Re: Regression with suspicious RCU usage splats with cpu_pm change

From	Tony Lindgren <tony@atomide.com>
Newsgroups	linux.kernel
Subject	Re: Regression with suspicious RCU usage splats with cpu_pm change
Date	2017-07-17 08:10 +0200
Message-ID	<u47oe-1fK-15@gated-at.bofh.it> (permalink)
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* Alex Shi <alex.shi@linaro.org> [170716 16:25]:
> I reused the rcu_irq_enter_irqson() from RCU_NONIDLE to avoid this issue. 
> It works fine.
> 
> Tony, Could you like to give a tested-by if this patch works for you.

Yeah that keeps things booting for me with no splats so:

Tested-by: Tony Lindgren <tony@atomide.com>

In general, it seems we're missing the knowledge in Linux kernel
of when the entire system is idle. Right now it seems that only
cpuidle_coupled knows that?

We could probably simplify things by adding some PM state for
entire system idle. Then cpuidle code and timer code could use
that to test when it's safe to do whatever the SoC needs to do
to enter deeper power states.

If we already have something like that, please do let me know :)

Regards,

Tony

Thread

Regression with suspicious RCU usage splats with cpu_pm change Tony Lindgren <tony@atomide.com> - 2017-07-13 09:10 +0200
  Re: Regression with suspicious RCU usage splats with cpu_pm change Alex Shi <alex.shi@linaro.org> - 2017-07-13 11:50 +0200
    Re: Regression with suspicious RCU usage splats with cpu_pm change "Rafael J. Wysocki" <rafael@kernel.org> - 2017-07-13 14:00 +0200
      Re: Regression with suspicious RCU usage splats with cpu_pm change "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-13 14:50 +0200
        Re: Regression with suspicious RCU usage splats with cpu_pm change Alex Shi <alex.shi@linaro.org> - 2017-07-17 01:30 +0200
          Re: Regression with suspicious RCU usage splats with cpu_pm change Tony Lindgren <tony@atomide.com> - 2017-07-17 08:10 +0200
            Re: Regression with suspicious RCU usage splats with cpu_pm change "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-17 14:40 +0200
              Re: Regression with suspicious RCU usage splats with cpu_pm change Tony Lindgren <tony@atomide.com> - 2017-07-18 07:50 +0200

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