6.6-stable review patch. If anyone has any objections, please let me know.
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From: Paolo Abeni pabeni@redhat.com
commit e226d9259dc4f5d2c19e6682ad1356fa97cf38f4 upstream.
The wake-up condition currently implemented by mptcp_epollin_ready() is wrong, as it could mark the MPTCP socket as readable even when no data are present and the system is under memory pressure.
Explicitly check for some data being available in the receive queue.
Fixes: 5684ab1a0eff ("mptcp: give rcvlowat some love") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://patch.msgid.link/20250113-net-mptcp-connect-st-flakes-v1-2-0d986ee7b... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mptcp/protocol.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
--- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -685,10 +685,15 @@ static inline u64 mptcp_data_avail(const
static inline bool mptcp_epollin_ready(const struct sock *sk) { + u64 data_avail = mptcp_data_avail(mptcp_sk(sk)); + + if (!data_avail) + return false; + /* mptcp doesn't have to deal with small skbs in the receive queue, - * at it can always coalesce them + * as it can always coalesce them */ - return (mptcp_data_avail(mptcp_sk(sk)) >= sk->sk_rcvlowat) || + return (data_avail >= sk->sk_rcvlowat) || (mem_cgroup_sockets_enabled && sk->sk_memcg && mem_cgroup_under_socket_pressure(sk->sk_memcg)) || READ_ONCE(tcp_memory_pressure);