From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
split_page() calls set_page_owner() to set up page_owner to each pages.
But, it has a drawback that head page and the others have different
stacktrace because callsite of set_page_owner() is slightly differnt.
To avoid this problem, this patch copies head page's page_owner to
the others. It needs to introduce new function, split_page_owner() but
it also remove the other function, get_page_owner_gfp() so looks good
to do.