It is unnecessary on modern Intel or AMD systems, and that is all we support
on x86-64

Also causes problems on various systems
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>