slab: introduce __kmemcg_cache_deactivate()

__kmem_cache_shrink() is called with %true @deactivate only for memcg
caches.  Remove @deactivate from __kmem_cache_shrink() and introduce
__kmemcg_cache_deactivate() instead.  Each memcg-supporting allocator
should implement it and it should deactivate and drain the cache.

This is to allow memcg cache deactivation behavior to further deviate
from simple shrinking without messing up __kmem_cache_shrink().

This is pure reorganization and doesn't introduce any observable
behavior changes.

v2: Dropped unnecessary ifdef in mm/slab.h as suggested by Vladimir.

Link: http://lkml.kernel.org/r/20170117235411.9408-8-tj@kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/mm/slab.c b/mm/slab.c
index 8a0e3392f181..bd63450a9b16 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2315,7 +2315,7 @@ out:
         return nr_freed;
 }
 
-int __kmem_cache_shrink(struct kmem_cache *cachep, bool deactivate)
+int __kmem_cache_shrink(struct kmem_cache *cachep)
 {
         int ret = 0;
         int node;
@@ -2333,9 +2333,16 @@ int __kmem_cache_shrink(struct kmem_cache *cachep, bool deactivate)
         return (ret ? 1 : 0);
 }
 
+#ifdef CONFIG_MEMCG
+void __kmemcg_cache_deactivate(struct kmem_cache *cachep)
+{
+        __kmem_cache_shrink(cachep);
+}
+#endif
+
 int __kmem_cache_shutdown(struct kmem_cache *cachep)
 {
-        return __kmem_cache_shrink(cachep, false);
+        return __kmem_cache_shrink(cachep);
 }
 
 void __kmem_cache_release(struct kmem_cache *cachep)