Re: [PATCH v2 00/23] mm: BPF OOM

Lance Yang
2025-10-31T16:48:57Z

From: Lance Yang <lance.yang@linux.dev>

On Fri, 31 Oct 2025 10:31:36 +0100, Michal Hocko wrote:
> On Mon 27-10-25 16:17:03, Roman Gushchin wrote:
> > The second part is related to the fundamental question on when to
> > declare the OOM event. It's a trade-off between the risk of
> > unnecessary OOM kills and associated work losses and the risk of
> > infinite trashing and effective soft lockups. In the last few years
> > several PSI-based userspace solutions were developed (e.g. OOMd [3] or
> > systemd-OOMd [4]). The common idea was to use userspace daemons to
> > implement custom OOM logic as well as rely on PSI monitoring to avoid
> > stalls. In this scenario the userspace daemon was supposed to handle
> > the majority of OOMs, while the in-kernel OOM killer worked as the
> > last resort measure to guarantee that the system would never deadlock
> > on the memory. But this approach creates additional infrastructure
> > churn: userspace OOM daemon is a separate entity which needs to be
> > deployed, updated, monitored. A completely different pipeline needs to
> > be built to monitor both types of OOM events and collect associated
> > logs. A userspace daemon is more restricted in terms on what data is
> > available to it. Implementing a daemon which can work reliably under a
> > heavy memory pressure in the system is also tricky.
>
> I do not see this part addressed in the series. Am I just missing
> something or this will follow up once the initial (plugging to the
> existing OOM handling) is merged?

I noticed that this thread only shows up to patch 10/23. The subsequent
patches (11-23) appear to be missing ...

This might be why we're not seeing the userspace OOM daemon part
addressed. I suspect the relevant code is likely in those subsequent
patches.

Cheers,
Lance