Re: SwSusp to disk doesn't work - Try 2

[Thomas Gleixner <tglx@linutronix.de>]

On Sun, 2007-03-11 at 22:09 +0100, Rafael J. Wysocki wrote:
> > >>>>>     update_sched_domains
> > >>>>>      detach_destroy_domains
> > >>>>>        [waits here] --> synchronize_sched (==synchronize_rcu)
> > >>>>>         
> > >>>> Well, I think the call to wait_for_completion() does not return, probably
> > >>>> because the task supposed to complete the completion is frozen at this
> > >>>> point.  Can you please try to confirm that it gets stuck on
> > >>>> wait_for_completion() in synchronize_rcu()?
> > >>>>       
> > >>> Yes, it's in wait_for_completion() in synchronize_rcu().
> > >>> As noted in some previous mail, it will wake up after
> > >>> event - key press etc.
> > >>>
> > >>> Patch in http://lkml.org/lkml/2007/3/7/255 solves different problem.
> > >>> I added it to my quilt and applied anyway -> no change.
> > >>>     
> > >> Does the problem go away if NO_HZ is unset?
> > >>   
> > > 
> > > i tried to boot with nohz=off, but the problem did persist.
> > 
> > Hmmmm, both variants (nohz=off or recompiled kernel without NO_HZ) works for me.
> 
> Definitely something strange is going on here.
> 
> I think we need an advice from someone who knows the RCU internals.

RCU synchronization depends on the timer interrupt. Which kernel version
are you guys talking about ?

	tglx