linux-kernel - Re: 3.0.0-rc2: Xen: powernow-k8: Kernel panic

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Date:	Wed, 15 Jun 2011 08:38:47 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Tobias Diedrich <ranma+xen@...edrich.de>,
	xen-users@...ts.xensource.com, linux-kernel@...r.kernel.org
Subject: Re: 3.0.0-rc2: Xen: powernow-k8: Kernel panic - not syncing:
 Attempted to kill init!

On Tue, Jun 14, 2011 at 11:28:27PM +0200, Tobias Diedrich wrote:
> Konrad Rzeszutek Wilk wrote:
> > On Tue, Jun 14, 2011 at 03:46:34PM +0200, Tobias Diedrich wrote:
> > > [    5.740826] powernow-k8: fid 0x2 (1000 MHz), vid 0x12
> > > [    5.740941] powernow-k8: fid 0xa (1800 MHz), vid 0xa
> > > [    5.741057] powernow-k8: fid 0xc (2000 MHz), vid 0x8
> > > [    5.741170] powernow-k8: fid 0xe (2200 MHz), vid 0x8
> > > [    5.741304] cpufreq_stats_create_table: policy->cur is 800000
> > > [    5.741475] last_index set to -1 in cpufreq_stats_create_table!
> > > 
> > > I think policy->cur used here probably set in powernowk8_cpu_init.
> > 
> > Yup, and there is not much that can be done there. Lets try this patch
> 
> Thanks, this works fine for suppressing the crash.

OK, can you do one more test? Can you reboot the kernel without Xen
and see whether the baremetal kernel still works? Wouldn't want to
cause a regression.

Is it OK if I stick Reported-by/Tested-by: Tobias .. on the patches
for upstream submission?

> 
> > diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
> > index 2368e38..7e4a664 100644
> > --- a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
> > +++ b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
> > @@ -1079,8 +1079,10 @@ static int transition_frequency_fidvid(struct powernow_k8_data *data,
> >  	}
> >  
> >  	res = transition_fid_vid(data, fid, vid);
> > -	freqs.new = find_khz_freq_from_fid(data->currfid);
> > +	if (res)
> > +		return res;
> >  
> > +	freqs.new = find_khz_freq_from_fid(data->currfid);
> >  	for_each_cpu(i, data->available_cores) {
> >  		freqs.cpu = i;
> >  		cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
> > @@ -1112,6 +1114,9 @@ static int transition_frequency_pstate(struct powernow_k8_data *data,
> >  	}
> >  
> >  	res = transition_pstate(data, pstate);
> > +	if (res)
> > +		return res;
> > +
> >  	freqs.new = find_khz_freq_from_pstate(data->powernow_table, pstate);
> >  
> >  	for_each_cpu(i, data->available_cores) {
> > diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
> > index 4f1b8de..0ecb1e2 100644
> > --- a/drivers/cpufreq/cpufreq_stats.c
> > +++ b/drivers/cpufreq/cpufreq_stats.c
> > @@ -298,11 +298,13 @@ static int cpufreq_stat_notifier_trans(struct notifier_block *nb,
> >  	old_index = stat->last_index;
> >  	new_index = freq_table_get_index(stat, freq->new);
> >  
> > -	cpufreq_stats_update(freq->cpu);
> > -	if (old_index == new_index)
> > +	/* We can't do stat->time_in_state[-1]= .. */
> > +	if (old_index == -1 || new_index == -1)
> >  		return 0;
> >  
> > -	if (old_index == -1 || new_index == -1)
> > +	cpufreq_stats_update(freq->cpu);
> > +
> > +	if (old_index == new_index)
> >  		return 0;
> >  
> >  	spin_lock(&cpufreq_stats_lock);
> 
> -- 
> Tobias						PGP: http://8ef7ddba.uguu.de
> --
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