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Message-ID: <1341225139.23484.4.camel@twins>
Subject: Re: rcu: BUG: spinlock recursion on CPU#3, trinity-child19/5970
From: Peter Zijlstra <peterz@infradead.org>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: paulmck@linux.vnet.ibm.com, Dave Jones <davej@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Date: Mon, 02 Jul 2012 12:32:19 +0200
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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.