linux-kernel - Re: Possible FPU context corruption w/ CONFIG

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Message-ID: <AANLkTimidOhwXPNwrCCS0HqiOrmzeLC14+bCuWgKj0vJ@mail.gmail.com>
Date:	Sat, 27 Nov 2010 00:34:39 -0500
From:	Brian Gerst <brgerst@...il.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Robert Richter <robert.richter@....com>,
	Dan Carpenter <error27@...il.com>, Avi Kivity <avi@...hat.com>,
	Bernd Machenschalk <Bernd.Machenschalk@....mpg.de>,
	Heinz-Bernd Eggenstein <hbeggenst@....com>,
	Oliver Bock <oliver.bock@....mpg.de>,
	"the arch/x86 maintainers" <x86@...nel.org>
Subject: Re: Possible FPU context corruption w/ CONFIG_PREEMPT

On Fri, Nov 26, 2010 at 10:31 AM, Tejun Heo <tj@...nel.org> wrote:
> Hello, guys.
>
> Heinz-Bernd Eggenstein reports a possible FPU context corruption w/
> CONFIG_PREEMPT.  Please take a look at the following forum post.
>
>  http://einstein.phys.uwm.edu/forum_thread.php?id=8516
>
> openSUSE 11.3 desktop kernel which has CONFIG_PREEMPT set is
> triggering SIGFPE while the default kernel w/o preemption works fine.
> He also notes that a similar bug was fixed in 2008 by commit 06c38d5e
> (x86-64: fix FPU corruption with signals and preemption) from Suresh.
> Does it ring anyone's bell?
>
> Heinz, is there a simple procedure to reproduce the problem, or would
> it be possible to lure you into bisection?
>
> Thanks.
>

This might be fixed by commit a4d4fbc7735bba6654b20f859135f9d3f8fe7f76
(Disable preemption when using TS_USEDFPU).

--
Brian Gerst
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