retiring laptop_mode? was Re: [PATCH] mm: vmscan: always allow writeback during memcg reclaim

Christoph Hellwig
2025-12-15T06:59:14Z

On Sun, Dec 14, 2025 at 11:12:00PM -0500, Johannes Weiner wrote:
> That reasoning doesn't make sense to me. Reclaim is always in response
> to an allocation need. The laptop_mode idea applies to cgroup reclaim
> as much as any other reclaim.
>
> Now obviously all of this is pretty dated. Reclaim doesn't do
> filesystem writes anymore, and I'm not sure there are a whole lot of
> laptops with rotational drives left, either. Also I doubt anybody is
> still using zone_reclaim_mode (which is where the may_unmap is from).

Yeah. I wonder if we should retire laptop_mode. It was a cute hack
back then, but it has it's ugly fingers in way to many places and
should be mostly obsolete by how writeback works these days.