svn commit: r195115 - user/kmacy/releng_7_2_fcs/sys/vm

[Kip Macy]

Author: kmacy
Date: Sat Jun 27 20:26:16 2009
New Revision: 195115
URL: http://svn.freebsd.org/changeset/base/195115

Log:
  The page object association is now protected by the page lock and not the global
  page queue lock, thus we need to acquire the page lock before validating the object
  and acquiring the object lock.

Modified:
  user/kmacy/releng_7_2_fcs/sys/vm/vm_pageout.c

Modified: user/kmacy/releng_7_2_fcs/sys/vm/vm_pageout.c
==============================================================================
--- user/kmacy/releng_7_2_fcs/sys/vm/vm_pageout.c	Sat Jun 27 20:06:56 2009	(r195114)
+++ user/kmacy/releng_7_2_fcs/sys/vm/vm_pageout.c	Sat Jun 27 20:26:16 2009	(r195115)
@@ -254,6 +254,8 @@ vm_pageout_fallback_object_lock(vm_page_
 	TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl,
 			   m, &marker, pageq);
 	vm_page_unlock_queues();
+	vm_page_unlock(m);
+	vm_page_lock(m);
 	VM_OBJECT_LOCK(object);
 	vm_page_lock_queues();
 
@@ -757,7 +759,6 @@ rescan0:
 			goto rescan0;
 
 		next = TAILQ_NEXT(m, pageq);
-		object = m->object;
 
 		/*
 		 * skip marker pages
@@ -774,6 +775,10 @@ rescan0:
 			continue;
 		}
 
+		if (vm_page_trylock(m) == 0 || (object = m->object) == NULL) {
+			addl_page_shortage++;
+			continue;
+		}
 		/*
 		 * Don't mess with busy pages, keep in the front of the
 		 * queue, most likely are being paged out.
@@ -781,12 +786,7 @@ rescan0:
 		if (!VM_OBJECT_TRYLOCK(object) &&
 		    !vm_pageout_fallback_object_lock(m, &next)) {
 			VM_OBJECT_UNLOCK(object);
-			addl_page_shortage++;
-			continue;
-		}
-		vm_page_lock_assert(m, MA_NOTOWNED);
-		if (vm_page_trylock(m) == 0) {
-			VM_OBJECT_UNLOCK(object);
+			vm_page_unlock(m);
 			addl_page_shortage++;
 			continue;
 		}
@@ -1088,7 +1088,6 @@ unlock_and_continue:
 		    ("vm_pageout_scan: page %p isn't active", m));
 
 		next = TAILQ_NEXT(m, pageq);
-		object = m->object;
 
 		/*
 		 * XXX note that the object == NULL check is a band-aid
@@ -1098,19 +1097,19 @@ unlock_and_continue:
 		 * trylocking the object which in turn complicates error
 		 * handling slightly
 		 */
-		if ((object == NULL) || (m->flags & PG_MARKER) != 0) {
+		if ((m->flags & PG_MARKER) != 0) {
 			m = next;
 			continue;
 		}
-		if (!VM_OBJECT_TRYLOCK(object) &&
-		    !vm_pageout_fallback_object_lock(m, &next)) {
-			VM_OBJECT_UNLOCK(object);
+
+		if (vm_page_trylock(m) == 0 || (object = m->object) == NULL) {
 			m = next;
 			continue;
 		}
-
-		if (vm_page_trylock(m) == 0) {
+		if (!VM_OBJECT_TRYLOCK(object) &&
+		    !vm_pageout_fallback_object_lock(m, &next)) {
 			VM_OBJECT_UNLOCK(object);
+			vm_page_unlock(m);
 			m = next;
 			continue;
 		}