diff --git a/include/net/tcp.h b/include/net/tcp.h
index 35cc7d0d3d47..85ea578195d4 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1630,9 +1630,6 @@ static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unli
 {
 	if (tcp_write_queue_empty(sk))
 		tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
-
-	if (tcp_sk(sk)->highest_sack == skb_unlinked)
-		tcp_sk(sk)->highest_sack = NULL;
 }
 
 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
@@ -1645,12 +1642,8 @@ static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb
 	__tcp_add_write_queue_tail(sk, skb);
 
 	/* Queue it, remembering where we must start sending. */
-	if (sk->sk_write_queue.next == skb) {
+	if (sk->sk_write_queue.next == skb)
 		tcp_chrono_start(sk, TCP_CHRONO_BUSY);
-
-		if (tcp_sk(sk)->highest_sack == NULL)
-			tcp_sk(sk)->highest_sack = skb;
-	}
 }
 
 /* Insert new before skb on the write queue of sk.  */
@@ -1708,9 +1701,7 @@ static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
 
 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
 {
-	struct sk_buff *next = skb_rb_next(skb);
-
-	tcp_sk(sk)->highest_sack = next ?: tcp_send_head(sk);
+	tcp_sk(sk)->highest_sack = skb_rb_next(skb);
 }
 
 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
@@ -1720,9 +1711,7 @@ static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
 
 static inline void tcp_highest_sack_reset(struct sock *sk)
 {
-	struct sk_buff *skb = tcp_rtx_queue_head(sk);
-
-	tcp_sk(sk)->highest_sack = skb ?: tcp_send_head(sk);
+	tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
 }
 
 /* Called when old skb is about to be deleted and replaced by new skb */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index c3447c5512fd..f0b572fe959a 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3534,7 +3534,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 		icsk->icsk_retransmits = 0;
 	}
 
-	prior_fack = tcp_highest_sack_seq(tp);
+	prior_fack = tcp_is_sack(tp) ? tcp_highest_sack_seq(tp) : tp->snd_una;
 	rs.prior_in_flight = tcp_packets_in_flight(tp);
 
 	/* ts_recent update must be made after we are sure that the packet