This only made sense for the alternate fastpath which was reverted last week.

Mathieu is working on a new version that addresses the fastpath issues but that
new code first needs to go through mm and it is not clear if we need the
unique end pointers with his new scheme.
Reviewed-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NChristoph Lameter <clameter@sgi.com>