FAILED: patch "[PATCH] mptcp: fix missing wakeups in edge scenarios" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 9d8d28738f24b75616d6ca7a27cb4aed88520343
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026061539-dreadlock-pacifier-9f96@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9d8d28738f24b75616d6ca7a27cb4aed88520343 Mon Sep 17 00:00:00 2001
From: Paolo Abeni <[email protected]>
Date: Tue, 2 Jun 2026 22:14:08 +1000
Subject: [PATCH] mptcp: fix missing wakeups in edge scenarios

The mptcp_recvmsg() can fill MPTCP socket receive queue via mptcp_move_skbs(), but currently does not try to wakeup any listener, because the same process is going to check the receive queue soon.

When multiple threads are reading from the same fd, the above can cause stall. Add the missing wakeup.

index a72a6ad6ee8b..5a20ab2789ae 100644
@@ -2276,6 +2276,10 @@ static bool mptcp_move_skbs(struct sock *sk)
 		mptcp_backlog_spooled(sk, moved, &skbs);
 	}
 	mptcp_data_unlock(sk);
+
+	if (enqueued && mptcp_epollin_ready(sk))
+		sk->sk_data_ready(sk);
+
 	return enqueued;
 }
 

From: Paolo Abeni <[email protected]>

[ Upstream commit 9d8d28738f24b75616d6ca7a27cb4aed88520343 ]

The mptcp_recvmsg() can fill MPTCP socket receive queue via mptcp_move_skbs(), but currently does not try to wakeup any listener, because the same process is going to check the receive queue soon.

When multiple threads are reading from the same fd, the above can cause stall. Add the missing wakeup.

---
 net/mptcp/protocol.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

index ff1632d03a96d1..cbaf794e876301 100644
@@ -2187,7 +2187,11 @@ static bool __mptcp_move_skbs(struct mptcp_sock *msk)
 	}
 	if (ret)
 		mptcp_check_data_fin((struct sock *)msk);
-	return !skb_queue_empty(&msk->receive_queue);
+
+	ret = !skb_queue_empty(&msk->receive_queue);
+	if (ret && mptcp_epollin_ready(sk))
+		sk->sk_data_ready(sk);
+	return ret;
 }
 
 static unsigned int mptcp_inq_hint(const struct sock *sk)

2.53.0