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From: Grygorii Strashko <grygorii.strashko@ti.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-rt-users <linux-rt-users@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [ANNOUNCE] v4.14.29-rt25
Date: Mon, 23 Apr 2018 11:57:39 -0500	[thread overview]
Message-ID: <764d0abc-7e88-a696-17a0-0bf807148d5b@ti.com> (raw)
In-Reply-To: <20180420171116.w2hxytgzvp4jgpyl@linutronix.de>



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

  reply	other threads:[~2018-04-23 16:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-25 10:12 Sebastian Andrzej Siewior
2018-03-27 18:01 ` Grygorii Strashko
2018-04-20 17:11   ` Sebastian Andrzej Siewior
2018-04-23 16:57     ` Grygorii Strashko [this message]
2018-04-23 19:10       ` Sebastian Andrzej Siewior
2018-05-01 15:04         ` Grygorii Strashko
2018-05-03 15:24           ` Sebastian Andrzej Siewior
2018-05-03 18:26             ` Grygorii Strashko

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