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

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Date:	Tue, 14 Jun 2011 15:46:34 +0200
From:	Tobias Diedrich <ranma+xen@...edrich.de>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	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!

Konrad Rzeszutek Wilk wrote:
> On Tue, Jun 14, 2011 at 02:13:33AM +0200, Tobias Diedrich wrote:
> > Tobias Diedrich wrote:
> > > Konrad Rzeszutek Wilk wrote:
> > > > > [    5.523199] rtc_cmos 00:05: setting system clock to 2011-06-13 20:20:00 UTC (1307996400)
> > > > > [    5.523400] powernow-k8: Found 1 AMD Athlon(tm) 64 Processor 3700+ (1 cpu cores) (version 2.20.00)
> > > > > [    5.530956] powernow-k8: fid 0x2 (1000 MHz), vid 0x12
> > > > > [    5.531072] powernow-k8: fid 0xa (1800 MHz), vid 0xa
> > > > > [    5.531187] powernow-k8: fid 0xc (2000 MHz), vid 0x8
> > > > > [    5.531301] powernow-k8: fid 0xe (2200 MHz), vid 0x8
> > > > > [    5.531460] Marking TSC unstable due to cpufreq changes
> > > > > [    5.531680] powernow-k8: fid trans failed, fid 0x2, curr 0x0
> > > > > [    5.531802] BUG: unable to handle kernel paging request at ffff880807e07b78
> > > > > [    5.531982] IP: [<ffffffff81479163>] cpufreq_stats_update+0x46/0x5b
> > > > 
> > > > For this one, you will have to fire out gdb and disassemble the code to
> > > > figure out where it failed. Look for 'gdb vmlinux' and 'disassembly' on this
> > > > mailing list - that should provide some hints.
> > > 
> > > Probably because of the 'fid trans failed' stat->last_index is -1
> > 
> > It's set to -1 in cpufreq_stats_create_table(), the second call to
> > freq_table_get_index() doesn't check against -1 (expecting the call
> > to always succeed):
> > 
> > 	stat->last_time = get_jiffies_64();
> > 	stat->last_index = freq_table_get_index(stat, policy->cur);
> 
> What is policy->cur? Is is 800000 ? If so, does this fix your problem:

Yes, it is 800000, but while the patch is probably the right thing
to do it doesn't help for cpufreq_stats_create_table:
[    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.

> diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
> index 83479b6..9be00d9 100644
> --- a/drivers/cpufreq/powernow-k8.c
> +++ b/drivers/cpufreq/powernow-k8.c
> @@ -1079,7 +1079,8 @@ 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)
> +               freqs.new = find_khz_freq_from_fid(data->currfid);
>  
>         for_each_cpu(i, data->available_cores) {
>                 freqs.cpu = i;
> 
> 
> 
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@...ts.xensource.com
> http://lists.xensource.com/xen-users
> 

-- 
Tobias						PGP: http://8ef7ddba.uguu.de
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