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authorVladimir Davydov <vdavydov@parallels.com>2015-02-10 14:11:47 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-10 14:30:34 -0800
commitd5b3cf7139b8770af4ed8bb36a1ab9d290ac39e9 (patch)
treed96432c889fcb6f3790f41651a13a489e6af8f5c /include/linux/slab.h
parent3e0350a36414a73c5c2d1e354f8c0ab4ace1296d (diff)
memcg: zap memcg_slab_caches and memcg_slab_mutex
mem_cgroup->memcg_slab_caches is a list of kmem caches corresponding to the given cgroup. Currently, it is only used on css free in order to destroy all caches corresponding to the memory cgroup being freed. The list is protected by memcg_slab_mutex. The mutex is also used to protect kmem_cache->memcg_params->memcg_caches arrays and synchronizes kmem_cache_destroy vs memcg_unregister_all_caches. However, we can perfectly get on without these two. To destroy all caches corresponding to a memory cgroup, we can walk over the global list of kmem caches, slab_caches, and we can do all the synchronization stuff using the slab_mutex instead of the memcg_slab_mutex. This patch therefore gets rid of the memcg_slab_caches and memcg_slab_mutex. Apart from this nice cleanup, it also: - assures that rcu_barrier() is called once at max when a root cache is destroyed or a memory cgroup is freed, no matter how many caches have SLAB_DESTROY_BY_RCU flag set; - fixes the race between kmem_cache_destroy and kmem_cache_create that exists, because memcg_cleanup_cache_params, which is called from kmem_cache_destroy after checking that kmem_cache->refcount=0, releases the slab_mutex, which gives kmem_cache_create a chance to make an alias to a cache doomed to be destroyed. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/slab.h')
-rw-r--r--include/linux/slab.h6
1 files changed, 2 insertions, 4 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h
index eca9ed303a1b..2e3b448cfa2d 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -116,8 +116,8 @@ struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
unsigned long,
void (*)(void *));
#ifdef CONFIG_MEMCG_KMEM
-struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *,
- struct kmem_cache *);
+void memcg_create_kmem_cache(struct mem_cgroup *, struct kmem_cache *);
+void memcg_destroy_kmem_caches(struct mem_cgroup *);
#endif
void kmem_cache_destroy(struct kmem_cache *);
int kmem_cache_shrink(struct kmem_cache *);
@@ -490,7 +490,6 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
* Child caches will hold extra metadata needed for its operation. Fields are:
*
* @memcg: pointer to the memcg this cache belongs to
- * @list: list_head for the list of all caches in this memcg
* @root_cache: pointer to the global, root cache, this cache was derived from
*/
struct memcg_cache_params {
@@ -502,7 +501,6 @@ struct memcg_cache_params {
};
struct {
struct mem_cgroup *memcg;
- struct list_head list;
struct kmem_cache *root_cache;
};
};