mm: memcontrol: remove unused mod_memcg_obj_state()

Since commit 991e767 ("mm: memcontrol: account kernel stack per
node") there is no user of the mod_memcg_obj_state().  So just remove
it.

Also rework type of the idx parameter of the mod_objcg_state() from int
to enum node_stat_item.

Link: https://lkml.kernel.org/r/20201013153504.92602-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Chris Down <chris@chrisdown.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/memcontrol.h

@@ -798,8 +798,6 @@ void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
 			int val);
 void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val);
 
-void mod_memcg_obj_state(void *p, int idx, int val);
-
 static inline void mod_lruvec_slab_state(void *p, enum node_stat_item idx,
 					 int val)
 {
@@ -1255,10 +1253,6 @@ static inline void mod_lruvec_slab_state(void *p, enum node_stat_item idx,
 	mod_node_page_state(page_pgdat(page), idx, val);
 }
 
-static inline void mod_memcg_obj_state(void *p, int idx, int val)
-{
-}
-
 static inline
 unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
 					    gfp_t gfp_mask,

mm/memcontrol.c

@@ -882,17 +882,6 @@ void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val)
 	rcu_read_unlock();
 }
 
-void mod_memcg_obj_state(void *p, int idx, int val)
-{
-	struct mem_cgroup *memcg;
-
-	rcu_read_lock();
-	memcg = mem_cgroup_from_obj(p);
-	if (memcg)
-		mod_memcg_state(memcg, idx, val);
-	rcu_read_unlock();
-}
-
 /**
  * __count_memcg_events - account VM events in a cgroup
  * @memcg: the memory cgroup

mm/slab.h

@@ -204,7 +204,7 @@ ssize_t slabinfo_write(struct file *file, const char __user *buffer,
 void __kmem_cache_free_bulk(struct kmem_cache *, size_t, void **);
 int __kmem_cache_alloc_bulk(struct kmem_cache *, gfp_t, size_t, void **);
 
-static inline int cache_vmstat_idx(struct kmem_cache *s)
+static inline enum node_stat_item cache_vmstat_idx(struct kmem_cache *s)
 {
 	return (s->flags & SLAB_RECLAIM_ACCOUNT) ?
 		NR_SLAB_RECLAIMABLE_B : NR_SLAB_UNRECLAIMABLE_B;
@@ -304,7 +304,7 @@ static inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s,
 
 static inline void mod_objcg_state(struct obj_cgroup *objcg,
 				   struct pglist_data *pgdat,
-				   int idx, int nr)
+				   enum node_stat_item idx, int nr)
 {
 	struct mem_cgroup *memcg;
 	struct lruvec *lruvec;