The delayed work/rcu deactivation infrastructure of non-root kmem_caches
can be also used for asynchronous release of these objects.  Let's get rid
of the word "deactivation" in corresponding names to make the code look
better after generalization.

It's easier to make the renaming first, so that the generalized code will
look consistent from scratch.

Let's rename struct memcg_cache_params fields:
  deact_fn -> work_fn
  deact_rcu_head -> rcu_head
  deact_work -> work

And RCU/delayed work callbacks in slab common code:
  kmemcg_deactivate_rcufn -> kmemcg_rcufn
  kmemcg_deactivate_workfn -> kmemcg_workfn

This patch contains no functional changes, only renamings.

Link: http://lkml.kernel.org/r/20190611231813.3148843-3-guro@fb.comSigned-off-by: NRoman Gushchin <guro@fb.com>
Acked-by: NVladimir Davydov <vdavydov.dev@gmail.com>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>