linux-kernel - Re: [PATCH 2/5] cpufreq: star/stop cpufreq timers on cpu hotplug

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Date:	Wed, 30 Jan 2013 14:12:02 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Fabio Baltieri <fabio.baltieri@...aro.org>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>, cpufreq@...r.kernel.org,
	linux-pm@...r.kernel.org, Linus Walleij <linus.walleij@...aro.org>,
	linux-kernel@...r.kernel.org, josephl@...dia.com,
	swarren@...dotorg.org, linaro-dev@...ts.linaro.org,
	Nicolas Pitre <nicolas.pitre@...aro.org>,
	mathieu.poirier@...aro.org
Subject: Re: [PATCH 2/5] cpufreq: star/stop cpufreq timers on cpu hotplug

On Wednesday, January 30, 2013 11:44:32 AM Fabio Baltieri wrote:
> Hi Viresh,
> 
> On Wed, Jan 30, 2013 at 10:22:37AM +0530, Viresh Kumar wrote:
> > Hi Fabio,
> > 
> > Sorry for waking up very late :)
> > 
> > The reason why i am starting this thread again is due to problem
> > reported by Joseph,
> > with latest linux-next/master branch (which contains few big patches
> > from me :) ):
> > 
> > Reboot is giving following to him:
> > 
> > * Will now halt
> > [ 193.756068] Disabling non-boot CPUs...
> > [ 193.760088] BUG: scheduling while atomic: halt/780/0x00000002
> > [ 193.765845] Modules linked in: brcmfmac brcmutil
> > [ 193.770613] [<c0014990>] (unwind_backtrace+0x0/0xf8) from [<c0049510>]
> > (__schedule_bug+0x44/0x5c)
> > [ 193.779548] [<c0049510>] (__schedule_bug+0x44/0x5c) from [<c04fa320>]
> > (__schedule+0x688/0x6ec)
> > [ 193.788206] [<c04fa320>] (__schedule+0x688/0x6ec) from [<c04fa75c>]
> > (schedule_preempt_disabled+0x24/0x34)
> > [ 193.797811] [<c04fa75c>] (schedule_preempt_disabled+0x24/0x34) from
> > [<c04f916c>] (__mutex_lock_slowpath+0x170/0x34c)
> > [ 193.808367] [<c04f916c>] (__mutex_lock_slowpath+0x170/0x34c) from
> > [<c04f9354>] (mutex_lock+0xc/0x24)
> > [ 193.817554] [<c04f9354>] (mutex_lock+0xc/0x24) from [<c04f1cdc>]
> > (unregister_cpu_notifier+0xc/0x24)
> > [ 193.826640] [<c04f1cdc>] (unregister_cpu_notifier+0xc/0x24) from
> > [<c033a8a4>] (cpufreq_governor_dbs+0x118/0x614)
> > [ 193.836866] [<c033a8a4>] (cpufreq_governor_dbs+0x118/0x614) from
> > [<c033747c>] (__cpufreq_governor+0x58/0xc0)
> > [ 193.846737] [<c033747c>] (__cpufreq_governor+0x58/0xc0) from
> > [<c0339104>] (__cpufreq_remove_dev.clone.7+0x58/0x320)
> > [ 193.857207] [<c0339104>] (__cpufreq_remove_dev.clone.7+0x58/0x320)
> > from [<c04f7958>] (cpufreq_cpu_callback+0x8c/0x9c)
> > [ 193.867850] [<c04f7958>] (cpufreq_cpu_callback+0x8c/0x9c) from
> > [<c0044f4c>] (notifier_call_chain+0x44/0x84)
> > [ 193.877623] [<c0044f4c>] (notifier_call_chain+0x44/0x84) from
> > [<c0026e24>] (__cpu_notify+0x2c/0x48)
> > [ 193.886704] [<c0026e24>] (__cpu_notify+0x2c/0x48) from [<c04f1b08>]
> > (_cpu_down+0xb0/0x23c)
> > [ 193.895004] [<c04f1b08>] (_cpu_down+0xb0/0x23c) from [<c00270ec>]
> > (disable_nonboot_cpus+0x68/0x104)
> > [ 193.904089] [<c00270ec>] (disable_nonboot_cpus+0x68/0x104) from
> > [<c0034fbc>] (kernel_power_off+0x24/0x48)
> > [ 193.913688] [<c0034fbc>] (kernel_power_off+0x24/0x48) from
> > [<c0035810>] (sys_reboot+0x104/0x1e0)
> > [ 193.922517] [<c0035810>] (sys_reboot+0x104/0x1e0) from [<c000e520>]
> > (ret_fast_syscall+0x0/0x30)
> > 
> > 
> > And the crash log show this patch of yours somewhere :)
> 
> It looks like the two patches clashed togher quite badly... :-)
> 
> On Wed, Jan 30, 2013 at 10:22:37AM +0530, Viresh Kumar wrote:
> [...]
> > First question: Is this patch still required? Because following patch
> > from me is
> > sending a STOP/START to governors on cpu hot-[un]plug ?
> > 
> > commit dbcb63407c095af73f3464767e00902cdee55e8b
> > Author: Viresh Kumar <viresh.kumar@...aro.org>
> > Date:   Sat Jan 12 05:14:39 2013 +0000
> > 
> >     cpufreq: Notify governors when cpus are hot-[un]plugged
> > 
> > For me, the answer is NO.
> 
> I confirm that your patch handles correctly the problem solved by this
> one so I agree on dropping mine.
> 
> Rafael, this is screwing up a bit on bisection for cpu hotplug problems
> so I'm sending a v7 with the cleanup on first patch and this one
> dropped if you are ok with rebasing your pm-cpufreq-next.  Let me know
> if you prefer me to just send a revert + cleanup patch instead.

I've dropped the $subject one already and please post an incremental fix on
top of the first one in your series.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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