On Tue, Aug 16, 2022 at 03:29:20PM +1000, Alistair Popple wrote:
> >> +static long check_and_migrate_movable_pages(unsigned long nr_pages,
> >> + struct page **pages)
> >> +{
> >> + int ret;
> >> + unsigned long collected;
> >> + LIST_HEAD(movable_page_list);
> >> +
> >> + collected = collect_longterm_unpinnable_pages(&movable_page_list, nr_pages, pages);
> >> + if (!collected)
> >> + return 0;
> >> +
> >> + ret = migrate_longterm_unpinnable_pages(&movable_page_list, nr_pages, pages);
> >> + if (!ret)
> >> + return -EAGAIN;
> >> + else
> >> + return ret;
> >
> > I would drop the else path and just return zero
>
> Unless I've misunderstood you I don't think that's correct though.
> check_and_migrate_movable_pages() needs to return one of 3 conditions:
>
> - 0: All pages are in the correct zone and are still pinned (ie. "success").
> - -EAGAIN: Some pages were migrated, all pages need re-pinning.
> - errno: Migration failed, pins were dropped and PUP should fail.
>
> John's suggested comment update spells this out more clearly.
But that is not what it does..
if (!ret) == if (ret != 0)
return -EAGAIN
thus ret == 0
return ret == return 0
Jason
