slub: Initialize per-cpu stats

As spotted by kmemcheck, we need to initialize the per-CPU ->stat array before
using it.

[kmem_cache_cpu structures are usually allocated from arrays defined via
DEFINE_PER_CPU that are zeroed so we have not noticed this so far --cl].

Reported-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

1 files changed, 3 insertions, 0 deletions

diff --git a/mm/slub.c b/mm/slub.c
index acc975fcc8cc..15a7a0d45d71 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1886,6 +1886,9 @@ static void init_kmem_cache_cpu(struct kmem_cache *s,
         c->node = 0;
         c->offset = s->offset / sizeof(void *);
         c->objsize = s->objsize;
+#ifdef CONFIG_SLUB_STATS
+        memset(c->stat, 0, NR_SLUB_STAT_ITEMS * sizeof(unsigned));
+#endif
 }
 
 static void init_kmem_cache_node(struct kmem_cache_node *n)