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Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace timers with utilization ...'

From Viresh Kumar <viresh.kumar@linaro.org>
Newsgroups linux.kernel
Subject Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace timers with utilization ...'
Date 2016-02-16 02:20 +0100
Message-ID <r2Ct3-Dq-5@gated-at.bofh.it> (permalink)
References <r2uOU-3Y1-53@gated-at.bofh.it> <r2wnF-4Wo-45@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 15-02-16, 19:41, Rafael J. Wysocki wrote:
> On Mon, Feb 15, 2016 at 6:05 PM, Guenter Roeck <linux@roeck-us.net> wrote:
> > [    1.340000] [<c0958e78>] (__cpufreq_driver_target) from [<c095ca58>] (dbs_check_cpu+0x1ac/0x1e8)
> > [    1.340000] [<c095ca58>] (dbs_check_cpu) from [<c095cd04>] (cpufreq_governor_dbs+0x1fc/0x608)
> > [    1.340000] [<c095cd04>] (cpufreq_governor_dbs) from [<c0959c5c>] (__cpufreq_governor+0x1a8/0x204)
> > [    1.340000] [<c0959c5c>] (__cpufreq_governor) from [<c095a2dc>] (cpufreq_init_policy+0x60/0x8c)
> > [    1.340000] [<c095a2dc>] (cpufreq_init_policy) from [<c095a5f0>] (cpufreq_online+0x2e8/0x708)
> > [    1.340000] [<c095a5f0>] (cpufreq_online) from [<c075674c>] (subsys_interface_register+0x80/0xc4)
> > [    1.340000] [<c075674c>] (subsys_interface_register) from [<c0959764>] (cpufreq_register_driver+0x144/0x1a0)
> 
> This is the registration of the cpufreq driver (cpufreq-dt in this case).
> 
> It does cpufreq_online()->cpufreq_init_policy()->__cpufreq_governor()->cpufreq_governor_dbs()->dbs_check_cpu().
> 
> The only way that can happen is when cpufreq_set_policy() finds that
> the "old" and the "new" policies use the same governor, so it goes and
> calls __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS), but I'm not sure
> how this is possible during the initialization ATM.
> 
> Viresh, any ideas?

You misread probably.

During init, policy->gov is NULL and new_policy->gov is set to the
default one, probably ondemand/conservative. And in that case, we do:
- INIT
- START
- LIMITS

So above sequence is guaranteed to happen rather.

-- 
viresh

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Thread

Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-15 18:10 +0100
  Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 19:50 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 19:50 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Marc Zyngier <marc.zyngier@arm.com> - 2016-02-15 20:00 +0100
      Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 20:00 +0100
        Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Marc Zyngier <marc.zyngier@arm.com> - 2016-02-15 20:10 +0100
          Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 20:20 +0100
            Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace timers with utilization ...' "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-15 20:30 +0100
              Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-15 20:50 +0100
                Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Tony Lindgren <tony@atomide.com> - 2016-02-15 21:00 +0100
              Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Tony Lindgren <tony@atomide.com> - 2016-02-15 20:50 +0100
          Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-02-15 20:30 +0100
            Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 21:50 +0100
        Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-02-15 20:10 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-02-15 20:10 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Tony Lindgren <tony@atomide.com> - 2016-02-15 20:10 +0100
      Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-15 20:50 +0100
        Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Tony Lindgren <tony@atomide.com> - 2016-02-15 21:00 +0100
          Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-15 21:10 +0100
            Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 21:40 +0100
          Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 21:40 +0100
            Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Tony Lindgren <tony@atomide.com> - 2016-02-15 22:40 +0100
              Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-16 02:40 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-16 02:20 +0100
      Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace timers with utilization ...' "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-16 02:30 +0100
        Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-16 02:40 +0100
  Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Peter Maydell <peter.maydell@linaro.org> - 2016-02-15 23:40 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-16 00:30 +0100

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