Re: [PATCH 2/2] mm/hugetlb: Use a folio in hugetlb_wp()

[zhangpeng (AS)]

On 2023/6/3 4:17, Matthew Wilcox wrote:

> On Fri, Jun 02, 2023 at 09:54:08AM +0800, Peng Zhang wrote:
> > From: ZhangPeng <zhangpeng362@xxxxxxxxxx>
> >
> > We can replace nine implict calls to compound_head() with one by using
> > old_folio. However, we still need to keep old_page because we need to
> > know which page in the folio we are copying.
> Do we?  It's my understanding (and I am far from an expert here ...)
> that the 'pte_t *' we are passed *inside hugetlbfs* is not in fact a pte
> pointer at all but actually a pmd or pud pointer.  See how we do this:
>
>          pte_t pte = huge_ptep_get(ptep);
>
> and so the page we get back is always a head page, and we can go
> directly to a folio.  ie this is different from the THP cases.

Yes, I'll remove ptepage and old_page in a v2. Thanks.

Best Regards,
Peng