---
 mm/slub.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

Index: slub/mm/slub.c
===================================================================
--- slub.orig/mm/slub.c	2007-06-08 11:12:40.000000000 -0700
+++ slub/mm/slub.c	2007-06-08 11:26:04.000000000 -0700
@@ -2738,7 +2738,15 @@ int kmem_cache_defrag(int percent, int n
 	unsigned long pages = 0;
 	void *scratch;
 
-	down_read(&slub_lock);
+	/*
+	 * kmem_cache_defrag may be called from the reclaim path which may be
+	 * called for any page allocator alloc. So there is the danger that we
+	 * get called in a situation where slub already acquired the slub_lock
+	 * for other purposes.
+	 */
+	if (!down_read_trylock(&slub_lock))
+		return 0;
+
 	list_for_each_entry(s, &slab_caches, list) {
 
 		/*