linux-kernel - Re: [PATCH] x86: sysctl to allow panic on IOCK NMI error

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Date:	Fri, 3 Jul 2009 09:59:24 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Borislav Petkov <borislav.petkov@....com>
Cc:	"Maciej W. Rozycki" <macro@...ux-mips.org>,
	Greg KH <gregkh@...e.de>, x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Kurt Garloff <garloff@...e.de>, linux-kernel@...r.kernel.org,
	Yinghai Lu <yinghai@...nel.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Doug Thompson <norsk5@...oo.com>,
	Dave Jiang <djiang@...sta.com>
Subject: Re: [PATCH] x86: sysctl to allow panic on IOCK NMI error


* Borislav Petkov <borislav.petkov@....com> wrote:

> On Thu, Jul 02, 2009 at 09:53:05AM +0200, Ingo Molnar wrote:
> > > That shouldn't be a problem if we were about to panic().  For a 
> > > more sophisticated attempt of recovery -- yes, that would have to 
> > > be addressed.
> > 
> > We are only panic-ing if the sysctl is set. The diagnostics 
> > would be useful anyway. The proper approach would be to defer it 
> > a bit in the non-panic case an read it out from some friendlier 
> > context - such as the EDAC core.
> 
> Quickly skimming through code shows some functionality is there: 
> drivers/edac/edac_pci{,_sysfs}.c but doesn't seem to be NMI safe. 
> CCing some more people.

the 'defer' would mean we put it into a softirq context or so and do 
it from there - not from NMI context.

But yes, if we are about to panic due to this and want to print out 
something useful, making EDAC NMI safe would be nice.

	Ingo
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