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Subject: Re: [PATCH 01/13] powerpc: Add rcu_read_lock() to gup_fast()
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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: paulmck@linux.vnet.ibm.com
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Date: Fri, 16 Apr 2010 16:54:51 +1000
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On Thu, 2010-04-15 at 07:28 -0700, Paul E. McKenney wrote:
> 
> Of course, with call_rcu_sched(), the corresponding RCU read-side
> critical
> sections are non-preemptible.  Therefore, in CONFIG_PREEMPT_RT, these
> read-side critical sections must use raw spinlocks.
> 
> Can the code in question accommodate these restrictions? 

What we protect against is always code that hard-disable IRQs (though
there seem to be a bug in the hugepages code there...). Would that
work ?

Cheers,
Ben.