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

Place the alien array cache locks of on slab malloc slab caches on a
seperate lockdep class.  This avoids false positives from lockdep

Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Shai Fultheim <shai@scalex86.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: 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 |   41 ++++++++++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 9 deletions(-)

diff -puN mm/slab.c~slab-fix-lockdep-warnings mm/slab.c
--- a/mm/slab.c~slab-fix-lockdep-warnings
+++ a/mm/slab.c
@@ -682,23 +682,43 @@ static struct kmem_cache cache_cache = {
  * The locking for this is tricky in that it nests within the locks
  * of all other slabs in a few places; to deal with this special
  * locking we put on-slab caches into a separate lock-class.
+ *
+ * We set lock class for alien array caches which are up during init.
+ * The lock annotation will be lost if all cpus of a node goes down and
+ * then comes back up during hotplug
  */
-static struct lock_class_key on_slab_key;
+static struct lock_class_key on_slab_l3_key;
+static struct lock_class_key on_slab_alc_key;
+
+static inline void init_lock_keys(void)
 
-static inline void init_lock_keys(struct cache_sizes *s)
 {
 	int q;
+	struct cache_sizes *s = malloc_sizes;
 
-	for (q = 0; q < MAX_NUMNODES; q++) {
-		if (!s->cs_cachep->nodelists[q] || OFF_SLAB(s->cs_cachep))
-			continue;
-		lockdep_set_class(&s->cs_cachep->nodelists[q]->list_lock,
-				  &on_slab_key);
+	while (s->cs_size != ULONG_MAX) {
+		for_each_node(q) {
+			struct array_cache **alc;
+			int r;
+			struct kmem_list3 *l3 = s->cs_cachep->nodelists[q];
+			if (!l3 || OFF_SLAB(s->cs_cachep))
+				continue;
+			lockdep_set_class(&l3->list_lock, &on_slab_l3_key);
+			alc = l3->alien;
+			if (!alc)
+				continue;
+			for_each_node(r) {
+				if (alc[r])
+					lockdep_set_class(&alc[r]->lock,
+					     &on_slab_alc_key);
+			}
+		}
+		s++;
 	}
 }
 
 #else
-static inline void init_lock_keys(struct cache_sizes *s)
+static inline void init_lock_keys()
 {
 }
 #endif
@@ -1421,7 +1441,6 @@ void __init kmem_cache_init(void)
 					ARCH_KMALLOC_FLAGS|SLAB_PANIC,
 					NULL, NULL);
 		}
-		init_lock_keys(sizes);
 
 		sizes->cs_dmacachep = kmem_cache_create(names->name_dma,
 					sizes->cs_size,
@@ -1495,6 +1514,10 @@ void __init kmem_cache_init(void)
 		mutex_unlock(&cache_chain_mutex);
 	}
 
+	/* Annotate slab for lockdep -- annotate the malloc caches */
+	init_lock_keys();
+
+
 	/* Done! */
 	g_cpucache_up = FULL;
 
_