On Wed, 14 Aug 2013 14:31:21 +0400 Andrey Vagin <avagin@xxxxxxxxxx> wrote:
> 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)
> 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);
> 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)
> 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)
--
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