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freebsd-nq/sys/vm/vm_object.c
Alan Cox 688559667f Correct a long-standing error in vm_object_page_remove(). Specifically, 
pmap_remove_all() must not be called on fictitious pages.  To date,
fictitious pages have been allocated from zeroed memory, effectively
hiding this problem because the fictitious pages appear to have an empty
pv list.  Submitted by: Kostik Belousov

Rewrite the comments describing vm_object_page_remove() to better
describe what it does.  Add an assertion.  Reviewed by: Kostik Belousov

MFC after: 1 week
2008-02-26 17:16:48 +00:00

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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/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>
#define EASY_SCAN_FACTOR 8
#define MSYNC_FLUSH_HARDSEQ 0x01
#define MSYNC_FLUSH_SOFTSEQ 0x02
/*
* msync / VM object flushing optimizations
*/
static int msync_flush_flags = MSYNC_FLUSH_HARDSEQ | MSYNC_FLUSH_SOFTSEQ;
SYSCTL_INT(_vm, OID_AUTO, msync_flush_flags,
CTLFLAG_RW, &msync_flush_flags, 0, "");
static int old_msync;
SYSCTL_INT(_vm, OID_AUTO, old_msync, CTLFLAG_RW, &old_msync, 0,
"Use old (insecure) msync behavior");
static void vm_object_qcollapse(vm_object_t object);
static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int curgeneration, int pagerflags);
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->flags = 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_store, "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_store, "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;
}
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)
{
struct vnode *vp;
if (object == NULL)
return;
VM_OBJECT_LOCK(object);
object->ref_count++;
if (object->type == OBJT_VNODE) {
int vfslocked;
vp = object->handle;
VM_OBJECT_UNLOCK(object);
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vget(vp, LK_RETRY, curthread);
VFS_UNLOCK_GIANT(vfslocked);
} else
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);
KASSERT((object->flags & OBJ_DEAD) == 0,
("vm_object_reference_locked: dead object referenced"));
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
object->ref_count--;
if (object->ref_count == 0) {
mp_fixme("Unlocked vflag access.");
vp->v_vflag &= ~VV_TEXT;
}
VM_OBJECT_UNLOCK(object);
/*
* vrele may need a vop lock
*/
vrele(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--;
temp->generation++;
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_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;
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, NULL, 0, 0);
VM_OBJECT_LOCK(object);
}
KASSERT(object->ref_count == 0,
("vm_object_terminate: object with references, ref_count=%d",
object->ref_count));
/*
* Now free any remaining pages. For internal objects, this also
* removes them from paging queues. Don't free wired pages, just
* remove them from the object.
*/
vm_page_lock_queues();
while ((p = TAILQ_FIRST(&object->memq)) != NULL) {
KASSERT(!p->busy && (p->oflags & VPO_BUSY) == 0,
("vm_object_terminate: freeing busy page %p "
"p->busy = %d, p->flags %x\n", p, p->busy, p->flags));
if (p->wire_count == 0) {
vm_page_free(p);
cnt.v_pfree++;
} else {
vm_page_remove(p);
}
}
vm_page_unlock_queues();
#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);
/*
* 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);
/*
* Free the space for the object.
*/
uma_zfree(obj_zone, object);
}
/*
* 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_pindex_t start, vm_pindex_t end, int flags)
{
vm_page_t p, np;
vm_pindex_t tstart, tend;
vm_pindex_t pi;
int clearobjflags;
int pagerflags;
int curgeneration;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
if (object->type != OBJT_VNODE ||
(object->flags & OBJ_MIGHTBEDIRTY) == 0)
return;
pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) ? VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK;
pagerflags |= (flags & OBJPC_INVAL) ? VM_PAGER_PUT_INVAL : 0;
vm_object_set_flag(object, OBJ_CLEANING);
tstart = start;
if (end == 0) {
tend = object->size;
} else {
tend = end;
}
vm_page_lock_queues();
/*
* If the caller is smart and only msync()s a range he knows is
* dirty, we may be able to avoid an object scan. This results in
* a phenominal improvement in performance. We cannot do this
* as a matter of course because the object may be huge - e.g.
* the size might be in the gigabytes or terrabytes.
*/
if (msync_flush_flags & MSYNC_FLUSH_HARDSEQ) {
vm_pindex_t tscan;
int scanlimit;
int scanreset;
scanreset = object->resident_page_count / EASY_SCAN_FACTOR;
if (scanreset < 16)
scanreset = 16;
pagerflags |= VM_PAGER_IGNORE_CLEANCHK;
scanlimit = scanreset;
tscan = tstart;
while (tscan < tend) {
curgeneration = object->generation;
p = vm_page_lookup(object, tscan);
if (p == NULL || p->valid == 0) {
if (--scanlimit == 0)
break;
++tscan;
continue;
}
vm_page_test_dirty(p);
if ((p->dirty & p->valid) == 0) {
if (--scanlimit == 0)
break;
++tscan;
continue;
}
/*
* If we have been asked to skip nosync pages and
* this is a nosync page, we can't continue.
*/
if ((flags & OBJPC_NOSYNC) && (p->oflags & VPO_NOSYNC)) {
if (--scanlimit == 0)
break;
++tscan;
continue;
}
scanlimit = scanreset;
/*
* This returns 0 if it was unable to busy the first
* page (i.e. had to sleep).
*/
tscan += vm_object_page_collect_flush(object, p, curgeneration, pagerflags);
}
/*
* If everything was dirty and we flushed it successfully,
* and the requested range is not the entire object, we
* don't have to mess with CLEANCHK or MIGHTBEDIRTY and can
* return immediately.
*/
if (tscan >= tend && (tstart || tend < object->size)) {
vm_page_unlock_queues();
vm_object_clear_flag(object, OBJ_CLEANING);
return;
}
pagerflags &= ~VM_PAGER_IGNORE_CLEANCHK;
}
/*
* Generally set CLEANCHK interlock and make the page read-only so
* we can then 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.
*/
clearobjflags = 1;
TAILQ_FOREACH(p, &object->memq, listq) {
p->oflags |= VPO_CLEANCHK;
if ((flags & OBJPC_NOSYNC) && (p->oflags & VPO_NOSYNC))
clearobjflags = 0;
else
pmap_remove_write(p);
}
if (clearobjflags && (tstart == 0) && (tend == object->size)) {
struct vnode *vp;
vm_object_clear_flag(object, OBJ_MIGHTBEDIRTY);
if (object->type == OBJT_VNODE &&
(vp = (struct vnode *)object->handle) != NULL) {
VI_LOCK(vp);
if (vp->v_iflag & VI_OBJDIRTY)
vp->v_iflag &= ~VI_OBJDIRTY;
VI_UNLOCK(vp);
}
}
rescan:
curgeneration = object->generation;
for (p = TAILQ_FIRST(&object->memq); p; p = np) {
int n;
np = TAILQ_NEXT(p, listq);
again:
pi = p->pindex;
if ((p->oflags & VPO_CLEANCHK) == 0 ||
(pi < tstart) || (pi >= tend) ||
p->valid == 0) {
p->oflags &= ~VPO_CLEANCHK;
continue;
}
vm_page_test_dirty(p);
if ((p->dirty & p->valid) == 0) {
p->oflags &= ~VPO_CLEANCHK;
continue;
}
/*
* 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) && (p->oflags & VPO_NOSYNC)) {
p->oflags &= ~VPO_CLEANCHK;
continue;
}
n = vm_object_page_collect_flush(object, p,
curgeneration, pagerflags);
if (n == 0)
goto rescan;
if (object->generation != curgeneration)
goto rescan;
/*
* Try to optimize the next page. If we can't we pick up
* our (random) scan where we left off.
*/
if (msync_flush_flags & MSYNC_FLUSH_SOFTSEQ) {
if ((p = vm_page_lookup(object, pi + n)) != NULL)
goto again;
}
}
vm_page_unlock_queues();
#if 0
VOP_FSYNC(vp, (pagerflags & VM_PAGER_PUT_SYNC)?MNT_WAIT:0, curproc);
#endif
vm_object_clear_flag(object, OBJ_CLEANING);
return;
}
static int
vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int curgeneration, int pagerflags)
{
int runlen;
int maxf;
int chkb;
int maxb;
int i;
vm_pindex_t pi;
vm_page_t maf[vm_pageout_page_count];
vm_page_t mab[vm_pageout_page_count];
vm_page_t ma[vm_pageout_page_count];
mtx_assert(&vm_page_queue_mtx, MA_OWNED);
pi = p->pindex;
while (vm_page_sleep_if_busy(p, TRUE, "vpcwai")) {
vm_page_lock_queues();
if (object->generation != curgeneration) {
return(0);
}
}
maxf = 0;
for(i = 1; i < vm_pageout_page_count; i++) {
vm_page_t tp;
if ((tp = vm_page_lookup(object, pi + i)) != NULL) {
if ((tp->oflags & VPO_BUSY) ||
((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 &&
(tp->oflags & VPO_CLEANCHK) == 0) ||
(tp->busy != 0))
break;
vm_page_test_dirty(tp);
if ((tp->dirty & tp->valid) == 0) {
tp->oflags &= ~VPO_CLEANCHK;
break;
}
maf[ i - 1 ] = tp;
maxf++;
continue;
}
break;
}
maxb = 0;
chkb = vm_pageout_page_count - maxf;
if (chkb) {
for(i = 1; i < chkb;i++) {
vm_page_t tp;
if ((tp = vm_page_lookup(object, pi - i)) != NULL) {
if ((tp->oflags & VPO_BUSY) ||
((pagerflags & VM_PAGER_IGNORE_CLEANCHK) == 0 &&
(tp->oflags & VPO_CLEANCHK) == 0) ||
(tp->busy != 0))
break;
vm_page_test_dirty(tp);
if ((tp->dirty & tp->valid) == 0) {
tp->oflags &= ~VPO_CLEANCHK;
break;
}
mab[ i - 1 ] = tp;
maxb++;
continue;
}
break;
}
}
for(i = 0; i < maxb; i++) {
int index = (maxb - i) - 1;
ma[index] = mab[i];
ma[index]->oflags &= ~VPO_CLEANCHK;
}
p->oflags &= ~VPO_CLEANCHK;
ma[maxb] = p;
for(i = 0; i < maxf; i++) {
int index = (maxb + i) + 1;
ma[index] = maf[i];
ma[index]->oflags &= ~VPO_CLEANCHK;
}
runlen = maxb + maxf + 1;
vm_pageout_flush(ma, runlen, pagerflags);
for (i = 0; i < runlen; i++) {
if (ma[i]->valid & ma[i]->dirty) {
pmap_remove_write(ma[i]);
ma[i]->oflags |= VPO_CLEANCHK;
/*
* maxf will end up being the actual number of pages
* we wrote out contiguously, non-inclusive of the
* first page. We do not count look-behind pages.
*/
if (i >= maxb + 1 && (maxf > i - maxb - 1))
maxf = i - maxb - 1;
}
}
return(maxf + 1);
}
/*
* 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,
OFF_TO_IDX(offset),
OFF_TO_IDX(offset + size + PAGE_MASK),
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;
}
}
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;
}
/*
* If the page is busy or not in a normal active state,
* we skip it. If the page is not managed there are no
* page queues to mess with. Things can break if we mess
* with pages in any of the below states.
*/
vm_page_lock_queues();
if (m->hold_count ||
m->wire_count ||
(m->flags & PG_UNMANAGED) ||
m->valid != VM_PAGE_BITS_ALL) {
vm_page_unlock_queues();
goto unlock_tobject;
}
if ((m->oflags & VPO_BUSY) || m->busy) {
vm_page_flag_set(m, PG_REFERENCED);
vm_page_unlock_queues();
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_queues();
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, 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++;
source->generation++;
#if VM_NRESERVLEVEL > 0
result->flags |= source->flags & (OBJ_NEEDGIANT | OBJ_COLORED);
result->pg_color = (source->pg_color + OFF_TO_IDX(*offset)) &
((1 << (VM_NFREEORDER - 1)) - 1);
#else
result->flags |= source->flags & OBJ_NEEDGIANT;
#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++;
source->generation++;
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;
}
new_object->flags |= orig_object->flags & OBJ_NEEDGIANT;
retry:
if ((m = TAILQ_FIRST(&orig_object->memq)) != NULL) {
if (m->pindex < offidxstart) {
m = vm_page_splay(offidxstart, orig_object->root);
if ((orig_object->root = m)->pindex < offidxstart)
m = TAILQ_NEXT(m, listq);
}
}
vm_page_lock_queues();
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_page_flag_set(m, PG_REFERENCED);
vm_page_unlock_queues();
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_rename(m, new_object, idx);
/* page automatically made dirty by rename and cache handled */
vm_page_busy(m);
}
vm_page_unlock_queues();
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_page_lock_queues();
vm_page_flag_set(p, PG_REFERENCED);
vm_page_unlock_queues();
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_queues();
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_queues();
p = next;
continue;
}
pp = vm_page_lookup(object, new_pindex);
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_queues();
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_queues();
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_queues();
vm_page_rename(p, object, new_pindex);
vm_page_unlock_queues();
/* 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--;
backing_object->generation++;
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.
*/
backing_object->backing_object->generation++;
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);
mtx_lock(&vm_object_list_mtx);
TAILQ_REMOVE(
&vm_object_list,
backing_object,
object_list
);
mtx_unlock(&vm_object_list_mtx);
uma_zfree(obj_zone, 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--;
backing_object->generation++;
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++;
new_backing_object->generation++;
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.
*
* 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:
vm_page_lock_queues();
if ((p = TAILQ_FIRST(&object->memq)) != NULL) {
if (p->pindex < start) {
p = vm_page_splay(start, object->root);
if ((object->root = p)->pindex < start)
p = TAILQ_NEXT(p, listq);
}
}
/*
* 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.
*/
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;
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->valid & p->dirty)
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_queues();
vm_object_pip_wakeup(object);
skipmemq:
if (__predict_false(object->cache != NULL))
vm_page_cache_free(object, start, 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
*
* 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)
{
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);
}
/*
* 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);
}
/*
* 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)
{
struct vnode *vp;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
if ((object->flags & OBJ_MIGHTBEDIRTY) != 0)
return;
vm_object_set_flag(object, OBJ_MIGHTBEDIRTY);
if (object->type == OBJT_VNODE &&
(vp = (struct vnode *)object->handle) != NULL) {
VI_LOCK(vp);
vp->v_iflag |= VI_OBJDIRTY;
VI_UNLOCK(vp);
}
}
#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\n",
object, (int)object->type, (uintmax_t)object->size,
object->resident_page_count, object->ref_count, object->flags);
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;
int nl = 0;
int c;
TAILQ_FOREACH(object, &vm_object_list, object_list) {
vm_pindex_t idx, fidx;
vm_pindex_t osize;
vm_paddr_t pa = -1;
int rcount;
vm_page_t m;
db_printf("new object: %p\n", (void *)object);
if (nl > 18) {
c = cngetc();
if (c != ' ')
return;
nl = 0;
}
nl++;
rcount = 0;
fidx = 0;
osize = object->size;
if (osize > 128)
osize = 128;
for (idx = 0; idx < osize; idx++) {
m = vm_page_lookup(object, idx);
if (m == NULL) {
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;
}
continue;
}
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 = idx;
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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