On Wed, Jun 18, 2025 at 02:04:18PM -0400, Zi Yan wrote:
> > Let's allow for not clearing a page type before freeing a page to the
> > buddy.
> >
> > We'll focus on having a type set on the first page of a larger
> > allocation only.
> >
> > With this change, we can reliably identify typed folios even though
> > they might be in the process of getting freed, which will come in handy
> > in migration code (at least in the transition phase).
> > + if (unlikely(page_has_type(page)))
> > + page->page_type = UINT_MAX;
> > +
> > if (is_check_pages_enabled()) {
> > if (free_page_is_bad(page))
> > bad++;
> > --
> > 2.49.0
>
> How does this preserve page type? Isn’t page->page_type = UINT_MAX clearing
> page_type?
The point is that the _caller_ used to have to clear the page type.
This patch allows the caller to free the page without clearing
the page type first.
