linux-kernel - Re: [BUG] oops in cpufreq driver with AMD Kaveri CPU

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Message-ID: <2067094.cJOA1APdny@spock>
Date:	Tue, 12 Aug 2014 21:54:11 +0300
From:	Oleksandr Natalenko <oleksandr@...alenko.name>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [BUG] oops in cpufreq driver with AMD Kaveri CPU

Updated logs.

Registered notifiers:

===
pf@...iant:~$ cat /var/log/kern.log | grep "Registered transition notifier"
Aug 12 21:50:13 defiant kernel: [    3.081759] cpufreq: Registered transition 
notifier: ffffffff81590378, (ffffffff81cb0ba0)
===

Triggered notifiers:

===
pf@...iant:~$ dmesg | grep CPUFREQ_NOTIFIER | awk '{ s = ""; for (i = 3; i <= 
NF; i++) s = s $i " "; print s }' | sort -u
CPUFREQ_NOTIFIER: acpi_processor_ppc_notifier 
CPUFREQ_NOTIFIER: acpi_thermal_cpufreq_notifier 
CPUFREQ_NOTIFIER: cpufreq_stat_notifier_trans 
===

On Tuesday 12 August 2014 21:18:09 Oleksandr Natalenko wrote:
> Hmm, looks like I've put pr_info to policy notifier instead of transition
> notifier. Will fix it now and post new logs.
> 
> On Tuesday 12 August 2014 21:04:30 Oleksandr Natalenko wrote:
> > Well, I've added the following code to cpufreq_register_notifier()
> > (drivers/cpufreq/cpufreq.c) to CPUFREQ_TRANSITION_NOTIFIER case:
> > 
> > ===
> > pr_info("Registered transition notifier: %p, (%p)\n", nb->notifier_call,
> > &nb-
> > 
> > >notifier_call);
> > 
> > ===
> > 
> > And got the following in my dmesg (only 1 line):
> > 
> > ===
> > $ cat /var/log/kern.log | grep "Registered transition notifier"
> > Aug 12 17:23:45 defiant kernel: [    3.084977] cpufreq: Registered
> > transition notifier: ffffffff81590378, (ffffffff81cb0ba0)
> > ===
> > 
> > System.map tells me, that ffffffff81590378 corresponds to
> > cpufreq_stat_notifier_trans() (in drivers/cpufreq/cpufreq_stats.c).
> > 
> > Also I've added
> > 
> > ===
> > pr_info("%s\n", __func__);
> > ===
> > 
> > to all callbacks (hello, LXR :)), and got the following occurrences in
> > dmesg:
> > 
> > ===
> > $ cat /var/log/kern.log | egrep -e '(acpi_|cpufreq|notifier)' | awk
> > '{print($7)}' | sort -u
> > acpi_processor_ppc_notifier
> > acpi_thermal_cpufreq_notifier
> > cpufreq_stat_notifier_policy
> > ===
> > 
> > No extra notifiers are involved so far, but also I haven't caught new hang
> > yet as it occurs randomly. Still waiting for it, but I hope my little
> > investigation could help somehow.
> > 
> > On Tuesday 12 August 2014 13:16:25 Viresh Kumar wrote:
> > > On Tue, Aug 12, 2014 at 12:56 PM, Oleksandr Natalenko
> > > 
> > > <oleksandr@...alenko.name> wrote:
> > > > Got that and will try to investigate ASAP.
> > > > 
> > > > Just to note: I tried to use powersave governor and got the same
> > > > result.
> > > > I
> > > > believe notifiers are used with powersave governor as well. Am I
> > > > wrong?
> > > 
> > > Notifiers are used from the cpufreq core when frequency is changed.
> > > And the powersave governor should have changed the frequency only
> > > ONCE, i.e. to go to lowest frequency.
> > > 
> > > So, it probably happened at the first & only change at that time as
> > > well..
> > > But it shouldn't happen any later. So, see what the log looks like on
> > > that crash.
-- 
Oleksandr post-factum Natalenko, MSc
pf-kernel community
https://natalenko.name/
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