From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Jones <davej@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: lockdep circular locking error (rcu_node_level_0 vs rq->lock)
Date: Wed, 13 Jul 2011 22:26:22 -0700 [thread overview]
Message-ID: <20110714052622.GA5366@linux.vnet.ibm.com> (raw)
In-Reply-To: <20110714042932.GA2932@linux.vnet.ibm.com>
On Wed, Jul 13, 2011 at 09:29:32PM -0700, Paul E. McKenney wrote:
> On Wed, Jul 13, 2011 at 09:33:09AM -0700, Paul E. McKenney wrote:
[ . . . ]
> Hmmm... Something is confused. I get boot time hangs with the
> occasional stack overflow, whether or not I add my patch on top.
> Left to myself, I would try applying your patch incrementally, and
> also disabling irqs before rcu_read_lock() and enabling them after
> rcu_read_unlock(), as this prevents rcu_read_unlock() from ever getting
> to the rcu_read_unlock_special() slowpath.
And the real question... Why did the rcu_read_unlock() called from
cpuacct_charge() enter rcu_read_unlock_special() in the first place?
If the runqueue lock is held, irqs should be disabled, so how did the
task get blocked or interrupted?
I need to get some sleep then figure out what is going on here.
Thanx, Paul
prev parent reply other threads:[~2011-07-14 5:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-11 23:19 lockdep circular locking error (rcu_node_level_0 vs rq->lock) Dave Jones
2011-07-12 20:20 ` Peter Zijlstra
2011-07-12 20:51 ` Paul E. McKenney
2011-07-12 21:44 ` Peter Zijlstra
2011-07-12 22:54 ` Paul E. McKenney
2011-07-13 8:24 ` Peter Zijlstra
2011-07-13 16:33 ` Paul E. McKenney
2011-07-14 4:29 ` Paul E. McKenney
2011-07-14 5:26 ` Paul E. McKenney [this message]
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