[PATCH] ARM: futex: fix clobbering oldval

[Jon Masters]

On Tue, 2011-12-06 at 19:11 +0000, Will Deacon wrote:
> 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 at 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.

Yea, Mark flagged that patch and it was included into the kernels on our
boards here. So far, it seems to be making some improvement, though we
still have stuck boards and weird signal issues sometimes. We are trying
to collect more data when this occurs (I gave the engineer concerned
some instructions around collecting data that will be of use). So I just
wondered if you saw any more futex issues, or if this is believe fixed.

Jon.