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

Michal Hocko
2025-10-31T09:31:40Z

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?

--
Michal Hocko
SUSE Labs