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SubjectRe: [ANNOUNCE] v4.14.29-rt25
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On 04/20/2018 12:11 PM, Sebastian Andrzej Siewior wrote:
> On 2018-03-27 13:01:07 [-0500], Grygorii Strashko wrote:
>> Hi Sebastian,
> Hi Grygorii,
>
>> I've took this RT version and applied "[RT] kernel/time/posix-timer: avoid schedule()
>> while holding the RCU lock" [1] on top. Then I run below tests:
> …
>> no stall or crashes were observed, but I've caught two "rcu_note_context_switch()" warnings
>
> the warning is unrelated to the patch I posted. This should mute it:
>
> Subject: [PATCH RT] rtmutex: annotate sleeping lock context
>
> The RCU code complains on schedule() within a rcu_readlock() section.
> The valid scenario on -RT is if a sleeping is held. In order to suppress
> the warning the mirgrate_disable counter was used to identify the
> invocation of schedule() due to lock contention.
>
> Grygorii Strashko report that during CPU hotplug we might see the
> warning via
> rt_spin_lock() -> migrate_disable() -> pin_current_cpu() -> __read_rt_lock()
>
> because the counter is not yet set.
> It is also possible to trigger the warning from cpu_chill()
> (seen on a kblockd_mod_delayed_work_on() caller).
>
> To address this RCU warning I annotate the sleeping lock context. The
> counter is incremented before migrate_disable() so the warning Grygorii
> should not trigger anymore. Additionally I use that counter in
> cpu_chill() to avoid the RCU warning from there.

Sry, but I can't apply it. What's you base?

>
> Reported-by: Grygorii Strashko <grygorii.strashko@ti.com>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
--
regards,
-grygorii

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