linux-kernel - RE: [PATCH] x86/MCE/AMD: Always give PANIC severity for UC errors in kernel context

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Date:   Tue, 26 Sep 2017 15:21:22 +0000
From:   "Ghannam, Yazen" <Yazen.Ghannam@....com>
To:     Borislav Petkov <bp@...en8.de>
CC:     "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        Tony Luck <tony.luck@...el.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] x86/MCE/AMD: Always give PANIC severity for UC errors in
 kernel context

> -----Original Message-----
> From: Borislav Petkov [mailto:bp@...en8.de]
> Sent: Tuesday, September 26, 2017 8:01 AM
> To: Ghannam, Yazen <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] x86/MCE/AMD: Always give PANIC severity for UC
> errors in kernel context
> 
> (drop CC:stable from CC list)
> 
> Do not add CC:stable when sending the patch with git send-email.
> 

How should I CC:stable? 

> On Tue, Sep 19, 2017 at 09:07:11AM -0500, Yazen Ghannam wrote:
> > From: Yazen Ghannam <yazen.ghannam@....com>
> >
> > Our current AMD severity logic can possibly give MCE_AR_SEVERITY for
> > uncorrectable errors in kernel context. The current #MC handler only
> > calls
> > memory_failure() on errors in user context, but older versions will
> > call
> > memory_failure() unconditionally.
> 
> Err, I don't understand this aspect: what does "older versions" mean here
> exactly?
> 
> There are no older versions of the #MC handler - there's only one version -
> the version against which this patch gets applied.
> 
> Hmmm?
> 

There are the stable branches on kernel.org and some distro kernels based on
older kernel versions.

The AMD severity grading function was introduced in v4.1 and has this issue.
However, the following commit was included in v4.6 and masks the issue.

b2f9d678e28c x86/mce: Check for faults tagged in EXTABLE_CLASS_FAULT exception table entries

This patch will apply to v4.9 and later. Another version will be needed to apply
to the v4.1 and v4.4. stable branches.

Thanks,
Yazen