memcg: cleanup static keys decrement

Move memcg_socket_limit_enabled decrement to tcp_destroy_cgroup (called
from memcg_destroy_kmem -> mem_cgroup_sockets_destroy) and zap a bunch of
wrapper functions.

Although this patch moves static keys decrement from __mem_cgroup_free to
mem_cgroup_css_free, it does not introduce any functional changes, because
the keys are incremented on setting the limit (tcp or kmem), which can
only happen after successful mem_cgroup_css_online.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/net/sock.h

@@ -1077,11 +1077,6 @@ static inline bool memcg_proto_active(struct cg_proto *cg_proto)
 	return test_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags);
 }
 
-static inline bool memcg_proto_activated(struct cg_proto *cg_proto)
-{
-	return test_bit(MEMCG_SOCK_ACTIVATED, &cg_proto->flags);
-}
-
 #ifdef SOCK_REFCNT_DEBUG
 static inline void sk_refcnt_debug_inc(struct sock *sk)
 {

mm/memcontrol.c

@@ -519,16 +519,6 @@ struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg)
 }
 EXPORT_SYMBOL(tcp_proto_cgroup);
 
-static void disarm_sock_keys(struct mem_cgroup *memcg)
-{
-	if (!memcg_proto_activated(&memcg->tcp_mem))
-		return;
-	static_key_slow_dec(&memcg_socket_limit_enabled);
-}
-#else
-static void disarm_sock_keys(struct mem_cgroup *memcg)
-{
-}
 #endif
 
 #ifdef CONFIG_MEMCG_KMEM
@@ -583,28 +573,8 @@ void memcg_put_cache_ids(void)
 struct static_key memcg_kmem_enabled_key;
 EXPORT_SYMBOL(memcg_kmem_enabled_key);
 
-static void disarm_kmem_keys(struct mem_cgroup *memcg)
-{
-	if (memcg->kmem_acct_activated)
-		static_key_slow_dec(&memcg_kmem_enabled_key);
-	/*
-	 * This check can't live in kmem destruction function,
-	 * since the charges will outlive the cgroup
-	 */
-	WARN_ON(page_counter_read(&memcg->kmem));
-}
-#else
-static void disarm_kmem_keys(struct mem_cgroup *memcg)
-{
-}
 #endif /* CONFIG_MEMCG_KMEM */
 
-static void disarm_static_keys(struct mem_cgroup *memcg)
-{
-	disarm_sock_keys(memcg);
-	disarm_kmem_keys(memcg);
-}
-
 static struct mem_cgroup_per_zone *
 mem_cgroup_zone_zoneinfo(struct mem_cgroup *memcg, struct zone *zone)
 {
@@ -4092,7 +4062,11 @@ static void memcg_deactivate_kmem(struct mem_cgroup *memcg)
 
 static void memcg_destroy_kmem(struct mem_cgroup *memcg)
 {
-	memcg_destroy_kmem_caches(memcg);
+	if (memcg->kmem_acct_activated) {
+		memcg_destroy_kmem_caches(memcg);
+		static_key_slow_dec(&memcg_kmem_enabled_key);
+		WARN_ON(page_counter_read(&memcg->kmem));
+	}
 	mem_cgroup_sockets_destroy(memcg);
 }
 #else
@@ -4523,8 +4497,6 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg)
 		free_mem_cgroup_per_zone_info(memcg, node);
 
 	free_percpu(memcg->stat);
-
-	disarm_static_keys(memcg);
 	kfree(memcg);
 }
 

net/ipv4/tcp_memcontrol.c

@@ -47,6 +47,10 @@ void tcp_destroy_cgroup(struct mem_cgroup *memcg)
 		return;
 
 	percpu_counter_destroy(&cg_proto->sockets_allocated);
+
+	if (test_bit(MEMCG_SOCK_ACTIVATED, &cg_proto->flags))
+		static_key_slow_dec(&memcg_socket_limit_enabled);
+
 }
 EXPORT_SYMBOL(tcp_destroy_cgroup);