Re: [PATCH v2 2/3] s390: Implement arch_do_panic

[Bradley Morgan]

On 28 July 2026 12:40:18 BST, Sven Schnelle <svens@xxxxxxxxxxxxx> wrote:
>Bradley Morgan <include@xxxxxxxxx> writes:
>
>> On 28 July 2026 11:43:17 BST, Mete Durlu <meted@xxxxxxxxxxxxx> wrote:
>>>On 27/07/2026 15:01, Bradley Morgan wrote:
>>>
>>>Hi Bradley,
>>>
>>>>> This now means that the panic_timeout value takes precedence over
>user
>>>>> defined on_panic behavior.
>>>> 
>>>> this is the part i want to poke at. distros routinely ship panic=N on
>>>> the cmdline. with this change, anyone who configured on_panic=dump on
>>>> such a system silently stops getting dumps, because
>>>> emergency_restart() runs first and never returns. a reboot instead of
>>>> the dump you explicitly asked for is strictly worse. if you and Sven
>>>> want that semantic, fine, but spell it out properly and give the s390
>>>> docs for on_panic a line about the new precedence.
>>>
>>>FWICT, there is no mention of shutdown actions in kernel documentation.
>>>s390's user documentation is a different story. I agree it should be
>>>documented on Linux on IBM systems documentation.
>>>
>>>I'd argue that specifying both on_panic=dump and panic=N (N>0) is
>>>a configuration error, but maybe a pr_warn() could be added to the
>>>when on_panic=dump is configured with panic=N is set. That could
>>>hint what is wrong if anyone investigating dmesg and trying to
>>>figure out why system didn't dump.
>>>
>>
>>
>> hey, sorry I'm out, so I can't do the most massive think ever, and I may
>> embarrass myself, heh.
>>
>> I think a BUG would be sufficient, we would want to shut down the system
>> with said bug, I know about panic on warn, but sometimes that's not
>always
>> enabled, something like a BUG would be good, what do you think?
>
>Err... No. You don't want to make a mistake while updating the kernel
>panic parameters just to figure out that on the next boot the kernel just
>BUGs()
>because of that. There are of course lots of reasons why changing the
>kernel
>command line could end up in a non-bootable system but this one would
>be ridiculous.
>

hey, yes, fair enough , thanks, I never said the warn was objectively
wrong, (fair enough), it was more a question.

Thanks!