Re: [PATCH v2] reboot: log the task that requested a reboot or shutdown

[Bradley Morgan]

On July 20, 2026 7:15:40 AM GMT+01:00, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>On Sun, 19 Jul 2026 16:09:38 +0000 Bradley Morgan <include@xxxxxxxxx>
>wrote:
>
>> When a machine reboots or powers off, the kernel log records what
>> happened but not who asked for it.  The reboot syscall throws the
>> caller identity away, and reconstructing it afterwards from userspace
>> logs is unreliable and more likely than not impossible.
>> "What made this reboot?" is a question every fleet operator has had to
>> answer with guesswork.
>
>There's a need for this?  May I ask your source for this information?

I had no source, at the time, I just thought it'd be obviously useful.

Now I did some research, I found this tool:
https://docs.memfault.com/docs/linux/reboot-reason-tracking



>> Log the comm and pid of the calling task in the reboot syscall, once
>> the requested command is committed and can no longer fail, e.g:
>> 
>>   reboot: initiated by systemd-shutdow[1]
>>   reboot: Restarting system
>
>I can see it might be useful.

Thanks

>> The existing "Restarting system", "System halted" and "Power down"
>> lines are left untouched, so anything parsing dmesg today keeps
>> working. The two ctrl alt del toggle commands are excluded so init
>> setting the mode does not add a line to dmesg on every boot.
>
>Perhaps kexec and suswp would benefit from the same treatment. 
>Perhaps add the relevant maintainers to cc and seek their input?

kexec is definitely gonna be able to use this, hibernation has /sys/power
Entry points. So not sure about them

>
>

Thanks!