On Tue, Aug 06, 2024 at 04:29:34PM +0100, Ryan Roberts wrote:
> >> Elsewhere in the file, this pattern is used:
> >>
> >> if (folio_test_hwpoison(folio) ||
> >> (folio_test_large(folio) && folio_test_has_hwpoisoned(folio))) {
> >
> > Ugh. The hwpoison stuff is too complicated. Because that's wrong too.
> > It should be ...
> >
> > if (folio_test_large(folio) && folio_test_has_hwpoisoned(folio) ||
> > !folio_test_large(folio) && folio_test_hwpoison(folio))
>
> Err... I clearly don't understand it properly. I guess you sometimes want to
> know if any page in the folio is poisioned, and sometimes if a specific page is
> poisoned? So
>
> // returns true if any page in the folio is hwpoisoned.
> // works for any folio (large or small).
> folio_test_hwpoison(folio);
>
> // returns true if the page at index within folio is hwpoisoned.
> // works for any folio (large or small).
> // BUGs if index out of range.
> folio_test_hwpoison_page(folio, index);
>
> Why isn't this the right interface? Why do we have a function that takes a folio
> but is only correct to call if the folio is large?
Well, quite. That would be a sane interface, although I think I'm fine
with leaving PageHWPoison(folio_page(folio, idx)) as the second API.
As always, HugeTLB makes things complicated. I need to finish rebasing
on current -next and then I'll work up a patch.
