Re: [vlan_device_event] BUG: unable to handle kernel paging request at 6b6b6ccf

On Thu, Nov 09, 2017 at 02:55:10PM +0800, Fengguang Wu wrote:

On Wed, Nov 08, 2017 at 10:34:10PM -0800, Cong Wang wrote:

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On Wed, Nov 8, 2017 at 7:12 PM, Fengguang Wu [off-list ref] wrote:

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Hi Alex,

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So looking over the trace the panic seems to be happening after a
decnet interface is getting deleted. Is there any chance we could try
compiling the kernel without decnet support to see if that is the
source of these issues? I don't know if anyone on the Intel Wired Lan
team is testing with that enabled so if we can eliminate that as a
possible cause that would be useful.

Sure and thank you for the suggestion!

It looks disabling DECNET still triggers the vlan_device_event BUG.
However when looking at the dmesgs, I find another warning just before
the vlan_device_event BUG. Not sure if it's related one or independent
now-fixed issue.

Those decnet symbols are probably noises.

Yes it's not related to CONFIG_DECNET.

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How do you reproduce it? And what is your setup? Vlan device on
top of your eth0 (e1000)?

It can basically be reproduced in one of our test machines --
lkp-wsx03, which is a Westmere EX server.

Anyway if you'd like to try, here are the steps. It'll auto download
the images and run QEMU.

        apt-get install lib32gcc-7-dev # or lib32gcc-6-dev
        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> job-script  # job-script is attached in this email

Note that even in our lkp-wsx03 machine, the chance of reproducing it
is only 3% (3 out of 100 boots).

Thanks,
Fengguang