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Code Activity

mptcp: fix spurious wake-up on under memory pressure

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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: 5684ab1a0e ("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-v1-2-0d986ee7b1b6@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Paolo Abeni 2025-01-13 16:44:57 +01:00 committed by Jakub Kicinski
parent 2ca06a2f65
commit e226d9259d
1 changed files with 7 additions and 2 deletions
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9
net/mptcp/protocol.h
View file

@ -760,10 +760,15 @@ static inline u64 mptcp_data_avail(const struct mptcp_sock *msk)
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);