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

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Date:   Mon, 20 Feb 2017 23:34:12 +0100
From:   Miloslav Hůla <miloslav.hula@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ben Hutchings <ben@...adent.org.uk>
Cc:     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 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.

King redards, Miloslav