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From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Dave Jones <davej@codemonkey.org.uk>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	Stephane Eranian <eranian@gmail.com>,
	Andi Kleen <andi@firstfloor.org>
Subject: Re: perf related lockdep bug
Date: Wed, 4 Nov 2015 16:36:51 +0100	[thread overview]
Message-ID: <20151104153651.GC11639@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20151104142058.GX3604@twins.programming.kicks-ass.net>

On Wed, Nov 04, 2015 at 03:20:58PM +0100, Peter Zijlstra wrote:
> On Wed, Nov 04, 2015 at 05:48:38AM -0800, Paul E. McKenney wrote:
> > This problem is caused by the IPI handler interrupting the RCU read-side
> > critical section.  One way to prevent the IPI from doing this is to
> > disable interrupts across the RCU read-side critical section instead
> > of merely disabling preemption.  This is a reasonable approach given
> > that acquiring the scheduler locks is going to disable interrupts
> > in any case.
> > 
> > The (untested) patch below takes this approach.
> > 
> > Thoughts?
> 
> Yes, this should work, but now I worry I need to go audit all of perf
> and sched for this :/

I can't find any other sites just now, so let me queue this.

I also had a brief look if you used any other locks under rnp->lock, but
aside from the printk and sched things it seems clean.



  parent reply	other threads:[~2015-11-04 15:36 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-04  5:17 perf related lockdep bug Dave Jones
2015-11-04 10:21 ` Peter Zijlstra
2015-11-04 10:28   ` Peter Zijlstra
2015-11-04 10:50     ` Peter Zijlstra
2015-11-04 13:48       ` Paul E. McKenney
2015-11-04 14:20         ` Peter Zijlstra
2015-11-04 15:34           ` Paul E. McKenney
2015-11-04 15:36           ` Peter Zijlstra [this message]
2015-11-04 15:51             ` Paul E. McKenney
2015-11-04 20:58         ` Andi Kleen
2015-11-05  0:55           ` Paul E. McKenney
2015-11-05  1:59             ` Paul E. McKenney
2015-11-05  2:46             ` Andi Kleen
2015-11-05 14:04               ` Paul E. McKenney
2015-11-11 13:29                 ` Paul E. McKenney
2015-11-10  6:39         ` [tip:perf/urgent] perf: Disable IRQs across RCU RS CS that acquires scheduler lock tip-bot for Paul E. McKenney
2015-11-04 14:01     ` perf related lockdep bug Paul E. McKenney
2015-11-04 14:34       ` Peter Zijlstra
2015-11-05  1:57         ` Paul E. McKenney

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