diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index af707ce0f624..09f24a456f73 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1516,8 +1516,16 @@ static void subflow_data_ready(struct sock *sk)
 		return;
 	}
 
-	WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
-		     !subflow->mp_join && !(state & TCPF_CLOSE));
+	if (!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
+	    !subflow->mp_join && !(state & TCPF_CLOSE)) {
+		spin_lock_bh(&msk->fallback_lock);
+		pr_err("fallaback under lock %d req mpc %d req mpj %d state %d parent state %d send %lld received %lld\n",
+			__mptcp_check_fallback(msk), subflow->request_mptcp,
+			subflow->request_join, state, parent->sk_state,
+			msk->bytes_sent, msk->bytes_received);
+		spin_unlock_bh(&msk->fallback_lock);
+		WARN_ON(1);
+	}
 
 	if (mptcp_subflow_data_available(sk)) {
 		mptcp_data_ready(parent, sk);