2013/8/15 Andrew Morton [off-list ref]

On Wed, 14 Aug 2013 14:31:21 +0400 Andrey Vagin [off-list ref] wrote:

quoted

The memcg_cache_params structure contains the common part and the union,
which represents two different types of data: one for root cashes and
another for child caches.

The size of child data is fixed. The size of the memcg_caches array is
calculated in runtime.

Currently the size of memcg_cache_params for root caches is calculated
incorrectly, because it includes the size of parameters for child caches.

ssize_t size = memcg_caches_array_size(num_groups);
size *= sizeof(void *);

size += sizeof(struct memcg_cache_params);

...

--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c

@@ -3140,7 +3140,7 @@ int memcg_update_cache_size(struct kmem_cache *s,

int num_groups)

quoted

              ssize_t size = memcg_caches_array_size(num_groups);

              size *= sizeof(void *);
-             size += sizeof(struct memcg_cache_params);
+             size += sizeof(offsetof(struct memcg_cache_params,

memcg_caches));

This looks wrong. offsetof() returns size_t, so this is equivalent to

                size += sizeof(size_t);

sizeof doesn't have to be here. I will resend this patch. Thanks.

size += offsetof(struct memcg_cache_params, memcg_caches)

quoted

              s->memcg_params = kzalloc(size, GFP_KERNEL);
              if (!s->memcg_params) {

@@ -3183,13 +3183,16 @@ int memcg_update_cache_size(struct kmem_cache

*s, int num_groups)

quoted

 int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s,
                       struct kmem_cache *root_cache)
 {
-     size_t size = sizeof(struct memcg_cache_params);
+     size_t size;

      if (!memcg_kmem_enabled())
              return 0;

-     if (!memcg)
+     if (!memcg) {
+             size = offsetof(struct memcg_cache_params, memcg_caches);
              size += memcg_limited_groups_array_size * sizeof(void *);
+     } else
+             size = sizeof(struct memcg_cache_params);

      s->memcg_params = kzalloc(size, GFP_KERNEL);
      if (!s->memcg_params)