On Wed, Nov 06, 2024 at 05:06:32PM -0500, Zi Yan wrote:
> >> + } else {
> >> + if (PageHead(head))
> >> + ClearPageCompound(head);
> >
> > Huh? You only have to test for PageHead() because it is inside the loop.
> > It has to be done after loop is done.
>
> You are right, will remove this and add the code below after the loop.
>
> if (!new_order && PageHead(&folio->page))
> ClearPageCompound(&folio->page);
PageHead(&forlio->page) is always true, isn't it?
> >> + if (folio_test_anon(folio) && folio_test_swapcache(folio)) {
> >> + if (!uniform_split)
> >> + return -EINVAL;
> >
> > Why this limitation?
>
> I am not closely following the status of mTHP support in swap. If it
> is supported, this can be removed. Right now, split_huge_page_to_list_to_order()
> only allows to split a swapcache folio to order 0[1].
>
> [1] https://elixir.bootlin.com/linux/v6.12-rc6/source/mm/huge_memory.c#L3397
It would be nice to clarify this or at least add a comment.
--
Kiryl Shutsemau / Kirill A. Shutemov
