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Date: Tue, 6 Dec 2011 19:11:09 +0000
From: Will Deacon <will.deacon@arm.com>
To: Jon Masters <jcm@redhat.com>
Cc: mhban <mhban@samsung.com>,
        "linux-arm-kernel@lists.infradead.org" 
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        Russell King <linux@arm.linux.org.uk>,
        Chris Metcalf <cmetcalf@tilera.com>
Subject: Re: [PATCH] ARM: futex: fix clobbering oldval
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Hi Jon,

On Tue, Dec 06, 2011 at 06:58:34PM +0000, Jon Masters wrote:
> On Thu, 2011-09-22 at 18:26 +0100, Will Deacon wrote:
> > Hi,
> > 
> > On Thu, Sep 22, 2011 at 03:53:35AM +0100, mhban wrote:
> > > This patch fixes clobbering oldval bug. oldval should be preserved for next
> > > compare operation.
> > > 
> > > Change-Id: I2a63bc1bdb8de330eb9e1ac02d7da1f77e6e8c3c
> > > Signed-off-by: Minho Ban <mhban@samsung.com>
> > 
> > It would have been nice to have been CC'd on this...
> > 
> > I ran LTP tests on this, so I'm surprised that this was broken (the tests
> > passed). Well spotted anyway!
> 
> This appears to be the cause of our "stuck builder" problem in Fedora
> building certain large packages, such as OpenJDK. Some of our guys are
> still monitoring the situation in case there's a secondary issue.
> 
> Was there ever any additional followup on this topic?

Yup, check commit df77abca ("ARM: 7099/1: futex: preserve oldval in SMP
__futex_atomic_op"). It should be in stable for all affected kernels too.

Cheers,

Will