linux-kernel - Re: 3.15-rc2: longhaul cpufreq stalls tasks for 120s+

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Date:	Fri, 25 Apr 2014 12:14:19 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Cc:	Meelis Roos <mroos@...ux.ee>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: Re: 3.15-rc2: longhaul cpufreq stalls tasks for 120s+

On 25 April 2014 01:14, Srivatsa S. Bhat
<srivatsa.bhat@...ux.vnet.ibm.com> wrote:
> On 04/25/2014 12:33 AM, Meelis Roos wrote:
>>> I see traces of mutex_lock_slowpath() etc in your logs.. Can you please
>>> enable lockdep and sleep-inside-atomic-section check and let us know if
>>> it complains? Specifically, enable these config options:
>>>
>>> CONFIG_LOCKDEP_SUPPORT=y
>>> CONFIG_DEBUG_RT_MUTEXES=y
>>> CONFIG_DEBUG_PI_LIST=y
>>> CONFIG_DEBUG_SPINLOCK=y
>>> CONFIG_DEBUG_MUTEXES=y
>>> CONFIG_DEBUG_LOCK_ALLOC=y
>>> CONFIG_PROVE_LOCKING=y
>>> CONFIG_LOCKDEP=y
>>> CONFIG_DEBUG_ATOMIC_SLEEP=y
>>
>> At boot, nothing special was in dmesg. After running cpufreq-info (which
>> hangs indefinitely), I get the following dmesg with hangs and lock info:
>
>
> Thank you for the logs, but unfortunately they don't give us much
> further insight into this issue.
>
> Just to be sure that our suspicion is right, can you try reverting
> commit 12478cf0c55 (cpufreq: Make sure frequency transitions are
> serialized) and check whether reverting the patch solves the problem?

You need to revert these three patches in the mentioned order.

236a980 cpufreq: Make cpufreq_notify_transition &
cpufreq_notify_post_transition static
8fec051 cpufreq: Convert existing drivers to use
cpufreq_freq_transition_{begin|end}
12478cf cpufreq: Make sure frequency transitions are serialized
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