Re: [RFC PATCH 0/3] mm, memcg: isolate deprecated v1 state from struct mem_cgroup

From: Michal Hocko

Date: Mon Nov 02 2026 - 12:59:12 EST


On Mon 02-11-26 16:52:44, Roman Gushchin wrote:
> Tao Cui <cui.tao@xxxxxxxxx> writes:
>
> > Hi Roman,
> >
> > 在 2026/10/30 14:05, Roman Gushchin 写道:
> >> I believe we want to delete this code sooner than later, why would we rewrite it before that?
> >>
> >
> > My assumption was that v1 would still be maintained for some time
> > before its eventual removal, and the goal was to reduce the coupling
> > between the remaining v1 code and the shared core structures during
> > that period, rather than to rewrite the implementation for its own
> > sake.
>
> I understand. But personally I don't see big issues with the current
> code caused by the v1 stuff. Maybe I miss something...
>
> The proposed changes on the other hand create difficulties for those
> who use v1 and maintain some local changes or simple backport upstream
> fixes. Of course, it's not a reason to not change the upstream code if
> it's justified, but in this case I'm hardly convinced.
>
> > If the expectation is that the remaining v1 implementation will be
> > removed in the near future, then I agree this work becomes much harder
> > to justify.
> >
> > Am I being too optimistic about how long the remaining v1 code is
> > expected to stay around?
>
> Well, Idk, it was considered deprecated for quite some time already,
> so maybe announcing that it will be deleted in a year is reasonable?
>
> Shakeel, Johannes, Michal, wdyt?

As I've said up in the thread I am not really convinced this is
something we should merge.

--
Michal Hocko
SUSE Labs