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freebsd-dev/sys/vm/vm_object.c
Jeff Roberson 5f51836645 - Add a general purpose resource allocator, vmem, from NetBSD. It was 
originally inspired by the Solaris vmem detailed in the proceedings
   of usenix 2001.  The NetBSD version was heavily refactored for bugs
   and simplicity.
 - Use this resource allocator to allocate the buffer and transient maps.
   Buffer cache defrags are reduced by 25% when used by filesystems with
   mixed block sizes.  Ultimately this may permit dynamic buffer cache
   sizing on low KVA machines.

Discussed with:	alc, kib, attilio
Tested by:	pho
Sponsored by:	EMC / Isilon Storage Division
2013-06-28 03:51:20 +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/resourcevar.h>
#include <sys/rwlock.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_radix.h>
#include <vm/vm_reserv.h>
#include <vm/uma.h>
static int old_msync;
SYSCTL_INT(_vm, OID_AUTO, old_msync, CTLFLAG_RW, &old_msync, 0,
"Use old (insecure) msync behavior");
static int vm_object_page_collect_flush(vm_object_t object, vm_page_t p,
int pagerflags, int flags, boolean_t *clearobjflags,
boolean_t *eio);
static boolean_t vm_object_page_remove_write(vm_page_t p, int flags,
boolean_t *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;
static 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 in its memq", object));
KASSERT(vm_radix_is_empty(&object->rtree),
("object %p has resident pages in its trie", object));
#if VM_NRESERVLEVEL > 0
KASSERT(LIST_EMPTY(&object->rvq),
("object %p has reservations",
object));
#endif
KASSERT(vm_object_cache_is_empty(object),
("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->lock, sizeof(object->lock));
rw_init_flags(&object->lock, "vm object", RW_DUPOK);
/* These are true for any object that has been freed */
object->rtree.rt_root = 0;
object->paging_in_progress = 0;
object->resident_page_count = 0;
object->shadow_count = 0;
object->cache.rt_root = 0;
return (0);
}
static 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->type = type;
switch (type) {
case OBJT_DEAD:
panic("_vm_object_allocate: can't create OBJT_DEAD");
case OBJT_DEFAULT:
case OBJT_SWAP:
object->flags = OBJ_ONEMAPPING;
break;
case OBJT_DEVICE:
case OBJT_SG:
object->flags = OBJ_FICTITIOUS | OBJ_UNMANAGED;
break;
case OBJT_MGTDEVICE:
object->flags = OBJ_FICTITIOUS;
break;
case OBJT_PHYS:
object->flags = OBJ_UNMANAGED;
break;
case OBJT_VNODE:
object->flags = 0;
break;
default:
panic("_vm_object_allocate: type %d is undefined", type);
}
object->size = size;
object->generation = 1;
object->ref_count = 1;
object->memattr = VM_MEMATTR_DEFAULT;
object->cred = NULL;
object->charge = 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
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);
rw_init(&kernel_object->lock, "kernel vm 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
rw_init(&kmem_object->lock, "kmem vm 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);
vm_radix_init();
}
void
vm_object_clear_flag(vm_object_t object, u_short bits)
{
VM_OBJECT_ASSERT_WLOCKED(object);
object->flags &= ~bits;
}
/*
* Sets the default memory attribute for the specified object. Pages
* that are allocated to this object are by default assigned this memory
* attribute.
*
* Presently, this function must be called before any pages are allocated
* to the object. In the future, this requirement may be relaxed for
* "default" and "swap" objects.
*/
int
vm_object_set_memattr(vm_object_t object, vm_memattr_t memattr)
{
VM_OBJECT_ASSERT_WLOCKED(object);
switch (object->type) {
case OBJT_DEFAULT:
case OBJT_DEVICE:
case OBJT_MGTDEVICE:
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);
default:
panic("vm_object_set_memattr: object %p is of undefined type",
object);
}
object->memattr = memattr;
return (KERN_SUCCESS);
}
void
vm_object_pip_add(vm_object_t object, short i)
{
VM_OBJECT_ASSERT_WLOCKED(object);
object->paging_in_progress += i;
}
void
vm_object_pip_subtract(vm_object_t object, short i)
{
VM_OBJECT_ASSERT_WLOCKED(object);
object->paging_in_progress -= i;
}
void
vm_object_pip_wakeup(vm_object_t object)
{
VM_OBJECT_ASSERT_WLOCKED(object);
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_ASSERT_WLOCKED(object);
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_ASSERT_WLOCKED(object);
while (object->paging_in_progress) {
object->flags |= OBJ_PIPWNT;
VM_OBJECT_SLEEP(object, 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_WLOCK(object);
vm_object_reference_locked(object);
VM_OBJECT_WUNLOCK(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_ASSERT_WLOCKED(object);
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;
VM_OBJECT_ASSERT_WLOCKED(object);
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_WUNLOCK(object);
/* vrele may need the vnode lock. */
vrele(vp);
} else {
vhold(vp);
VM_OBJECT_WUNLOCK(object);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
vdrop(vp);
VM_OBJECT_WLOCK(object);
object->ref_count--;
if (object->type == OBJT_DEAD) {
VM_OBJECT_WUNLOCK(object);
VOP_UNLOCK(vp, 0);
} else {
if (object->ref_count == 0)
VOP_UNSET_TEXT(vp);
VM_OBJECT_WUNLOCK(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;
struct vnode *vp;
while (object != NULL) {
VM_OBJECT_WLOCK(object);
if (object->type == OBJT_VNODE) {
vm_object_vndeallocate(object);
return;
}
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_WUNLOCK(object);
return;
} else if (object->ref_count == 1) {
if (object->type == OBJT_SWAP &&
(object->flags & OBJ_TMPFS) != 0) {
vp = object->un_pager.swp.swp_tmpfs;
vhold(vp);
VM_OBJECT_WUNLOCK(object);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
vdrop(vp);
VM_OBJECT_WLOCK(object);
if (object->type == OBJT_DEAD ||
object->ref_count != 1) {
VM_OBJECT_WUNLOCK(object);
VOP_UNLOCK(vp, 0);
return;
}
if ((object->flags & OBJ_TMPFS) != 0)
VOP_UNSET_TEXT(vp);
VOP_UNLOCK(vp, 0);
}
if (object->shadow_count == 0 &&
object->handle == NULL &&
(object->type == OBJT_DEFAULT ||
(object->type == OBJT_SWAP &&
(object->flags & OBJ_TMPFS) == 0))) {
vm_object_set_flag(object, OBJ_ONEMAPPING);
} else if ((object->shadow_count == 1) &&
(object->handle == NULL) &&
(object->type == OBJT_DEFAULT ||
object->type == OBJT_SWAP)) {
KASSERT((object->flags & OBJ_TMPFS) == 0,
("shadowed tmpfs v_object %p", object));
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_TRYWLOCK(robject)) {
/*
* Avoid a potential deadlock.
*/
object->ref_count++;
VM_OBJECT_WUNLOCK(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_WUNLOCK(object);
vm_object_pip_wait(robject,
"objde1");
temp = robject->backing_object;
if (object == temp) {
VM_OBJECT_WLOCK(object);
goto retry;
}
} else if (object->paging_in_progress) {
VM_OBJECT_WUNLOCK(robject);
object->flags |= OBJ_PIPWNT;
VM_OBJECT_SLEEP(object, object,
PDROP | PVM, "objde2", 0);
VM_OBJECT_WLOCK(robject);
temp = robject->backing_object;
if (object == temp) {
VM_OBJECT_WLOCK(object);
goto retry;
}
} else
VM_OBJECT_WUNLOCK(object);
if (robject->ref_count == 1) {
robject->ref_count--;
object = robject;
goto doterm;
}
object = robject;
vm_object_collapse(object);
VM_OBJECT_WUNLOCK(object);
continue;
}
VM_OBJECT_WUNLOCK(robject);
}
VM_OBJECT_WUNLOCK(object);
return;
}
doterm:
temp = object->backing_object;
if (temp != NULL) {
VM_OBJECT_WLOCK(temp);
LIST_REMOVE(object, shadow_list);
temp->shadow_count--;
VM_OBJECT_WUNLOCK(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_WUNLOCK(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_ASSERT_WLOCKED(object);
/*
* 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_WUNLOCK(object);
vinvalbuf(vp, V_SAVE, 0, 0);
VM_OBJECT_WLOCK(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) {
vm_radix_reclaim_allnodes(&object->rtree);
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(!vm_object_cache_is_empty(object)))
vm_page_cache_free(object, 0, 0);
/*
* Let the pager know object is dead.
*/
vm_pager_deallocate(object);
VM_OBJECT_WUNLOCK(object);
vm_object_destroy(object);
}
/*
* Make the page read-only so that we can clear the object flags. However, if
* this is a nosync mmap then the object is likely to stay dirty so do not
* mess with the page and do not clear the object flags. Returns TRUE if the
* page should be flushed, and FALSE otherwise.
*/
static boolean_t
vm_object_page_remove_write(vm_page_t p, int flags, boolean_t *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 = FALSE;
return (FALSE);
} else {
pmap_remove_write(p);
return (p->dirty != 0);
}
}
/*
* vm_object_page_clean
*
* Clean all dirty pages in the specified range of object. Leaves page
* on whatever queue it is currently on. If NOSYNC is set then do not
* write out pages with 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.
*
* Returns FALSE if some page from the range was not written, as
* reported by the pager, and TRUE otherwise.
*/
boolean_t
vm_object_page_clean(vm_object_t object, vm_ooffset_t start, vm_ooffset_t end,
int flags)
{
vm_page_t np, p;
vm_pindex_t pi, tend, tstart;
int curgeneration, n, pagerflags;
boolean_t clearobjflags, eio, res;
VM_OBJECT_ASSERT_WLOCKED(object);
/*
* The OBJ_MIGHTBEDIRTY flag is only set for OBJT_VNODE
* objects. The check below prevents the function from
* operating on non-vnode objects.
*/
if ((object->flags & OBJ_MIGHTBEDIRTY) == 0 ||
object->resident_page_count == 0)
return (TRUE);
pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) != 0 ?
VM_PAGER_PUT_SYNC : VM_PAGER_CLUSTER_OK;
pagerflags |= (flags & OBJPC_INVAL) != 0 ? VM_PAGER_PUT_INVAL : 0;
tstart = OFF_TO_IDX(start);
tend = (end == 0) ? object->size : OFF_TO_IDX(end + PAGE_MASK);
clearobjflags = tstart == 0 && tend >= object->size;
res = TRUE;
rescan:
curgeneration = object->generation;
for (p = vm_page_find_least(object, tstart); p != NULL; p = np) {
pi = p->pindex;
if (pi >= tend)
break;
np = TAILQ_NEXT(p, listq);
if (p->valid == 0)
continue;
if (vm_page_sleep_if_busy(p, TRUE, "vpcwai")) {
if (object->generation != curgeneration) {
if ((flags & OBJPC_SYNC) != 0)
goto rescan;
else
clearobjflags = FALSE;
}
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, &eio);
if (eio) {
res = FALSE;
clearobjflags = FALSE;
}
if (object->generation != curgeneration) {
if ((flags & OBJPC_SYNC) != 0)
goto rescan;
else
clearobjflags = FALSE;
}
/*
* If the VOP_PUTPAGES() did a truncated write, so
* that even the first page of the run is not fully
* written, vm_pageout_flush() returns 0 as the run
* length. Since the condition that caused truncated
* write may be permanent, e.g. exhausted free space,
* accepting n == 0 would cause an infinite loop.
*
* Forwarding the iterator leaves the unwritten page
* behind, but there is not much we can do there if
* filesystem refuses to write it.
*/
if (n == 0) {
n = 1;
clearobjflags = FALSE;
}
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);
return (res);
}
static int
vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int pagerflags,
int flags, boolean_t *clearobjflags, boolean_t *eio)
{
vm_page_t ma[vm_pageout_page_count], p_first, tp;
int count, i, mreq, runlen;
vm_page_lock_assert(p, MA_NOTOWNED);
VM_OBJECT_ASSERT_WLOCKED(object);
count = 1;
mreq = 0;
for (tp = p; count < vm_pageout_page_count; count++) {
tp = vm_page_next(tp);
if (tp == NULL || 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, eio);
return (runlen);
}
/*
* Note that there is absolutely no sense in writing out
* anonymous objects, so we track down the vnode object
* to write out.
* We invalidate (remove) all pages from the address space
* for semantic correctness.
*
* If the backing object is a device object with unmanaged pages, then any
* mappings to the specified range of pages must be removed before this
* function is called.
*
* Note: certain anonymous maps, such as MAP_NOSYNC maps,
* may start out with a NULL object.
*/
boolean_t
vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
boolean_t syncio, boolean_t invalidate)
{
vm_object_t backing_object;
struct vnode *vp;
struct mount *mp;
int error, flags, fsync_after;
boolean_t res;
if (object == NULL)
return (TRUE);
res = TRUE;
error = 0;
VM_OBJECT_WLOCK(object);
while ((backing_object = object->backing_object) != NULL) {
VM_OBJECT_WLOCK(backing_object);
offset += object->backing_object_offset;
VM_OBJECT_WUNLOCK(object);
object = backing_object;
if (object->size < OFF_TO_IDX(offset + size))
size = IDX_TO_OFF(object->size) - offset;
}
/*
* Flush pages if writing is allowed, invalidate them
* if invalidation requested. Pages undergoing I/O
* will be ignored by vm_object_page_remove().
*
* We cannot lock the vnode and then wait for paging
* to complete without deadlocking against vm_fault.
* Instead we simply call vm_object_page_remove() and
* allow it to block internally on a page-by-page
* basis when it encounters pages undergoing async
* I/O.
*/
if (object->type == OBJT_VNODE &&
(object->flags & OBJ_MIGHTBEDIRTY) != 0) {
vp = object->handle;
VM_OBJECT_WUNLOCK(object);
(void) vn_start_write(vp, &mp, V_WAIT);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
if (syncio && !invalidate && offset == 0 &&
OFF_TO_IDX(size) == object->size) {
/*
* If syncing the whole mapping of the file,
* it is faster to schedule all the writes in
* async mode, also allowing the clustering,
* and then wait for i/o to complete.
*/
flags = 0;
fsync_after = TRUE;
} else {
flags = (syncio || invalidate) ? OBJPC_SYNC : 0;
flags |= invalidate ? (OBJPC_SYNC | OBJPC_INVAL) : 0;
fsync_after = FALSE;
}
VM_OBJECT_WLOCK(object);
res = vm_object_page_clean(object, offset, offset + size,
flags);
VM_OBJECT_WUNLOCK(object);
if (fsync_after)
error = VOP_FSYNC(vp, MNT_WAIT, curthread);
VOP_UNLOCK(vp, 0);
vn_finished_write(mp);
if (error != 0)
res = FALSE;
VM_OBJECT_WLOCK(object);
}
if ((object->type == OBJT_VNODE ||
object->type == OBJT_DEVICE) && invalidate) {
if (object->type == OBJT_DEVICE)
/*
* The option OBJPR_NOTMAPPED must be passed here
* because vm_object_page_remove() cannot remove
* unmanaged mappings.
*/
flags = OBJPR_NOTMAPPED;
else if (old_msync)
flags = 0;
else
flags = OBJPR_CLEANONLY;
vm_object_page_remove(object, OFF_TO_IDX(offset),
OFF_TO_IDX(offset + size + PAGE_MASK), flags);
}
VM_OBJECT_WUNLOCK(object);
return (res);
}
/*
* vm_object_madvise:
*
* Implements the madvise function at the object/page level.
*
* MADV_WILLNEED (any object)
*
* Activate the specified pages if they are resident.
*
* MADV_DONTNEED (any object)
*
* Deactivate the specified pages if they are resident.
*
* MADV_FREE (OBJT_DEFAULT/OBJT_SWAP objects,
* OBJ_ONEMAPPING only)
*
* Deactivate and clean the specified pages if they are
* resident. This permits the process to reuse the pages
* without faulting or the kernel to reclaim the pages
* without I/O.
*/
void
vm_object_madvise(vm_object_t object, vm_pindex_t pindex, vm_pindex_t end,
int advise)
{
vm_pindex_t tpindex;
vm_object_t backing_object, tobject;
vm_page_t m;
if (object == NULL)
return;
VM_OBJECT_WLOCK(object);
/*
* 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->flags & OBJ_UNMANAGED) != 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_WLOCK(backing_object);
tpindex += OFF_TO_IDX(tobject->backing_object_offset);
if (tobject != object)
VM_OBJECT_WUNLOCK(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) == 0,
("vm_object_madvise: page %p is fictitious", m));
KASSERT((m->oflags & VPO_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_aflag_set(m, PGA_REFERENCED);
}
vm_page_unlock(m);
if (object != tobject)
VM_OBJECT_WUNLOCK(object);
m->oflags |= VPO_WANTED;
VM_OBJECT_SLEEP(tobject, m, PDROP | PVM, "madvpo", 0);
VM_OBJECT_WLOCK(object);
goto relookup;
}
if (advise == MADV_WILLNEED) {
vm_page_activate(m);
} else {
vm_page_advise(m, advise);
}
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_WUNLOCK(tobject);
}
VM_OBJECT_WUNLOCK(object);
}
/*
* vm_object_shadow:
*
* Create a new object which is backed by the
* specified existing object range. The source
* object reference is deallocated.
*
* The new object and offset into that object
* are returned in the source parameters.
*/
void
vm_object_shadow(
vm_object_t *object, /* 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_WLOCK(source);
if (source->ref_count == 1 &&
source->handle == NULL &&
(source->type == OBJT_DEFAULT ||
source->type == OBJT_SWAP)) {
VM_OBJECT_WUNLOCK(source);
return;
}
VM_OBJECT_WUNLOCK(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_WLOCK(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_WUNLOCK(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_WUNLOCK(orig_object);
offidxstart = OFF_TO_IDX(entry->offset);
size = atop(entry->end - entry->start);
/*
* If swap_pager_copy() is later called, it will convert new_object
* into a swap object.
*/
new_object = vm_object_allocate(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_WLOCK(new_object);
VM_OBJECT_WLOCK(orig_object);
source = orig_object->backing_object;
if (source != NULL) {
VM_OBJECT_WLOCK(source);
if ((source->flags & OBJ_DEAD) != 0) {
VM_OBJECT_WUNLOCK(source);
VM_OBJECT_WUNLOCK(orig_object);
VM_OBJECT_WUNLOCK(new_object);
vm_object_deallocate(new_object);
VM_OBJECT_WLOCK(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_WUNLOCK(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_WUNLOCK(new_object);
m->oflags |= VPO_WANTED;
VM_OBJECT_SLEEP(orig_object, m, PVM, "spltwt", 0);
VM_OBJECT_WLOCK(new_object);
goto retry;
}
#if VM_NRESERVLEVEL > 0
/*
* If some of the reservation's allocated pages remain with
* the original object, then transferring the reservation to
* the new object is neither particularly beneficial nor
* particularly harmful as compared to leaving the reservation
* with the original object. If, however, all of the
* reservation's allocated pages are transferred to the new
* object, then transferring the reservation is typically
* beneficial. Determining which of these two cases applies
* would be more costly than unconditionally renaming the
* reservation.
*/
vm_reserv_rename(m, new_object, orig_object, offidxstart);
#endif
vm_page_lock(m);
vm_page_rename(m, new_object, idx);
vm_page_unlock(m);
/* page automatically made dirty by rename and cache handled */
if (orig_object->type == OBJT_SWAP)
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);
TAILQ_FOREACH(m, &new_object->memq, listq)
vm_page_wakeup(m);
/*
* Transfer any cached pages from orig_object to new_object.
* If swap_pager_copy() found swapped out pages within the
* specified range of orig_object, then it changed
* new_object's type to OBJT_SWAP when it transferred those
* pages to new_object. Otherwise, new_object's type
* should still be OBJT_DEFAULT and orig_object should not
* contain any cached pages within the specified range.
*/
if (__predict_false(!vm_object_cache_is_empty(orig_object)))
vm_page_cache_transfer(orig_object, offidxstart,
new_object);
}
VM_OBJECT_WUNLOCK(orig_object);
VM_OBJECT_WUNLOCK(new_object);
entry->object.vm_object = new_object;
entry->offset = 0LL;
vm_object_deallocate(orig_object);
VM_OBJECT_WLOCK(new_object);
}
#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_ASSERT_WLOCKED(object);
VM_OBJECT_ASSERT_WLOCKED(object->backing_object);
backing_object = object->backing_object;
backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
/*
* 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_WUNLOCK(object);
p->oflags |= VPO_WANTED;
VM_OBJECT_SLEEP(backing_object, p,
PDROP | PVM, "vmocol", 0);
VM_OBJECT_WLOCK(object);
VM_OBJECT_WLOCK(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_ASSERT_WLOCKED(object);
VM_OBJECT_ASSERT_WLOCKED(backing_object);
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_ASSERT_WLOCKED(object);
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_WLOCK(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_WUNLOCK(backing_object);
break;
}
if (
object->paging_in_progress != 0 ||
backing_object->paging_in_progress != 0
) {
vm_object_qcollapse(object);
VM_OBJECT_WUNLOCK(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.
* Since swap_pager_copy() is being asked to
* destroy the source, it will change the
* backing_object's type to OBJT_DEFAULT.
*/
swap_pager_copy(
backing_object,
object,
OFF_TO_IDX(object->backing_object_offset), TRUE);
/*
* Free any cached pages from backing_object.
*/
if (__predict_false(
!vm_object_cache_is_empty(backing_object)))
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_WLOCK(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_WUNLOCK(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_WUNLOCK(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_WUNLOCK(backing_object);
break;
}
/*
* Make the parent shadow the next object in the
* chain. Deallocating backing_object will not remove
* it, since its reference count is at least 2.
*/
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_WLOCK(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_WUNLOCK(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_WUNLOCK(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 the option
* OBJPR_CLEANONLY. As a special case, if "end" is zero, then the range
* extends from "start" to the end of the object. If the option
* OBJPR_CLEANONLY is specified, then only the non-dirty pages within the
* specified range are affected. If the option OBJPR_NOTMAPPED is
* specified, then the pages within the specified range must have no
* mappings. Otherwise, if this option is not specified, any mappings to
* the specified pages are removed before the pages are freed or
* invalidated.
*
* In general, this operation should only be performed on objects that
* contain managed pages. There are, however, two exceptions. First, it
* is performed on the kernel and kmem objects by vm_map_entry_delete().
* Second, it is used by msync(..., MS_INVALIDATE) to invalidate device-
* backed pages. In both of these cases, the option OBJPR_CLEANONLY must
* not be specified and the option OBJPR_NOTMAPPED must be specified.
*
* The object must be locked.
*/
void
vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
int options)
{
vm_page_t p, next;
int wirings;
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT((object->flags & OBJ_UNMANAGED) == 0 ||
(options & (OBJPR_CLEANONLY | OBJPR_NOTMAPPED)) == OBJPR_NOTMAPPED,
("vm_object_page_remove: illegal options for object %p", object));
if (object->resident_page_count == 0)
goto skipmemq;
vm_object_pip_add(object, 1);
again:
p = vm_page_find_least(object, start);
/*
* Here, the variable "p" is either (1) the page with the least pindex
* greater than or equal to the parameter "start" or (2) NULL.
*/
for (; p != NULL && (p->pindex < end || end == 0); p = next) {
next = TAILQ_NEXT(p, listq);
/*
* If the page is wired for any reason besides the existence
* of managed, wired mappings, then it cannot be freed. For
* example, fictitious pages, which represent device memory,
* are inherently wired and cannot be freed. They can,
* however, be invalidated if the option OBJPR_CLEANONLY is
* not specified.
*/
vm_page_lock(p);
if ((wirings = p->wire_count) != 0 &&
(wirings = pmap_page_wired_mappings(p)) != p->wire_count) {
if ((options & OBJPR_NOTMAPPED) == 0) {
pmap_remove_all(p);
/* Account for removal of wired mappings. */
if (wirings != 0)
p->wire_count -= wirings;
}
if ((options & OBJPR_CLEANONLY) == 0) {
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 ((options & OBJPR_CLEANONLY) != 0 && p->valid != 0) {
if ((options & OBJPR_NOTMAPPED) == 0)
pmap_remove_write(p);
if (p->dirty) {
vm_page_unlock(p);
continue;
}
}
if ((options & OBJPR_NOTMAPPED) == 0) {
pmap_remove_all(p);
/* Account for removal of wired mappings. */
if (wirings != 0) {
KASSERT(p->wire_count == wirings,
("inconsistent wire count %d %d %p",
p->wire_count, wirings, p));
p->wire_count = 0;
atomic_subtract_int(&cnt.v_wire_count, 1);
}
}
vm_page_free(p);
vm_page_unlock(p);
}
vm_object_pip_wakeup(object);
skipmemq:
if (__predict_false(!vm_object_cache_is_empty(object)))
vm_page_cache_free(object, start, end);
}
/*
* vm_object_page_cache:
*
* For the given object, attempt to move the specified clean
* pages to the cache queue. If a page is wired for any reason,
* then it will not be changed. Pages are specified by the given
* range ["start", "end"). As a special case, if "end" is zero,
* then the range extends from "start" to the end of the object.
* Any mappings to the specified pages are removed before the
* pages are moved to the cache queue.
*
* This operation should only be performed on objects that
* contain non-fictitious, managed pages.
*
* The object must be locked.
*/
void
vm_object_page_cache(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
{
struct mtx *mtx, *new_mtx;
vm_page_t p, next;
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT((object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0,
("vm_object_page_cache: illegal object %p", object));
if (object->resident_page_count == 0)
return;
p = vm_page_find_least(object, start);
/*
* Here, the variable "p" is either (1) the page with the least pindex
* greater than or equal to the parameter "start" or (2) NULL.
*/
mtx = NULL;
for (; p != NULL && (p->pindex < end || end == 0); p = next) {
next = TAILQ_NEXT(p, listq);
/*
* Avoid releasing and reacquiring the same page lock.
*/
new_mtx = vm_page_lockptr(p);
if (mtx != new_mtx) {
if (mtx != NULL)
mtx_unlock(mtx);
mtx = new_mtx;
mtx_lock(mtx);
}
vm_page_try_to_cache(p);
}
if (mtx != NULL)
mtx_unlock(mtx);
}
/*
* 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_ASSERT_WLOCKED(object);
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_WLOCK(prev_object);
if (prev_object->type != OBJT_DEFAULT &&
prev_object->type != OBJT_SWAP) {
VM_OBJECT_WUNLOCK(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_WUNLOCK(prev_object);
return (FALSE);
}
prev_size >>= PAGE_SHIFT;
next_size >>= PAGE_SHIFT;
next_pindex = OFF_TO_IDX(prev_offset) + prev_size;
if ((prev_object->ref_count > 1) &&
(prev_object->size != next_pindex)) {
VM_OBJECT_WUNLOCK(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, 0);
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_WUNLOCK(prev_object);
return (TRUE);
}
void
vm_object_set_writeable_dirty(vm_object_t object)
{
VM_OBJECT_ASSERT_WLOCKED(object);
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;
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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