missing helper used by arch/i386/mm/highmem.c, which is pulled
into build on that configuration.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Acked-by: NJeff Dike <jdike@addtoit.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>