socket: initial cgroup code.

The goal of this work is to move the memory pressure tcp
controls to a cgroup, instead of just relying on global
conditions.

To avoid excessive overhead in the network fast paths,
the code that accounts allocated memory to a cgroup is
hidden inside a static_branch(). This branch is patched out
until the first non-root cgroup is created. So when nobody
is using cgroups, even if it is mounted, no significant performance
penalty should be seen.

This patch handles the generic part of the code, and has nothing
tcp-specific.

Signed-off-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtsu.com>
CC: Kirill A. Shutemov <kirill@shutemov.name>
CC: David S. Miller <davem@davemloft.net>
CC: Eric W. Biederman <ebiederm@xmission.com>
CC: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 44 insertions, 2 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9fbcff71245e..3de3901ae0a7 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -379,7 +379,48 @@ enum mem_type {
 
 static void mem_cgroup_get(struct mem_cgroup *memcg);
 static void mem_cgroup_put(struct mem_cgroup *memcg);
-static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg);
+
+/* Writing them here to avoid exposing memcg's inner layout */
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+#ifdef CONFIG_INET
+#include <net/sock.h>
+
+static bool mem_cgroup_is_root(struct mem_cgroup *memcg);
+void sock_update_memcg(struct sock *sk)
+{
+        /* A socket spends its whole life in the same cgroup */
+        if (sk->sk_cgrp) {
+                WARN_ON(1);
+                return;
+        }
+        if (static_branch(&memcg_socket_limit_enabled)) {
+                struct mem_cgroup *memcg;
+
+                BUG_ON(!sk->sk_prot->proto_cgroup);
+
+                rcu_read_lock();
+                memcg = mem_cgroup_from_task(current);
+                if (!mem_cgroup_is_root(memcg)) {
+                        mem_cgroup_get(memcg);
+                        sk->sk_cgrp = sk->sk_prot->proto_cgroup(memcg);
+                }
+                rcu_read_unlock();
+        }
+}
+EXPORT_SYMBOL(sock_update_memcg);
+
+void sock_release_memcg(struct sock *sk)
+{
+        if (static_branch(&memcg_socket_limit_enabled) && sk->sk_cgrp) {
+                struct mem_cgroup *memcg;
+                WARN_ON(!sk->sk_cgrp->memcg);
+                memcg = sk->sk_cgrp->memcg;
+                mem_cgroup_put(memcg);
+        }
+}
+#endif /* CONFIG_INET */
+#endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
+
 static void drain_all_stock_async(struct mem_cgroup *memcg);
 
 static struct mem_cgroup_per_zone *
@@ -4932,12 +4973,13 @@ static void mem_cgroup_put(struct mem_cgroup *memcg)
 /*
  * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
  */
-static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
+struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
 {
         if (!memcg->res.parent)
                 return NULL;
         return mem_cgroup_from_res_counter(memcg->res.parent, res);
 }
+EXPORT_SYMBOL(parent_mem_cgroup);
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 static void __init enable_swap_cgroup(void)