linux-kernel - Re: [PATCH] acpi/ghes: add TAINT_MACHINE

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Message-ID: <aGVe4nv18dRHHV16@agluck-desk3>
Date: Wed, 2 Jul 2025 09:31:30 -0700
From: "Luck, Tony" <tony.luck@...el.com>
To: Breno Leitao <leitao@...ian.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
	James Morse <james.morse@....com>, Borislav Petkov <bp@...en8.de>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-team@...a.com
Subject: Re: [PATCH] acpi/ghes: add TAINT_MACHINE_CHECK on GHES panic path

On Wed, Jul 02, 2025 at 08:39:51AM -0700, Breno Leitao wrote:
> When a GHES (Generic Hardware Error Source) triggers a panic, add the
> TAINT_MACHINE_CHECK taint flag to the kernel. This explicitly marks the

While it might not strictly be a machine check that caused GHES to
panic, it seems close enough from the available TAINT options.

So unless someone feels it would be better to create a new TAINT
flag (TAINT_FATAL_GHES? TAINT_FIRMWARE_REPORTED_FATAL_ERRROR?)
then this seems OK to me.

Reviewed-by: Tony Luck <tony.luck@...el.com>

> kernel as tainted due to a machine check event, improving diagnostics
> and post-mortem analysis. The taint is set with LOCKDEP_STILL_OK to
> indicate lockdep remains valid.
> 
> At large scale deployment, this helps to quickly determin panics that
> are coming due to hardware failures.
> 
> Signed-off-by: Breno Leitao <leitao@...ian.org>
> ---
>  drivers/acpi/apei/ghes.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index f0584ccad4519..3d44f926afe8e 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -1088,6 +1088,8 @@ static void __ghes_panic(struct ghes *ghes,
>  
>  	__ghes_print_estatus(KERN_EMERG, ghes->generic, estatus);
>  
> +	add_taint(TAINT_MACHINE_CHECK, LOCKDEP_STILL_OK);
> +
>  	ghes_clear_estatus(ghes, estatus, buf_paddr, fixmap_idx);
>  
>  	if (!panic_timeout)
> 
> ---
> base-commit: e96ee511c906c59b7c4e6efd9d9b33917730e000
> change-id: 20250702-add_tain-902925f3eb96
> 
> Best regards,
> --  
> Breno Leitao <leitao@...ian.org>
>