Commit 90c7a79c authored Sep 11, 2013 by Andrey Vagin Committed by Linus Torvalds Sep 11, 2013

kmemcg: don't allocate extra memory for root memcg_cache_params



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);

v2: Fix a typo in calculations

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Cc: Glauber Costa <glommer@openvz.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent e76b63f8

mm/memcontrol.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -3121,7 +3121,7 @@ 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 += offsetof(struct memcg_cache_params, memcg_caches);

		s->memcg_params = kzalloc(size, GFP_KERNEL);
		if (!s->memcg_params) {
		@@ -3164,13 +3164,16 @@ 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)