From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <levinsasha928@gmail.com>,
Dave Jones <davej@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: rcu: BUG: spinlock recursion on CPU#3, trinity-child19/5970
Date: Mon, 2 Jul 2012 04:35:41 -0700 [thread overview]
Message-ID: <20120702113541.GI2907@linux.vnet.ibm.com> (raw)
In-Reply-To: <1341225139.23484.4.camel@twins>
On Mon, Jul 02, 2012 at 12:32:19PM +0200, Peter Zijlstra wrote:
> On Fri, 2012-06-29 at 23:40 +0200, Sasha Levin wrote:
> >
> > The bad news are that what you saw was a lockdep enabled run
> > (CONFIG_PROVE_RCU is enabled, and lockdep was enabled). There were no
> > lockdep warnings at any point while reproducing it.
>
> rcu_switch_from() -> rcu_preempt_note_context_switch() is called _after_
> the lockdep context switch annotation. Therefore lockdep things the prev
> task isn't holding any locks anymore.
In other words, moving rcu_preempt_note_context_switch() deeper into
the scheduler is totally bogus, and I need to move it back out into the
original rcu_note_context_switch(), reverting 616c310e (Move PREEMPT_RCU
preemption to switch_to() invocation), correct?
Sigh. "It seemed like a good idea at the time."
Thanx, Paul
next prev parent reply other threads:[~2012-07-02 11:36 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-29 10:09 rcu: BUG: spinlock recursion on CPU#3, trinity-child19/5970 Sasha Levin
2012-06-29 17:23 ` Paul E. McKenney
2012-06-29 21:40 ` Sasha Levin
2012-06-29 22:27 ` Paul E. McKenney
2012-06-29 22:40 ` Sasha Levin
2012-06-29 23:01 ` Paul E. McKenney
2012-07-02 10:32 ` Peter Zijlstra
2012-07-02 11:35 ` Paul E. McKenney [this message]
2012-07-02 11:59 ` Peter Zijlstra
2012-07-02 13:12 ` Sasha Levin
2012-07-02 13:33 ` Paul E. McKenney
2012-07-02 14:22 ` Paul E. McKenney
2012-07-02 14:36 ` Sasha Levin
2012-07-02 14:59 ` Paul E. McKenney
2012-07-04 14:54 ` Sasha Levin
2012-07-04 19:07 ` Paul E. McKenney
2012-06-30 11:36 ` Sasha Levin
2012-06-30 13:14 ` Paul E. McKenney
2012-06-30 13:28 ` Sasha Levin
2012-06-30 13:58 ` Paul E. McKenney
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