On Tue, Jul 14, 2015 at 09:49:09PM +0100, Russell King - ARM Linux wrote:
> On Tue, Jul 14, 2015 at 09:26:00AM -0700, Paul E. McKenney wrote:
> > On Tue, Jul 14, 2015 at 01:06:32PM -0300, Fabio Estevam wrote:
> > > Hi Paul,
> > >
> > > On Tue, Jul 14, 2015 at 1:00 PM, Paul E. McKenney
> > > <paul...@linux.vnet.ibm.com> wrote:
> > >
> > > > Does this patch help?
> > > >
> > > > https://lkml.org/lkml/2015/5/12/885
> > >
> > > I am using an ARM 32-bit machine, so I used this one instead:
> > > https://lkml.org/lkml/2015/5/12/892
> > >
> > > , and it fixes the problem. Thanks!
> > >
> > > Feel free to add:
> > >
> > > Tested-by: Fabio Estevam <fabio.este...@freescale.com>
> >
> > Glad it helped!
> >
> > Russell, did you want me to push this, or would you rather take it?
>
> If it's the one I'm thinking of (using the generic code) because it
> doesn't actually solve the problem we have. It may shut up the RCU
> warning, but it doesn't solve the underlying problem - one which is
> caused by the use of atomics (which use the exclusive instructions)
> vs cache line migration between CPUs vs speculative prefetching...
>
> It's possible right now that _dirty_ cache lines can be migrated to
> the dying CPU, which are then lost on power down - and if we disable
> the caches on the dying CPU, we then can't use exclusives, so atomics
> (and all of the other normal kernel synchronisation mechanisms) are
> out of the question.
OK, that could explain any number of failures.
I will leave this issue in your hands, then.
Thanx, Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
