Re: [tip:sched/locking] sched: Add p->pi_lock to task_rq_lock()

[Mike Galbraith]

On Sun, 2011-06-05 at 08:01 +0200, Arne Jansen wrote:
> On 05.06.2011 00:08, Peter Zijlstra wrote:
> > On Sun, 2011-06-05 at 06:29 +0900, Linus Torvalds wrote:
> >> On Fri, Jun 3, 2011 at 10:05 PM, Arne Jansen<lists@xxxxxxxxxxxxxx>  wrote:
> >>>
> >>> No change. Also git bisect quite clearly points to
> >>> 0122ec5b02f766c and ab2515c4b98f7bc4, both are older than
> >>> b1c43f82c5aa2654 mentioned in the other thread.
> >>
> >> Ok, I haven't heard anything further on this. Ingo? Peter?
> >
> > I'm a bit stumped, and not being able to reproduce at all :/
> 
> I'm willing to take any number of round trips to get to the true
> nature of the bug. From the description I have a feeling that the
> offending patch might just shift the timing slightly, so even if
> the problem is gone for me, it might just be buried deeper.
> I can also try to reproduce it on a second machine and give you
> access to it, though this might take a few days.

My x3550 M3 with your config plus a couple drivers I need is exhibiting
hard lockups with no watchdog triggered.  If I use both serial and tty
consoles, I get all kinds of gripes from soft lockup and rcu when
loading Peter's test module, but that's the tty problem.

With serial console and earlyprintk=serial alone, box may or may not
boot all the way without hard locking silently.  Ditto on restart after
loading/unloading Peter's test module.  I always see all 10k messages
though, IFF I have no tty console active.

	-Mike

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