1 files changed, 14 insertions, 5 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 94da8ee9e2c2..9c72d5d5372a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -381,16 +381,25 @@ static void mem_cgroup_put(struct mem_cgroup *memcg);
 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);
 
+                /* Socket cloning can throw us here with sk_cgrp 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.
+                 *
+                 * Respecting the original socket's memcg is a better
+                 * decision in this case.
+                 */
+                if (sk->sk_cgrp) {
+                        BUG_ON(mem_cgroup_is_root(sk->sk_cgrp->memcg));
+                        mem_cgroup_get(sk->sk_cgrp->memcg);
+                        return;
+                }
+
                 rcu_read_lock();
                 memcg = mem_cgroup_from_task(current);
                 if (!mem_cgroup_is_root(memcg)) {