From: Peter Zijlstra <peterz@infradead.org>
To: bsegall@google.com
Cc: Roman Gushchin <klamm@yandex-team.ru>,
linux-kernel@vger.kernel.org, pjt@google.com,
chris.j.arges@canonical.com, gregkh@linuxfoundation.org
Subject: Re: [PATCH] sched: tg_set_cfs_bandwidth() causes rq->lock deadlock
Date: Mon, 19 May 2014 12:40:11 +0200 [thread overview]
Message-ID: <20140519104011.GY30445@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <xm26k39n3pl9.fsf@sword-of-the-dawn.mtv.corp.google.com>
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On Thu, May 15, 2014 at 10:43:14AM -0700, bsegall@google.com wrote:
> I just did notice however that sched_cfs_period_timer reads
> cfs_b->period without any locks, which can in fact race with an update
> to period (and isn't fixed by this patch). If this write doesn't happen
> to be atomic (which is certainly not guaranteed, and is entirely
> plausible on say 32-bit x86, much less other archs), we could read a
> partially written value and move the timer incorrectly. Pulling the
> lock/unlock out of do_sched_cfs_period_timer should fix this easily
> enough.
>
> unthrottle_offline_cfs_rqs could cause similar issues with its unlocked
> read of quota, and can also be easily fixed.
Ben, will you send patches for this?
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prev parent reply other threads:[~2014-05-19 10:40 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-15 16:58 [PATCH] sched: tg_set_cfs_bandwidth() causes rq->lock deadlock Roman Gushchin
2014-05-15 17:43 ` bsegall
2014-05-16 8:38 ` Roman Gushchin
2014-05-16 17:57 ` bsegall
2014-05-19 11:10 ` Roman Gushchin
2014-05-19 17:40 ` bsegall
2014-05-19 10:32 ` Peter Zijlstra
2014-05-19 11:37 ` Roman Gushchin
2014-05-19 17:35 ` bsegall
2014-05-19 17:30 ` bsegall
2014-05-20 13:15 ` Peter Zijlstra
2014-05-20 14:01 ` Peter Zijlstra
2014-05-20 14:55 ` Peter Zijlstra
2014-05-20 14:21 ` Roman Gushchin
2014-05-20 14:28 ` Peter Zijlstra
2014-05-20 14:34 ` Roman Gushchin
2014-05-20 19:08 ` bsegall
2014-05-21 7:58 ` Peter Zijlstra
2014-05-19 10:40 ` Peter Zijlstra [this message]
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