[PATH V2 4/6] arm: mm: Enable RCU fast_gup

[Catalin Marinas]

On Thu, Aug 21, 2014 at 04:43:30PM +0100, Steve Capper wrote:
> Activate the RCU fast_gup for ARM. We also need to force THP splits to
> broadcast an IPI s.t. we block in the fast_gup page walker. As THP
> splits are comparatively rare, this should not lead to a noticeable
> performance degradation.
> 
> Some pre-requisite functions pud_write and pud_page are also added.
> 
> Signed-off-by: Steve Capper <steve.capper at linaro.org>

Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>