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| author | Vladimir Davydov | 2014-04-08 00:39:27 +0200 |
|---|---|---|
| committer | Linus Torvalds | 2014-04-08 01:36:12 +0200 |
| commit | 051dd46050f2a9bdfff8cc067f8987069eae1743 (patch) | |
| tree | 64ccd763fcdda9a1087063f154f0d96fc6ab573a /mm/memcontrol.c | |
| parent | memcg, slab: separate memcg vs root cache creation paths (diff) | |
| download | kernel-qcow2-linux-051dd46050f2a9bdfff8cc067f8987069eae1743.tar.gz kernel-qcow2-linux-051dd46050f2a9bdfff8cc067f8987069eae1743.tar.xz kernel-qcow2-linux-051dd46050f2a9bdfff8cc067f8987069eae1743.zip | |
memcg, slab: unregister cache from memcg before starting to destroy it
Currently, memcg_unregister_cache(), which deletes the cache being
destroyed from the memcg_slab_caches list, is called after
__kmem_cache_shutdown() (see kmem_cache_destroy()), which starts to
destroy the cache.
As a result, one can access a partially destroyed cache while traversing
a memcg_slab_caches list, which can have deadly consequences (for
instance, cache_show() called for each cache on a memcg_slab_caches list
from mem_cgroup_slabinfo_read() will dereference pointers to already
freed data).
To fix this, let's move memcg_unregister_cache() before the cache
destruction process beginning, issuing memcg_register_cache() on failure.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Glauber Costa <glommer@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 451523c3bd4e..c22d8bf42d9a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3140,6 +3140,7 @@ int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s, s->memcg_params->root_cache = root_cache; INIT_WORK(&s->memcg_params->destroy, kmem_cache_destroy_work_func); + css_get(&memcg->css); } else s->memcg_params->is_root_cache = true; @@ -3148,6 +3149,10 @@ int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s, void memcg_free_cache_params(struct kmem_cache *s) { + if (!s->memcg_params) + return; + if (!s->memcg_params->is_root_cache) + css_put(&s->memcg_params->memcg->css); kfree(s->memcg_params); } @@ -3170,9 +3175,6 @@ void memcg_register_cache(struct kmem_cache *s) memcg = s->memcg_params->memcg; id = memcg_cache_id(memcg); - css_get(&memcg->css); - - /* * Since readers won't lock (see cache_from_memcg_idx()), we need a * barrier here to ensure nobody will see the kmem_cache partially @@ -3221,10 +3223,8 @@ void memcg_unregister_cache(struct kmem_cache *s) * after removing it from the memcg_slab_caches list, otherwise we can * fail to convert memcg_params_to_cache() while traversing the list. */ - VM_BUG_ON(!root->memcg_params->memcg_caches[id]); + VM_BUG_ON(root->memcg_params->memcg_caches[id] != s); root->memcg_params->memcg_caches[id] = NULL; - - css_put(&memcg->css); } /* |