Re: [PATCH 1/3] migration/colo: Deprecate COLO migration framework

[Markus Armbruster <armbru@redhat.com>]

Peter Xu <peterx@redhat.com> writes:

> On Fri, Jan 16, 2026 at 10:41:28AM +0100, Markus Armbruster wrote:
>> Zhang Chen <zhangckid@gmail.com> writes:
>> 
>> > On Fri, Jan 16, 2026 at 2:26 PM Markus Armbruster <armbru@redhat.com> wrote:

[...]

>> >> I think we should deprecate COLO now to send a clear distress signal.
>> >> The deprecation notice should explain it doesn't work, and will be
>> >> removed unless people step up to fix it and to maintain it.  This will
>> >> ensure progress one way or the other.  Doing nothing now virtually
>> >> ensures we'll have the same discussion again later.
>> >>
>> >> "Broken for two releases without anyone noticing" and "maintainer absent
>> >> for more than four years" doesn't exacltly inspire hope, though.  We
>> >> should seriously consider removing it right away.
>> >>
>> >> Lukas, can you give us hope?
>> >>
>> >
>> > Hi Markus,
>> > Maybe you missed something?
>> > I think Lukas is ready to maintain this code in his previous emails.
>> > https://lore.kernel.org/qemu-devel/20260115224516.7f0309ba@penguin/T/#mc99839451d6841366619c4ec0d5af5264e2f6464
>> 
>> Patch to MAINTAINERS or it didn't happen ;)
>
> I'd even say MAINTAINERS file is, in many cases, cosmetic..
>
> It definitely is helpful for people to do lookups or scripts to fetch
> information, but IMHO we need more than one single entry, and in some sense
> that entry is less important than the activities.
>
> We need someone to be first familiar with a piece of code, spend time on
> it, actively reply to the relevant queries upstream, proper testing /
> gating to make sure the feature is usable as stated - either fully
> maintained or odd fixes or others, and more.

Yes, we need a maintainer not just in name, but for real.

(My one-liner was an attempt at a joke)

> I used to request Lukas help reviewing the loadvm threadify series [1,2]
> which definitely touches COLO, I didn't really get a respond.  That's also
> a sign I don't feel like Lucas cares enough about COLO, after I explicitly
> pointing out something might be changing and might be risky.
>
> It's like Hailiang is also in the MAINTAINERS file but Hailiang is
> unfortunately not active anymore recently over the years.

We're bad at updating the MAINTAINERS file when maintainers have
wandered off.

> Frankly, it was Zhijian and Chen that were always helping from that regard.
> I would rather think anyone of both would be more suitable at least from
> all the discussions I had with COLO, but this is a promise I can't do.  I
> also still want to remove it as I proposed, in case it releases everyone.
>
> So an update in the file isn't even enough if we accept it.  We need
> activity corresponding to the file change.  That's also why I still think
> we should remove COLO regardless if 11.0 doesn't improve in this condition,
> as I stated in the other email.

Concur.

> [1] https://lore.kernel.org/qemu-devel/aSSx28slqi1ywg2v@x1.local
> [2] https://lore.kernel.org/all/20251022192612.2737648-1-peterx@redhat.com
>
> Thanks,