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author | Muchun Song <songmuchun@bytedance.com> | 2020-07-24 07:15:27 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-07-24 22:42:41 +0300 |
commit | d38a2b7a9c939e6d7329ab92b96559ccebf7b135 (patch) | |
tree | 160c2e50d11e032e35e531b4a3ba15a8d21b6583 /.mailmap | |
parent | 8d22a9351035ef2ff12ef163a1091b8b8cf1e49c (diff) | |
download | linux-d38a2b7a9c939e6d7329ab92b96559ccebf7b135.tar.xz |
mm: memcg/slab: fix memory leak at non-root kmem_cache destroy
If the kmem_cache refcount is greater than one, we should not mark the
root kmem_cache as dying. If we mark the root kmem_cache dying
incorrectly, the non-root kmem_cache can never be destroyed. It
resulted in memory leak when memcg was destroyed. We can use the
following steps to reproduce.
1) Use kmem_cache_create() to create a new kmem_cache named A.
2) Coincidentally, the kmem_cache A is an alias for kmem_cache B,
so the refcount of B is just increased.
3) Use kmem_cache_destroy() to destroy the kmem_cache A, just
decrease the B's refcount but mark the B as dying.
4) Create a new memory cgroup and alloc memory from the kmem_cache
B. It leads to create a non-root kmem_cache for allocating memory.
5) When destroy the memory cgroup created in the step 4), the
non-root kmem_cache can never be destroyed.
If we repeat steps 4) and 5), this will cause a lot of memory leak. So
only when refcount reach zero, we mark the root kmem_cache as dying.
Fixes: 92ee383f6daa ("mm: fix race between kmem_cache destroy, create and deactivate")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
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: Shakeel Butt <shakeelb@google.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200716165103.83462-1-songmuchun@bytedance.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '.mailmap')
0 files changed, 0 insertions, 0 deletions