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| author | Vladimir Davydov <vdavydov@parallels.com> | 2014-01-23 15:53:06 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-23 16:36:51 -0800 |
| commit | f8570263ee16eb1d5038b8e20d7db3a68bbb2b49 (patch) | |
| tree | 06d54d7f5f357622604d1e8338478b906729409d /include | |
| parent | f717eb3abb5ea38f60e671dbfdbf512c2c93d22e (diff) | |
| download | linux-f8570263ee16eb1d5038b8e20d7db3a68bbb2b49.tar.bz2 | |
memcg, slab: RCU protect memcg_params for root caches
We relocate root cache's memcg_params whenever we need to grow the
memcg_caches array to accommodate all kmem-active memory cgroups.
Currently on relocation we free the old version immediately, which can
lead to use-after-free, because the memcg_caches array is accessed
lock-free (see cache_from_memcg_idx()). This patch fixes this by making
memcg_params RCU-protected for root caches.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: 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')
| -rw-r--r-- | include/linux/slab.h | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h index 1e2f4fe12773..a060142aa5f5 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -513,7 +513,9 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node) * * Both the root cache and the child caches will have it. For the root cache, * this will hold a dynamically allocated array large enough to hold - * information about the currently limited memcgs in the system. + * information about the currently limited memcgs in the system. To allow the + * array to be accessed without taking any locks, on relocation we free the old + * version only after a grace period. * * Child caches will hold extra metadata needed for its operation. Fields are: * @@ -528,7 +530,10 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node) struct memcg_cache_params { bool is_root_cache; union { - struct kmem_cache *memcg_caches[0]; + struct { + struct rcu_head rcu_head; + struct kmem_cache *memcg_caches[0]; + }; struct { struct mem_cgroup *memcg; struct list_head list; |