linux-kernel - Re: [PATCH] x86, FPU: Fix FPU initialization

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Message-ID: <20130416092528.GF9569@gmail.com>
Date:	Tue, 16 Apr 2013 11:25:28 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Borislav Petkov <bp@...en8.de>
Cc:	"H. Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>, Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH] x86, FPU: Fix FPU initialization


* Borislav Petkov <bp@...en8.de> wrote:

> On Mon, Apr 15, 2013 at 05:54:15PM +0200, Borislav Petkov wrote:
> > On Mon, Apr 15, 2013 at 12:18:25PM +0200, Ingo Molnar wrote:
> > > It was tip:master with x86/cpu merged in freshly.
> > 
> > Ok, some more observations. I can trigger some oops similar yours (I
> > haven't caught mine yet over serial or such) with latest tip/master +
> > tip:x86/cpu.
> 
> Ok, here's the deal - it looks like a corruption which causes a couple
> of different backtraces with different functions in the call trace. I've
> bisected tip:x86/cpu and the evildoers are:

Correct, 'late effects of memory corruption' was my first impression too, from the 
crash pattern.

> 
> commit 3019653a57585602690fd38679326e9337f7ed7f
> Author: Borislav Petkov <bp@...e.de>
> Date:   Wed Apr 10 21:37:03 2013 +0200
> 
>     x86/fpu: Fix FPU initialization
> 
> commit c70293d0e3fef6b989cd8268027d410cf06ce384
> Author: H. Peter Anvin <hpa@...or.com>
> Date:   Mon Apr 8 17:57:43 2013 +0200
> 
>     x86: Get rid of ->hard_math and all the FPU asm fu
> 
> 
> I'll venture a guess and say that if you revert those, your .config
> would boot on your K8 too.
> 
> So, I'd propose we take those 2 out for more careful inspection and
> fixing and the rest of tip:x86/cpu can go upstream in the upcoming merge
> window. IMHO of course.

I've got limited extra capacity right now - but if Peter rebases tip:x86/cpu or 
you send a pullable update of tip:x86/cpu I can stick it into -tip testing and 
yell if it goes wrong.

Thanks,

	Ingo
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