netdev - Re: [Patch net 00/16] net_sched: fix races with RCU callbacks

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Message-ID: <CAM_iQpXCHbPG0JfWLET+d7AEB5W=Rhxu6xB_kLgBjzwGq43jXg@mail.gmail.com>
Date:   Tue, 31 Oct 2017 15:09:57 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Lucas Bates <lucasb@...atatu.com>
Cc:     Jamal Hadi Salim <jhs@...atatu.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Chris Mi <chrism@...lanox.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jiri Pirko <jiri@...nulli.us>,
        John Fastabend <john.fastabend@...il.com>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [Patch net 00/16] net_sched: fix races with RCU callbacks

On Tue, Oct 31, 2017 at 12:13 PM, Lucas Bates <lucasb@...atatu.com> wrote:
> On Tue, Oct 31, 2017 at 2:55 PM, Lucas Bates <lucasb@...atatu.com> wrote:
>> Unfortunately it doesn't seem to have had any effect, I'm still seeing
>> the same bug as yesterday. At Jamal's suggestion I put in a delay

As I replied to you privately, it is probably because idrinfo is freed
before action itself. So just RTNL is not enough.


>> after tdc completed running the tests but before it deleted the
>> container - and I didn't run into the bug after many runs. I had no
>> luck getting serial console access on any of our other systems so I
>> have another stack trace photo which I'll send to you directly.
>
> I forgot to mention: it appears the bug appears to be related to
> deleting the container. Test d052 is the last to run before tdc does
> its teardown and deletes the container; if I add the sleep the bug
> never gets triggered.

This almost rules out the guilty of this patchset.

I will provide a patch for you to test, since I can't reproduce it here.

Thanks!