diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 0e7c5471010bda14c7a17f096036cdf425b63fc3..5288fba56e553fdd858c636e98e117f85d8d3a44 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -68,6 +68,8 @@ static inline bool rsk_is_mptcp(const struct request_sock *req)
 	return tcp_rsk(req)->is_mptcp;
 }
 
+void mptcp_space(const struct sock *ssk, int *space, int *full_space);
+
 void mptcp_parse_option(const struct sk_buff *skb, const unsigned char *ptr,
 			int opsize, struct tcp_options_received *opt_rx);
 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
@@ -197,6 +199,7 @@ static inline bool mptcp_sk_is_subflow(const struct sock *sk)
 	return false;
 }
 
+static inline void mptcp_space(const struct sock *ssk, int *s, int *fs) { }
 static inline void mptcp_seq_show(struct seq_file *seq) { }
 #endif /* CONFIG_MPTCP */
 
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 2f45cde168c4abca8248fb835f79149260c7f418..ba4482130f08ea386913bfa5de3253e9bbfa3030 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2772,8 +2772,12 @@ u32 __tcp_select_window(struct sock *sk)
 	int mss = icsk->icsk_ack.rcv_mss;
 	int free_space = tcp_space(sk);
 	int allowed_space = tcp_full_space(sk);
-	int full_space = min_t(int, tp->window_clamp, allowed_space);
-	int window;
+	int full_space, window;
+
+	if (sk_is_mptcp(sk))
+		mptcp_space(sk, &free_space, &allowed_space);
+
+	full_space = min_t(int, tp->window_clamp, allowed_space);
 
 	if (unlikely(mss > full_space)) {
 		mss = full_space;
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index fabd06f2ff455e76cf281c4e6fc2d41b144ac2d9..87c094702d6377a37c2a69fe733ecbe214954a54 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -821,6 +821,24 @@ bool mptcp_subflow_data_available(struct sock *sk)
 	return subflow->data_avail;
 }
 
+/* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
+ * not the ssk one.
+ *
+ * In mptcp, rwin is about the mptcp-level connection data.
+ *
+ * Data that is still on the ssk rx queue can thus be ignored,
+ * as far as mptcp peer is concerened that data is still inflight.
+ * DSS ACK is updated when skb is moved to the mptcp rx queue.
+ */
+void mptcp_space(const struct sock *ssk, int *space, int *full_space)
+{
+	const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+	const struct sock *sk = subflow->conn;
+
+	*space = tcp_space(sk);
+	*full_space = tcp_full_space(sk);
+}
+
 static void subflow_data_ready(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);