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From: Peter Zijlstra <peterz@infradead.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] sched: Fix get_push_task() vs migrate_disable()
Date: Thu, 26 Aug 2021 18:56:31 +0200	[thread overview]
Message-ID: <YSfHv7Ptrprccmgp@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210826133738.yiotqbtdaxzjsnfj@linutronix.de>

On Thu, Aug 26, 2021 at 03:37:38PM +0200, Sebastian Andrzej Siewior wrote:
> push_rt_task() attempts to move the currently running task away if the
> next runnable task has migration disabled and therefore is pinned on the
> current CPU.
> 
> The current task is retrieved via get_push_task() which only checks for
> nr_cpus_allowed == 1, but does not check whether the task has migration
> disabled and therefore cannot be moved either. The consequence is a
> pointless invocation of the migration thread which correctly observes
> that the task cannot be moved.
> 
> Return NULL if the task has migration disabled and cannot be moved to
> another CPU.
> 
> Fixes: a7c81556ec4d3 ("sched: Fix migrate_disable() vs rt/dl balancing")
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Thanks!

  parent reply	other threads:[~2021-08-26 16:59 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-26 13:37 [PATCH] sched: Fix get_push_task() vs migrate_disable() Sebastian Andrzej Siewior
2021-08-26 16:24 ` Tao Zhou
2021-08-26 19:38   ` Thomas Gleixner
2021-08-26 22:53     ` Tao Zhou
2021-08-26 16:56 ` Peter Zijlstra [this message]
2021-08-26 17:07 ` [tip: sched/urgent] " tip-bot2 for Sebastian Andrzej Siewior

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