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Subject: Re: [PATCH v8 24/26] drivers: firmware: psci: Deal with CPU hotplug
 when using OSI mode
To:     Ulf Hansson <ulf.hansson@linaro.org>
Cc:     "Rafael J . Wysocki" <rjw@rjwysocki.net>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Linux PM <linux-pm@vger.kernel.org>,
        Kevin Hilman <khilman@kernel.org>,
        Lina Iyer <ilina@codeaurora.org>,
        Lina Iyer <lina.iyer@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Stephen Boyd <sboyd@kernel.org>,
        Juri Lelli <juri.lelli@arm.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
References: <20180620172226.15012-1-ulf.hansson@linaro.org>
 <20180620172226.15012-25-ulf.hansson@linaro.org>
 <9bf3713b-df00-03b3-d235-7549565382c7@codeaurora.org>
 <CAPDyKFond=Q-cWsjKwGToprjPTFj=WA_-nsAoUFJdNCdkki8Rw@mail.gmail.com>
From:   Raju P L S S S N <rplsssn@codeaurora.org>
Message-ID: <5bbdf737-2542-cd5e-f4f2-5aabe8702639@codeaurora.org>
Date:   Tue, 20 Nov 2018 16:17:22 +0530
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Hi Ulf, This is noticed in v4.19 as well. Could you please check if 
CONFIG_DEBUG_ATOMIC_SLEEP is enabled in your case? I think with current 
patch the scenario would be applicable.

On 11/20/2018 3:20 PM, Ulf Hansson wrote:
> On 19 November 2018 at 20:50, Raju P L S S S N <rplsssn@codeaurora.org> wrote:
>> Hi Ulf,
>>
>> Got one issue in hotplug path where of_genpd_detach_cpu calls
>> dev_pm_qos_remove_notifier which can be sleeping as per below call stack. I
>> think it should be applicable for current patch as well right? Please let me
>> know what am I missing? why didn't you see this issue with this patch?
> 
> Weird.
> 
>>
>>
>> [ 8103.221387] BUG: sleeping function called from invalid context at
>> /mnt/host/source/src/third_party/kernel/v4.14/kernel/locking/mutex.c:238
> 
> Could it be due to some other patch in your v.4.14 kernel?
> 
>> [ 8103.221455] in_atomic(): 1, irqs_disabled(): 128, pid: 11, name:
>> migration/0
>> [ 8103.221487] Preemption disabled at:
>> [ 8103.221529] [<ffffff800814dfb0>] cpu_stopper_thread+0x98/0x118
>> [ 8103.221600] ------------[ cut here ]------------
>> [ 8103.221636] kernel BUG at
>> /mnt/host/source/src/third_party/kernel/v4.14/kernel/sched/core.c:6102!
>> [ 8103.221678] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
>> [ 8103.222396] CPU: 0 PID: 11 Comm: migration/0 Tainted: G        W  4.14.72
>> #1
>> [ 8103.222428] Hardware name: Google Cheza (rev1) (DT)
>> [ 8103.222460] task: ffffffc0f842d580 task.stack: ffffff8009c18000
>> [ 8103.222504] PC is at ___might_sleep+0x138/0x140
>> [ 8103.222542] LR is at ___might_sleep+0x138/0x140
>> [ 8103.222577] pc : [<ffffff80080d8f04>] lr : [<ffffff80080d8f04>] pstate:
>> 60c001c9
>> [ 8103.222605] sp : ffffff8009c1bb40
>> ….
>> [ 8103.223924] [<ffffff80080d8f04>] ___might_sleep+0x138/0x140
>> [ 8103.223965] [<ffffff80080d8d98>] __might_sleep+0x4c/0x80
>> [ 8103.224009] [<ffffff80088e4258>] mutex_lock+0x28/0x60
>> [ 8103.224054] [<ffffff800850fa2c>] dev_pm_qos_remove_notifier+0x1c/0x54
>> [ 8103.224097] [<ffffff8008517814>] genpd_remove_device+0x3c/0x10c
>> [ 8103.224140] [<ffffff800851949c>] genpd_dev_pm_detach+0x48/0x108
>> [ 8103.224183] [<ffffff80085193e0>] of_genpd_detach_cpu+0x48/0xbc
>> [ 8103.224227] [<ffffff80083edea4>] cpu_pd_dying+0x28/0x38
>> [ 8103.224268] [<ffffff80080ab2c0>] cpuhp_invoke_callback+0x254/0x5f0
>> [ 8103.224308] [<ffffff80080acdec>] take_cpu_down+0x60/0x9c
>> [ 8103.224346] [<ffffff800814d898>] multi_cpu_stop+0xac/0x104
>> [ 8103.224385] [<ffffff800814dfb8>] cpu_stopper_thread+0xa0/0x118
>> [ 8103.224427] [<ffffff80080cff74>] smpboot_thread_fn+0x19c/0x278
>> [ 8103.224472] [<ffffff80080cc0c4>] kthread+0x120/0x130
>> [ 8103.224513] [<ffffff8008084608>] ret_from_fork+0x10/0x18
> 
> Thanks for the report, I will double check my series before I post the
> new version of my series. If nothing unexpected shows up, that should
> be in a couple of days from now.
> 
> I keep you cc.
> 
> [...]
> 
> Kind regards
> Uffe
>