linux-kernel - Re: [RFC 0/9] mce recovery for Sandy Bridge server

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Message-ID: <20110524214139.GP27634@elte.hu>
Date:	Tue, 24 May 2011 23:41:39 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Borislav Petkov <bp@...64.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Huang, Ying" <ying.huang@...el.com>,
	Andi Kleen <andi@...stfloor.org>,
	Borislav Petkov <bp@...en8.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mauro Carvalho Chehab <mchehab@...hat.com>
Subject: Re: [RFC 0/9] mce recovery for Sandy Bridge server


* Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote:

> On Tue, 2011-05-24 at 14:30 -0700, Linus Torvalds wrote:
> > On Tue, May 24, 2011 at 2:24 PM, Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote:
> > >
> > > Right, so you can't do things like that from NMI context, but what perf
> > > can do is raise a self-IPI and continue from IRQ context (question for
> > > the HW folks, can there be cycles between the NMI iret and IRQ assert
> > > from whatever context was before the NMI hit?)
> > 
> > Of course there can be - the code where the NMI hit may have
> > interrupts disabled.
> 
> D'0h yes of course!..
> 
> Then I can't immediately see a way to stop a thread dead in its tracks.
> Userspace yes, but not kernel-space.

It's a best-effort thing: run proper kernel code (hardirq context) as soon as 
possible - but obviously not sooner than that! :-)

Thanks,

	Ingo
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