From: Ravikiran G Thirumalai <kiran@scalex86.org>

Fix oops due to alien cache lockdep annotation on non NUMA configurations. 
A plain alien != NULL won't work as l3->alien is initialized with
0x01020304ul

Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Cc: Shai Fultheim <shai@scalex86.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 mm/slab.c |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff -puN mm/slab.c~slab-fix-lockdep-warnings-fix mm/slab.c
--- a/mm/slab.c~slab-fix-lockdep-warnings-fix
+++ a/mm/slab.c
@@ -674,6 +674,8 @@ static struct kmem_cache cache_cache = {
 #endif
 };
 
+#define BAD_ALIEN_MAGIC 0x01020304ul
+
 #ifdef CONFIG_LOCKDEP
 
 /*
@@ -705,7 +707,14 @@ static inline void init_lock_keys(void)
 				continue;
 			lockdep_set_class(&l3->list_lock, &on_slab_l3_key);
 			alc = l3->alien;
-			if (!alc)
+			/*
+			 * FIXME: This check for BAD_ALIEN_MAGIC
+			 * should go away when common slab code is taught to
+			 * work even without alien caches.
+			 * Currently, non NUMA code returns BAD_ALIEN_MAGIC
+			 * for alloc_alien_cache,
+			 */
+			if (!alc || (unsigned long)alc == BAD_ALIEN_MAGIC)
 				continue;
 			for_each_node(r) {
 				if (alc[r])
@@ -1111,7 +1120,7 @@ static inline int cache_free_alien(struc
 
 static inline struct array_cache **alloc_alien_cache(int node, int limit)
 {
-	return (struct array_cache **) 0x01020304ul;
+	return (struct array_cache **)BAD_ALIEN_MAGIC;
 }
 
 static inline void free_alien_cache(struct array_cache **ac_ptr)
_