From f3f511e1ce6f1a6f0a5bb8320e9f802e76f6b999 Mon Sep 17 00:00:00 2001 From: Glauber Costa Date: Thu, 5 Jan 2012 20:16:39 +0000 Subject: [PATCH] net: fix sock_clone reference mismatch with tcp memcontrol Sockets can also be created through sock_clone. Because it copies all data in the sock structure, it also copies the memcg-related pointer, and all should be fine. However, since we now use reference counts in socket creation, we are left with some sockets that have no reference counts. It matters when we destroy them, since it leads to a mismatch. Signed-off-by: Glauber Costa CC: David S. Miller CC: Greg Thelen CC: Hiroyouki Kamezawa CC: Laurent Chavey Signed-off-by: David S. Miller --- include/net/sock.h | 6 ++++++ mm/memcontrol.c | 19 ++++++++++++++----- net/core/sock.c | 2 ++ 3 files changed, 22 insertions(+), 5 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index bb972d254dff..0ed65e3a0bea 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1103,6 +1103,12 @@ sk_sockets_allocated_read_positive(struct sock *sk) return percpu_counter_sum_positive(prot->sockets_allocated); } +static inline void sk_update_clone(const struct sock *sk, struct sock *newsk) +{ + if (mem_cgroup_sockets_enabled && sk->sk_cgrp) + sock_update_memcg(newsk); +} + static inline int proto_sockets_allocated_sum_positive(struct proto *prot) { 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)) { diff --git a/net/core/sock.c b/net/core/sock.c index 002939cfc069..e80b64fbd663 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1362,6 +1362,8 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority) sk_set_socket(newsk, NULL); newsk->sk_wq = NULL; + sk_update_clone(sk, newsk); + if (newsk->sk_prot->sockets_allocated) sk_sockets_allocated_inc(newsk);