svn commit: r282660 - head/sys/vm
John Baldwin
jhb at FreeBSD.org
Fri May 8 19:43:40 UTC 2015
Author: jhb
Date: Fri May 8 19:43:37 2015
New Revision: 282660
URL: https://svnweb.freebsd.org/changeset/base/282660
Log:
Place VM objects on the object list when created and never remove them.
This is ok since objects come from a NOFREE zone and allows objects to
be locked while traversing the object list without triggering a LOR.
Ensure that objects on the list are marked DEAD while free or stillborn,
and that they have a refcount of zero. This required updating most of
the pagers to explicitly mark an object as dead when deallocating it.
(Only the vnode pager did this previously.)
Differential Revision: https://reviews.freebsd.org/D2423
Reviewed by: alc, kib (earlier version)
MFC after: 2 weeks
Sponsored by: Norse Corp, Inc.
Modified:
head/sys/vm/default_pager.c
head/sys/vm/device_pager.c
head/sys/vm/phys_pager.c
head/sys/vm/sg_pager.c
head/sys/vm/swap_pager.c
head/sys/vm/vm_meter.c
head/sys/vm/vm_object.c
Modified: head/sys/vm/default_pager.c
==============================================================================
--- head/sys/vm/default_pager.c Fri May 8 19:41:04 2015 (r282659)
+++ head/sys/vm/default_pager.c Fri May 8 19:43:37 2015 (r282660)
@@ -113,6 +113,7 @@ default_pager_dealloc(object)
/*
* OBJT_DEFAULT objects have no special resources allocated to them.
*/
+ object->type = OBJT_DEAD;
}
/*
Modified: head/sys/vm/device_pager.c
==============================================================================
--- head/sys/vm/device_pager.c Fri May 8 19:41:04 2015 (r282659)
+++ head/sys/vm/device_pager.c Fri May 8 19:43:37 2015 (r282660)
@@ -254,6 +254,8 @@ dev_pager_dealloc(object)
!= NULL)
dev_pager_free_page(object, m);
}
+ object->handle = NULL;
+ object->type = OBJT_DEAD;
}
static int
Modified: head/sys/vm/phys_pager.c
==============================================================================
--- head/sys/vm/phys_pager.c Fri May 8 19:41:04 2015 (r282659)
+++ head/sys/vm/phys_pager.c Fri May 8 19:43:37 2015 (r282660)
@@ -131,6 +131,8 @@ phys_pager_dealloc(vm_object_t object)
mtx_unlock(&phys_pager_mtx);
VM_OBJECT_WLOCK(object);
}
+ object->handle = NULL;
+ object->type = OBJT_DEAD;
}
/*
Modified: head/sys/vm/sg_pager.c
==============================================================================
--- head/sys/vm/sg_pager.c Fri May 8 19:41:04 2015 (r282659)
+++ head/sys/vm/sg_pager.c Fri May 8 19:43:37 2015 (r282660)
@@ -130,6 +130,8 @@ sg_pager_dealloc(vm_object_t object)
sg = object->handle;
sglist_free(sg);
+ object->handle = NULL;
+ object->type = OBJT_DEAD;
}
static int
Modified: head/sys/vm/swap_pager.c
==============================================================================
--- head/sys/vm/swap_pager.c Fri May 8 19:41:04 2015 (r282659)
+++ head/sys/vm/swap_pager.c Fri May 8 19:43:37 2015 (r282660)
@@ -697,6 +697,8 @@ swap_pager_dealloc(vm_object_t object)
* if paging is still in progress on some objects.
*/
swp_pager_meta_free_all(object);
+ object->handle = NULL;
+ object->type = OBJT_DEAD;
}
/************************************************************************
Modified: head/sys/vm/vm_meter.c
==============================================================================
--- head/sys/vm/vm_meter.c Fri May 8 19:41:04 2015 (r282659)
+++ head/sys/vm/vm_meter.c Fri May 8 19:43:37 2015 (r282660)
@@ -111,14 +111,7 @@ vmtotal(SYSCTL_HANDLER_ARGS)
*/
mtx_lock(&vm_object_list_mtx);
TAILQ_FOREACH(object, &vm_object_list, object_list) {
- if (!VM_OBJECT_TRYWLOCK(object)) {
- /*
- * Avoid a lock-order reversal. Consequently,
- * the reported number of active pages may be
- * greater than the actual number.
- */
- continue;
- }
+ VM_OBJECT_WLOCK(object);
vm_object_clear_flag(object, OBJ_ACTIVE);
VM_OBJECT_WUNLOCK(object);
}
@@ -196,10 +189,9 @@ vmtotal(SYSCTL_HANDLER_ARGS)
mtx_lock(&vm_object_list_mtx);
TAILQ_FOREACH(object, &vm_object_list, object_list) {
/*
- * Perform unsynchronized reads on the object to avoid
- * a lock-order reversal. In this case, the lack of
- * synchronization should not impair the accuracy of
- * the reported statistics.
+ * Perform unsynchronized reads on the object. In
+ * this case, the lack of synchronization should not
+ * impair the accuracy of the reported statistics.
*/
if ((object->flags & OBJ_FICTITIOUS) != 0) {
/*
Modified: head/sys/vm/vm_object.c
==============================================================================
--- head/sys/vm/vm_object.c Fri May 8 19:41:04 2015 (r282659)
+++ head/sys/vm/vm_object.c Fri May 8 19:43:37 2015 (r282660)
@@ -166,6 +166,8 @@ vm_object_zdtor(void *mem, int size, voi
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),
@@ -187,6 +189,9 @@ vm_object_zdtor(void *mem, int size, voi
KASSERT(object->shadow_count == 0,
("object %p shadow_count = %d",
object, object->shadow_count));
+ KASSERT(object->type == OBJT_DEAD,
+ ("object %p has non-dead type %d",
+ object, object->type));
}
#endif
@@ -199,6 +204,8 @@ vm_object_zinit(void *mem, int size, int
rw_init_flags(&object->lock, "vm object", RW_DUPOK | RW_NEW);
/* These are true for any object that has been freed */
+ object->type = OBJT_DEAD;
+ object->ref_count = 0;
object->rtree.rt_root = 0;
object->rtree.rt_flags = 0;
object->paging_in_progress = 0;
@@ -206,6 +213,10 @@ vm_object_zinit(void *mem, int size, int
object->shadow_count = 0;
object->cache.rt_root = 0;
object->cache.rt_flags = 0;
+
+ mtx_lock(&vm_object_list_mtx);
+ TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
+ mtx_unlock(&vm_object_list_mtx);
return (0);
}
@@ -252,10 +263,6 @@ _vm_object_allocate(objtype_t type, vm_p
#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);
}
/*
@@ -671,19 +678,9 @@ 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,
- ("%s: non-swap obj %p has cred", __func__, object));
swap_release_by_cred(object->charge, object->cred);
object->charge = 0;
crfree(object->cred);
@@ -788,6 +785,10 @@ vm_object_terminate(vm_object_t object)
if (__predict_false(!vm_object_cache_is_empty(object)))
vm_page_cache_free(object, 0, 0);
+ KASSERT(object->cred == NULL || object->type == OBJT_DEFAULT ||
+ object->type == OBJT_SWAP,
+ ("%s: non-swap obj %p has cred", __func__, object));
+
/*
* Let the pager know object is dead.
*/
@@ -1803,6 +1804,8 @@ vm_object_collapse(vm_object_t object)
KASSERT(backing_object->ref_count == 1, (
"backing_object %p was somehow re-referenced during collapse!",
backing_object));
+ backing_object->type = OBJT_DEAD;
+ backing_object->ref_count = 0;
VM_OBJECT_WUNLOCK(backing_object);
vm_object_destroy(backing_object);
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