Re: [PATCH 0/5] mm/khugepaged: add collapse hint machanism for khugepaged and use in mglru

[Lorenzo Stoakes <ljs@kernel.org>]

On Tue, Jun 09, 2026 at 04:17:45AM -0600, Nico Pache wrote:
> I had future plans for something similar as part of the thp=auto work;
> however that requires significant thought and investigation into how
> we can properly gather hints for collapse/split THP candidates. From
> my perspective we'd want a more global structure/system outside of
> khugepaged, that would directly call khugepaged (and others like
> split, etc). It would also tie into the allocator so that at fault
> time it could leverage the hints to make better decisions. My fear
> with this series is that making a decision now might complicate future
> work by adding complexity we may eventually want to remove for a
> better solution.

I know this is future planning stuff, but I want to point out that we need
to see significant rework of the THP code base before accepting any further
major changes.

>
> If you have the chance perhaps you can lead a discussion on your
> proposal at the biweekly MM alignment session.
>
> +David Rientjes as he leads those discussions. We could use that time
> to layout a plan for what needs to be done for this work, and for the
> work surrounding thp=auto as I beleive they will be interdependent :)

We prefer to discuss THP topics in the THP cabal meeting, which both THP
maintainers regularly attend :) having separate sessions we might not be aware
of isn't really helpful.

And 'THP auto' is a broad topic rather than a new feature. I don't think it
should be seen as a topic 'owned' by anybody, but rather something that we
as a community should discuss.

Series that appear from nowhere trying to implement significant changes
along those lines without community disucssion will not be hugely
appreciated :)

Thanks, Lorenzo