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

Jens Axboe
2025-12-15T16:33:45Z

On 12/14/25 11:59 PM, Christoph Hellwig wrote:
> 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.

I'd be all for that.

--
Jens Axboe