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