linux-kernel - Re: [PATCH v3] vmcoreinfo: Track and log recoverable hardware errors

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Message-ID: <4w7adjalaisxhdx4l2zzl6ghanky4geijl523q2ezz7b5kj4kq@fr44nlwsw6qa>
Date: Wed, 30 Jul 2025 10:22:55 -0700
From: Breno Leitao <leitao@...ian.org>
To: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc: Shuai Xue <xueshuai@...ux.alibaba.com>, 
	Tony Luck <tony.luck@...el.com>, Borislav Petkov <bp@...en8.de>, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>, James Morse <james.morse@....com>, 
	Robert Moore <robert.moore@...el.com>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, Hanjun Guo <guohanjun@...wei.com>, 
	Mauro Carvalho Chehab <mchehab@...nel.org>, Mahesh J Salgaonkar <mahesh@...ux.ibm.com>, 
	Oliver O'Halloran <oohall@...il.com>, Bjorn Helgaas <bhelgaas@...gle.com>, linux-acpi@...r.kernel.org, 
	linux-kernel@...r.kernel.org, acpica-devel@...ts.linux.dev, osandov@...ndov.com, 
	konrad.wilk@...cle.com, linux-edac@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, 
	linux-pci@...r.kernel.org, kernel-team@...a.com
Subject: Re: [PATCH v3] vmcoreinfo: Track and log recoverable hardware errors

Hello Mauro,

On Wed, Jul 30, 2025 at 06:21:37PM +0200, Mauro Carvalho Chehab wrote:
> Em Wed, 30 Jul 2025 06:11:52 -0700
> Breno Leitao <leitao@...ian.org> escreveu:
> > On Wed, Jul 30, 2025 at 10:13:13AM +0800, Shuai Xue wrote:
> > > In ghes_log_hwerr(), you're counting both CPER_SEV_CORRECTED and
> > > CPER_SEV_RECOVERABLE errors:  
> > 
> > Thanks. I was reading this code a bit more, and I want to make sure my
> > understanding is correct, giving I was confused about CORRECTED and
> > RECOVERABLE errors.
> > 
> > CPER_SEV_CORRECTED means it is corrected in the background, and the OS
> > was not even notified about it. That includes 1-bit ECC error.
> > THose are not the errors we are interested in, since they are irrelavant
> > to the OS.
> 
> Hardware-corrected errors aren't irrelevant. The rasdaemon utils capture
> such errors, as they may be a symptom of a hardware defect. In a matter
> of fact, at rasdamon, thresholds can be set to trigger an action, like
> for instance, disable memory blocks that contain defective memories.

Sorry, I meant that Hardware-corrected errors aren't relevant in the
context of this patch, where we are errors that the OS has some
influence and decision.

> This is specially relevant on HPC and supercomputer workloads, where
> it is a lot cheaper to disable a block of bad memory than to lose
> an entire job because that could take several weeks of run time on
> a supercomputer, just because a defective memory ended causing a
> failure at the application.

Agree. These errors are used in several ways, including to detect
hardware aging and hardware replacement at maintenance windows.

In this patchset, I am more focused on what information to add to
crashdump, so, it makes it easy to correlate crashes to hardware events,
and RECOVERABLE are the main ones.