Re: [GIT PULL rcu/next] rcu commits for 2.6.40

[Ingo Molnar]

* Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote:

> On Mon, May 09, 2011 at 02:09:21PM -0700, Yinghai Lu wrote:
> > On Mon, May 9, 2011 at 12:36 AM, Ingo Molnar <mingo@xxxxxxx> wrote:
> > >
> > > * Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> > >
> > >> Hello, Ingo,
> > >>
> > >> This pull request covers RCU chnages for 2.6.40.  The major new features
> > >> are RCU priority boosting and the addition of kfree_rcu(), the latter
> > >> courtesy of Lai Jiangshan.  These two features cover well over half
> > >> of the commits.  There are a number of smaller features and bug fixes.
> > >> All have been sent to LKML in the following batches:
> > >>
> > >> 0.    https://lkml.org/lkml/2011/2/22/660: RCU priority boosting preview
> > >> 1.    https://lkml.org/lkml/2011/5/1/19: RCU priority boosting, kfree_rcu()
> > >> 2.    https://lkml.org/lkml/2011/5/2/40: More uses of kfree_rcu()
> > >> 3.    https://lkml.org/lkml/2011/5/8/60: miscellaneous
> > >>
> > >> The kfree_rcu() uses in the pull request have Acked-by:s from the
> > >> maintainers.  I have some additional kfree_rcu() requests that lack
> > >> Acked-by:s, and I will deal with these later.
> > >>
> > >> These channges are available in the -rcu git repository at:
> > >>
> > >>   git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu.git rcu/next
> > >
> > > Pulled, thanks a lot Paul!
> > >
> > 
> > it seems with this one in tip, my 8 sockets test setup will report cpu stall.
> > 
> > after hard code to enable rcu_cpu_stall_suppress
> > 
> > Index: linux-2.6/kernel/rcutree.c
> > ===================================================================
> > --- linux-2.6.orig/kernel/rcutree.c
> > +++ linux-2.6/kernel/rcutree.c
> > @@ -174,7 +174,7 @@ module_param(blimit, int, 0);
> >  module_param(qhimark, int, 0);
> >  module_param(qlowmark, int, 0);
> > 
> > -int rcu_cpu_stall_suppress __read_mostly;
> > +int rcu_cpu_stall_suppress __read_mostly = 1;
> >  module_param(rcu_cpu_stall_suppress, int, 0644);
> > 
> >  static void force_quiescent_state(struct rcu_state *rsp, int relaxed);
> > 
> > will get system hang after pnp ACPI init.
> 
> Could you please send the stack traces from the RCU CPU stall?  Also,
> you do have ce31332d3c77532d6ea97ddcb475a2b02dd358b4 applied, correct?

if the failure is reproducible then bisection would be helpful as well.

Thanks,

	Ingo
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