Re: INFO: possible circular locking dependency detected

From: Sergey Senozhatsky
Date: Thu Jul 14 2011 - 15:17:23 EST


On (07/14/11 09:57), Paul E. McKenney wrote:
>
> On Thu, Jul 14, 2011 at 06:41:39PM +0200, Peter Zijlstra wrote:
> > On Thu, 2011-07-14 at 17:49 +0300, Sergey Senozhatsky wrote:
> > > Hello,
> > >
> > > [ 4172.371094] =======================================================
> > > [ 4172.371097] [ INFO: possible circular locking dependency detected ]
> > > [ 4172.371103] 3.0.0-rc7-dbg-00565-g6b31efc #644
> > > [ 4172.371105] -------------------------------------------------------
> > > [ 4172.371108] make/11702 is trying to acquire lock:
> > > [ 4172.371111] (rcu_node_level_0){..-...}, at: [<ffffffff810a55e2>] __rcu_read_unlock+0xb9/0x217
> > > [ 4172.371123]
> > > [ 4172.371123] but task is already holding lock:
> > > [ 4172.371125] (&p->pi_lock){-.-.-.}, at: [<ffffffff8103775e>] try_to_wake_up+0x29/0x28b
> > > [ 4172.371135]
> > > [ 4172.371135] which lock already depends on the new lock.
> >
> > Happen to have a .config and means of reproduction? We're a little
> > stumped at trying to explain how this can actually happen.
>
> What Peter said! Sergey, could also you please tell us what tree you
> are using? I am not seeing commit 6b31efc in mainline or -tip.
>

I'm using vanilla kernel
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git

$git pull
Already up-to-date.


Sergey

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