From f7161b234f2ec7f18999009c4becc04eeb6b12a7 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Fri, 15 Aug 2025 20:16:14 +0000 Subject: [PATCH] net-memcg: Introduce mem_cgroup_from_sk(). We will store a flag in the lowest bit of sk->sk_memcg. Then, directly dereferencing sk->sk_memcg will be illegal, and we do not want to allow touching the raw sk->sk_memcg in many places. Let's introduce mem_cgroup_from_sk(). Other places accessing the raw sk->sk_memcg will be converted later. Note that we cannot define the helper as an inline function in memcontrol.h as we cannot access any fields of struct sock there due to circular dependency, so it is placed in sock.h. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Acked-by: Roman Gushchin Acked-by: Shakeel Butt Link: https://patch.msgid.link/20250815201712.1745332-7-kuniyu@google.com Signed-off-by: Jakub Kicinski --- include/net/sock.h | 12 ++++++++++++ mm/memcontrol.c | 13 +++++++++---- net/ipv4/inet_connection_sock.c | 2 +- 3 files changed, 22 insertions(+), 5 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index c8a4b283df6fc..811f95ea8d00c 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2594,6 +2594,18 @@ static inline gfp_t gfp_memcg_charge(void) return in_softirq() ? GFP_ATOMIC : GFP_KERNEL; } +#ifdef CONFIG_MEMCG +static inline struct mem_cgroup *mem_cgroup_from_sk(const struct sock *sk) +{ + return sk->sk_memcg; +} +#else +static inline struct mem_cgroup *mem_cgroup_from_sk(const struct sock *sk) +{ + return NULL; +} +#endif + static inline long sock_rcvtimeo(const struct sock *sk, bool noblock) { return noblock ? 0 : READ_ONCE(sk->sk_rcvtimeo); diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 46713b9ece063..d8a52d1d08fa4 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5020,19 +5020,24 @@ out: void mem_cgroup_sk_free(struct sock *sk) { - if (sk->sk_memcg) - css_put(&sk->sk_memcg->css); + struct mem_cgroup *memcg = mem_cgroup_from_sk(sk); + + if (memcg) + css_put(&memcg->css); } void mem_cgroup_sk_inherit(const struct sock *sk, struct sock *newsk) { + struct mem_cgroup *memcg; + if (sk->sk_memcg == newsk->sk_memcg) return; mem_cgroup_sk_free(newsk); - if (sk->sk_memcg) - css_get(&sk->sk_memcg->css); + memcg = mem_cgroup_from_sk(sk); + if (memcg) + css_get(&memcg->css); newsk->sk_memcg = sk->sk_memcg; } diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 724bd9ed6cd48..93569bbe00f44 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -718,7 +718,7 @@ struct sock *inet_csk_accept(struct sock *sk, struct proto_accept_arg *arg) lock_sock(newsk); mem_cgroup_sk_alloc(newsk); - if (newsk->sk_memcg) { + if (mem_cgroup_from_sk(newsk)) { /* The socket has not been accepted yet, no need * to look at newsk->sk_wmem_queued. */ -- 2.51.0