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From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	Sebastian Siewior <bigeasy@linutronix.de>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	"David S. Miller" <davem@davemloft.net>,
	Fenghua Yu <fenghua.yu@intel.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Len Brown <lenb@kernel.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Tejun Heo <tj@kernel.org>, Tony Luck <tony.luck@intel.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	linux-acpi@vger.kernel.org
Subject: Re: [patch 08/13] ACPI/processor: Replace racy task affinity logic.
Date: Thu, 13 Apr 2017 14:52:24 +0200	[thread overview]
Message-ID: <20170413125224.5uu36nekq4r72b4y@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <alpine.DEB.2.20.1704131345160.2408@nanos>

On Thu, Apr 13, 2017 at 02:01:42PM +0200, Thomas Gleixner wrote:
> On Thu, 13 Apr 2017, Peter Zijlstra wrote:
> > 
> > That makes my machine sad...
> > [    9.786610]  work_on_cpu+0x82/0x90
> > [    9.790404]  ? __usermodehelper_disable+0x110/0x110
> > [    9.795846]  ? __acpi_processor_get_throttling+0x20/0x20
> > [    9.801773]  acpi_processor_set_throttling+0x199/0x220
> > [    9.807506]  ? trace_hardirqs_on_caller+0xfb/0x1d0
> > [    9.812851]  acpi_processor_get_throttling_ptc+0xec/0x180
> > [    9.818876]  __acpi_processor_get_throttling+0xf/0x20
> > [    9.824511]  work_for_cpu_fn+0x14/0x20
> > [    9.828692]  process_one_work+0x261/0x670
> > [    9.833165]  worker_thread+0x21b/0x3f0
> > [    9.837348]  kthread+0x108/0x140
> > [    9.840947]  ? process_one_work+0x670/0x670
> > [    9.845611]  ? kthread_create_on_node+0x40/0x40
> > [    9.850667]  ret_from_fork+0x31/0x40
> 
> Yuck. So the call chain is:
> 
> acpi_processor_get_throttling()
>   work_on_cpu(acpi_processor_get_throttling)
> 
> That work does:
> 
> __acpi_processor_get_throttling()
>     acpi_processor_get_throttling_ptc()
>       acpi_processor_set_throttling()
>         work_on_cpu(__acpi_processor_set_throttling)
> 
> Why the heck calls a get_throttling() function set_throttling()? I'm mildly
> surprised.
> 
> Does the delta patch below cure the problem?

Yes, aside from a compile warn.

But that's disgusting... then again, you merely reintroduced this hack.

  reply	other threads:[~2017-04-13 12:52 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-12 20:07 [patch 00/13] sched/treewide: Clean up various racy task affinity issues Thomas Gleixner
2017-04-12 20:07 ` [patch 01/13] ia64/topology: Remove cpus_allowed manipulation Thomas Gleixner
2017-04-15 14:15   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 02/13] workqueue: Provide work_on_cpu_safe() Thomas Gleixner
2017-04-13 11:11   ` Dou Liyang
2017-04-13 21:28     ` Thomas Gleixner
2017-04-14  4:18   ` Tejun Heo
2017-04-14  8:54   ` Peter Zijlstra
2017-04-14  9:51     ` Thomas Gleixner
2017-04-14  9:56       ` Peter Zijlstra
2017-04-15 14:16   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 03/13] ia64/salinfo: Replace racy task affinity logic Thomas Gleixner
2017-04-15 14:17   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 04/13] ia64/sn/hwperf: " Thomas Gleixner
2017-04-12 20:53   ` [patch V 2 " Thomas Gleixner
2017-04-15 14:17     ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 05/13] powerpc/smp: Replace open coded " Thomas Gleixner
2017-04-13  5:47   ` Michael Ellerman
2017-04-15 14:18   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 06/13] sparc/sysfs: Replace racy " Thomas Gleixner
2017-04-13  1:52   ` David Miller
2017-04-13  8:17     ` [patch V2 " Thomas Gleixner
2017-04-15 14:18       ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 07/13] ACPI/processor: Fix error handling in __acpi_processor_start() Thomas Gleixner
2017-04-15 14:19   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 08/13] ACPI/processor: Replace racy task affinity logic Thomas Gleixner
2017-04-13 11:39   ` Peter Zijlstra
2017-04-13 12:01     ` Thomas Gleixner
2017-04-13 12:52       ` Peter Zijlstra [this message]
2017-04-15 14:19   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 09/13] cpufreq/ia64: " Thomas Gleixner
2017-04-12 20:55   ` [patch V2 " Thomas Gleixner
2017-04-15 14:20     ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-13  2:42   ` [patch 09/13] " Viresh Kumar
2017-04-12 20:07 ` [patch 10/13] cpufreq/sh: " Thomas Gleixner
2017-04-13  2:46   ` Viresh Kumar
2017-04-15 14:20   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 11/13] cpufreq/sparc-us3: " Thomas Gleixner
2017-04-13  2:48   ` Viresh Kumar
2017-04-15 14:21   ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-12 20:07 ` [patch 12/13] cpufreq/sparc-us2e: " Thomas Gleixner
2017-04-13  2:50   ` Viresh Kumar
2017-04-13  8:19   ` [patch V2 " Thomas Gleixner
2017-04-13  8:22     ` [patch V3 " Thomas Gleixner
2017-04-15 14:21       ` [tip:sched/core] " tip-bot for Thomas Gleixner
2017-04-13 14:50     ` [patch V2 12/13] " David Miller
2017-04-12 20:07 ` [patch 13/13] crypto: n2 - " Thomas Gleixner
2017-04-13  4:56   ` Herbert Xu
2017-04-13  8:20   ` [patch V2 " Thomas Gleixner
2017-04-13 14:51     ` David Miller
2017-04-15 14:22     ` [tip:sched/core] crypto: N2 " tip-bot for Thomas Gleixner
2017-04-13  9:02 ` [patch 00/13] sched/treewide: Clean up various racy task affinity issues Peter Zijlstra

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