On Sat, Jul 31, 2021 at 12:39:38AM -0600, Yu Zhao wrote:
> @@ -267,13 +308,19 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma,
>   * Get rid of all migration entries and replace them by
>   * references to the indicated page.
>   */
> -void remove_migration_ptes(struct page *old, struct page *new, bool locked)
> +void remove_migration_ptes(struct page *old, struct page *new, bool locked, bool unmap_clean)
>  {
> +     struct rmap_walk_arg rmap_walk_arg = {
> +             .page = old,
> +             .unmap_clean = unmap_clean,
> +     };
>       struct rmap_walk_control rwc = {
>               .rmap_one = remove_migration_pte,
> -             .arg = old,
> +             .arg = &rmap_walk_arg,
>       };

'old' pointer has few low always-zero bit :P