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

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Message-ID: <aQjx91L6IlG-qtjX@tiehlicka>
Date: Mon, 3 Nov 2025 19:18:31 +0100
From: Michal Hocko <mhocko@...e.com>
To: Roman Gushchin <roman.gushchin@...ux.dev>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org,
	Alexei Starovoitov <ast@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	Johannes Weiner <hannes@...xchg.org>,
	Andrii Nakryiko <andrii@...nel.org>,
	JP Kobryn <inwardvessel@...il.com>, linux-mm@...ck.org,
	cgroups@...r.kernel.org, bpf@...r.kernel.org,
	Martin KaFai Lau <martin.lau@...nel.org>,
	Song Liu <song@...nel.org>,
	Kumar Kartikeya Dwivedi <memxor@...il.com>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH v2 00/23] mm: BPF OOM

On Sun 02-11-25 12:53:53, Roman Gushchin wrote:
> Michal Hocko <mhocko@...e.com> writes:
> 
> > 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?
> 
> Did you receive patches 11-23?

OK, I found it. Patches 11-23 are threaded separately (patch 11
with Message-ID: <20251027232206.473085-1-roman.gushchin@...ux.dev> doesn't
seem to have In-reply-to in header) and I have missed them previously. I
will have a look in upcoming days.


-- 
Michal Hocko
SUSE Labs