On Thu, 26 Oct 2006, Stephen Rothwell wrote:

This is needed on bigendian 64bit architectures. The obvious way to do
this (taking the other compat_ routines in this file as examples) is to
use compat_alloc_user_space and copy the bitmasks back there, however you
cannot call compat_alloc_user_space twice for a single system call and
this method saves two copies of the bitmasks.

Well this means also that sys_mbind and sys_set_mempolicy are also
broken because these functions also use get_nodes().

Fixing get_nodes() to do the proper thing would fix all of these 
without having to touch sys_migrate_pages or creating a compat_ function 
(which usually is placed in kernel/compat.c)