Subject: bug#22548: Kernel panic after system reconfiguration

From: Alex Kost <[email-masked]>
Date: Thu, 04 Feb 2016 15:55:37 +0300

Mark H Weaver (2016-02-04 01:14 +0300) wrote:

> Albin <[email-masked]> writes:
>
>> Hi again,
>>
>> I got rid of the kernel panic by removing the following from the config
>> and reconfiguring (as suggested by Mark Weaver):
>>
>>> (swap-devices '("/swapfile"))
>>
>> It would be nice to be able to enable swap again though. On my system it
>> needs to be done with a swap file.
>
> I suspect this never worked, but that before the error was silently
> ignored.  In my case, I had:
>
>   (swap-devices '("/dev/disk/by-label/jojen-swap"))
>
> and /dev/disk went away at some point due to another problem.  For a
> long time, I simply had no swap.  With the dmd -> shepherd transition,
> it started causing a fatal error during boot, leading to a kernel panic.
> Unfortunately, the error message scrolled off the screen very quickly,
> obscured by a useless kernel backtrace.

I faced the same kernel panic as I also had "/dev/disk/..." swap device.

Obviously it didn't work for some time when dmd was the init system
(because on GuixSD there is no "/dev/disk/" since… I don't know when as
I've never noticed it before).

And as reported by several people on #guix (I count at least 4 including
me and Mark) a wrong swap device leads to a kernel panic if shepherd is
used as the init system.

Until I realized that it was a wrong swap, I made bisecting on shepherd
to find out which commit introduced this bug.  It gave me commit
852341e¹: when I reconfigured my system (with a wrong swap) using
shepherd on this commit, I had a kernel panic, while with shepherd on
the previous commit the system booted successfully.

¹ http://git.savannah.gnu.org/cgit/shepherd.git/commit/?id=852341ed0c08941cbdd022135f8bef7be2d7ec54

-- 
Alex