Re: [PATCH v1 05/29] mm/balloon_compaction: make PageOffline sticky until the page is freed

Lorenzo Stoakes
2025-06-30T16:19:31Z

On Mon, Jun 30, 2025 at 12:14:01PM -0400, Zi Yan wrote:
> On 30 Jun 2025, at 12:01, Lorenzo Stoakes wrote:
>
> > On Mon, Jun 30, 2025 at 02:59:46PM +0200, David Hildenbrand wrote:
> >> Let the page freeing code handle clearing the page type.
> >
> > Why is this advantageous? We want to keep the page marked offline for longer?
> >
> >>
> >> Acked-by: Zi Yan <ziy@nvidia.com>
> >> Acked-by: Harry Yoo <harry.yoo@oracle.com>
> >> Signed-off-by: David Hildenbrand <david@redhat.com>
> >
> > On assumption this UINT_MAX stuff is sane :)) I mean this is straightforward I
> > guess:
>
> This is how page type is cleared.
> See: https://elixir.bootlin.com/linux/v6.15.4/source/include/linux/page-flags.h#L1013.

Doh did go looking there but missed this!

I hate these macros so much. Almost designed to obfuscate.

>
> I agree with you that patch 4 should have a comment in free_pages_prepare()
> about what the code is for and why UINT_MAX is used.

Thx!

>
>
> Best Regards,
> Yan, Zi