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

[Andrew Morton]

On Tue, 26 May 2026 09:33:08 +0100 Lorenzo Stoakes <ljs@xxxxxxxxxx> wrote:

> [trimmed cc list to avoid noise, apologies if I excluded anybody who is
> interested in this!]
> 
> On Fri, May 22, 2026 at 11:13:42PM +0200, David Hildenbrand (Arm) wrote:
> > On 5/22/26 18:11, Nico Pache wrote:
> > > On Fri, May 22, 2026 at 9:13 AM Vlastimil Babka (SUSE)
> > > <vbabka@xxxxxxxxxx> wrote:
> > >>
> > >> On 5/22/26 17:07, Nico Pache wrote:
> > >>>
> > >>> Whoops I manually changed the coverletter subject to reflect that this
> > >>> in on mm-hotfixes-unstable but never updated the others...
> > >>
> > >> But why? That branch is for hotfixes that would go to the current 7.1-rcX
> > >> series. mm-unstable would be the correct one for this, AFAICT.
> > >
> > > Sorry this was a misunderstanding. The goal here was to base this off
> > > the closest base commit behind where my v17 already lies in the tree.
> >
> > Ah, I guess this is a problem of "v17 is already in mm-unstable, so against what
> > to base v18".
> >
> > Yeah, we touched on that problem in the LSF/MM process discussion ...
> 
> I may be misremembering but... :) [correct me if wrong]:
> 
> Wasn't the general conclusion that we maintain a stable branch (Linus's tree +
> stuff that's been reviewed and is locked in for next release), and have people
> base work against that?

That was the plan when I initially set up the mm.git branches.

It turned out to be quite impractical because it takes so long to get
material into mm-stable worthiness: around -rc4/-rc5.

We could address that by delaying everything by four weeks - so MM's
window is out of phase with Linus's.  So there's a lot of "stable"
material in mm.git when Linus is at -rc1/-rc2.  Problem with this is
that by -rc5/-rc6 we'll have a large amount of material queued up for the
next -rc cycle and it is against linux-next rules to add this to -next.
And until it's had decent -next exposure we can't declare it "stable".

This needs a diagram ;)