As time goes, the code changes a lot, and this leads to that
some old-days comments scatter around , which instead of faciliating
understanding, but make more confusion. So this patch cleans up them.

Also, this patch unifies some variables naming.
Acked-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NJianyu Zhan <nasa4836@gmail.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>