linux-kernel - Re: [PATCH V2 0/7] cpufreq: governors: Fix ABBA lockups

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Date:	Fri, 5 Feb 2016 08:19:26 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
Cc:	Juri Lelli <juri.lelli@....com>,
	Rafael Wysocki <rjw@...ysocki.net>,
	linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
	skannan@...eaurora.org, peterz@...radead.org,
	mturquette@...libre.com, steve.muckle@...aro.org,
	vincent.guittot@...aro.org, morten.rasmussen@....com,
	dietmar.eggemann@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 0/7] cpufreq: governors: Fix ABBA lockups

On 05-02-16, 02:20, Shilpasri G Bhat wrote:
> I could see the previous lockdep warnings on pm/next and on top of patch[4].
> On Patch[5-7] I see the below lockdep trace on running './runme' on a Power8 box.

> [  710.336130] Chain exists of:
>   s_active#91 --> &dbs_data->mutex --> od_dbs_cdata.mutex
> 
> [  710.336376]  Possible unsafe locking scenario:
> 
> [  710.336488]        CPU0                    CPU1
> [  710.336577]        ----                    ----
> [  710.336666]   lock(od_dbs_cdata.mutex);
> [  710.336778]                                lock(&dbs_data->mutex);
> [  710.336911]                                lock(od_dbs_cdata.mutex);
> [  710.337064]   lock(s_active#91);
> [  710.337176]

This is the same lockdep, just that we have added another mutex
(dbs_data->mutex) to it.

Have you tried if all the lockdeps go away with the 8th patch that I
provided yesterday ?

-- 
viresh