Re: Weird rcu lockdep warning

From: Paul E. McKenney
Date: Thu Apr 15 2010 - 15:48:10 EST


On Thu, Apr 15, 2010 at 08:57:05PM +0200, Frederic Weisbecker wrote:
> On Wed, Apr 14, 2010 at 09:24:26PM -0700, Paul E. McKenney wrote:
> > On Wed, Apr 14, 2010 at 09:00:57AM -0700, Paul E. McKenney wrote:
> > > On Wed, Apr 14, 2010 at 05:51:11PM +0200, Frederic Weisbecker wrote:
> >
> > [ . . .]
> >
> > > > Note I just tested the patch the previous one and it looks fine now.
> > > > You can then safely consider the "general idea" fixes the problem :)
> > >
> > > Thank you, Frederic!!!
> >
> > And here is what I hope is the official fix.
> >
> > Could you please test it?
> >
> > Thanx, Paul
> >
> > ------------------------------------------------------------------------
> >
> > commit 9be39c445a41e458d53cf9a57d25dbfa4b74c970
> > Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> > Date: Tue Apr 13 18:45:51 2010 -0700
> >
> > rcu: Make RCU lockdep check the lockdep_recursion variable
> >
> > The lockdep facility temporarily disables lockdep checking by incrementing
> > the current->lockdep_recursion variable. Such disabling happens in NMIs
> > and in other situations where lockdep might expect to recurse on itself.
> > This patch therefore checks current->lockdep_recursion, disabling RCU
> > lockdep splats when this variable is non-zero. In addition, this patch
> > removes the "likely()", as suggested by Lai Jiangshan.
> >
> > Reported-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> > Reported-by: David Miller <davem@xxxxxxxxxxxxx>
> > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
>
> Tested-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>

Thank you, Frederic!

Thanx, Paul
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