Hi Paul,

Paul E. McKenney wrote:
> o	The rcu_pending() and rcu_needs_cpu() primitives are now
> 	much more aggressive about permitting CPUs to enter dynticks
> 	idle mode.  Only CPUs that have RCU callbacks are kept out
> 	of dynticks idle mode.
>   

I've noticed that right now rcu_enter_nohz() can be nested within 
rcu_irq_enter():
irq_exit() first calls tick_nohz_stop_sched_tick(), then rcu_irq_exit().
And tick_nohz_stop_sched_tick() can switch into nohz mode.

Is that intentional? Does rcupreempt support that? It broke my rcustate 
code on x86-64.

I would prefer if something like the attached patch is applied. What do 
you think?
Do you need the patch as well?

--
    Manfred