diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst
index 76d939e688b84..b0d4da71e68ef 100644
--- a/Documentation/networking/mptcp-sysctl.rst
+++ b/Documentation/networking/mptcp-sysctl.rst
@@ -45,3 +45,15 @@ allow_join_initial_addr_port - BOOLEAN
 	This is a per-namespace sysctl.
 
 	Default: 1
+
+stale_loss_cnt - INTEGER
+	The number of MPTCP-level retransmission intervals with no traffic and
+	pending outstanding data on a given subflow required to declare it stale.
+	The packet scheduler ignores stale subflows.
+	A low stale_loss_cnt  value allows for fast active-backup switch-over,
+	an high value maximize links utilization on edge scenarios e.g. lossy
+	link with high BER or peer pausing the data processing.
+
+	This is a per-namespace sysctl.
+
+	Default: 4
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 7d738bd06f2c9..8b235468c88ff 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -21,43 +21,50 @@ struct mptcp_pernet {
 	struct ctl_table_header *ctl_table_hdr;
 #endif
 
-	u8 mptcp_enabled;
 	unsigned int add_addr_timeout;
+	unsigned int stale_loss_cnt;
+	u8 mptcp_enabled;
 	u8 checksum_enabled;
 	u8 allow_join_initial_addr_port;
 };
 
-static struct mptcp_pernet *mptcp_get_pernet(struct net *net)
+static struct mptcp_pernet *mptcp_get_pernet(const struct net *net)
 {
 	return net_generic(net, mptcp_pernet_id);
 }
 
-int mptcp_is_enabled(struct net *net)
+int mptcp_is_enabled(const struct net *net)
 {
 	return mptcp_get_pernet(net)->mptcp_enabled;
 }
 
-unsigned int mptcp_get_add_addr_timeout(struct net *net)
+unsigned int mptcp_get_add_addr_timeout(const struct net *net)
 {
 	return mptcp_get_pernet(net)->add_addr_timeout;
 }
 
-int mptcp_is_checksum_enabled(struct net *net)
+int mptcp_is_checksum_enabled(const struct net *net)
 {
 	return mptcp_get_pernet(net)->checksum_enabled;
 }
 
-int mptcp_allow_join_id0(struct net *net)
+int mptcp_allow_join_id0(const struct net *net)
 {
 	return mptcp_get_pernet(net)->allow_join_initial_addr_port;
 }
 
+unsigned int mptcp_stale_loss_cnt(const struct net *net)
+{
+	return mptcp_get_pernet(net)->stale_loss_cnt;
+}
+
 static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 {
 	pernet->mptcp_enabled = 1;
 	pernet->add_addr_timeout = TCP_RTO_MAX;
 	pernet->checksum_enabled = 0;
 	pernet->allow_join_initial_addr_port = 1;
+	pernet->stale_loss_cnt = 4;
 }
 
 #ifdef CONFIG_SYSCTL
@@ -95,6 +102,12 @@ static struct ctl_table mptcp_sysctl_table[] = {
 		.extra1       = SYSCTL_ZERO,
 		.extra2       = SYSCTL_ONE
 	},
+	{
+		.procname = "stale_loss_cnt",
+		.maxlen = sizeof(unsigned int),
+		.mode = 0644,
+		.proc_handler = proc_douintvec_minmax,
+	},
 	{}
 };
 
@@ -114,6 +127,7 @@ static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
 	table[1].data = &pernet->add_addr_timeout;
 	table[2].data = &pernet->checksum_enabled;
 	table[3].data = &pernet->allow_join_initial_addr_port;
+	table[4].data = &pernet->stale_loss_cnt;
 
 	hdr = register_net_sysctl(net, MPTCP_SYSCTL_PATH, table);
 	if (!hdr)
diff --git a/net/mptcp/mib.c b/net/mptcp/mib.c
index ff2cc0e3273df..3a7c4e7b2d790 100644
--- a/net/mptcp/mib.c
+++ b/net/mptcp/mib.c
@@ -45,6 +45,8 @@ static const struct snmp_mib mptcp_snmp_list[] = {
 	SNMP_MIB_ITEM("MPPrioTx", MPTCP_MIB_MPPRIOTX),
 	SNMP_MIB_ITEM("MPPrioRx", MPTCP_MIB_MPPRIORX),
 	SNMP_MIB_ITEM("RcvPruned", MPTCP_MIB_RCVPRUNED),
+	SNMP_MIB_ITEM("SubflowStale", MPTCP_MIB_SUBFLOWSTALE),
+	SNMP_MIB_ITEM("SubflowRecover", MPTCP_MIB_SUBFLOWRECOVER),
 	SNMP_MIB_SENTINEL
 };
 
diff --git a/net/mptcp/mib.h b/net/mptcp/mib.h
index 0663cb12b448b..8ec16c991aac0 100644
--- a/net/mptcp/mib.h
+++ b/net/mptcp/mib.h
@@ -38,6 +38,8 @@ enum linux_mptcp_mib_field {
 	MPTCP_MIB_MPPRIOTX,		/* Transmit a MP_PRIO */
 	MPTCP_MIB_MPPRIORX,		/* Received a MP_PRIO */
 	MPTCP_MIB_RCVPRUNED,		/* Incoming packet dropped due to memory limit */
+	MPTCP_MIB_SUBFLOWSTALE,		/* Subflows entered 'stale' status */
+	MPTCP_MIB_SUBFLOWRECOVER,	/* Subflows returned to active status after being stale */
 	__MPTCP_MIB_MAX
 };
 
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 4452455aef7fa..e37b6f2fb5144 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -975,9 +975,11 @@ static void ack_update_msk(struct mptcp_sock *msk,
 	old_snd_una = msk->snd_una;
 	new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
 
-	/* ACK for data not even sent yet? Ignore. */
-	if (after64(new_snd_una, snd_nxt))
-		new_snd_una = old_snd_una;
+	/* ACK for data not even sent yet and even above recovery bound? Ignore.*/
+	if (unlikely(after64(new_snd_una, snd_nxt))) {
+		if (!msk->recovery || after64(new_snd_una, msk->recovery_snd_nxt))
+			new_snd_una = old_snd_una;
+	}
 
 	new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd;
 
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 639271e09604a..0ed3e565f8f81 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -10,6 +10,8 @@
 #include <net/mptcp.h>
 #include "protocol.h"
 
+#include "mib.h"
+
 /* path manager command handlers */
 
 int mptcp_pm_announce_addr(struct mptcp_sock *msk,
@@ -308,6 +310,25 @@ int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
 	return mptcp_pm_nl_get_local_id(msk, skc);
 }
 
+void mptcp_pm_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
+{
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+	u32 rcv_tstamp = READ_ONCE(tcp_sk(ssk)->rcv_tstamp);
+
+	/* keep track of rtx periods with no progress */
+	if (!subflow->stale_count) {
+		subflow->stale_rcv_tstamp = rcv_tstamp;
+		subflow->stale_count++;
+	} else if (subflow->stale_rcv_tstamp == rcv_tstamp) {
+		if (subflow->stale_count < U8_MAX)
+			subflow->stale_count++;
+		mptcp_pm_nl_subflow_chk_stale(msk, ssk);
+	} else {
+		subflow->stale_count = 0;
+		mptcp_subflow_set_active(subflow);
+	}
+}
+
 void mptcp_pm_data_init(struct mptcp_sock *msk)
 {
 	msk->pm.add_addr_signaled = 0;
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 56263c2c4014c..ac0aa6faacfa4 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -46,6 +46,7 @@ struct pm_nl_pernet {
 	spinlock_t		lock;
 	struct list_head	local_addr_list;
 	unsigned int		addrs;
+	unsigned int		stale_loss_cnt;
 	unsigned int		add_addr_signal_max;
 	unsigned int		add_addr_accept_max;
 	unsigned int		local_addr_max;
@@ -899,6 +900,43 @@ static const struct nla_policy mptcp_pm_policy[MPTCP_PM_ATTR_MAX + 1] = {
 	[MPTCP_PM_ATTR_SUBFLOWS]	= { .type	= NLA_U32,	},
 };
 
+void mptcp_pm_nl_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
+{
+	struct mptcp_subflow_context *iter, *subflow = mptcp_subflow_ctx(ssk);
+	struct sock *sk = (struct sock *)msk;
+	unsigned int active_max_loss_cnt;
+	struct net *net = sock_net(sk);
+	unsigned int stale_loss_cnt;
+	bool slow;
+
+	stale_loss_cnt = mptcp_stale_loss_cnt(net);
+	if (subflow->stale || !stale_loss_cnt || subflow->stale_count <= stale_loss_cnt)
+		return;
+
+	/* look for another available subflow not in loss state */
+	active_max_loss_cnt = max_t(int, stale_loss_cnt - 1, 1);
+	mptcp_for_each_subflow(msk, iter) {
+		if (iter != subflow && mptcp_subflow_active(iter) &&
+		    iter->stale_count < active_max_loss_cnt) {
+			/* we have some alternatives, try to mark this subflow as idle ...*/
+			slow = lock_sock_fast(ssk);
+			if (!tcp_rtx_and_write_queues_empty(ssk)) {
+				subflow->stale = 1;
+				__mptcp_retransmit_pending_data(sk);
+				MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_SUBFLOWSTALE);
+			}
+			unlock_sock_fast(ssk, slow);
+
+			/* always try to push the pending data regarless of re-injections:
+			 * we can possibly use backup subflows now, and subflow selection
+			 * is cheap under the msk socket lock
+			 */
+			__mptcp_push_pending(sk, 0);
+			return;
+		}
+	}
+}
+
 static int mptcp_pm_family_to_addr(int family)
 {
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
@@ -1922,6 +1960,7 @@ static int __net_init pm_nl_init_net(struct net *net)
 
 	INIT_LIST_HEAD_RCU(&pernet->local_addr_list);
 	pernet->next_id = 1;
+	pernet->stale_loss_cnt = 4;
 	spin_lock_init(&pernet->lock);
 
 	/* No need to initialize other pernet fields, the struct is zeroed at
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index a889249478152..22214a58d8925 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -411,16 +411,29 @@ static void mptcp_set_datafin_timeout(const struct sock *sk)
 				       TCP_RTO_MIN << icsk->icsk_retransmits);
 }
 
-static void mptcp_set_timeout(const struct sock *sk, const struct sock *ssk)
+static void __mptcp_set_timeout(struct sock *sk, long tout)
 {
-	long tout = ssk && inet_csk(ssk)->icsk_pending ?
-				      inet_csk(ssk)->icsk_timeout - jiffies : 0;
-
-	if (tout <= 0)
-		tout = mptcp_sk(sk)->timer_ival;
 	mptcp_sk(sk)->timer_ival = tout > 0 ? tout : TCP_RTO_MIN;
 }
 
+static long mptcp_timeout_from_subflow(const struct mptcp_subflow_context *subflow)
+{
+	const struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+
+	return inet_csk(ssk)->icsk_pending && !subflow->stale_count ?
+	       inet_csk(ssk)->icsk_timeout - jiffies : 0;
+}
+
+static void mptcp_set_timeout(struct sock *sk)
+{
+	struct mptcp_subflow_context *subflow;
+	long tout = 0;
+
+	mptcp_for_each_subflow(mptcp_sk(sk), subflow)
+		tout = max(tout, mptcp_timeout_from_subflow(subflow));
+	__mptcp_set_timeout(sk, tout);
+}
+
 static bool tcp_can_send_ack(const struct sock *ssk)
 {
 	return !((1 << inet_sk_state_load(ssk)) &
@@ -531,7 +544,6 @@ static bool mptcp_check_data_fin(struct sock *sk)
 		}
 
 		ret = true;
-		mptcp_set_timeout(sk, NULL);
 		mptcp_send_ack(msk);
 		mptcp_close_wake_up(sk);
 	}
@@ -791,10 +803,7 @@ static void mptcp_reset_timer(struct sock *sk)
 	if (unlikely(inet_sk_state_load(sk) == TCP_CLOSE))
 		return;
 
-	/* should never be called with mptcp level timer cleared */
-	tout = READ_ONCE(mptcp_sk(sk)->timer_ival);
-	if (WARN_ON_ONCE(!tout))
-		tout = TCP_RTO_MIN;
+	tout = mptcp_sk(sk)->timer_ival;
 	sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + tout);
 }
 
@@ -1046,8 +1055,14 @@ static void __mptcp_clean_una(struct sock *sk)
 		if (after64(dfrag->data_seq + dfrag->data_len, snd_una))
 			break;
 
-		if (WARN_ON_ONCE(dfrag == msk->first_pending))
-			break;
+		if (unlikely(dfrag == msk->first_pending)) {
+			/* in recovery mode can see ack after the current snd head */
+			if (WARN_ON_ONCE(!msk->recovery))
+				break;
+
+			WRITE_ONCE(msk->first_pending, mptcp_send_next(sk));
+		}
+
 		dfrag_clear(sk, dfrag);
 		cleaned = true;
 	}
@@ -1056,8 +1071,14 @@ static void __mptcp_clean_una(struct sock *sk)
 	if (dfrag && after64(snd_una, dfrag->data_seq)) {
 		u64 delta = snd_una - dfrag->data_seq;
 
-		if (WARN_ON_ONCE(delta > dfrag->already_sent))
-			goto out;
+		/* prevent wrap around in recovery mode */
+		if (unlikely(delta > dfrag->already_sent)) {
+			if (WARN_ON_ONCE(!msk->recovery))
+				goto out;
+			if (WARN_ON_ONCE(delta > dfrag->data_len))
+				goto out;
+			dfrag->already_sent += delta - dfrag->already_sent;
+		}
 
 		dfrag->data_seq += delta;
 		dfrag->offset += delta;
@@ -1068,6 +1089,10 @@ static void __mptcp_clean_una(struct sock *sk)
 		cleaned = true;
 	}
 
+	/* all retransmitted data acked, recovery completed */
+	if (unlikely(msk->recovery) && after64(msk->snd_una, msk->recovery_snd_nxt))
+		msk->recovery = false;
+
 out:
 	if (cleaned) {
 		if (tcp_under_memory_pressure(sk)) {
@@ -1076,8 +1101,8 @@ static void __mptcp_clean_una(struct sock *sk)
 		}
 	}
 
-	if (snd_una == READ_ONCE(msk->snd_nxt)) {
-		if (msk->timer_ival && !mptcp_data_fin_enabled(msk))
+	if (snd_una == READ_ONCE(msk->snd_nxt) && !msk->recovery) {
+		if (mptcp_timer_pending(sk) && !mptcp_data_fin_enabled(msk))
 			mptcp_stop_timer(sk);
 	} else {
 		mptcp_reset_timer(sk);
@@ -1366,16 +1391,44 @@ struct subflow_send_info {
 	u64 ratio;
 };
 
+void mptcp_subflow_set_active(struct mptcp_subflow_context *subflow)
+{
+	if (!subflow->stale)
+		return;
+
+	subflow->stale = 0;
+	MPTCP_INC_STATS(sock_net(mptcp_subflow_tcp_sock(subflow)), MPTCP_MIB_SUBFLOWRECOVER);
+}
+
+bool mptcp_subflow_active(struct mptcp_subflow_context *subflow)
+{
+	if (unlikely(subflow->stale)) {
+		u32 rcv_tstamp = READ_ONCE(tcp_sk(mptcp_subflow_tcp_sock(subflow))->rcv_tstamp);
+
+		if (subflow->stale_rcv_tstamp == rcv_tstamp)
+			return false;
+
+		mptcp_subflow_set_active(subflow);
+	}
+	return __mptcp_subflow_active(subflow);
+}
+
+/* implement the mptcp packet scheduler;
+ * returns the subflow that will transmit the next DSS
+ * additionally updates the rtx timeout
+ */
 static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 {
 	struct subflow_send_info send_info[2];
 	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
 	int i, nr_active = 0;
 	struct sock *ssk;
+	long tout = 0;
 	u64 ratio;
 	u32 pace;
 
-	sock_owned_by_me((struct sock *)msk);
+	sock_owned_by_me(sk);
 
 	if (__mptcp_check_fallback(msk)) {
 		if (!msk->first)
@@ -1386,8 +1439,10 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 	/* re-use last subflow, if the burst allow that */
 	if (msk->last_snd && msk->snd_burst > 0 &&
 	    sk_stream_memory_free(msk->last_snd) &&
-	    mptcp_subflow_active(mptcp_subflow_ctx(msk->last_snd)))
+	    mptcp_subflow_active(mptcp_subflow_ctx(msk->last_snd))) {
+		mptcp_set_timeout(sk);
 		return msk->last_snd;
+	}
 
 	/* pick the subflow with the lower wmem/wspace ratio */
 	for (i = 0; i < 2; ++i) {
@@ -1400,6 +1455,7 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 		if (!mptcp_subflow_active(subflow))
 			continue;
 
+		tout = max(tout, mptcp_timeout_from_subflow(subflow));
 		nr_active += !subflow->backup;
 		if (!sk_stream_memory_free(subflow->tcp_sock) || !tcp_sk(ssk)->snd_wnd)
 			continue;
@@ -1415,6 +1471,7 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 			send_info[subflow->backup].ratio = ratio;
 		}
 	}
+	__mptcp_set_timeout(sk, tout);
 
 	/* pick the best backup if no other subflow is active */
 	if (!nr_active)
@@ -1433,12 +1490,11 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 static void mptcp_push_release(struct sock *sk, struct sock *ssk,
 			       struct mptcp_sendmsg_info *info)
 {
-	mptcp_set_timeout(sk, ssk);
 	tcp_push(ssk, 0, info->mss_now, tcp_sk(ssk)->nonagle, info->size_goal);
 	release_sock(ssk);
 }
 
-static void __mptcp_push_pending(struct sock *sk, unsigned int flags)
+void __mptcp_push_pending(struct sock *sk, unsigned int flags)
 {
 	struct sock *prev_ssk = NULL, *ssk = NULL;
 	struct mptcp_sock *msk = mptcp_sk(sk);
@@ -1501,12 +1557,11 @@ static void __mptcp_push_pending(struct sock *sk, unsigned int flags)
 		mptcp_push_release(sk, ssk, &info);
 
 out:
-	if (copied) {
-		/* start the timer, if it's not pending */
-		if (!mptcp_timer_pending(sk))
-			mptcp_reset_timer(sk);
+	/* ensure the rtx timer is running */
+	if (!mptcp_timer_pending(sk))
+		mptcp_reset_timer(sk);
+	if (copied)
 		__mptcp_check_send_data_fin(sk);
-	}
 }
 
 static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
@@ -1567,7 +1622,6 @@ static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
 	 */
 	__mptcp_update_wmem(sk);
 	if (copied) {
-		mptcp_set_timeout(sk, ssk);
 		tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle,
 			 info.size_goal);
 		if (!mptcp_timer_pending(sk))
@@ -2083,10 +2137,11 @@ static void mptcp_timeout_timer(struct timer_list *t)
  *
  * A backup subflow is returned only if that is the only kind available.
  */
-static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk)
+static struct sock *mptcp_subflow_get_retrans(struct mptcp_sock *msk)
 {
+	struct sock *backup = NULL, *pick = NULL;
 	struct mptcp_subflow_context *subflow;
-	struct sock *backup = NULL;
+	int min_stale_count = INT_MAX;
 
 	sock_owned_by_me((const struct sock *)msk);
 
@@ -2096,14 +2151,14 @@ static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk)
 	mptcp_for_each_subflow(msk, subflow) {
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 
-		if (!mptcp_subflow_active(subflow))
+		if (!__mptcp_subflow_active(subflow))
 			continue;
 
-		/* still data outstanding at TCP level?  Don't retransmit. */
-		if (!tcp_write_queue_empty(ssk)) {
-			if (inet_csk(ssk)->icsk_ca_state >= TCP_CA_Loss)
-				continue;
-			return NULL;
+		/* still data outstanding at TCP level? skip this */
+		if (!tcp_rtx_and_write_queues_empty(ssk)) {
+			mptcp_pm_subflow_chk_stale(msk, ssk);
+			min_stale_count = min_t(int, min_stale_count, subflow->stale_count);
+			continue;
 		}
 
 		if (subflow->backup) {
@@ -2112,10 +2167,15 @@ static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk)
 			continue;
 		}
 
-		return ssk;
+		if (!pick)
+			pick = ssk;
 	}
 
-	return backup;
+	if (pick)
+		return pick;
+
+	/* use backup only if there are no progresses anywhere */
+	return min_stale_count > 1 ? backup : NULL;
 }
 
 static void mptcp_dispose_initial_subflow(struct mptcp_sock *msk)
@@ -2126,6 +2186,50 @@ static void mptcp_dispose_initial_subflow(struct mptcp_sock *msk)
 	}
 }
 
+bool __mptcp_retransmit_pending_data(struct sock *sk)
+{
+	struct mptcp_data_frag *cur, *rtx_head;
+	struct mptcp_sock *msk = mptcp_sk(sk);
+
+	if (__mptcp_check_fallback(mptcp_sk(sk)))
+		return false;
+
+	if (tcp_rtx_and_write_queues_empty(sk))
+		return false;
+
+	/* the closing socket has some data untransmitted and/or unacked:
+	 * some data in the mptcp rtx queue has not really xmitted yet.
+	 * keep it simple and re-inject the whole mptcp level rtx queue
+	 */
+	mptcp_data_lock(sk);
+	__mptcp_clean_una_wakeup(sk);
+	rtx_head = mptcp_rtx_head(sk);
+	if (!rtx_head) {
+		mptcp_data_unlock(sk);
+		return false;
+	}
+
+	/* will accept ack for reijected data before re-sending them */
+	if (!msk->recovery || after64(msk->snd_nxt, msk->recovery_snd_nxt))
+		msk->recovery_snd_nxt = msk->snd_nxt;
+	msk->recovery = true;
+	mptcp_data_unlock(sk);
+
+	msk->first_pending = rtx_head;
+	msk->tx_pending_data += msk->snd_nxt - rtx_head->data_seq;
+	msk->snd_nxt = rtx_head->data_seq;
+	msk->snd_burst = 0;
+
+	/* be sure to clear the "sent status" on all re-injected fragments */
+	list_for_each_entry(cur, &msk->rtx_queue, list) {
+		if (!cur->already_sent)
+			break;
+		cur->already_sent = 0;
+	}
+
+	return true;
+}
+
 /* subflow sockets can be either outgoing (connect) or incoming
  * (accept).
  *
@@ -2138,6 +2242,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 			      struct mptcp_subflow_context *subflow)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
+	bool need_push;
 
 	list_del(&subflow->node);
 
@@ -2149,6 +2254,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 	if (ssk->sk_socket)
 		sock_orphan(ssk);
 
+	need_push = __mptcp_retransmit_pending_data(sk);
 	subflow->disposable = 1;
 
 	/* if ssk hit tcp_done(), tcp_cleanup_ulp() cleared the related ops
@@ -2176,6 +2282,9 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 
 	if (msk->subflow && ssk == msk->subflow->sk)
 		mptcp_dispose_initial_subflow(msk);
+
+	if (need_push)
+		__mptcp_push_pending(sk, 0);
 }
 
 void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
@@ -2313,7 +2422,6 @@ static void __mptcp_retrans(struct sock *sk)
 			 info.size_goal);
 	}
 
-	mptcp_set_timeout(sk, ssk);
 	release_sock(ssk);
 
 reset_timer:
@@ -2384,10 +2492,12 @@ static int __mptcp_init_sock(struct sock *sk)
 	msk->wmem_reserved = 0;
 	WRITE_ONCE(msk->rmem_released, 0);
 	msk->tx_pending_data = 0;
+	msk->timer_ival = TCP_RTO_MIN;
 
 	msk->first = NULL;
 	inet_csk(sk)->icsk_sync_mss = mptcp_sync_mss;
 	WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk)));
+	msk->recovery = false;
 
 	mptcp_pm_data_init(msk);
 
@@ -2472,7 +2582,6 @@ void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how)
 			tcp_shutdown(ssk, how);
 		} else {
 			pr_debug("Sending DATA_FIN on subflow %p", ssk);
-			mptcp_set_timeout(sk, ssk);
 			tcp_send_ack(ssk);
 			if (!mptcp_timer_pending(sk))
 				mptcp_reset_timer(sk);
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 0f0c026c5f8bb..8bdd038def383 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -230,12 +230,17 @@ struct mptcp_sock {
 	struct sock	*last_snd;
 	int		snd_burst;
 	int		old_wspace;
+	u64		recovery_snd_nxt;	/* in recovery mode accept up to this seq;
+						 * recovery related fields are under data_lock
+						 * protection
+						 */
 	u64		snd_una;
 	u64		wnd_end;
 	unsigned long	timer_ival;
 	u32		token;
 	int		rmem_released;
 	unsigned long	flags;
+	bool		recovery;		/* closing subflow write queue reinjected */
 	bool		can_ack;
 	bool		fully_established;
 	bool		rcv_data_fin;
@@ -427,7 +432,8 @@ struct mptcp_subflow_context {
 		send_mp_prio : 1,
 		rx_eof : 1,
 		can_ack : 1,        /* only after processing the remote a key */
-		disposable : 1;	    /* ctx can be free at ulp release time */
+		disposable : 1,	    /* ctx can be free at ulp release time */
+		stale : 1;	    /* unable to snd/rcv data, do not use for xmit */
 	enum mptcp_data_avail data_avail;
 	u32	remote_nonce;
 	u64	thmac;
@@ -439,11 +445,13 @@ struct mptcp_subflow_context {
 	u8	reset_seen:1;
 	u8	reset_transient:1;
 	u8	reset_reason:4;
+	u8	stale_count;
 
 	long	delegated_status;
 	struct	list_head delegated_node;   /* link into delegated_action, protected by local BH */
 
-	u32 setsockopt_seq;
+	u32	setsockopt_seq;
+	u32	stale_rcv_tstamp;
 
 	struct	sock *tcp_sock;	    /* tcp sk backpointer */
 	struct	sock *conn;	    /* parent mptcp_sock */
@@ -549,12 +557,15 @@ static inline void mptcp_subflow_delegated_done(struct mptcp_subflow_context *su
 	clear_bit(MPTCP_DELEGATE_SEND, &subflow->delegated_status);
 }
 
-int mptcp_is_enabled(struct net *net);
-unsigned int mptcp_get_add_addr_timeout(struct net *net);
-int mptcp_is_checksum_enabled(struct net *net);
-int mptcp_allow_join_id0(struct net *net);
+int mptcp_is_enabled(const struct net *net);
+unsigned int mptcp_get_add_addr_timeout(const struct net *net);
+int mptcp_is_checksum_enabled(const struct net *net);
+int mptcp_allow_join_id0(const struct net *net);
+unsigned int mptcp_stale_loss_cnt(const struct net *net);
 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
 				     struct mptcp_options_received *mp_opt);
+bool __mptcp_retransmit_pending_data(struct sock *sk);
+void __mptcp_push_pending(struct sock *sk, unsigned int flags);
 bool mptcp_subflow_data_available(struct sock *sk);
 void __init mptcp_subflow_init(void);
 void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how);
@@ -573,7 +584,7 @@ void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
 			 struct sockaddr_storage *addr,
 			 unsigned short family);
 
-static inline bool mptcp_subflow_active(struct mptcp_subflow_context *subflow)
+static inline bool __mptcp_subflow_active(struct mptcp_subflow_context *subflow)
 {
 	struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 
@@ -585,6 +596,10 @@ static inline bool mptcp_subflow_active(struct mptcp_subflow_context *subflow)
 	return ((1 << ssk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT));
 }
 
+void mptcp_subflow_set_active(struct mptcp_subflow_context *subflow);
+
+bool mptcp_subflow_active(struct mptcp_subflow_context *subflow);
+
 static inline void mptcp_subflow_tcp_fallback(struct sock *sk,
 					      struct mptcp_subflow_context *ctx)
 {
@@ -690,6 +705,8 @@ void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac);
 
 void __init mptcp_pm_init(void);
 void mptcp_pm_data_init(struct mptcp_sock *msk);
+void mptcp_pm_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk);
+void mptcp_pm_nl_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk);
 void mptcp_pm_new_connection(struct mptcp_sock *msk, const struct sock *ssk, int server_side);
 void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk, gfp_t gfp);
 bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 966f777d35ce9..1151926d335b2 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -435,10 +435,12 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 			goto do_reset;
 		}
 
+		subflow->backup = mp_opt.backup;
 		subflow->thmac = mp_opt.thmac;
 		subflow->remote_nonce = mp_opt.nonce;
-		pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u", subflow,
-			 subflow->thmac, subflow->remote_nonce);
+		pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d",
+			 subflow, subflow->thmac, subflow->remote_nonce,
+			 subflow->backup);
 
 		if (!subflow_thmac_valid(subflow)) {
 			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index f02f4de2f3a08..52762eaa2d8e3 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -3,8 +3,10 @@
 
 ret=0
 sin=""
+sinfail=""
 sout=""
 cin=""
+cinfail=""
 cinsent=""
 cout=""
 ksft_skip=4
@@ -76,6 +78,14 @@ init()
 	done
 }
 
+init_shapers()
+{
+	for i in `seq 1 4`; do
+		tc -n $ns1 qdisc add dev ns1eth$i root netem rate 20mbit delay 1
+		tc -n $ns2 qdisc add dev ns2eth$i root netem rate 20mbit delay 1
+	done
+}
+
 cleanup_partial()
 {
 	rm -f "$capout"
@@ -88,8 +98,8 @@ cleanup_partial()
 
 cleanup()
 {
-	rm -f "$cin" "$cout"
-	rm -f "$sin" "$sout" "$cinsent"
+	rm -f "$cin" "$cout" "$sinfail"
+	rm -f "$sin" "$sout" "$cinsent" "$cinfail"
 	cleanup_partial
 }
 
@@ -211,11 +221,15 @@ link_failure()
 {
 	ns="$1"
 
-	l=$((RANDOM%4))
-	l=$((l+1))
+	if [ -z "$FAILING_LINKS" ]; then
+		l=$((RANDOM%4))
+		FAILING_LINKS=$((l+1))
+	fi
 
-	veth="ns1eth$l"
-	ip -net "$ns" link set "$veth" down
+	for l in $FAILING_LINKS; do
+		veth="ns1eth$l"
+		ip -net "$ns" link set "$veth" down
+	done
 }
 
 # $1: IP address
@@ -280,10 +294,17 @@ do_transfer()
 		local_addr="0.0.0.0"
 	fi
 
-	timeout ${timeout_test} \
-		ip netns exec ${listener_ns} \
-			$mptcp_connect -t ${timeout_poll} -l -p $port -s ${srv_proto} \
-				${local_addr} < "$sin" > "$sout" &
+	if [ "$test_link_fail" -eq 2 ];then
+		timeout ${timeout_test} \
+			ip netns exec ${listener_ns} \
+				$mptcp_connect -t ${timeout_poll} -l -p $port -s ${cl_proto} \
+					${local_addr} < "$sinfail" > "$sout" &
+	else
+		timeout ${timeout_test} \
+			ip netns exec ${listener_ns} \
+				$mptcp_connect -t ${timeout_poll} -l -p $port -s ${srv_proto} \
+					${local_addr} < "$sin" > "$sout" &
+	fi
 	spid=$!
 
 	sleep 1
@@ -294,7 +315,7 @@ do_transfer()
 				$mptcp_connect -t ${timeout_poll} -p $port -s ${cl_proto} \
 					$connect_addr < "$cin" > "$cout" &
 	else
-		( cat "$cin" ; sleep 2; link_failure $listener_ns ; cat "$cin" ) | \
+		( cat "$cinfail" ; sleep 2; link_failure $listener_ns ; cat "$cinfail" ) | \
 			tee "$cinsent" | \
 			timeout ${timeout_test} \
 				ip netns exec ${connector_ns} \
@@ -434,7 +455,11 @@ do_transfer()
 		return 1
 	fi
 
-	check_transfer $sin $cout "file received by client"
+	if [ "$test_link_fail" -eq 2 ];then
+		check_transfer $sinfail $cout "file received by client"
+	else
+		check_transfer $sin $cout "file received by client"
+	fi
 	retc=$?
 	if [ "$test_link_fail" -eq 0 ];then
 		check_transfer $cin $sout "file received by server"
@@ -477,29 +502,33 @@ run_tests()
 	lret=0
 	oldin=""
 
-	if [ "$test_linkfail" -eq 1 ];then
-		size=$((RANDOM%1024))
+	# create the input file for the failure test when
+	# the first failure test run
+	if [ "$test_linkfail" -ne 0 -a -z "$cinfail" ]; then
+		# the client file must be considerably larger
+		# of the maximum expected cwin value, or the
+		# link utilization will be not predicable
+		size=$((RANDOM%2))
 		size=$((size+1))
-		size=$((size*128))
+		size=$((size*8192))
+		size=$((size + ( $RANDOM % 8192) ))
 
-		oldin=$(mktemp)
-		cp "$cin" "$oldin"
-		make_file "$cin" "client" $size
+		cinfail=$(mktemp)
+		make_file "$cinfail" "client" $size
 	fi
 
-	do_transfer ${listener_ns} ${connector_ns} MPTCP MPTCP ${connect_addr} \
-		${test_linkfail} ${addr_nr_ns1} ${addr_nr_ns2} ${speed} ${bkup}
-	lret=$?
+	if [ "$test_linkfail" -eq 2 -a -z "$sinfail" ]; then
+		size=$((RANDOM%16))
+		size=$((size+1))
+		size=$((size*2048))
 
-	if [ "$test_linkfail" -eq 1 ];then
-		cp "$oldin" "$cin"
-		rm -f "$oldin"
+		sinfail=$(mktemp)
+		make_file "$sinfail" "server" $size
 	fi
 
-	if [ $lret -ne 0 ]; then
-		ret=$lret
-		return
-	fi
+	do_transfer ${listener_ns} ${connector_ns} MPTCP MPTCP ${connect_addr} \
+		${test_linkfail} ${addr_nr_ns1} ${addr_nr_ns2} ${speed} ${bkup}
+	lret=$?
 }
 
 chk_csum_nr()
@@ -593,6 +622,46 @@ chk_join_nr()
 	fi
 }
 
+# a negative value for 'stale_max' means no upper bound:
+# for bidirectional transfer, if one peer sleep for a while
+# - as these tests do - we can have a quite high number of
+# stale/recover conversions, proportional to
+# sleep duration/ MPTCP-level RTX interval.
+chk_stale_nr()
+{
+	local ns=$1
+	local stale_min=$2
+	local stale_max=$3
+	local stale_delta=$4
+	local dump_stats
+	local stale_nr
+	local recover_nr
+
+	printf "%-39s %-18s" " " "stale"
+	stale_nr=`ip netns exec $ns nstat -as | grep MPTcpExtSubflowStale | awk '{print $2}'`
+	[ -z "$stale_nr" ] && stale_nr=0
+	recover_nr=`ip netns exec $ns nstat -as | grep MPTcpExtSubflowRecover | awk '{print $2}'`
+	[ -z "$recover_nr" ] && recover_nr=0
+
+	if [ $stale_nr -lt $stale_min ] ||
+	   [ $stale_max -gt 0 -a $stale_nr -gt $stale_max ] ||
+	   [ $((stale_nr - $recover_nr)) -ne $stale_delta ]; then
+		echo "[fail] got $stale_nr stale[s] $recover_nr recover[s], " \
+		     " expected stale in range [$stale_min..$stale_max]," \
+		     " stale-recover delta $stale_delta "
+		ret=1
+		dump_stats=1
+	else
+		echo "[ ok ]"
+	fi
+
+	if [ "${dump_stats}" = 1 ]; then
+		echo $ns stats
+		ip netns exec $ns ip -s link show
+		ip netns exec $ns nstat -as | grep MPTcp
+	fi
+}
+
 chk_add_nr()
 {
 	local add_nr=$1
@@ -801,6 +870,27 @@ chk_prio_nr()
 	fi
 }
 
+chk_link_usage()
+{
+	local ns=$1
+	local link=$2
+	local out=$3
+	local expected_rate=$4
+	local tx_link=`ip netns exec $ns cat /sys/class/net/$link/statistics/tx_bytes`
+	local tx_total=`ls -l $out | awk '{print $5}'`
+	local tx_rate=$((tx_link * 100 / $tx_total))
+	local tolerance=5
+
+	printf "%-39s %-18s" " " "link usage"
+	if [ $tx_rate -lt $((expected_rate - $tolerance)) -o \
+	     $tx_rate -gt $((expected_rate + $tolerance)) ]; then
+		echo "[fail] got $tx_rate% usage, expected $expected_rate%"
+		ret=1
+	else
+		echo "[ ok ]"
+	fi
+}
+
 subflows_tests()
 {
 	reset
@@ -924,14 +1014,80 @@ link_failure_tests()
 {
 	# accept and use add_addr with additional subflows and link loss
 	reset
+
+	# without any b/w limit each veth could spool the packets and get
+	# them acked at xmit time, so that the corresponding subflow will
+	# have almost always no outstanding pkts, the scheduler will pick
+	# always the first subflow and we will have hard time testing
+	# active backup and link switch-over.
+	# Let's set some arbitrary (low) virtual link limits.
+	init_shapers
 	ip netns exec $ns1 ./pm_nl_ctl limits 0 3
-	ip netns exec $ns1 ./pm_nl_ctl add 10.0.2.1 flags signal
+	ip netns exec $ns1 ./pm_nl_ctl add 10.0.2.1 dev ns1eth2 flags signal
 	ip netns exec $ns2 ./pm_nl_ctl limits 1 3
-	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
-	ip netns exec $ns2 ./pm_nl_ctl add 10.0.4.2 flags subflow
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 dev ns2eth3 flags subflow
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.4.2 dev ns2eth4 flags subflow
 	run_tests $ns1 $ns2 10.0.1.1 1
 	chk_join_nr "multiple flows, signal, link failure" 3 3 3
 	chk_add_nr 1 1
+	chk_stale_nr $ns2 1 5 1
+
+	# accept and use add_addr with additional subflows and link loss
+	# for bidirectional transfer
+	reset
+	init_shapers
+	ip netns exec $ns1 ./pm_nl_ctl limits 0 3
+	ip netns exec $ns1 ./pm_nl_ctl add 10.0.2.1 dev ns1eth2 flags signal
+	ip netns exec $ns2 ./pm_nl_ctl limits 1 3
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 dev ns2eth3 flags subflow
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.4.2 dev ns2eth4 flags subflow
+	run_tests $ns1 $ns2 10.0.1.1 2
+	chk_join_nr "multi flows, signal, bidi, link fail" 3 3 3
+	chk_add_nr 1 1
+	chk_stale_nr $ns2 1 -1 1
+
+	# 2 subflows plus 1 backup subflow with a lossy link, backup
+	# will never be used
+	reset
+	init_shapers
+	ip netns exec $ns1 ./pm_nl_ctl limits 0 2
+	ip netns exec $ns1 ./pm_nl_ctl add 10.0.2.1 dev ns1eth2 flags signal
+	ip netns exec $ns2 ./pm_nl_ctl limits 1 2
+	export FAILING_LINKS="1"
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 dev ns2eth3 flags subflow,backup
+	run_tests $ns1 $ns2 10.0.1.1 1
+	chk_join_nr "backup subflow unused, link failure" 2 2 2
+	chk_add_nr 1 1
+	chk_link_usage $ns2 ns2eth3 $cinsent 0
+
+	# 2 lossy links after half transfer, backup will get half of
+	# the traffic
+	reset
+	init_shapers
+	ip netns exec $ns1 ./pm_nl_ctl limits 0 2
+	ip netns exec $ns1 ./pm_nl_ctl add 10.0.2.1 dev ns1eth2 flags signal
+	ip netns exec $ns2 ./pm_nl_ctl limits 1 2
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 dev ns2eth3 flags subflow,backup
+	export FAILING_LINKS="1 2"
+	run_tests $ns1 $ns2 10.0.1.1 1
+	chk_join_nr "backup flow used, multi links fail" 2 2 2
+	chk_add_nr 1 1
+	chk_stale_nr $ns2 2 4 2
+	chk_link_usage $ns2 ns2eth3 $cinsent 50
+
+	# use a backup subflow with the first subflow on a lossy link
+	# for bidirectional transfer
+	reset
+	init_shapers
+	ip netns exec $ns1 ./pm_nl_ctl limits 0 2
+	ip netns exec $ns1 ./pm_nl_ctl add 10.0.2.1 dev ns1eth2 flags signal
+	ip netns exec $ns2 ./pm_nl_ctl limits 1 3
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 dev ns2eth3 flags subflow,backup
+	run_tests $ns1 $ns2 10.0.1.1 2
+	chk_join_nr "backup flow used, bidi, link failure" 2 2 2
+	chk_add_nr 1 1
+	chk_stale_nr $ns2 1 -1 2
+	chk_link_usage $ns2 ns2eth3 $cinsent 50
 }
 
 add_addr_timeout_tests()