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Fri, 31 Oct 2025 09:48:55 -0700 (PDT) From: Lance Yang To: mhocko@suse.com Cc: akpm@linux-foundation.org, andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, cgroups@vger.kernel.org, hannes@cmpxchg.org, inwardvessel@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, martin.lau@kernel.org, memxor@gmail.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, song@kernel.org, surenb@google.com, tj@kernel.org, Lance Yang Subject: Re: [PATCH v2 00/23] mm: BPF OOM Date: Sat, 1 Nov 2025 00:48:44 +0800 Message-ID: <20251031164844.27060-1-ioworker0@gmail.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Lance Yang 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