From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Sasha Levin <sasha.levin@oracle.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: timers: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
Date: Fri, 29 Jan 2016 16:27:35 +0100 [thread overview]
Message-ID: <20160129152735.GB407@worktop> (raw)
In-Reply-To: <20160115231410.GA16973@linux.vnet.ibm.com>
On Fri, Jan 15, 2016 at 03:14:10PM -0800, Paul E. McKenney wrote:
> And if I make the scheduling-clock interrupt send extra wakeups to the RCU
> grace-period kthread when needed, things work even with CPU hotplug going.
>
> The "when needed" means any time that the RCU grace-period kthread has
> been sleeping three times as long as the timeout interval. If the first
> wakeup does nothing, it does another wakeup once per second.
>
> So it looks like this change makes an existing problem much worse, as
> opposed to introducing a new problem.
I have a vague idea about a possible race window. Have you been
observing this on PPC or x86?
The reason I'm asking is that PPC (obviously) allows for more races :-)
next prev parent reply other threads:[~2016-01-29 15:27 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-12 20:03 timers: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected Sasha Levin
2016-01-12 20:18 ` Peter Zijlstra
2016-01-12 20:52 ` Paul E. McKenney
2016-01-13 9:05 ` Thomas Gleixner
2016-01-13 16:16 ` Paul E. McKenney
2016-01-14 17:43 ` Thomas Gleixner
2016-01-14 18:18 ` Paul E. McKenney
2016-01-14 19:47 ` Thomas Gleixner
2016-01-15 1:42 ` Paul E. McKenney
2016-01-15 10:03 ` Thomas Gleixner
2016-01-15 21:11 ` Paul E. McKenney
2016-01-15 22:10 ` Paul E. McKenney
2016-01-15 23:14 ` Paul E. McKenney
2016-01-29 15:27 ` Peter Zijlstra [this message]
2016-01-31 0:28 ` Paul E. McKenney
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