Re: Process (was Re: [PATCH mm-hotfixes-unstable v18 00/14] khugepaged: add mTHP) collapse support

[Lorenzo Stoakes <ljs@kernel.org>]

On Sun, May 31, 2026 at 09:49:02PM +0200, David Hildenbrand (Arm) wrote:
> >
> >> and have people
> >> base work against that?
> >
> > This I'm not so sure how it would work. Assuming we have submaintainers with
> > their trees and branches, the final "stable branch" is merged from those.
> > But it's not a good base for work targeting the same merge window, as that
> > work would likely go to one of those submaintainer trees. But then it can't
> > be based on the result of merge of all submaintainer trees. That could only
> > work for patches targetting the next cycle (after the stable branch becomes
> > part of rc1).
> >
> > So either patches can be based on rc1 and applied as topic branches in a
> > submaintainer tree and then merged, or if they really depend on something
> > already in a submaintainer tree, then based on the respective topic branch
> > that's part of it.
>
> Right, most patches can be sent against the "stable branch", but cherry-picked
> on a submaintainers branch / topic tree.

I think life will be easier with submaintainer separate trees for this honestly
:) or it could become a horrible mess in one tree I think.

I think the simplest is what I suggested in reply to Vlasta, where each
submaintainer tree has their own set of changes against mm-next/mm-stable and
then we merge each week.

But am open to learning about what other subsystems in the kernel do...

>
>
> >
> >> This would be 'source of truth' and what we eventually send to Linus.
> >
> > Yes.
> >
> >> In that world, the maintainers perform conflict resolution, but with git rerere
> >> we need only do this once.
> >
> > I think the conflicts would arise from merging the submaintainers' branches
> > to the mm-next tree, and if they get updated and the merges are recreated
> > (like linux-next works) git rerere avoids resolving the same conflicts again.
> >
> > Hm like Andrew said, this needs a diagram indeed :)
>
> It's one of the first things we'll discuss in the upcoming meetings ... I want
> to talk to some other folks (in particular, TIP and KVM) to understand how they
> are handling that.

Yes let's definitely see what works for others and use that to figure things
out.

>
> Hopefully I'll find some time after my inbox calmed down a bit ... jeez, 1500
> mails in one week if my eyes didn't betray me.

Yeah, it's crazy again lately...

>
> --
> Cheers,
>
> David

Cheers, Lorenzo