Author: alc
Date: Sun Sep 23 17:42:39 2012
New Revision: 240862
URL: http://svn.freebsd.org/changeset/base/240862
Log:
Address a race condition that was introduced in r238212. Unless the page
queues lock is acquired before the page lock is released, there is no
guarantee that the page will still be in that same page queue when
vm_page_requeue() is called.
Reported by: pho
In collaboration with: kib
MFC after: 3 days
Modified:
head/sys/vm/vm_pageout.c
Modified: head/sys/vm/vm_pageout.c
==============================================================================
--- head/sys/vm/vm_pageout.c Sun Sep 23 17:36:01 2012 (r240861)
+++ head/sys/vm/vm_pageout.c Sun Sep 23 17:42:39 2012 (r240862)
@@ -1125,9 +1125,9 @@ vm_pageout_scan(int pass)
* Those objects are in a "rundown" state.
*/
if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
+ vm_page_lock_queues();
vm_page_unlock(m);
VM_OBJECT_UNLOCK(object);
- vm_page_lock_queues();
queues_locked = TRUE;
vm_page_requeue(m);
goto relock_queues;
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