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

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Moving the s390 on_panic trigger execution to arch_do_panic() causes it to be completely skipped if a non-zero panic_timeout is configured, silently breaking hardware crash dumps.
--

--- Patch [2]: [PATCH v2 2/3] s390: Implement arch_do_panic ---
commit c54479b24863a9224f8701eeac5365ad207e8313
Author: Mete Durlu <meted@linux.ibm.com>

s390: Implement arch_do_panic

This commit moves the s390-specific panic handling out of the panic_notifier
call chain and into the arch_do_panic hook. The stated intention is to
allow the generic panic_timeout to take precedence over the architecture's
user-defined panic behavior.

> diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
> --- a/arch/s390/kernel/ipl.c
> +++ b/arch/s390/kernel/ipl.c

[ ... ]

> @@ -2115,7 +2115,7 @@ static ssize_t on_panic_store(struct kobject *kobj,
>  }
>  static struct kobj_attribute on_panic_attr = __ATTR_RW(on_panic);
>  
> -static void do_panic(void)
> +void arch_do_panic(void)
>  {
>  	lgr_info_log();
>  	on_panic_trigger.action->fn(&on_panic_trigger);
>  	stop_run(&on_panic_trigger);
>  }

[Severity: High]
If a non-zero panic_timeout is configured, vpanic calls emergency_restart
which never returns.

Since arch_do_panic is invoked at the very end of vpanic after the timeout
logic:

kernel/panic.c:vpanic() {
        ...
        if (panic_timeout != 0) {
                ...
                emergency_restart();
        }
        ...
        arch_do_panic();
        ...
}

Does this mean the s390 hardware dump logic here will be completely skipped
instead of taking lower precedence? Could this regression silently break
crash dumps configured via on_panic=dump when a generic timeout parameter
is set?

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260727-arch_do_panic-v2-0-4e25ceb05075@linux.ibm.com?part=2