6.12-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit ea33537d82921e71f852ea2ed985acc562125efe ]
If the application can not drain fast enough a TCP socket queue, tcp_rcv_space_adjust() can overestimate tp->rcvq_space.space.
Then sk->sk_rcvbuf can grow and hit tcp_rmem[2] for no good reason.
Fix this by taking into acount the number of available bytes.
Keeping sk->sk_rcvbuf at the right size allows better cache efficiency.
Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: Wei Wang weiwan@google.com Link: https://patch.msgid.link/20250513193919.1089692-5-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/tcp.h | 2 +- net/ipv4/tcp_input.c | 6 ++++-- 2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 6a5e08b937b31..5f56fa8780131 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -336,7 +336,7 @@ struct tcp_sock { } rcv_rtt_est; /* Receiver queue space */ struct { - u32 space; + int space; u32 seq; u64 time; } rcvq_space; diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 7e772b6cb45b6..c59c1cc1a8fed 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -749,8 +749,7 @@ static inline void tcp_rcv_rtt_measure_ts(struct sock *sk, void tcp_rcv_space_adjust(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); - u32 copied; - int time; + int time, inq, copied;
trace_tcp_rcv_space_adjust(sk);
@@ -761,6 +760,9 @@ void tcp_rcv_space_adjust(struct sock *sk)
/* Number of bytes copied to user in last RTT */ copied = tp->copied_seq - tp->rcvq_space.seq; + /* Number of bytes in receive queue. */ + inq = tp->rcv_nxt - tp->copied_seq; + copied -= inq; if (copied <= tp->rcvq_space.space) goto new_measure;