Re: [2.6.25-rc1] System no longer powers off after shutdown

Greg KH
2008-02-15T06:53:04Z

On Thu, Feb 14, 2008 at 03:38:13PM -0800, Yinghai Lu wrote:
> On Wed, Feb 13, 2008 at 8:58 AM, Greg KH <gregkh@suse.de> wrote:
> >
> > On Wed, Feb 13, 2008 at 12:39:13PM +0100, Frans Pop wrote:
> > > On Tuesday 12 February 2008, Greg KH wrote:
> > > > On Tue, Feb 12, 2008 at 09:39:14PM +0100, Frans Pop wrote:
> > > > > On Monday 11 February 2008, Frans Pop wrote:
> > > > > > In general 2.6.25 if looking quite good on my desktop, but there's
> > > > > > one important issue: the system no longer powers off after shutdown.
> > > > > > This works fine with 2.6.24.
> > > > >
> > > > > Don't ask me why, but bisection shows this commit to be the cause of
> > > > > the failure to power off:
> > > > > commit c10997f6575f476ff38442fa18fd4a0d80345f9d
> > > > > Author: Greg Kroah-Hartman <gregkh@suse.de>
> > > > > Date: Thu Dec 20 08:13:05 2007 -0800
> > > > >
> > > > > Kobject: convert drivers/* from kobject_unregister() to
> > > > > kobject_put()
> > > > >
> > > > > Because it seemed somewhat unlikely, I have double checked this by
> > > > > doing an extra compilation for this commit and its predecessor.
> > > >
> > > > What is the symptom of not powering off?
> > >
> > > I already noticed yesterday that there's one hunk in that commit that's not
> > > a straight replacement:
> > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > > index 9e102af..5efd555 100644
> > > --- a/drivers/cpufreq/cpufreq.c
> > > +++ b/drivers/cpufreq/cpufreq.c
> > > @@ -1030,8 +1030,6 @@ static int __cpufreq_remove_dev (struct sys_device * sys_dev)
> > >
> > > unlock_policy_rwsem_write(cpu);
> > >
> > > - kobject_unregister(&data->kobj);
> > > -
> > > kobject_put(&data->kobj);
> > >
> > > /* we need to make sure that the underlying kobj is actually
> > >
> > >
> > > So, just on the off chance, I applied the patch below and bingo, the system
> > > powers off again. I doubt this will be the correct solution, but just in
> > > case it is, here's my signed off. A comment why the double put is needed
> > > would probably be good though.
> >
> > There is a bug in the cpufreq kref logic that makes this "double put"
> > necessary. A real fix has already been posted to solve this issue, and
> > I think it should be on it's way to Linus for -rc2 already.
> >
> > Please let me know if -rc2 comes out without this needed fix.
>
> after disable cpufreq, i got
>
> ACPI: Preparing to enter system sleep state S5
> Disabling non-boot CPUs ...
> kvm: disabling virtualization on CPU1
> CPU 1 is now offline
> CPU1 is down
> kvm: disabling virtualization on CPU2
> CPU 2 is now offline
> ================> hang here.
>
> but x86.git/mm could go through down all the cpus....

Ugh, sorry, I was mistaken, it's not a cpufreq issue, it's a
CONFIG_DETECT_SOFTLOCKUP issue. Or that is what I was told before.

But the fact that you fixed the problem with an extra kobject_put()
makes me worry. There might be a reference issue still there. I'll
look into it.

thanks,

greg k-h