linux-kernel - Re: [PATCH v8] panic: add panic_force_cpu= parameter to redirect panic to a specific CPU

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Message-ID: <aXuIcrRvkhwITdWI@pathway.suse.cz>
Date: Thu, 29 Jan 2026 17:21:02 +0100
From: Petr Mladek <pmladek@...e.com>
To: Pnina Feder <pnina.feder@...ileye.com>
Cc: akpm@...ux-foundation.org, bhe@...hat.com, linux-kernel@...r.kernel.org,
	lkp@...el.com, mgorman@...e.de, mingo@...hat.com,
	peterz@...radead.org, rostedt@...dmis.org, senozhatsky@...omium.org,
	tglx@...utronix.de, vkondra@...ileye.com
Subject: Re: [PATCH v8] panic: add panic_force_cpu= parameter to redirect
 panic to a specific CPU

On Thu 2026-01-22 12:24:57, Pnina Feder wrote:
> Some platforms require panic handling to execute on a specific CPU for
> crash dump to work reliably. This can be due to firmware limitations,
> interrupt routing constraints, or platform-specific requirements where
> only a single CPU is able to safely enter the crash kernel.
> 
> Add the panic_force_cpu= kernel command-line parameter to redirect panic
> execution to a designated CPU. When the parameter is provided, the CPU
> that initially triggers panic forwards the panic context to the target
> CPU via IPI, which then proceeds with the normal panic and kexec flow.
> 
> The IPI delivery is implemented as a weak function (panic_smp_redirect_cpu)
> so architectures with NMI support can override it for more reliable delivery.
> 
> If the specified CPU is invalid, offline, or a panic is already in
> progress on another CPU, the redirection is skipped and panic continues
> on the current CPU.
> 
> Signed-off-by: Pnina Feder <pnina.feder@...ileye.com>

I can't see any obvious problem any longer ;-)
Feel free to use:

Reviewed-by: Petr Mladek <pmladek@...e.com>

Best Regards,
Petr