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From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Guenter Roeck <linux@roeck-us.net>,
	linux-kernel@vger.kernel.org, Don Zickus <dzickus@redhat.com>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: Crashes in perf_event_ctx_lock_nested
Date: Wed, 1 Nov 2017 09:14:50 +0100
Message-ID: <20171101081450.waqzz2ftebaw3tal@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <alpine.DEB.2.20.1710312145190.1942@nanos>

On Tue, Oct 31, 2017 at 10:32:00PM +0100, Thomas Gleixner wrote:
> That means we can have the following situation:
> 
>     lock(watchdog_mutex);
>     lockup_detector_reconfigure();
>         cpus_read_lock();
> 	stop();
> 	   park()
> 	update();
> 	start();
> 	   unpark()
> 	cpus_read_unlock();		thread runs()
> 	cleanup();						
>     unlock(watchdog_mutex);
> 

Isn't there also a where hardlockup_detector_perf_init() creates an
event to 'probe' stuff, and then hardlockup_detector_perf_enable()
_again_ creates the event?

  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-30 22:45 Guenter Roeck
2017-10-31 13:48 ` Peter Zijlstra
2017-10-31 17:16   ` Guenter Roeck
2017-10-31 18:50     ` Don Zickus
2017-10-31 20:12       ` Guenter Roeck
2017-10-31 20:23         ` Don Zickus
2017-10-31 21:32   ` Thomas Gleixner
2017-10-31 22:11     ` Guenter Roeck
2017-11-01 18:11       ` Don Zickus
2017-11-01 18:34         ` Guenter Roeck
2017-11-01 19:46         ` [tip:core/urgent] watchdog/hardlockup/perf: Use atomics to track in-use cpu counter tip-bot for Don Zickus
2017-11-01 20:28         ` tip-bot for Don Zickus
2017-11-01 18:22       ` Crashes in perf_event_ctx_lock_nested Thomas Gleixner
2017-11-01  8:14     ` Peter Zijlstra [this message]
2017-11-01  8:26       ` Thomas Gleixner
2017-11-01 19:46     ` [tip:core/urgent] watchdog/harclockup/perf: Revert a33d44843d45 ("watchdog/hardlockup/perf: Simplify deferred event destroy") tip-bot for Thomas Gleixner
2017-11-01 20:32       ` Guenter Roeck
2017-11-01 20:52         ` Thomas Gleixner
2017-11-01 20:27     ` tip-bot for Thomas Gleixner
2017-10-31 18:48 ` Crashes in perf_event_ctx_lock_nested Don Zickus

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