Re: [LSF/MM/BPF TOPIC] Towards Unified and Extensible Memory Reclaim (reclaim_ext)

[Lorenzo Stoakes (Oracle)]

On Thu, Mar 26, 2026 at 08:03:34AM +0100, Michal Hocko wrote:
> On Wed 25-03-26 19:05:47, Andrew Morton wrote:
> > On Wed, 25 Mar 2026 14:06:37 -0700 Shakeel Butt <shakeel.butt@xxxxxxxxx> wrote:
> >
> > > We should unify both algorithms into a single code path.
> >
> > I'm here to ask the questions which others fear will sound dumb.
>
> Not dumb at all and recently discussed here https://lore.kernel.org/all/CAMgjq7AkYOtUL2HuZjBu5dJw=RTL7W2L1+zVv=SCOyHKYwc3AA@xxxxxxxxxxxxxx/T/#u
>
> > Is it indeed the plan to maintain both implementations?  I thought the
> > long-term ambition was to knock MGLRU into shape and to drop the legacy LRU?
>
> Yes, but MGLRU is not there yet and with development pace last year or
> so we are not much closer than at the time MGLRU has been merged
> unfortunatelly.

I'm quite concerned about maintainership, as it seems the MGLRU maintainers have
not been all that active, and the MGLRU to me at least is currently a black box.

I'm not the only one who's raised this (see [0]).

That'd very much have to be resolved and the community reassured that MGLRU is
_actively_ maintained before we could even contemplate it replacing the
'classic' reclaim approach IMO.

I hope that Kairu, Barry, Zicheng and others who are interested int it resolve
this, however!

Thanks, Lorenzo

[0]:https://lore.kernel.org/linux-mm/aaBsrrmV25FTIkVX@xxxxxxxxxxxxxxxxxxxx/

> --
> Michal Hocko
> SUSE Labs