Re: [linux-pm] [2.6.30-rc1-git2 regressions] Hibernation broken and (minor but annoying) audio problem

Linus Torvalds
2009-04-11T01:23:45Z

On Sat, 11 Apr 2009, Rafael J. Wysocki wrote:
>
> On Friday 10 April 2009, Linus Torvalds wrote:
> >
> > On Fri, 10 Apr 2009, Rafael J. Wysocki wrote:
> > >
> > > I've just verified that the resume-after-hibernation issue goes away after
> > > reverting commit 9710794383ee5008d67f1a6613a4717bf6de47bc
> > > (async: remove the temporary (2.6.29) "async is off by default" code) , so it
> > > is async-related.
> >
> > Arjan? Clearly all the necessary fixes weren't found..
> >
> > There _is_ a module loading problem wrt initmem - I think you found that
> > and we added a hack for it for the ACPI battery driver. I wonder if we're
> > hitting a similar issue now with module discovery: modules that use
> > "async_schedule()" to do their discovery asynchronously are now not
> > necessarily fully "done" when the module is loaded.
> >
> > And so, anything that expected the devices to be available after module
> > load (like they used to) would be screwed.
> >
> > IOW, maybe something like the totally untested patch appended here (that
> > should also allow us to make the ACPI battery code to go back to using
> > __init).
>
> I tested it and it worked.

Hmm.

I'm not 100% sure that patch is good.

The reason? I think it's going to deadlock if an async caller ends up
wanting to load a module, because then the nestecd
"async_synchronize_full()" will basically want to wait for itself.

So it's a good test-patch, and maybe no async caller ever loads a module,
but it makes me a bit nervous.

But the fact that it fixes things for you at least means that the _reason_
for the problem is know, and maybe there are alternative solutions. Arjan?

Linus