linux-kernel - RE: [PATCHv3 2/2] drm/amdgpu: Register MCE notifier for Aldebaran RAS

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Date:   Thu, 23 Sep 2021 18:34:33 +0000
From:   "Joshi, Mukul" <Mukul.Joshi@....com>
To:     "Ghannam, Yazen" <Yazen.Ghannam@....com>
CC:     "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bp@...en8.de" <bp@...en8.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "mchehab@...nel.org" <mchehab@...nel.org>,
        "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>
Subject: RE: [PATCHv3 2/2] drm/amdgpu: Register MCE notifier for Aldebaran RAS

[AMD Official Use Only]



> -----Original Message-----
> From: Ghannam, Yazen <Yazen.Ghannam@....com>
> Sent: Thursday, September 23, 2021 1:23 PM
> To: Joshi, Mukul <Mukul.Joshi@....com>
> Cc: linux-edac@...r.kernel.org; x86@...nel.org; linux-kernel@...r.kernel.org;
> bp@...en8.de; mingo@...hat.com; mchehab@...nel.org; amd-
> gfx@...ts.freedesktop.org
> Subject: Re: [PATCHv3 2/2] drm/amdgpu: Register MCE notifier for Aldebaran
> RAS
> 
> On Thu, Sep 23, 2021 at 11:30:55AM -0400, Joshi, Mukul wrote:
> ...
> > > > +		return NOTIFY_DONE;
> > > > +
> > > > +	/*
> > > > +	 * If it is correctable error, return.
> > > > +	 */
> > > > +	if (mce_is_correctable(m))
> > > > +		return NOTIFY_OK;
> > >
> > > Shouldn't this be "NOTIFY_DONE" if "don't care" about this error?
> >
> > The thinking is we want to stop calling further consumers since it's a
> correctable error in GPU UMC and we are not taking any action about the
> correctable errors.
> 
Sorry I have to retract this back a bit. I remembered I started with the intention
Of using NOTIFY_STOP but realized that we would not be doing any accounting in this function.

> Shouldn't the error still be reported to EDAC for decoding and counting? I think
> users want this.
> 
> But it looks to me that either NOTIFY_OK or NOTIFY_DONE will allow this, so it's
> not a big deal. Was this intended to be NOTIFY_STOP?
> 

Sorry I have to retract my previous comment about stopping further consumers a bit.
I remembered I started with the intention to use NOTIFY_STOP but realized we were not doing any accounting in this function.
Later I guess I went by the comments put against NOTIFY_OK in notifier.h:
#define NOTIFY_DONE		0x0000		/* Don't care */
#define NOTIFY_OK		0x0001		/* Suits me */

Because this was a correctable error on GPU UMC, NOTIFY_OK ("Suits me") was probably more suited to this condition,
even though we were not taking any action on the correctable errors. 

Thanks,
Mukul

> Thanks,
> Yazen