Re: [RFC 0/2] mm: add source selectors to memory.reclaim

[Gregory Price <gourry@gourry.net>]

On Thu, Oct 22, 2026 at 05:43:49PM +0800, Li Zhe wrote:
> On 10/22/26 11:56 AM, Gregory Price (Meta) wrote:
> 
> So userspace cannot rely on one write to memory.reclaim to produce a
> final per-node distribution. The intended usage is a feedback loop: the
> controller observes the memcg's resident distribution, chooses the source
> nodes it wants to relieve, applies source-scoped reclaim pressure,
> observes the new distribution, and iterates.
>

I think the critical question is what CAN userspace rely on?

We can make a bunch of feedback loop interfaces, but there's no
guarantee they'll actually be useful.

> >
> > At the very least i think you need to add details in your cover that
> > demonstrates the process of doing something like per-node resident
> > ratios, and show that it works as you intend.
>
> Agreed. I will update the cover letter to make this model clearer. I
> will also make clear that source=nodes is not a final net per-node
> footprint guarantee and does not change memory.reclaim completion
> accounting.
> 

To be clear, I think not just making it clearer, but if you can show
some tests that demonstrate the reliable behavior of the interface
extension under different scenarios - that would be compelling.

~Gregory