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

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Message-ID: <87ldkonoke.fsf@linux.dev>
Date: Sun, 02 Nov 2025 12:53:53 -0800
From: Roman Gushchin <roman.gushchin@...ux.dev>
To: Michal Hocko <mhocko@...e.com>
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

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?
git send-email failed on patch 10, so I had to send the second part separately.
It seems like the second part did at least to some recipients, as I got
feedback to some patches from that part.

In any case, you can find the whole series here:
https://github.com/rgushchin/linux/tree/bpfoom.2

And thank you for reviewing the series!