linux-kernel - Re: Bug#855183: linux-image-4.9.0-0.bpo.1-amd64: modprobe intel_rapl

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Date:   Tue, 21 Feb 2017 10:10:51 +0100
From:   Miloslav Hůla <miloslav.hula@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Ben Hutchings <ben@...adent.org.uk>, x86@...nel.org,
        855183@...s.debian.org, LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Kan Liang <kan.liang@...el.com>
Subject: Re: Bug#855183: linux-image-4.9.0-0.bpo.1-amd64: modprobe
 intel_rapl_perf stay in uninterruptible sleep

Dne 21.02.2017 v 0:24 Thomas Gleixner napsal(a):
> On Mon, 20 Feb 2017, Miloslav Hůla wrote:
>> Dne 17.02.2017 v 11:47 Thomas Gleixner napsal(a):
>>> What's really confusing is this information from the bug report:
>>>
>>> " When I changed:
>>>
>>>   Power technology:
>>>   - from Energy Efficient
>>>   - to Custom
>>>
>>>   Energy Performance BIAS Setting:
>>>   - from Balanced Performance
>>>   - to Performance
>>>
>>>   problem disappeared. systemd-udevd starts normally, module can be
>>>   normally rmmod/insmod'ed now, load is 0.07."
>>>
>>> Miloslav: Is there any chance you can try a 4.10-rc8 kernel on that
>>> machine?
>>
>> I compiled 4.10-rc8 kernel with a stock '/boot/config-4.9.0-0.bpo.1-amd64'
>> config from Debian Jessie backports. Then I reverted BIOS settings to previous
>> state and rebooted the server. Kernel and all modules loaded normally,
>> rmmod/insmod intel_rapl_perf passed normally.
>>
>> Then, without any BIOS change, I rebooted with stock 4.9.0-0.bpo.1-amd64 and
>> suprisingly, everything works, I cannot reproduce it.
>>
>> My knowledge on the field of BIOS are shallow. I don't know what I can do to
>> reproduce the bug now.
>
> Did you just reboot or go through a cold start? That might make a difference.

Reboot only. I'll test it again in next maintenance window.

Regards, Milo