linux-kernel - Re: [PATCH 1/2] x86/mce: Remove old CMCI storm mitigation code

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Date:   Thu, 24 Feb 2022 16:14:05 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>,
        x86@...nel.org, linux-edac@...r.kernel.org,
        linux-kernel@...r.kernel.org, "H . Peter Anvin" <hpa@...or.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Yazen Ghannam <yazen.ghannam@....com>
Subject: Re: [PATCH 1/2] x86/mce: Remove old CMCI storm mitigation code

On Thu, Feb 17, 2022 at 09:35:52AM -0800, Luck, Tony wrote:
> When a "storm" of CMCI is detected this code mitigates by
> disabling CMCI interrupt signalling from all of the banks
> owned by the CPU that saw the storm.
> 
> There are problems with this approach:
> 
> 1) It is very coarse grained. In all liklihood only one of the

Unknown word [liklihood] in commit message.
Suggestions: ['likelihood', 'livelihood']

> banks was geenrating the interrupts, but CMCI is disabled for all.

Unknown word [geenrating] in commit message.
Suggestions: ['generating', 'penetrating', 'germinating', 'entreating', 'ingratiating']

Do I need to give you the whole spiel about using a spellchecker?

:)

> This means Linux may delay seeing and processing errors logged
> from other banks.
> 
> 2) Although CMCI stands for Corrected Machine Check Interrupt, it
> is also used to signal when an uncorrected error is logged. This
> is a problem because these errors should be handled in a timely
> manner.
> 
> Delete all this code in preparation for a finer grained solution.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>  arch/x86/kernel/cpu/mce/core.c     |  20 +---
>  arch/x86/kernel/cpu/mce/intel.c    | 145 -----------------------------
>  arch/x86/kernel/cpu/mce/internal.h |   6 --
>  3 files changed, 1 insertion(+), 170 deletions(-)

Yah, can't complain about diffstats like that.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette