[Midnightbsd-cvs] src [8011] trunk/sys: drop page queues mutex on each iteration of vm_pageout_scan over the inactive queue, unless busy page is found.
laffer1 at midnightbsd.org
laffer1 at midnightbsd.org
Thu Sep 15 05:00:03 EDT 2016
Revision: 8011
http://svnweb.midnightbsd.org/src/?rev=8011
Author: laffer1
Date: 2016-09-15 05:00:03 -0400 (Thu, 15 Sep 2016)
Log Message:
-----------
drop page queues mutex on each iteration of vm_pageout_scan over the inactive queue, unless busy page is found. Avoid vm page queues lock leak.
Modified Paths:
--------------
trunk/sys/sys/vmmeter.h
trunk/sys/vm/vm_pageout.c
Modified: trunk/sys/sys/vmmeter.h
===================================================================
--- trunk/sys/sys/vmmeter.h 2016-09-15 08:56:10 UTC (rev 8010)
+++ trunk/sys/sys/vmmeter.h 2016-09-15 09:00:03 UTC (rev 8011)
@@ -79,7 +79,7 @@
u_int v_pdpages; /* (q) pages analyzed by daemon */
u_int v_tcached; /* (p) total pages cached */
- u_int v_dfree; /* (q) pages freed by daemon */
+ u_int v_dfree; /* (p) pages freed by daemon */
u_int v_pfree; /* (p) pages freed by exiting processes */
u_int v_tfree; /* (p) total pages freed */
/*
Modified: trunk/sys/vm/vm_pageout.c
===================================================================
--- trunk/sys/vm/vm_pageout.c 2016-09-15 08:56:10 UTC (rev 8010)
+++ trunk/sys/vm/vm_pageout.c 2016-09-15 09:00:03 UTC (rev 8011)
@@ -743,6 +743,7 @@
int actcount;
int vnodes_skipped = 0;
int maxlaunder;
+ boolean_t queues_locked;
/*
* Decrease registered cache sizes.
@@ -784,6 +785,7 @@
if (pass)
maxlaunder = 10000;
vm_page_lock_queues();
+ queues_locked = TRUE;
rescan0:
addl_page_shortage = addl_page_shortage_init;
maxscan = cnt.v_inactive_count;
@@ -791,6 +793,8 @@
for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl);
m != NULL && maxscan-- > 0 && page_shortage > 0;
m = next) {
+ KASSERT(queues_locked, ("unlocked queues"));
+ mtx_assert(&vm_page_queue_mtx, MA_OWNED);
cnt.v_pdpages++;
@@ -850,6 +854,16 @@
}
/*
+ * We unlock vm_page_queue_mtx, invalidating the
+ * 'next' pointer. Use our marker to remember our
+ * place.
+ */
+ TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl,
+ m, &marker, pageq);
+ vm_page_unlock_queues();
+ queues_locked = FALSE;
+
+ /*
* If the object is not being used, we ignore previous
* references.
*/
@@ -873,7 +887,7 @@
vm_page_unlock(m);
m->act_count += actcount + ACT_ADVANCE;
VM_OBJECT_UNLOCK(object);
- continue;
+ goto relock_queues;
}
/*
@@ -889,7 +903,7 @@
vm_page_unlock(m);
m->act_count += actcount + ACT_ADVANCE + 1;
VM_OBJECT_UNLOCK(object);
- continue;
+ goto relock_queues;
}
/*
@@ -924,7 +938,7 @@
* Invalid pages can be easily freed
*/
vm_page_free(m);
- cnt.v_dfree++;
+ PCPU_INC(cnt.v_dfree);
--page_shortage;
} else if (m->dirty == 0) {
/*
@@ -947,6 +961,8 @@
* the thrash point for a heavily loaded machine.
*/
m->flags |= PG_WINATCFLS;
+ vm_page_lock_queues();
+ queues_locked = TRUE;
vm_page_requeue(m);
} else if (maxlaunder > 0) {
/*
@@ -976,21 +992,13 @@
if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
vm_page_unlock(m);
VM_OBJECT_UNLOCK(object);
+ vm_page_lock_queues();
+ queues_locked = TRUE;
vm_page_requeue(m);
- continue;
+ goto relock_queues;
}
/*
- * Following operations may unlock
- * vm_page_queue_mtx, invalidating the 'next'
- * pointer. To prevent an inordinate number
- * of restarts we use our marker to remember
- * our place.
- *
- */
- TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl,
- m, &marker, pageq);
- /*
* The object is already known NOT to be dead. It
* is possible for the vget() to block the whole
* pageout daemon, but the new low-memory handling
@@ -1014,7 +1022,6 @@
* of time.
*/
if (object->type == OBJT_VNODE) {
- vm_page_unlock_queues();
vm_page_unlock(m);
vp = object->handle;
if (vp->v_type == VREG &&
@@ -1023,7 +1030,6 @@
++pageout_lock_miss;
if (object->flags & OBJ_MIGHTBEDIRTY)
vnodes_skipped++;
- vm_page_lock_queues();
goto unlock_and_continue;
}
KASSERT(mp != NULL,
@@ -1034,7 +1040,6 @@
if (vget(vp, LK_EXCLUSIVE | LK_TIMELOCK,
curthread)) {
VM_OBJECT_LOCK(object);
- vm_page_lock_queues();
++pageout_lock_miss;
if (object->flags & OBJ_MIGHTBEDIRTY)
vnodes_skipped++;
@@ -1044,6 +1049,7 @@
VM_OBJECT_LOCK(object);
vm_page_lock(m);
vm_page_lock_queues();
+ queues_locked = TRUE;
/*
* The page might have been moved to another
* queue during potential blocking in vget()
@@ -1081,6 +1087,8 @@
vnodes_skipped++;
goto unlock_and_continue;
}
+ vm_page_unlock_queues();
+ queues_locked = FALSE;
}
/*
@@ -1093,32 +1101,37 @@
* the (future) cleaned page. Otherwise we could wind
* up laundering or cleaning too many pages.
*/
- vm_page_unlock_queues();
if (vm_pageout_clean(m) != 0) {
--page_shortage;
--maxlaunder;
}
- vm_page_lock_queues();
unlock_and_continue:
vm_page_lock_assert(m, MA_NOTOWNED);
VM_OBJECT_UNLOCK(object);
if (mp != NULL) {
- vm_page_unlock_queues();
+ if (queues_locked) {
+ vm_page_unlock_queues();
+ queues_locked = FALSE;
+ }
if (vp != NULL)
vput(vp);
VFS_UNLOCK_GIANT(vfslocked);
vm_object_deallocate(object);
vn_finished_write(mp);
- vm_page_lock_queues();
}
- next = TAILQ_NEXT(&marker, pageq);
- TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl,
- &marker, pageq);
vm_page_lock_assert(m, MA_NOTOWNED);
- continue;
+ goto relock_queues;
}
vm_page_unlock(m);
VM_OBJECT_UNLOCK(object);
+relock_queues:
+ if (!queues_locked) {
+ vm_page_lock_queues();
+ queues_locked = TRUE;
+ }
+ next = TAILQ_NEXT(&marker, pageq);
+ TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl,
+ &marker, pageq);
}
/*
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