From: Vishwanath Pai <vpai@akamai.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Yunsheng Lin <linyunsheng@huawei.com>,
"Hunt, Joshua" <johunt@akamai.com>,
Jamal Hadi Salim <jhs@mojatatu.com>,
Jiri Pirko <jiri@resnulli.us>, David Miller <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"linuxarm@huawei.com" <linuxarm@huawei.com>,
John Fastabend <john.fastabend@gmail.com>,
Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH v2 net] net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc
Date: Wed, 28 Oct 2020 16:04:52 -0400 [thread overview]
Message-ID: <19f888c2-8bc1-ea56-6e19-4cb4841c4da0@akamai.com> (raw)
In-Reply-To: <CAM_iQpX0XzNDCzc2U5=g6aU-HGYs3oryHx=rmM3ue9sH=Jd4Gw@mail.gmail.com>
On 10/28/20 1:47 PM, Cong Wang wrote:
> On Wed, Oct 28, 2020 at 8:37 AM Pai, Vishwanath <vpai@akamai.com> wrote:
>> Hi,
>>
>> We noticed some problems when testing the latest 5.4 LTS kernel and
traced it
>> back to this commit using git bisect. When running our tests the
machine stops
>> responding to all traffic and the only way to recover is a reboot. I
do not see
>> a stack trace on the console.
>
> Do you mean the machine is still running fine just the network is down?
>
> If so, can you dump your tc config with stats when the problem is
happening?
> (You can use `tc -s -d qd show ...`.)
>
>>
>> This can be reproduced using the packetdrill test below, it should
be run a
>> few times or in a loop. You should hit this issue within a few tries but
>> sometimes might take up to 15-20 tries.
> ...
>> I can reproduce the issue easily on v5.4.68, and after reverting
this commit it
>> does not happen anymore.
>
> This is odd. The patch in this thread touches netdev reset path, if
packetdrill
> is the only thing you use to trigger the bug (that is netdev is
always active),
> I can not connect them.
>
> Thanks.
Hi Cong,
> Do you mean the machine is still running fine just the network is down?
I was able to access the machine via serial console, it looks like it is
up and running, just that networking is down.
> If so, can you dump your tc config with stats when the problem is
happening?
> (You can use `tc -s -d qd show ...`.)
If I try running tc when the machine is in this state the command never
returns. It doesn't print anything but doesn't exit either.
> This is odd. The patch in this thread touches netdev reset path, if
packetdrill
> is the only thing you use to trigger the bug (that is netdev is
always active),
> I can not connect them.
I think packetdrill creates a tun0 interface when it starts the
test and tears it down at the end, so it might be hitting this code path
during teardown.
P.S: My mail server is having connectivity issues with vger.kernel.org
so messages aren't getting delivered to netdev. It'll hopefully get
resolved soon.
Thanks,
Vishwanath
next prev parent reply other threads:[~2020-10-29 2:00 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-08 11:02 [PATCH v2 net] net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc Yunsheng Lin
2020-09-10 19:39 ` David Miller
2020-09-10 20:07 ` Cong Wang
2020-09-11 8:13 ` Yunsheng Lin
2020-09-11 8:25 ` Yunsheng Lin
2020-09-17 19:26 ` Cong Wang
[not found] ` <CAP12E-+3DY-dgzVercKc-NYGPExWO1NjTOr1Gf3tPLKvp6O6+g@mail.gmail.com>
2020-10-28 15:37 ` Pai, Vishwanath
2020-10-28 17:47 ` Cong Wang
2020-10-28 20:04 ` Vishwanath Pai [this message]
2020-10-29 2:37 ` Yunsheng Lin
2020-10-29 4:50 ` Vishwanath Pai
2020-10-29 10:24 ` Yunsheng Lin
2020-10-29 17:20 ` Vishwanath Pai
2020-11-02 9:08 ` Yunsheng Lin
2020-11-02 18:23 ` Vishwanath Pai
2020-10-28 17:46 ` Vishwanath Pai
2020-10-29 2:52 ` Yunsheng Lin
2020-10-29 19:05 ` Cong Wang
2020-10-30 7:37 ` Yunsheng Lin
2020-11-02 16:55 ` Cong Wang
2020-11-03 7:24 ` Yunsheng Lin
2020-11-05 6:04 ` Cong Wang
2020-11-05 6:16 ` Cong Wang
2020-11-05 6:32 ` Yunsheng Lin
2020-11-05 6:22 ` Yunsheng Lin
2020-09-09 4:07 kernel test robot
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