linux-kernel - Re: mmiotracer hangs the system

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Message-ID: <CAEXux-awb2tAiLSRu35LO_WACm6Fb3ZRtWC=69uB3kWOnqYjMA@mail.gmail.com>
Date:   Fri, 19 Aug 2016 17:08:06 +0200
From:   karol herbst <karolherbst@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: mmiotracer hangs the system

2016-08-19 15:02 GMT+02:00 Andy Shevchenko <andy.shevchenko@...il.com>:
> On Fri, Aug 19, 2016 at 1:35 PM, karol herbst <karolherbst@...il.com> wrote:
>> is there any update on that issue I missed somehow? I really don't
>> want to leave the mmiotracer in a state, where it breaks something
>> while fixing other issues.
>
> No updates. I'm busy right now with more priority tasks and revert
> works for me. Issue is reproducible in my case 100%.
>

Is there something I could do with a "normal" haswell desktop system
to reproduce this issue?

I'll try to play around the next days a bit and maybe I find something
that works out here as well. It seems to be related to
unmapping-mapping cycles.

Because if this only happens with the pwm-lpss driver, it may be
really troublesome to debug, because I don't really know the code that
well to be sure where the issue might be.

> So, I would able to attach dmesg in case it would be helpful.
> Otherwise tell me exact instructions how to debug the issue.
>
> Here you are:
> http://pastebin.com/raw/VfTZENt7
>
>> But for now, without being able to even reproduce the issue, I can't
>> really do much, because the code in the current state looks sane to
>> me. Maybe this case includes the mmiotracer cleaning things up and
>> arms new region for mmiotracing and that's why it fails? Besides that,
>> I have no idea and no way to reproduce this, so I can't help this way.
>
> Maybe. First thing happened is iounmap().
>
>> 2016-08-02 18:13 GMT+02:00 Steven Rostedt <rostedt@...dmis.org>:
>> > On Tue, 2 Aug 2016 19:08:24 +0300
>> > Andy Shevchenko <andy.shevchenko@...il.com> wrote:
>> >
>> >> I don't think so, since linux-next doesn't work until I revert this commit.
>> >>
>> >> I can try exactly v4.6 (yep, I tried stable versions, including
>> >> v4.4.16 that's why all of them failed to me) if you still would like
>> >> me to do so.
>> >
>> > If linux-next doesn't work, then don't bother.
>> >
>> > That commit obviously broke something and you'll probably need help
>> > from Karol to fix it.
>
> --
> With Best Regards,
> Andy Shevchenko