPSE_NOWAIT)) {
vm_page_t pp;
if (op & OBSC_COLLAPSE_NOWAIT) {
if ((p->oflags & VPO_BUSY) ||
!p->valid ||
p->busy) {
p = next;
continue;
}
} else if (op & OBSC_COLLAPSE_WAIT) {
if ((p->oflags & VPO_BUSY) || p->busy) {
VM_OBJECT_UNLOCK(object);
p->oflags |= VPO_WANTED;
msleep(p, VM_OBJECT_MTX(backing_object),
PDROP | PVM, "vmocol", 0);
VM_OBJECT_LOCK(object);
VM_OBJECT_LOCK(backing_object);
/*
* If we slept, anything could have
* happened. Since the object is
* marked dead, the backing offset
* should not have changed so we
* just restart our scan.
*/
p = TAILQ_FIRST(&backing_object->memq);
continue;
}
}
KASSERT(
p->object == backing_object,
("vm_object_backing_scan: object mismatch")
);
/*
* Destroy any associated swap
*/
if (backing_object->type == OBJT_SWAP) {
swap_pager_freespace(
backing_object,
p->pindex,
1
);
}
if (
p->pindex < backing_offset_index ||
new_pindex >= object->size
) {
/*
* Page is out of the parent object's range, we
* can simply destroy it.
*/
vm_page_lock(p);
KASSERT(!pmap_page_is_mapped(p),
("freeing mapped page %p", p));
if (p->wire_count == 0)
vm_page_free(p);
else
vm_page_remove(p);
vm_page_unlock(p);
p = next;
continue;
}
pp = vm_page_lookup(object, new_pindex);
if (
(op & OBSC_COLLAPSE_NOWAIT) != 0 &&
(pp != NULL && pp->valid == 0)
) {
/*
* The page in the parent is not (yet) valid.
* We don't know anything about the state of
* the original page. It might be mapped,
* so we must avoid the next if here.
*
* This is due to a race in vm_fault() where
* we must unbusy the original (backing_obj)
* page before we can (re)lock the parent.
* Hence we can get here.
*/
p = next;
continue;
}
if (
pp != NULL ||
vm_pager_has_page(object, new_pindex, NULL, NULL)
) {
/*
* page already exists in parent OR swap exists
* for this location in the parent. Destroy
* the original page from the backing object.
*
* Leave the parent's page alone
*/
vm_page_lock(p);
KASSERT(!pmap_page_is_mapped(p),
("freeing mapped page %p", p));
if (p->wire_count == 0)
vm_page_free(p);
else
vm_page_remove(p);
vm_page_unlock(p);
p = next;
continue;
}
#if VM_NRESERVLEVEL > 0
/*
* Rename the reservation.
*/
vm_reserv_rename(p, object, backing_object,
backing_offset_index);
#endif
/*
* 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_lock(p);
vm_page_rename(p, object, new_pindex);
vm_page_unlock(p);
/* page automatically made dirty by rename */
}
p = next;
}
return (r);
}
/*
* this version of collapse allows the operation to occur earlier and
* when paging_in_progress is true for an object... This is not a complete
* operation, but should plug 99.9% of the rest of the leaks.
*/
static void
vm_object_qcollapse(vm_object_t object)
{
vm_object_t backing_object = object->backing_object;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
VM_OBJECT_LOCK_ASSERT(backing_object, MA_OWNED);
if (backing_object->ref_count != 1)
return;
vm_object_backing_scan(object, OBSC_COLLAPSE_NOWAIT);
}
/*
* 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_LOCK_ASSERT(object, MA_OWNED);
while (TRUE) {
vm_object_t backing_object;
/*
* Verify that the conditions are right for collapse:
*
* The object exists and the backing object exists.
*/
if ((backing_object = object->backing_object) == NULL)
break;
/*
* we check the backing object first, because it is most likely
* not collapsable.
*/
VM_OBJECT_LOCK(backing_object);
if (backing_object->handle != NULL ||
(backing_object->type != OBJT_DEFAULT &&
backing_object->type != OBJT_SWAP) ||
(backing_object->flags & OBJ_DEAD) ||
object->handle != NULL ||
(object->type != OBJT_DEFAULT &&
object->type != OBJT_SWAP) ||
(object->flags & OBJ_DEAD)) {
VM_OBJECT_UNLOCK(backing_object);
break;
}
if (
object->paging_in_progress != 0 ||
backing_object->paging_in_progress != 0
) {
vm_object_qcollapse(object);
VM_OBJECT_UNLOCK(backing_object);
break;
}
/*
* 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.
*
* This is ignoring pager-backed pages such as swap pages.
* vm_object_backing_scan fails the shadowing test in this
* case.
*/
if (backing_object->ref_count == 1) {
/*
* If there is exactly one reference to the backing
* object, we can collapse it into the parent.
*/
vm_object_backing_scan(object, OBSC_COLLAPSE_WAIT);
#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->type == OBJT_SWAP) {
/*
* 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);
/*
* Free any cached pages from backing_object.
*/
if (__predict_false(backing_object->cache != NULL))
vm_page_cache_free(backing_object, 0, 0);
}
/*
* Object now shadows whatever backing_object did.
* Note that the reference to
* backing_object->backing_object moves from within
* backing_object to within object.
*/
LIST_REMOVE(object, shadow_list);
backing_object->shadow_count--;
if (backing_object->backing_object) {
VM_OBJECT_LOCK(backing_object->backing_object);
LIST_REMOVE(backing_object, shadow_list);
LIST_INSERT_HEAD(
&backing_object->backing_object->shadow_head,
object, shadow_list);
/*
* The shadow_count has not changed.
*/
VM_OBJECT_UNLOCK(backing_object->backing_object);
}
object->backing_object = backing_object->backing_object;
object->backing_object_offset +=
backing_object->backing_object_offset;
/*
* 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_UNLOCK(backing_object);
vm_object_destroy(backing_object);
object_collapses++;
} else {
vm_object_t new_backing_object;
/*
* If we do not entirely shadow the backing object,
* there is nothing we can do so we give up.
*/
if (object->resident_page_count != object->size &&
vm_object_backing_scan(object,
OBSC_TEST_ALL_SHADOWED) == 0) {
VM_OBJECT_UNLOCK(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.
*/
LIST_REMOVE(object, shadow_list);
backing_object->shadow_count--;
new_backing_object = backing_object->backing_object;
if ((object->backing_object = new_backing_object) != NULL) {
VM_OBJECT_LOCK(new_backing_object);
LIST_INSERT_HEAD(
&new_backing_object->shadow_head,
object,
shadow_list
);
new_backing_object->shadow_count++;
vm_object_reference_locked(new_backing_object);
VM_OBJECT_UNLOCK(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.
*/
backing_object->ref_count--;
VM_OBJECT_UNLOCK(backing_object);
object_bypasses++;
}
/*
* 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 Boolean "clean_only". As a
* special case, if "end" is zero, then the range extends from
* "start" to the end of the object. If "clean_only" is TRUE,
* then only the non-dirty pages within the specified range are
* affected.
*
* In general, this operation should only be performed on objects
* that contain managed pages. There are two exceptions. First,
* it may be performed on the kernel and kmem objects. Second,
* it may be used by msync(..., MS_INVALIDATE) to invalidate
* device-backed pages. In both of these cases, "clean_only"
* must be FALSE.
*
* The object must be locked.
*/
void
vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
boolean_t clean_only)
{
vm_page_t p, next;
int wirings;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
if (object->resident_page_count == 0)
goto skipmemq;
/*
* Since physically-backed objects do not use managed pages, we can't
* remove pages from the object (we must instead remove the page
* references, and then destroy the object).
*/
KASSERT(object->type != OBJT_PHYS || object == kernel_object ||
object == kmem_object,
("attempt to remove pages from a physical object"));
vm_object_pip_add(object, 1);
again:
p = vm_page_find_least(object, start);
/*
* Assert: the variable p is either (1) the page with the
* least pindex greater than or equal to the parameter pindex
* or (2) NULL.
*/
for (;
p != NULL && (p->pindex < end || end == 0);
p = next) {
next = TAILQ_NEXT(p, listq);
/*
* 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 "clean_only" is FALSE.
*/
vm_page_lock(p);
if ((wirings = p->wire_count) != 0 &&
(wirings = pmap_page_wired_mappings(p)) != p->wire_count) {
/* Fictitious pages do not have managed mappings. */
if ((p->flags & PG_FICTITIOUS) == 0)
pmap_remove_all(p);
/* Account for removal of managed, wired mappings. */
p->wire_count -= wirings;
if (!clean_only) {
p->valid = 0;
vm_page_undirty(p);
}
vm_page_unlock(p);
continue;
}
if (vm_page_sleep_if_busy(p, TRUE, "vmopar"))
goto again;
KASSERT((p->flags & PG_FICTITIOUS) == 0,
("vm_object_page_remove: page %p is fictitious", p));
if (clean_only && p->valid) {
pmap_remove_write(p);
if (p->dirty) {
vm_page_unlock(p);
continue;
}
}
pmap_remove_all(p);
/* Account for removal of managed, wired mappings. */
if (wirings != 0)
p->wire_count -= wirings;
vm_page_free(p);
vm_page_unlock(p);
}
vm_object_pip_wakeup(object);
skipmemq:
if (__predict_false(object->cache != NULL))
vm_page_cache_free(object, start, end);
}
/*
* 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, ma[1];
vm_pindex_t pindex;
int rv;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
for (pindex = start; pindex < end; pindex++) {
m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL |
VM_ALLOC_RETRY);
if (m->valid != VM_PAGE_BITS_ALL) {
ma[0] = m;
rv = vm_pager_get_pages(object, ma, 1, 0);
m = vm_page_lookup(object, pindex);
if (m == NULL)
break;
if (rv != VM_PAGER_OK) {
vm_page_lock(m);
vm_page_free(m);
vm_page_unlock(m);
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_wakeup(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);
VM_OBJECT_LOCK(prev_object);
if (prev_object->type != OBJT_DEFAULT &&
prev_object->type != OBJT_SWAP) {
VM_OBJECT_UNLOCK(prev_object);
return (FALSE);
}
/*
* 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_UNLOCK(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)) {
VM_OBJECT_UNLOCK(prev_object);
return (FALSE);
}
/*
* Account for the charge.
*/
if (prev_object->cred != NULL) {
/*
* If prev_object was charged, then this mapping,
* althought 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)) {
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, FALSE);
if (prev_object->type == OBJT_SWAP)
swap_pager_freespace(prev_object,
next_pindex, next_size);
#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_UNLOCK(prev_object);
return (TRUE);
}
void
vm_object_set_writeable_dirty(vm_object_t object)
{
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
if (object->type != OBJT_VNODE)
return;
object->generation++;
if ((object->flags & OBJ_MIGHTBEDIRTY) != 0)
return;
vm_object_set_flag(object, OBJ_MIGHTBEDIRTY);
}
#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;
int entcount;
if (map == 0)
return 0;
if (entry == 0) {
tmpe = map->header.next;
entcount = map->nentries;
while (entcount-- && (tmpe != &map->header)) {
if (_vm_object_in_map(map, object, tmpe)) {
return 1;
}
tmpe = tmpe->next;
}
} else if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) {
tmpm = entry->object.sub_map;
tmpe = tmpm->header.next;
entcount = tmpm->nentries;
while (entcount-- && tmpe != &tmpm->header) {
if (_vm_object_in_map(tmpm, object, tmpe)) {
return 1;
}
tmpe = tmpe->next;
}
} 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;
if (_vm_object_in_map(kmem_map, object, 0))
return 1;
if (_vm_object_in_map(pager_map, object, 0))
return 1;
if (_vm_object_in_map(buffer_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->handle == NULL &&
(object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) {
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);
}
}
}
}
/*
* 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 (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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