Why don't we increase nonresident_age when inactive pages are moved to the head of the inactive list again?

Hello,

The current refault algorithm only increases nonresident_age when pages are
promoted or evicted. When a page is removed from the tail of the inactive list
and then added to the head again, all other pages are moved one slot backward.
This is also an aging process. I wonder why we don't increase nonresident_age
in this circumstance. Thanks.

Regards,
Hao Lee