Re: [PATCH v8 24/26] drivers: firmware: psci: Deal with CPU hotplug when using OSI mode

[Raju P L S S S N]

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@xxxxxxxxxxxxxx> 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
> > â.
> > [ 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