diff options
authorGreg Thelen <>2016-11-10 10:46:41 -0800
committerLinus Torvalds <>2016-11-11 08:12:37 -0800
commitf773e36de3d77c4000ca914c9d146f55f2fd51e8 (patch)
parent70d78fe7c8b640b5acfad56ad341985b3810998a (diff)
memcg: prevent memcg caches to be both OFF_SLAB & OBJFREELIST_SLAB
While testing OBJFREELIST_SLAB integration with pagealloc, we found a bug where kmem_cache(sys) would be created with both CFLGS_OFF_SLAB & CFLGS_OBJFREELIST_SLAB. When it happened, critical allocations needed for loading drivers or creating new caches will fail. The original kmem_cache is created early making OFF_SLAB not possible. When kmem_cache(sys) is created, OFF_SLAB is possible and if pagealloc is enabled it will try to enable it first under certain conditions. Given kmem_cache(sys) reuses the original flag, you can have both flags at the same time resulting in allocation failures and odd behaviors. This fix discards allocator specific flags from memcg before calling create_cache. The bug exists since 4.6-rc1 and affects testing debug pagealloc configurations. Fixes: b03a017bebc4 ("mm/slab: introduce new slab management type, OBJFREELIST_SLAB") Link: Signed-off-by: Greg Thelen <> Signed-off-by: Thomas Garnier <> Tested-by: Thomas Garnier <> Acked-by: Christoph Lameter <> Cc: Pekka Enberg <> Cc: David Rientjes <> Cc: Joonsoo Kim <> Cc: Vladimir Davydov <> Cc: Michal Hocko <> Cc: Johannes Weiner <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 71f0b28a1bec..329b03843863 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -533,8 +533,8 @@ void memcg_create_kmem_cache(struct mem_cgroup *memcg,
s = create_cache(cache_name, root_cache->object_size,
root_cache->size, root_cache->align,
- root_cache->flags, root_cache->ctor,
- memcg, root_cache);
+ root_cache->flags & CACHE_CREATE_MASK,
+ root_cache->ctor, memcg, root_cache);
* If we could not create a memcg cache, do not complain, because
* that's not critical at all as we can always proceed with the root