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

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Date:	Thu, 14 Feb 2008 15:38:13 -0800
From:	"Yinghai Lu" <yhlu.kernel@...il.com>
To:	"Greg KH" <gregkh@...e.de>, "Ingo Molnar" <mingo@...e.hu>
Cc:	"Frans Pop" <elendil@...net.nl>, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org
Subject: Re: [2.6.25-rc1] System no longer powers off after shutdown

On Wed, Feb 13, 2008 at 8:58 AM, Greg KH <gregkh@...e.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@...e.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....

interesting...

YH
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