Re: Weird rcu lockdep warning

From: Frederic Weisbecker
Date: Thu Apr 15 2010 - 14:57:31 EST


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>

Thanks!

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