Re: [RFC PATCH 0/1] mm: Reduce direct reclaim stalls with RAM-backed swap

[Matt Fleming <matt@readmodwrite.com>]

On Tue, Mar 03, 2026 at 06:59:04AM -0800, Shakeel Butt wrote:
> Hi Matt,
> 
> Thanks for the report and one request I have is to avoid cover letter for a
> single patch to avoid partitioning the discussion.
 
Noted.

> Have you tried zswap and if you see similar issues with zswap?
 
Yes, we've started experimenting with zswap but that's still in
progress.

> Over the time we (kernel MM community) have implicitly decided to keep the
> kernel oom-killer very conservative as adding more heuristics in the reclaim/oom
> path makes the kernel more unreliable and punt the aggressiveness of oom-killing
> to the userspace as a policy. All major Linux deployments have started using
> userspace oom-killers like systemd-oomd, Android's LMKD, fb-oomd or some
> internal alternatives. That provides more flexibility to define the
> aggressiveness of oom-killing based on your business needs.
> 
> Though userspace oom-killers are prone to reliability issues (oom-killer getting
> stuck in reclaim or not getting enough CPU), so we (Roman) are working on adding
> support for BPF based oom-killer where wen think we can do oom policies more
> reliably.
> 
> Anyways, I am wondering if you have tried systemd-oomd or some userspace
> alternative. If you are interested in BPF oom-killer, we can help with that as
> well.

oomd is also being discussed but so far we haven't experimented with it
yet.

What's the status of BPF oom-killer: is this the latest?

  https://lore.kernel.org/all/20260127024421.494929-1-roman.gushchin@linux.dev/

Thanks,
Matt