Re: Help needed: Resume problems in 2.6.32-rc, perhaps related to preempt_count leakage in keventd

Thomas Gleixner
2009-11-09T19:15:07Z

On Mon, 9 Nov 2009, Rafael J. Wysocki wrote:
> On Monday 09 November 2009, Mike Galbraith wrote:
> > On Mon, 2009-11-09 at 16:47 +0100, Rafael J. Wysocki wrote:
> > > On Monday 09 November 2009, Mike Galbraith wrote:
> >
> > > > > Very likely. What did you do to fix it?
> > > >
> > > > You don't really wanna know. In 31 with newidle enabled, the below
> > > > fixed it. It won't fix 32, though it might cure the resume problem.
> > >
> > > OK, I'll give it a try.
>
> It doesn't help.
>
> Also, I can reproduce the issue with current -git and kernel preepmtion
> disabled.
>
> > I just tried to trigger badness via high speed online/offline combined
> > with taskset with CONFIG_PREEMPT enabled, and couldn't make it explode.
>
> I'm not able to do it this way too, so resume seems to be necessary to trigger
> it. I'm going try with the suspend debug in the "core" mode.
>
> > (damn, wish i could s2ram this box)
>
> That need not suffice. I have two other boxes that suspend and resume
> correctly with 2.6.32-rc, AFAICS.
>
> However, there seems to be a systematic error somewhere, since the failure
> always happens at the same place, ie. list_del_init(cwq->worklist.next); in
> run_workqueue(), in preemptible as well as in non-preemptible kernels.
>
> Which is kind of strange, given the !list_empty(&cwq->worklist) test right
> before it.

Hmm, no. list_empty() just tells you whether the list is empty or
not. It does not care whether the list is corrupted or not. Have you
tried to run with list debugging enabled ?

Thanks,

tglx