From: David Miller <davem@davemloft.net>
To: fweisbec@gmail.com
Cc: paulmck@linux.vnet.ibm.com, a.p.zijlstra@chello.nl,
mingo@elte.hu, sparclinux@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: Weird rcu lockdep warning
Date: Wed, 14 Apr 2010 00:13:06 +0000 [thread overview]
Message-ID: <20100413.171306.25868761.davem@davemloft.net> (raw)
In-Reply-To: <20100414000226.GH5602@nowhere>
From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Wed, 14 Apr 2010 02:02:27 +0200
> I just have a guess though....
> This seems to always happen from NMI path, and lockdep is disabled on NMI.
> I suspect the lock_acquire() performed by rcu_read_lock() is just ignored
> and then the rcu_read_lock_held() check has the wrong result...
Yeah, I bet that's it too.
lock_is_held() can't return anything meaningful while lockdep is
disabled, which it is during NMIs.
WARNING: multiple messages have this Message-ID (diff)
From: David Miller <davem@davemloft.net>
To: fweisbec@gmail.com
Cc: paulmck@linux.vnet.ibm.com, a.p.zijlstra@chello.nl,
mingo@elte.hu, sparclinux@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: Weird rcu lockdep warning
Date: Tue, 13 Apr 2010 17:13:06 -0700 (PDT) [thread overview]
Message-ID: <20100413.171306.25868761.davem@davemloft.net> (raw)
In-Reply-To: <20100414000226.GH5602@nowhere>
From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Wed, 14 Apr 2010 02:02:27 +0200
> I just have a guess though....
> This seems to always happen from NMI path, and lockdep is disabled on NMI.
> I suspect the lock_acquire() performed by rcu_read_lock() is just ignored
> and then the rcu_read_lock_held() check has the wrong result...
Yeah, I bet that's it too.
lock_is_held() can't return anything meaningful while lockdep is
disabled, which it is during NMIs.
next prev parent reply other threads:[~2010-04-14 0:13 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-13 20:04 Weird rcu lockdep warning Frederic Weisbecker
2010-04-13 20:04 ` Frederic Weisbecker
2010-04-13 23:40 ` Paul E. McKenney
2010-04-13 23:40 ` Paul E. McKenney
2010-04-14 0:02 ` Frederic Weisbecker
2010-04-14 0:02 ` Frederic Weisbecker
2010-04-14 0:13 ` David Miller [this message]
2010-04-14 0:13 ` David Miller
2010-04-14 1:49 ` Paul E. McKenney
2010-04-14 1:49 ` Paul E. McKenney
2010-04-14 1:51 ` David Miller
2010-04-14 1:51 ` David Miller
2010-04-14 3:34 ` Lai Jiangshan
2010-04-14 3:34 ` Lai Jiangshan
2010-04-14 15:43 ` Paul E. McKenney
2010-04-14 15:43 ` Paul E. McKenney
2010-04-14 15:51 ` Frederic Weisbecker
2010-04-14 15:51 ` Frederic Weisbecker
2010-04-14 16:00 ` Paul E. McKenney
2010-04-14 16:00 ` Paul E. McKenney
2010-04-15 4:24 ` Paul E. McKenney
2010-04-15 4:24 ` Paul E. McKenney
2010-04-15 18:57 ` Frederic Weisbecker
2010-04-15 18:57 ` Frederic Weisbecker
2010-04-15 19:47 ` Paul E. McKenney
2010-04-15 19:47 ` Paul E. McKenney
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