From 68c7c386714512219e3517ec1097d164aee102fb Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Fri, 21 Nov 2025 18:02:03 +0100 Subject: [PATCH] mptcp: fix memcg accounting for passive sockets The passive sockets never got proper memcg accounting: the msk socket is associated with the memcg at accept time, but the passive subflows never got it right. At accept time, traverse the subflows list and associate each of them with the msk memcg, and try to do the same at join completion time, if the msk has been already accepted. Fixes: cf7da0d66cc1 ("mptcp: Create SUBFLOW socket for incoming connections") Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/298 Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/597 Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20251121-net-next-mptcp-memcg-backlog-imp-v1-4-1f34b6c1e0b1@kernel.org Signed-off-by: Jakub Kicinski --- net/mptcp/protocol.c | 38 +++++++++++++++++++++++++++----------- net/mptcp/protocol.h | 1 + net/mptcp/subflow.c | 10 ++++++++++ 3 files changed, 38 insertions(+), 11 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 2104ab1eda1df..67732d3c502c0 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3651,8 +3651,11 @@ static void mptcp_sock_check_graft(struct sock *sk, struct sock *ssk) write_lock_bh(&sk->sk_callback_lock); sock = sk->sk_socket; write_unlock_bh(&sk->sk_callback_lock); - if (sock) + if (sock) { mptcp_sock_graft(ssk, sock); + __mptcp_inherit_cgrp_data(sk, ssk); + __mptcp_inherit_memcg(sk, ssk, GFP_ATOMIC); + } } bool mptcp_finish_join(struct sock *ssk) @@ -3970,6 +3973,28 @@ unlock: return err; } +static void mptcp_graft_subflows(struct sock *sk) +{ + struct mptcp_subflow_context *subflow; + struct mptcp_sock *msk = mptcp_sk(sk); + + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk = mptcp_subflow_tcp_sock(subflow); + + lock_sock(ssk); + + /* Set ssk->sk_socket of accept()ed flows to mptcp socket. + * This is needed so NOSPACE flag can be set from tcp stack. + */ + if (!ssk->sk_socket) + mptcp_sock_graft(ssk, sk->sk_socket); + + __mptcp_inherit_cgrp_data(sk, ssk); + __mptcp_inherit_memcg(sk, ssk, GFP_KERNEL); + release_sock(ssk); + } +} + static int mptcp_stream_accept(struct socket *sock, struct socket *newsock, struct proto_accept_arg *arg) { @@ -4017,16 +4042,7 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock, msk = mptcp_sk(newsk); msk->in_accept_queue = 0; - /* set ssk->sk_socket of accept()ed flows to mptcp socket. - * This is needed so NOSPACE flag can be set from tcp stack. - */ - mptcp_for_each_subflow(msk, subflow) { - struct sock *ssk = mptcp_subflow_tcp_sock(subflow); - - if (!ssk->sk_socket) - mptcp_sock_graft(ssk, newsock); - } - + mptcp_graft_subflows(newsk); mptcp_rps_record_subflows(msk); /* Do late cleanup for the first subflow as necessary. Also diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 6d9de13c1f9cd..8c27f4b1789fe 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -707,6 +707,7 @@ mptcp_subflow_delegated_next(struct mptcp_delegated_action *delegated) return ret; } +void __mptcp_inherit_memcg(struct sock *sk, struct sock *ssk, gfp_t gfp); void __mptcp_inherit_cgrp_data(struct sock *sk, struct sock *ssk); int mptcp_is_enabled(const struct net *net); diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index d98d151392d2d..72b7efe388db9 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1712,6 +1712,16 @@ err_out: return err; } +void __mptcp_inherit_memcg(struct sock *sk, struct sock *ssk, gfp_t gfp) +{ + /* Only if the msk has been accepted already (and not orphaned).*/ + if (!mem_cgroup_sockets_enabled || !sk->sk_socket) + return; + + mem_cgroup_sk_inherit(sk, ssk); + __sk_charge(ssk, gfp); +} + void __mptcp_inherit_cgrp_data(struct sock *sk, struct sock *ssk) { #ifdef CONFIG_SOCK_CGROUP_DATA -- 2.47.3