linux-kernel - Re: [PATCH] sched: idle: Avoid retaining the tick when it has been stopped

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Date:   Tue, 21 Aug 2018 16:21:44 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Ingo Molnar <mingo@...nel.org>, Leo Yan <leo.yan@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Kevin Hilman <khilman@...libre.com>, linux-omap@...r.kernel.org
Subject: Re: [PATCH] sched: idle: Avoid retaining the tick when it has been
 stopped

* Rafael J. Wysocki <rjw@...ysocki.net> [691231 23:00]:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> If the tick has been stopped already, but the governor has not asked to
> stop it (which it can do sometimes), the idle loop should invoke
> tick_nohz_idle_stop_tick(), to let tick_nohz_stop_tick() take care
> of this case properly.
> 
> Fixes: 554c8aa8ecad (sched: idle: Select idle state before stopping the tick)

This patch seems to fix an issue where boot hangs occasionally
on beagleboard-xm with ARM multi_v7_defconfig as reported by
kernelci.org and Mark Brown earlier at [0].

At least so far no boot hangs for me with this fix, so:

Tested-by: Tony Lindgren <tony@...mide.com>

[0] https://www.spinics.net/lists/linux-mmc/msg50480.html