linux-kernel - Re: [PATCH v2] x86/MCE/AMD: Always give PANIC severity for UC errors IN

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Date:   Fri, 3 Nov 2017 13:02:08 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Yazen Ghannam <Yazen.Ghannam@....com>
Cc:     linux-edac@...r.kernel.org, Tony Luck <tony.luck@...el.com>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] x86/MCE/AMD: Always give PANIC severity for UC errors
 IN_KERNEL context

On Wed, Nov 01, 2017 at 01:59:06PM -0500, Yazen Ghannam wrote:
> From: Yazen Ghannam <yazen.ghannam@....com>
> 
> The AMD severity grading function was introduced in v4.1 and has remained
> logically unchanged with the exception of a separate SMCA severity grading
> function for SMCA systems. The current logic can possibly give
> MCE_AR_SEVERITY for uncorrectable errors in kernel context. The system may
> then get stuck in a loop as memory_failure() will try to handle the bad
> kernel memory and find it busy.
> 
> Return MCE_PANIC_SEVERITY for all UC errors IN_KERNEL context on AMD
> systems.
> 
> After:
> 
>   b2f9d678e28c ("x86/mce: Check for faults tagged in EXTABLE_CLASS_FAULT exception table entries")
> 
> was accepted in v4.6, this issue was masked because of the tail-end attempt
> at kernel mode recovery in the #MC handler.
> 
> However, uncorrectable errors IN_KERNEL context should always be considered
> unrecoverable and cause a panic.
> 
> Fixes: bf80bbd7dcf5 (x86/mce: Add an AMD severities-grading function)
> 
> Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
> [ This needs to be reworked to apply to v4.1 and v4.4 stable branches.]
> Cc: <stable@...r.kernel.org> # 4.9.x
> ---
> Link:
> https://lkml.kernel.org/r/1505830031-9630-1-git-send-email-Yazen.Ghannam@amd.com
> 
> v1->v2:
> * Update commit message.
> 
>  arch/x86/kernel/cpu/mcheck/mce-severity.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)

Applied, thanks.

-- 
Regards/Gruss,
    Boris.

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