memcg: prevent memcg caches to be both OFF_SLAB & OBJFREELIST_SLAB
authorGreg Thelen <gthelen@google.com>
Thu, 10 Nov 2016 18:46:41 +0000 (10:46 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 11 Nov 2016 16:12:37 +0000 (08:12 -0800)
commitf773e36de3d77c4000ca914c9d146f55f2fd51e8
tree978203b466246cc405c1249f18fcde4340e51810
parent70d78fe7c8b640b5acfad56ad341985b3810998a
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: http://lkml.kernel.org/r/1478553075-120242-1-git-send-email-thgarnie@google.com
Signed-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Thomas Garnier <thgarnie@google.com>
Tested-by: Thomas Garnier <thgarnie@google.com>
Acked-by: 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: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/slab_common.c