Re: [PATCH 01/13] powerpc: Add rcu_read_lock() to gup_fast() implementation

Rik van Riel
2010-04-08T20:33:01Z

On 04/08/2010 03:17 PM, Peter Zijlstra wrote:
> The powerpc page table freeing relies on the fact that IRQs hold off
> an RCU grace period, this is currently true for all existing RCU
> implementations but is not an assumption Paul wants to support.
>
> Therefore, also take the RCU read lock along with disabling IRQs to
> ensure the RCU grace period does at least cover these lookups.
>
> Requested-by: Paul E. McKenney<paulmck@linux.vnet.ibm.com>
> Signed-off-by: Peter Zijlstra<a.p.zijlstra@chello.nl>
> Cc: Nick Piggin<npiggin@suse.de>
> Cc: Benjamin Herrenschmidt<benh@kernel.crashing.org>

Reviewed-by: Rik van Riel <riel@redhat.com>