svn commit: r209290 - stable/8/sys/vm

[Konstantin Belousov]

Author: kib
Date: Fri Jun 18 09:25:00 2010
New Revision: 209290
URL: http://svn.freebsd.org/changeset/base/209290

Log:
  MFC r208340:
  When waiting for the busy page, do not unlock the object unless unlock
  cannot be avoided.

Modified:
  stable/8/sys/vm/vm_fault.c
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (props changed)
  stable/8/sys/cddl/contrib/opensolaris/   (props changed)
  stable/8/sys/contrib/dev/acpica/   (props changed)
  stable/8/sys/contrib/pf/   (props changed)
  stable/8/sys/dev/xen/xenpci/   (props changed)
  stable/8/sys/geom/sched/   (props changed)

Modified: stable/8/sys/vm/vm_fault.c
==============================================================================
--- stable/8/sys/vm/vm_fault.c	Fri Jun 18 09:01:44 2010	(r209289)
+++ stable/8/sys/vm/vm_fault.c	Fri Jun 18 09:25:00 2010	(r209290)
@@ -361,9 +361,13 @@ RetryFault:;
 			 */
 			if ((fs.m->oflags & VPO_BUSY) || fs.m->busy) {
 				vm_page_unlock_queues();
-				VM_OBJECT_UNLOCK(fs.object);
 				if (fs.object != fs.first_object) {
-					VM_OBJECT_LOCK(fs.first_object);
+					if (!VM_OBJECT_TRYLOCK(
+					    fs.first_object)) {
+						VM_OBJECT_UNLOCK(fs.object);
+						VM_OBJECT_LOCK(fs.first_object);
+						VM_OBJECT_LOCK(fs.object);
+					}
 					vm_page_lock_queues();
 					vm_page_free(fs.first_m);
 					vm_page_unlock_queues();
@@ -372,7 +376,6 @@ RetryFault:;
 					fs.first_m = NULL;
 				}
 				unlock_map(&fs);
-				VM_OBJECT_LOCK(fs.object);
 				if (fs.m == vm_page_lookup(fs.object,
 				    fs.pindex)) {
 					vm_page_sleep_if_busy(fs.m, TRUE,