slab: fix typo in allocation failure handling

This patch fixes wrong array index in allocation failure handling.

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slab.c

@@ -1043,7 +1043,7 @@ static struct array_cache **alloc_alien_cache(int node, int limit)
 			}
 			ac_ptr[i] = alloc_arraycache(node, limit, 0xbaadf00d);
 			if (!ac_ptr[i]) {
-				for (i--; i <= 0; i--)
+				for (i--; i >= 0; i--)
 					kfree(ac_ptr[i]);
 				kfree(ac_ptr);
 				return NULL;