Re: [PATCH RFC v2 17/18] mm: add free_frozen_pages_hint and put_page_hint APIs

David Hildenbrand (Arm)
2026-04-21T10:56:13Z

On 4/20/26 14:51, Michael S. Tsirkin wrote:
> Add free_frozen_pages_hint(page, order, hints) to free a page
> while marking it as pre-zeroed when PGHINT_ZEROED is set.
> The PG_zeroed flag is set after __free_pages_prepare so it
> survives on the free list.
>
> Add __folio_put_hint(), folio_put_hint(), and put_page_hint()
> wrappers for the put_page path.

Can we defer that change?

Putting a page with a hint, when there might still be other users of the
page is a weird interface.

In the long term, all balloon pages (PG_offline pages) will be frozen
pages, and definitely not folios.

Frozen pages don't have a refcount.

It would then be sufficient to have the single owner of the page call
something like free_frozen_zeroed_page().

Now, to convert balloon pages to be frozen requires some more work,
primarily to balloon migration handling, unfortunately. I have it on my
todo list, but it will take a while.

--
Cheers,

David