Re: [PATCH v5 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:
- [Medium] The newly introduced `arch_do_panic()` hook is placed before the final console flushes, which causes the 'end Kernel panic' marker to remain unflushed in deferred printk contexts on s390.
--

--- Patch [2]: [PATCH v5 2/3] s390: Implement arch_do_panic() ---
commit b9b01d12abb499c817ce8c2a246d404e0331bf81
Author: Mete Durlu <meted@linux.ibm.com>

s390: Implement arch_do_panic()

This commit introduces a s390-specific arch_do_panic() implementation, removing
an ifdef section from vpanic(). It moves the disabled_wait() call so it occurs
after the "end Kernel panic" marker is printed.

> diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
> index 564403496a7ce..309d3d3e95fd9 100644
> --- a/arch/s390/kernel/traps.c
> +++ b/arch/s390/kernel/traps.c
[ ... ]
> @@ -275,6 +277,11 @@ static void monitor_event_exception(struct pt_regs *regs)
>  	}
>  }
>  
> +void arch_do_panic(void)
> +{
> +	disabled_wait();
> +}
> +

[Severity: Medium]
Will this prevent the final console flushes from executing on s390?

Looking at vpanic() in kernel/panic.c, arch_do_panic() is called before the
final console flushes:

	pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);

	arch_do_panic();
	/* Do not scroll important messages printed above */
	suppress_printk = 1;

	/*
	 * The final messages may not have been printed if in a context that
	 * defers printing (such as NMI) and irq_work is not available.
	 * Explicitly flush the kernel log buffer one last time.
	 */
	console_flush_on_panic(CONSOLE_FLUSH_PENDING);
	nbcon_atomic_flush_unsafe();

Since disabled_wait() puts the CPU into an infinite wait state, it never
returns to vpanic(). If the panic occurs in a context that defers printk
(such as an NMI), does this mean the "end Kernel panic" marker will remain
unflushed and not visible on the console?

>  void kernel_stack_invalid(struct pt_regs *regs)
>  {

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260810-arch_do_panic-v5-0-e86ae992c253@linux.ibm.com?part=2