Commit f1008365 authored Feb 12, 2015 by Vladimir Davydov Committed by Linus Torvalds Feb 12, 2015

slab: use css id for naming per memcg caches



Currently, we use mem_cgroup->kmemcg_id to guarantee kmem_cache->name
uniqueness.  This is correct, because kmemcg_id is only released on css
free after destroying all per memcg caches.

However, I am going to change that and release kmemcg_id on css offline,
because it is not wise to keep it for so long, wasting valuable entries of
memcg_cache_params->memcg_caches arrays.  Therefore, to preserve cache
name uniqueness, let us switch to css->id.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 01e58659

mm/slab_common.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -488,6 +488,7 @@ void memcg_create_kmem_cache(struct mem_cgroup *memcg,
		struct kmem_cache *root_cache)
		{
		static char memcg_name_buf[NAME_MAX + 1]; /* protected by slab_mutex */
		struct cgroup_subsys_state *css = mem_cgroup_css(memcg);
		struct memcg_cache_array *arr;
		struct kmem_cache *s = NULL;
		char *cache_name;
		@@ -510,10 +511,9 @@ void memcg_create_kmem_cache(struct mem_cgroup *memcg,
		if (arr->entries[idx])
		goto out_unlock;

		cgroup_name(mem_cgroup_css(memcg)->cgroup,
		memcg_name_buf, sizeof(memcg_name_buf));
		cgroup_name(css->cgroup, memcg_name_buf, sizeof(memcg_name_buf));
		cache_name = kasprintf(GFP_KERNEL, "%s(%d:%s)", root_cache->name,
		idx, memcg_name_buf);
		css->id, memcg_name_buf);
		if (!cache_name)
		goto out_unlock;