diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 4c6a35d07a08..208f46967ee5 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -2444,7 +2444,11 @@ fib_multipath_hash_policy - INTEGER
 
 	Possible values:
 
-	- 0 - Layer 3 (source and destination addresses plus flow label)
+	- 0 - Layer 3 (source and destination addresses plus flow label).
+	  For IPv6 TCP, the local ECMP path is selected from the socket
+	  txhash rather than the flow label, and may change after a TCP
+	  rehash event (such as a retransmission timeout) to recover from
+	  path failure.  The on-wire flow label is unaffected.
 	- 1 - Layer 4 (standard 5-tuple)
 	- 2 - Layer 3 or inner Layer 3 if present
 	- 3 - Custom multipath hash. Fields used for multipath hash calculation
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 1dec81faff28..3de07e738538 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -955,6 +955,18 @@ static inline u32 ip6_multipath_hash_fields(const struct net *net)
 }
 #endif
 
+/* Derive the IPv6 ECMP hash from txhash so a rehash may pick a different path;
+ * policy 0 only, and only when txhash is set.  >> 1 clears the top bit
+ * (fib6_select_path() uses mp_hash as a signed 31-bit value); ?: 1 keeps the
+ * result non-zero, since mp_hash 0 falls back to rt6_multipath_hash().
+ */
+static inline void ip6_ecmp_set_mp_hash(const struct net *net,
+					struct flowi6 *fl6, u32 txhash)
+{
+	if (ip6_multipath_hash_policy(net) == 0 && txhash)
+		fl6->mp_hash = (txhash >> 1) ?: 1;
+}
+
 /*
  *	Header manipulation
  */
diff --git a/include/net/sock.h b/include/net/sock.h
index 91ddc1a6fd60..51185222aac2 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2262,6 +2262,20 @@ sk_dst_reset(struct sock *sk)
 	sk_dst_set(sk, NULL);
 }
 
+/* Re-roll the socket txhash.  On a rehash, IPv6 also drops the cached route
+ * so the next transmit re-selects an ECMP path; IPv4 keeps its route, since
+ * IPv4 ECMP path selection does not use sk_txhash.
+ */
+static inline bool __sk_rethink_txhash_reset_dst(struct sock *sk)
+{
+	if (sk_rethink_txhash(sk)) {
+		if (sk->sk_family == AF_INET6)
+			__sk_dst_reset(sk);
+		return true;
+	}
+	return false;
+}
+
 struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie);
 
 struct dst_entry *sk_dst_check(struct sock *sk, u32 cookie);
diff --git a/include/net/tcp.h b/include/net/tcp.h
index f063eccbbba3..0632cf39d20a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2540,22 +2540,30 @@ extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops;
 
 #ifdef CONFIG_SYN_COOKIES
 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
-					 const struct sock *sk, struct sk_buff *skb,
-					 __u16 *mss)
+					 struct sk_buff *skb, __u16 *mss)
 {
-	tcp_synq_overflow(sk);
-	__NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
 	return ops->cookie_init_seq(skb, mss);
 }
 #else
 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
-					 const struct sock *sk, struct sk_buff *skb,
-					 __u16 *mss)
+					 struct sk_buff *skb, __u16 *mss)
 {
 	return 0;
 }
 #endif
 
+#ifdef CONFIG_SYN_COOKIES
+static inline void cookie_record_sent(const struct sock *sk)
+{
+	tcp_synq_overflow(sk);
+	__NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
+}
+#else
+static inline void cookie_record_sent(const struct sock *sk)
+{
+}
+#endif
+
 struct tcp_key {
 	union {
 		struct {
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index df479277fb80..73e129768184 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -280,9 +280,13 @@ static int cookie_tcp_reqsk_init(struct sock *sk, struct sk_buff *skb,
 	treq->snt_synack = 0;
 	treq->snt_tsval_first = 0;
 	treq->tfo_listener = false;
-	treq->txhash = net_tx_rndhash();
 	treq->rcv_isn = ntohl(th->seq) - 1;
 	treq->snt_isn = ntohl(th->ack_seq) - 1;
+	/* The request socket was freed after the SYN-ACK; use the cookie
+	 * (snt_isn) as txhash so the full socket and the SYN-ACK make the
+	 * same egress choice (IPv6 ECMP path; IPv4 TX queue).
+	 */
+	treq->txhash = treq->snt_isn;
 	treq->syn_tos = TCP_SKB_CB(skb)->ip_dsfield;
 
 #if IS_ENABLED(CONFIG_MPTCP)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 8560a9c6d382..61045a8886e4 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5022,8 +5022,9 @@ static void tcp_rcv_spurious_retrans(struct sock *sk,
 	    skb->protocol == htons(ETH_P_IPV6) &&
 	    (tcp_sk(sk)->inet_conn.icsk_ack.lrcv_flowlabel !=
 	     ntohl(ip6_flowlabel(ipv6_hdr(skb)))) &&
-	    sk_rethink_txhash(sk))
+	    __sk_rethink_txhash_reset_dst(sk)) {
 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDUPLICATEDATAREHASH);
+	}
 
 	/* Save last flowlabel after a spurious retrans. */
 	tcp_save_lrcv_flowlabel(sk, skb);
@@ -7635,6 +7636,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 	tcp_rsk(req)->af_specific = af_ops;
 	tcp_rsk(req)->ts_off = 0;
 	tcp_rsk(req)->req_usec_ts = false;
+	tcp_rsk(req)->txhash = net_tx_rndhash();
 #if IS_ENABLED(CONFIG_MPTCP)
 	tcp_rsk(req)->is_mptcp = 0;
 #endif
@@ -7658,7 +7660,15 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 	/* Note: tcp_v6_init_req() might override ir_iif for link locals */
 	inet_rsk(req)->ir_iif = inet_request_bound_dev_if(sk, skb);
 
-	dst = af_ops->route_req(sk, skb, &fl, req, isn);
+	if (want_cookie) {
+		isn = cookie_init_sequence(af_ops, skb, &req->mss);
+		/* Use the cookie as txhash so the SYN-ACK and the later full
+		 * socket make the same egress choice (IPv6 ECMP path; IPv4 TX queue).
+		 */
+		tcp_rsk(req)->txhash = isn;
+	}
+
+	dst = af_ops->route_req(sk, skb, &fl, req, want_cookie ? 0 : isn);
 	if (!dst)
 		goto drop_and_free;
 
@@ -7698,7 +7708,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 	tcp_ecn_create_request(req, skb, sk, dst);
 
 	if (want_cookie) {
-		isn = cookie_init_sequence(af_ops, sk, skb, &req->mss);
+		cookie_record_sent(sk);
 		if (!tmp_opt.tstamp_ok)
 			inet_rsk(req)->ecn_ok = 0;
 	}
@@ -7716,7 +7726,6 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 	}
 #endif
 	tcp_rsk(req)->snt_isn = isn;
-	tcp_rsk(req)->txhash = net_tx_rndhash();
 	tcp_rsk(req)->syn_tos = TCP_SKB_CB(skb)->ip_dsfield;
 	tcp_openreq_init_rwin(req, sk, dst);
 	sk_rx_queue_set(req_to_sk(req), skb);
diff --git a/net/ipv4/tcp_plb.c b/net/ipv4/tcp_plb.c
index c11a0cd3f8fe..bcc2f0add6af 100644
--- a/net/ipv4/tcp_plb.c
+++ b/net/ipv4/tcp_plb.c
@@ -78,7 +78,7 @@ void tcp_plb_check_rehash(struct sock *sk, struct tcp_plb_state *plb)
 	if (plb->pause_until)
 		return;
 
-	sk_rethink_txhash(sk);
+	__sk_rethink_txhash_reset_dst(sk);
 	plb->consec_cong_rounds = 0;
 	WRITE_ONCE(tcp_sk(sk)->plb_rehash, tcp_sk(sk)->plb_rehash + 1);
 	NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPPLBREHASH);
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 322db13333c7..bf171b5e1eb3 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -297,7 +297,7 @@ static int tcp_write_timeout(struct sock *sk)
 		return 1;
 	}
 
-	if (sk_rethink_txhash(sk)) {
+	if (__sk_rethink_txhash_reset_dst(sk)) {
 		WRITE_ONCE(tp->timeout_rehash, tp->timeout_rehash + 1);
 		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPTIMEOUTREHASH);
 	}
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 48dd7711d659..282912a11999 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -822,6 +822,8 @@ int inet6_sk_rebuild_header(struct sock *sk)
 	fl6->flowi6_uid = sk_uid(sk);
 	security_sk_classify_flow(sk, flowi6_to_flowi_common(fl6));
 
+	ip6_ecmp_set_mp_hash(sock_net(sk), fl6, sk->sk_txhash);
+
 	rcu_read_lock();
 	final_p = fl6_update_dst(fl6, rcu_dereference(np->opt), &np->final);
 	rcu_read_unlock();
diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
index 4665d84a7380..3e4ce8cb478e 100644
--- a/net/ipv6/inet6_connection_sock.c
+++ b/net/ipv6/inet6_connection_sock.c
@@ -48,6 +48,8 @@ struct dst_entry *inet6_csk_route_req(const struct sock *sk,
 	fl6->flowi6_uid = sk_uid(sk);
 	security_req_classify_flow(req, flowi6_to_flowi_common(fl6));
 
+	ip6_ecmp_set_mp_hash(sock_net(sk), fl6, tcp_rsk(req)->txhash);
+
 	if (!dst) {
 		dst = ip6_dst_lookup_flow(sock_net(sk), sk, fl6, final_p);
 		if (IS_ERR(dst))
@@ -70,6 +72,9 @@ struct dst_entry *inet6_csk_route_socket(struct sock *sk,
 	fl6->saddr = np->saddr;
 	fl6->flowlabel = np->flow_label;
 	IP6_ECN_flow_xmit(sk, fl6->flowlabel);
+
+	if (sk->sk_protocol == IPPROTO_TCP)
+		ip6_ecmp_set_mp_hash(sock_net(sk), fl6, sk->sk_txhash);
 	fl6->flowi6_oif = sk->sk_bound_dev_if;
 	fl6->flowi6_mark = sk->sk_mark;
 	fl6->fl6_sport = inet->inet_sport;
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 4f6f0d751d6c..b581cb1ee2e8 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -245,6 +245,8 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 		fl6.flowi6_uid = sk_uid(sk);
 		security_req_classify_flow(req, flowi6_to_flowi_common(&fl6));
 
+		ip6_ecmp_set_mp_hash(net, &fl6, tcp_rsk(req)->txhash);
+
 		dst = ip6_dst_lookup_flow(net, sk, &fl6, final_p);
 		if (IS_ERR(dst)) {
 			SKB_DR_SET(reason, IP_OUTNOROUTES);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index c219f3334835..ebe161d72fbd 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -258,6 +258,8 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr_unsized *uaddr,
 	if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr))
 		saddr = &sk->sk_v6_rcv_saddr;
 
+	sk_set_txhash(sk);
+
 	fl6->flowi6_proto = IPPROTO_TCP;
 	fl6->daddr = sk->sk_v6_daddr;
 	fl6->saddr = saddr ? *saddr : np->saddr;
@@ -275,6 +277,14 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr_unsized *uaddr,
 
 	security_sk_classify_flow(sk, flowi6_to_flowi_common(fl6));
 
+	/* Non-zero mp_hash bypasses rt6_multipath_hash() in
+	 * fib6_select_path(), letting txhash control ECMP path
+	 * selection so that sk_rethink_txhash() rehashes onto a
+	 * different path.  Policies 1-3 derive a deterministic
+	 * hash from the flow keys and must not be overridden.
+	 */
+	ip6_ecmp_set_mp_hash(net, fl6, sk->sk_txhash);
+
 	dst = ip6_dst_lookup_flow(net, sk, fl6, final_p);
 	if (IS_ERR(dst)) {
 		err = PTR_ERR(dst);
@@ -315,8 +325,6 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr_unsized *uaddr,
 	if (err)
 		goto late_failure;
 
-	sk_set_txhash(sk);
-
 	if (likely(!tp->repair)) {
 		union tcp_seq_and_ts_off st;
 
@@ -957,6 +965,13 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
 	if (txhash) {
 		/* autoflowlabel/skb_get_hash_flowi6 rely on buff->hash */
 		skb_set_hash(buff, txhash, PKT_HASH_TYPE_L4);
+
+		/* Select the local ECMP path from the connection's txhash,
+		 * so a control packet (RST, or ACK from a time-wait socket)
+		 * uses the same nexthop as the data.  Only policy 0 uses
+		 * mp_hash; policies 1-3 derive a deterministic hash.
+		 */
+		ip6_ecmp_set_mp_hash(net, &fl6, txhash);
 	}
 	fl6.flowi6_mark = IP6_REPLY_MARK(net, skb->mark) ?: mark;
 	fl6.fl6_dport = t1->dest;