linux-kernel - Re: [PATCH bpf-next v3 00/17] mm: BPF OOM

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Message-ID: <CAADnVQ+vQFndDdgDBwLSRcdqrsyE_gU1Wx7STy0Qa=6MFnHSHg@mail.gmail.com>
Date: Wed, 28 Jan 2026 10:53:50 -0800
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Roman Gushchin <roman.gushchin@...ux.dev>
Cc: Michal Hocko <mhocko@...e.com>, bpf <bpf@...r.kernel.org>, 
	Alexei Starovoitov <ast@...nel.org>, Matt Bobrowski <mattbobrowski@...gle.com>, 
	Shakeel Butt <shakeel.butt@...ux.dev>, JP Kobryn <inwardvessel@...il.com>, 
	LKML <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>, 
	Suren Baghdasaryan <surenb@...gle.com>, Johannes Weiner <hannes@...xchg.org>, 
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH bpf-next v3 00/17] mm: BPF OOM

On Wed, Jan 28, 2026 at 10:23 AM Roman Gushchin
<roman.gushchin@...ux.dev> wrote:
>
> Alexei Starovoitov <alexei.starovoitov@...il.com> writes:
>
> > On Wed, Jan 28, 2026 at 12:06 AM Michal Hocko <mhocko@...e.com> wrote:
> >>
> >>
> >> > Another viable idea (also suggested by Andrew Morton) is to develop
> >> > a production ready memcg-aware OOM killer in BPF, put the source code
> >> > into the kernel tree and make it loadable by default (obviously under a
> >> > config option). Myself or one of my colleagues will try to explore it a
> >> > bit later: the tricky part is this by-default loading because there are
> >> > no existing precedents.
> >>
> >> It certainly makes sense to have trusted implementation of a commonly
> >> requested oom policy that we couldn't implement due to specific nature
> >> that doesn't really apply to many users. And have that in the tree. I am
> >> not thrilled about auto-loading because this could be easily done by a
> >> simple tooling.
> >
> > Production ready bpf-oom program(s) must be part of this set.
> > We've seen enough attempts to add bpf st_ops in various parts of
> > the kernel without providing realistic bpf progs that will drive
> > those hooks. It's great to have flexibility and people need
> > to have a freedom to develop their own bpf-oom policy, but
> > the author of the patch set who's advocating for the new
> > bpf hooks must provide their real production progs and
> > share their real use case with the community.
> > It's not cool to hide it.
>
> In my case it's not about hiding, it's a chicken and egg problem:
> the upstream first model contradicts with the idea to include the
> production results into the patchset. In other words, I want to settle
> down the interface before shipping something to prod.
>
> I guess the compromise here is to initially include a bpf oom policy
> inspired by what systemd-oomd does and what is proven to work for a
> broad range of users.

Works for me.

> Policies suited for large datacenters can be
> added later, but also their generic usefulness might be limited by the
> need of proprietary userspace orchestration engines.

Agree. That's the flexibility part that makes the whole thing worth
while and the reason to do such oom policy as bpf progs.
But something tangible and useful needs to be there from day one.
systmed-oomd-like sounds very reasonable.