Re: [PATCH v4 10/13] mm/collapse: open-code collapse_single_pmd() in its two callers

[Kiryl Shutsemau]

On Wed, Oct 14, 2026 at 11:33:46AM +0200, David Hildenbrand (Arm) wrote:
> On 10/13/26 23:38, Andrew Morton wrote:
> > On Tue, 13 Oct 2026 22:25:21 +0200 "David Hildenbrand (Arm)" <david@xxxxxxxxxx> wrote:
> > 
> >>>
> >>> I see the appeal of the single entry point for the collapse engine. I do.
> >>>
> >>> But it costs us on both the locking picture and the scan rate. That
> >>> does not work for me.
> >>
> >> So this is in mm-unstable and I want at least the first 9 patches to go to
> >> mm-stable rather sooner than later.
> >>
> >> As raised in person, I don't like the open-coding here; it just results in weird
> >> API. I wonder whether we can come up with a better interface, while keeping the
> >> locking as per your requirement cheap (scan performance).
> >>
> >> While we figure that out, does it make sense to send out revised patch 1..9 to
> >> move them to mm-stable while we figure out the remainder of the new API?
> > 
> > I've suggested to Kyril that we park this series until the next -rc
> > cycle.
> > 
> > But I can bring it back - we have a couple of weeks, three if we get a
> > 3-week merge window.
> 
> I'd say we move forward with the uncontroversial parts, and keep discussing the
> controversial bits. Either these make it still in this cycle or we'll simply
> have them for the next cycle.

Agreed.

Andrew, could you pick up 1-9 and leave 10-13 out for now?

I want to experiment with a few ideas for the rest and will get back.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov