RE: [PATCH] drm/amdgpu: Register bad page handler for Aldebaran

["Joshi, Mukul" <Mukul.Joshi@amd.com>]

[AMD Official Use Only]



> -----Original Message-----
> From: amd-gfx <amd-gfx-bounces@lists.freedesktop.org> On Behalf Of Joshi,
> Mukul
> Sent: Thursday, July 29, 2021 8:00 PM
> To: Ghannam, Yazen <Yazen.Ghannam@amd.com>
> Cc: x86-ml <x86@kernel.org>; Kasiviswanathan, Harish
> <Harish.Kasiviswanathan@amd.com>; lkml <linux-kernel@vger.kernel.org>;
> amd-gfx@lists.freedesktop.org; Borislav Petkov <bp@alien8.de>; Alex Deucher
> <alexdeucher@gmail.com>
> Subject: RE: [PATCH] drm/amdgpu: Register bad page handler for Aldebaran
> 
> [CAUTION: External Email]
> 
> [AMD Official Use Only]
> 
> 
> 
> > -----Original Message-----
> > From: Ghannam, Yazen <Yazen.Ghannam@amd.com>
> > Sent: Thursday, June 3, 2021 5:13 PM
> > To: Joshi, Mukul <Mukul.Joshi@amd.com>
> > Cc: Borislav Petkov <bp@alien8.de>; Alex Deucher
> > <alexdeucher@gmail.com>; x86-ml <x86@kernel.org>; Kasiviswanathan,
> > Harish <Harish.Kasiviswanathan@amd.com>; lkml
> > <linux-kernel@vger.kernel.org>; amd-gfx@lists.freedesktop.org
> > Subject: Re: [PATCH] drm/amdgpu: Register bad page handler for
> > Aldebaran
> >
> > On Thu, May 27, 2021 at 03:54:27PM -0400, Joshi, Mukul wrote:
> > ...
> > > > Is that the same deferred interrupt which calls
> > > > amd_deferred_error_interrupt() ?
> > >
> > > Sorry picking this up after sometime. I thought I had replied to this email.
> > > Yes it is the same deferred interrupt which calls
> > amd_deferred_error_interrupt().
> > >
> >
> > Mukul,
> >
> > Do you expect that the driver will need to mark pages with high
> > correctable error counts as bad? I think the hardware folks may want
> > the GPU memory errors to be handled more aggressively than CPU memory
> > errors. The specific threshold may change from product to product, so
> > it may make sense to hardcode this in the driver.
> >
> 
> Sorry I missed this email completely. Just saw it so responding now.
> 
> At the moment, we don't have a requirement to mark a page "bad" if there is a
> high correctable error counts.
> Our previous GPU ASICs which support RAS, also do not have such a feature.
> But you make a good point. It might be worthwhile to go and ask the hardware
> folks about it.
> 
> > We have similar functionality in the Correctable Errors Collector. But
> > enterprise users may prefer a direct approach done in the driver
> > (based on the hardware experts' guidance) instead of configuring the kernel at
> runtime.
> >
> > So I think having a separate priority may make sense if some special
> > functionality, or combination of behaviors, is needed which don't fall
> > under any exisiting things. In this case, "special functionality"
> > could be that the GPU memory needs to be handled differently than CPU
> memory.
> >
> > Another thing is that this behavior is similar to the NFIT behavior,
> > i.e. there's a memory error on an external device that needs to be
> > handled by the device's driver. So maybe we can rename MCE_PRIO_NFIT
> > to be generic
> > (MCE_PRIO_EXTERNAL?) and use that? Multiple notifiers with the same
> > priority is okay, right?
> >
> With respect to MCE priority, I was thinking of using the MCE_PRIO_EDAC
> instead of creating a new priority as the code in the GPU driver is doing error
> detection and handling the uncorrectable errors.
> Not sure if that aligns with the definition of EDAC device in the kernel.
> 
> What do you think?
> 
> Regards,
> Mukul
> 

After talking to Yazen, MCE_PRIO_UC might be a better choice for the MCE priority as we are dealing
only with uncorrectable errors.
I will be sending out a v2 patch with changes to use the MCE_PRIO_UC and drop the MCE_PRIO_ACCEL and see what the feedback is.

Thanks,
Mukul

> > Thanks,
> > Yazen
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