From: Michal Kubecek <mkubecek@suse.cz>
To: Yunsheng Lin <linyunsheng@huawei.com>
Cc: Jiri Kosina <jikos@kernel.org>, Hillf Danton <hdanton@sina.com>,
John Fastabend <john.fastabend@gmail.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
Paolo Abeni <pabeni@redhat.com>,
Kehuan Feng <kehuan.feng@gmail.com>,
Jike Song <albcamus@gmail.com>,
Jonas Bonn <jonas.bonn@netrounds.com>,
Michael Zhivich <mzhivich@akamai.com>,
David Miller <davem@davemloft.net>,
LKML <linux-kernel@vger.kernel.org>,
Netdev <netdev@vger.kernel.org>, Josh Hunt <johunt@akamai.com>
Subject: Re: Packet gets stuck in NOLOCK pfifo_fast qdisc
Date: Tue, 6 Apr 2021 09:06:59 +0200 [thread overview]
Message-ID: <20210406070659.t6csfgkskbmmxtx5@lion.mk-sys.cz> (raw)
In-Reply-To: <eaff25bc-9b64-037e-b9bc-c06fc4a5a9fb@huawei.com>
On Tue, Apr 06, 2021 at 08:55:41AM +0800, Yunsheng Lin wrote:
>
> Hi, Jiri
> Do you have a reproducer that can be shared here?
> With reproducer, I can debug and test it myself too.
I'm afraid we are not aware of a simple reproducer. As mentioned in the
original discussion, the race window is extremely small and the other
thread has to do quite a lot in the meantime which is probably why, as
far as I know, this was never observed on real hardware, only in
virtualization environments. NFS may also be important as, IIUC, it can
often issue an RPC request from a different CPU right after a data
transfer. Perhaps you could cheat a bit and insert a random delay
between the empty queue check and releasing q->seqlock to make it more
likely to happen.
Other than that, it's rather just "run this complex software in a xen VM
and wait".
Michal
next prev parent reply other threads:[~2021-04-06 7:07 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 6:46 Packet gets stuck in NOLOCK pfifo_fast qdisc Jonas Bonn
2019-10-09 19:14 ` Paolo Abeni
2019-10-10 6:27 ` Jonas Bonn
2019-10-11 0:39 ` Jonas Bonn
2020-06-23 13:42 ` Michael Zhivich
2020-06-30 19:14 ` Josh Hunt
2020-07-01 7:53 ` Jonas Bonn
2020-07-01 16:05 ` Cong Wang
2020-07-01 19:58 ` Cong Wang
2020-07-01 22:02 ` Josh Hunt
2020-07-02 6:14 ` Jonas Bonn
2020-07-02 9:45 ` Paolo Abeni
2020-07-02 18:08 ` Josh Hunt
2020-07-07 14:18 ` Paolo Abeni
2020-07-08 20:16 ` Cong Wang
2020-07-09 9:20 ` Paolo Abeni
2020-07-08 20:33 ` Zhivich, Michael
2020-08-20 7:43 ` Jike Song
2020-08-20 18:13 ` Josh Hunt
[not found] ` <20200822032800.16296-1-hdanton@sina.com>
2020-08-25 2:18 ` Fengkehuan Feng
[not found] ` <20200825032312.11776-1-hdanton@sina.com>
2020-08-25 7:14 ` Fengkehuan Feng
[not found] ` <20200825162329.11292-1-hdanton@sina.com>
2020-08-26 2:38 ` Kehuan Feng
[not found] ` <CACS=qqKptAQQGiMoCs1Zgs9S4ZppHhasy1AK4df2NxnCDR+vCw@mail.gmail.com>
[not found] ` <5f46032e.1c69fb81.9880c.7a6cSMTPIN_ADDED_MISSING@mx.google.com>
2020-08-27 6:56 ` Kehuan Feng
[not found] ` <20200827125747.5816-1-hdanton@sina.com>
2020-08-28 1:45 ` Kehuan Feng
2020-09-03 5:01 ` Cong Wang
2020-09-03 8:39 ` Paolo Abeni
2020-09-03 17:43 ` Cong Wang
2020-09-04 5:07 ` John Fastabend
2020-09-10 20:15 ` Cong Wang
2020-09-10 21:07 ` John Fastabend
2020-09-10 21:40 ` Paolo Abeni
2021-04-02 19:25 ` Jiri Kosina
2021-04-02 19:33 ` Josh Hunt
[not found] ` <20210403003537.2032-1-hdanton@sina.com>
2021-04-03 12:23 ` Jiri Kosina
2021-04-06 0:55 ` Yunsheng Lin
2021-04-06 7:06 ` Michal Kubecek [this message]
2021-04-06 10:13 ` Juergen Gross
2021-04-06 12:17 ` Yunsheng Lin
2021-04-06 1:49 ` Cong Wang
2021-04-06 2:46 ` Yunsheng Lin
2021-04-06 7:31 ` Michal Kubecek
2021-04-06 12:24 ` Yunsheng Lin
[not found] ` <20200903101957.428-1-hdanton@sina.com>
2020-09-04 3:20 ` Kehuan Feng
2020-09-10 20:19 ` Cong Wang
2020-09-14 2:10 ` Yunsheng Lin
2020-09-17 19:52 ` Cong Wang
2020-09-18 2:06 ` Kehuan Feng
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