[PATCH 3/3] mm: memcontrol: consolidate cgroup socket tracking

[Johannes Weiner]

The cgroup core and the memory controller need to track socket
ownership for different purposes, but the tracking sites being
entirely different is kind of ugly.

Be a better citizen and rename the memory controller callbacks to
match the cgroup core callbacks, then move them to the same place.

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
 include/linux/memcontrol.h |  4 ++--
 mm/memcontrol.c            | 19 +++++++++++--------
 net/core/sock.c            |  6 +++---
 net/ipv4/tcp.c             |  2 --
 net/ipv4/tcp_ipv4.c        |  3 ---
 5 files changed, 16 insertions(+), 18 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 0710143723bc..ca11b3e6dd65 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -773,8 +773,8 @@ static inline void mem_cgroup_wb_stats(struct bdi_writeback *wb,
 #endif	/* CONFIG_CGROUP_WRITEBACK */
 
 struct sock;
-void sock_update_memcg(struct sock *sk);
-void sock_release_memcg(struct sock *sk);
+void mem_cgroup_sk_alloc(struct sock *sk);
+void mem_cgroup_sk_free(struct sock *sk);
 bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages);
 void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages);
 #ifdef CONFIG_MEMCG
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 60bb830abc34..2caf1ee86e78 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2939,7 +2939,7 @@ static int memcg_update_tcp_limit(struct mem_cgroup *memcg, unsigned long limit)
 		/*
 		 * The active flag needs to be written after the static_key
 		 * update. This is what guarantees that the socket activation
-		 * function is the last one to run. See sock_update_memcg() for
+		 * function is the last one to run. See mem_cgroup_sk_alloc() for
 		 * details, and note that we don't mark any socket as belonging
 		 * to this memcg until that flag is up.
 		 *
@@ -2948,7 +2948,7 @@ static int memcg_update_tcp_limit(struct mem_cgroup *memcg, unsigned long limit)
 		 * as accounted, but the accounting functions are not patched in
 		 * yet, we'll lose accounting.
 		 *
-		 * We never race with the readers in sock_update_memcg(),
+		 * We never race with the readers in mem_cgroup_sk_alloc(),
 		 * because when this value change, the code to process it is not
 		 * patched in yet.
 		 */
@@ -5651,11 +5651,15 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
 DEFINE_STATIC_KEY_FALSE(memcg_sockets_enabled_key);
 EXPORT_SYMBOL(memcg_sockets_enabled_key);
 
-void sock_update_memcg(struct sock *sk)
+void mem_cgroup_sk_alloc(struct sock *sk)
 {
 	struct mem_cgroup *memcg;
 
-	/* Socket cloning can throw us here with sk_cgrp already
+	if (!mem_cgroup_sockets_enabled)
+		return;
+
+	/*
+	 * Socket cloning can throw us here with sk_memcg already
 	 * filled. It won't however, necessarily happen from
 	 * process context. So the test for root memcg given
 	 * the current task's memcg won't help us in this case.
@@ -5680,12 +5684,11 @@ void sock_update_memcg(struct sock *sk)
 out:
 	rcu_read_unlock();
 }
-EXPORT_SYMBOL(sock_update_memcg);
 
-void sock_release_memcg(struct sock *sk)
+void mem_cgroup_sk_free(struct sock *sk)
 {
-	WARN_ON(!sk->sk_memcg);
-	css_put(&sk->sk_memcg->css);
+	if (sk->sk_memcg)
+		css_put(&sk->sk_memcg->css);
 }
 
 /**
diff --git a/net/core/sock.c b/net/core/sock.c
index 038e660ef844..c73e28fc9c2a 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1363,6 +1363,7 @@ static void sk_prot_free(struct proto *prot, struct sock *sk)
 	slab = prot->slab;
 
 	cgroup_sk_free(&sk->sk_cgrp_data);
+	mem_cgroup_sk_free(sk);
 	security_sk_free(sk);
 	if (slab != NULL)
 		kmem_cache_free(slab, sk);
@@ -1399,6 +1400,7 @@ struct sock *sk_alloc(struct net *net, int family, gfp_t priority,
 		sock_net_set(sk, net);
 		atomic_set(&sk->sk_wmem_alloc, 1);
 
+		mem_cgroup_sk_alloc(sk);
 		cgroup_sk_alloc(&sk->sk_cgrp_data);
 		sock_update_classid(&sk->sk_cgrp_data);
 		sock_update_netprioidx(&sk->sk_cgrp_data);
@@ -1545,6 +1547,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
 		newsk->sk_incoming_cpu = raw_smp_processor_id();
 		atomic64_set(&newsk->sk_cookie, 0);
 
+		mem_cgroup_sk_alloc(newsk);
 		cgroup_sk_alloc(&newsk->sk_cgrp_data);
 
 		/*
@@ -1569,9 +1572,6 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
 		sk_set_socket(newsk, NULL);
 		newsk->sk_wq = NULL;
 
-		if (mem_cgroup_sockets_enabled && sk->sk_memcg)
-			sock_update_memcg(newsk);
-
 		if (newsk->sk_prot->sockets_allocated)
 			sk_sockets_allocated_inc(newsk);
 
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index a13fcb369f52..fc76ef51a5f4 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -421,8 +421,6 @@ void tcp_init_sock(struct sock *sk)
 	sk->sk_rcvbuf = sysctl_tcp_rmem[1];
 
 	local_bh_disable();
-	if (mem_cgroup_sockets_enabled)
-		sock_update_memcg(sk);
 	sk_sockets_allocated_inc(sk);
 	local_bh_enable();
 }
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 04b989328558..b8fc74a66299 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1872,9 +1872,6 @@ void tcp_v4_destroy_sock(struct sock *sk)
 	local_bh_disable();
 	sk_sockets_allocated_dec(sk);
 	local_bh_enable();
-
-	if (mem_cgroup_sockets_enabled && sk->sk_memcg)
-		sock_release_memcg(sk);
 }
 EXPORT_SYMBOL(tcp_v4_destroy_sock);
 
-- 
2.9.3