mm/slub: Fix sysfs circular locking dependency

v2:
- Use regular cmpxchg() instead of x86-only try_cmpxchg() in patch 2.
- Add patches 3 and 4 to fix circular locking dependency showing up at shutdown time.

With lockdep enabled, issuing the following command to the slub sysfs files will cause splat about circular locking dependency to show up either immediately afterwards or at shutdown time.

 # echo 1 > validate
 # echo 1 > shrink

This patchset fixes these lockdep splats by replacing slab_mutex with memcg_cache_ids_sem as well as changing some of the lock operations with trylock.

Waiman Long (4):
mm, slab: Revert "extend slab/shrink to shrink all memcg caches" mm/slub: Fix slab_mutex circular locking problem in slab_attr_store() mm/slub: Fix another circular locking dependency in slab_attr_store() mm/slub: Fix sysfs shrink circular locking dependency

 include/linux/memcontrol.h     |  1 +
 include/linux/memory_hotplug.h |  2 +
 mm/memcontrol.c                |  5 ++
 mm/memory_hotplug.c            |  5 ++
 mm/slab.h                      |  1 -
 mm/slab_common.c               | 37 -------------
 mm/slub.c                      | 98 +++++++++++++++++++++++++++++-----
 7 files changed, 99 insertions(+), 50 deletions(-)

2.18.1