Hi Eric, I'm sorry that I didn't write enough clearly. We're running the pristine 4.19.125 linux kernel (the latest LTS version) and have been haunted by such an issue. This patch is high-important, I think. So I'm going to resend this email with the [patch 4.19] on the headline and cc Greg.
Thanks, Jason On Tue, Jun 2, 2020 at 9:05 PM Eric Dumazet <eduma...@google.com> wrote: > > On Tue, Jun 2, 2020 at 1:05 AM <kerneljasonx...@gmail.com> wrote: > > > > From: Jason Xing <kerneljasonx...@gmail.com> > > > > TCP socks cannot be released because of the sock_hold() increasing the > > sk_refcnt in the manner of tcp_internal_pacing() when RTO happens. > > Therefore, this situation could increase the slab memory and then trigger > > the OOM if the machine has beening running for a long time. This issue, > > however, can happen on some machine only running a few days. > > > > We add one exception case to avoid unneeded use of sock_hold if the > > pacing_timer is enqueued. > > > > Reproduce procedure: > > 0) cat /proc/slabinfo | grep TCP > > 1) switch net.ipv4.tcp_congestion_control to bbr > > 2) using wrk tool something like that to send packages > > 3) using tc to increase the delay in the dev to simulate the busy case. > > 4) cat /proc/slabinfo | grep TCP > > 5) kill the wrk command and observe the number of objects and slabs in TCP. > > 6) at last, you could notice that the number would not decrease. > > > > Signed-off-by: Jason Xing <kerneljasonx...@gmail.com> > > Signed-off-by: liweishi <liwei...@kuaishou.com> > > Signed-off-by: Shujin Li <lishu...@kuaishou.com> > > --- > > net/ipv4/tcp_output.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c > > index cc4ba42..5cf63d9 100644 > > --- a/net/ipv4/tcp_output.c > > +++ b/net/ipv4/tcp_output.c > > @@ -969,7 +969,8 @@ static void tcp_internal_pacing(struct sock *sk, const > > struct sk_buff *skb) > > u64 len_ns; > > u32 rate; > > > > - if (!tcp_needs_internal_pacing(sk)) > > + if (!tcp_needs_internal_pacing(sk) || > > + hrtimer_is_queued(&tcp_sk(sk)->pacing_timer)) > > return; > > rate = sk->sk_pacing_rate; > > if (!rate || rate == ~0U) > > -- > > 1.8.3.1 > > > > Hi Jason. > > Please do not send patches that do not apply to current upstream trees. > > Instead, backport to your kernels the needed fixes. > > I suspect that you are not using a pristine linux kernel, but some > heavily modified one and something went wrong in your backports. > Do not ask us to spend time finding what went wrong. > > Thank you.
