memcg, slab: merge memcg_{bind,release}_pages to memcg_{un}charge_slab

Currently we have two pairs of kmemcg-related functions that are called on
slab alloc/free.  The first is memcg_{bind,release}_pages that count the
total number of pages allocated on a kmem cache.  The second is
memcg_{un}charge_slab that {un}charge slab pages to kmemcg resource
counter.  Let's just merge them to keep the code clean.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/slab.h b/mm/slab.h
index b59447a..961a3fb 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -121,18 +121,6 @@
 	return !s->memcg_params || s->memcg_params->is_root_cache;
 }
 
-static inline void memcg_bind_pages(struct kmem_cache *s, int order)
-{
-	if (!is_root_cache(s))
-		atomic_add(1 << order, &s->memcg_params->nr_pages);
-}
-
-static inline void memcg_release_pages(struct kmem_cache *s, int order)
-{
-	if (!is_root_cache(s))
-		atomic_sub(1 << order, &s->memcg_params->nr_pages);
-}
-
 static inline bool slab_equal_or_root(struct kmem_cache *s,
 					struct kmem_cache *p)
 {
@@ -198,8 +186,7 @@
 		return 0;
 	if (is_root_cache(s))
 		return 0;
-	return memcg_charge_kmem(s->memcg_params->memcg, gfp,
-				 PAGE_SIZE << order);
+	return __memcg_charge_slab(s, gfp, order);
 }
 
 static __always_inline void memcg_uncharge_slab(struct kmem_cache *s, int order)
@@ -208,7 +195,7 @@
 		return;
 	if (is_root_cache(s))
 		return;
-	memcg_uncharge_kmem(s->memcg_params->memcg, PAGE_SIZE << order);
+	__memcg_uncharge_slab(s, order);
 }
 #else
 static inline bool is_root_cache(struct kmem_cache *s)
@@ -216,14 +203,6 @@
 	return true;
 }
 
-static inline void memcg_bind_pages(struct kmem_cache *s, int order)
-{
-}
-
-static inline void memcg_release_pages(struct kmem_cache *s, int order)
-{
-}
-
 static inline bool slab_equal_or_root(struct kmem_cache *s,
 				      struct kmem_cache *p)
 {