From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-172.mta1.migadu.com (out-172.mta1.migadu.com [95.215.58.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D8E01343D76 for ; Mon, 18 Aug 2025 17:01:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755536511; cv=none; b=ONOV8xcOA+XV5Mn5+OMMrf/pc4pR/H6zItAn0+KgOj9JYz7czSveHela7Ce17dIFqpOyp+2gDT3cEWyL5xtqnhLKN/ED0VQa+mbpoJbMUwu2ziL+OJ0ogpmjZ+ZAc/mEe/EBzmIC2cbYzLeXntuJ0txgJdVhvD+hAn57yxy5o60= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755536511; c=relaxed/simple; bh=lwNLAN/DotVsyA3UfSNAQkHIgywR9xfwVNScnHiTT+4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=lh3Dkt6hbv0hSXn+6tNyl4QJQ4qM1RpHgzh9237uJC1gxg6zqgGGGy4e4XkoOopMW4C54ILh+WEwFaVl8ylLVwh9WFv7Nt8VOoxpKyp4+lOJbwHKwjJnumwGa77CfaPgmVxXLhdWD23yw4ZVhrLjQiPboN9BxWFArGdUmjMPEI8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=OFXcVi3P; arc=none smtp.client-ip=95.215.58.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="OFXcVi3P" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1755536507; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=9GgSRJiKCu3BOGI+c6Rkf7dEZO8accJ0kdmdmhdiQ9o=; b=OFXcVi3PUjmW38+SokI8waULo25wFMZMn4kwm4Cx6LY8Pe9wvfHWPTz0sDnlzsleOficHh F6LoRf3O0xQ1Munzo0yjiS2Qn+Q2gwY6LHsrDy75Ofvz9U6yiK/T19wxi1SL5u32/hPdeD lMrzNzcO/0iws375mn0AGpWK+i8v/qk= From: Roman Gushchin To: linux-mm@kvack.org, bpf@vger.kernel.org Cc: Suren Baghdasaryan , Johannes Weiner , Michal Hocko , David Rientjes , Matt Bobrowski , Song Liu , Kumar Kartikeya Dwivedi , Alexei Starovoitov , Andrew Morton , linux-kernel@vger.kernel.org, Roman Gushchin Subject: [PATCH v1 00/14] mm: BPF OOM Date: Mon, 18 Aug 2025 10:01:22 -0700 Message-ID: <20250818170136.209169-1-roman.gushchin@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT This patchset adds an ability to customize the out of memory handling using bpf. It focuses on two parts: 1) OOM handling policy, 2) PSI-based OOM invocation. The idea to use bpf for customizing the OOM handling is not new, but unlike the previous proposal [1], which augmented the existing task ranking policy, this one tries to be as generic as possible and leverage the full power of the modern bpf. It provides a generic interface which is called before the existing OOM killer code and allows implementing any policy, e.g. picking a victim task or memory cgroup or potentially even releasing memory in other ways, e.g. deleting tmpfs files (the last one might require some additional but relatively simple changes). The past attempt to implement memory-cgroup aware policy [2] showed that there are multiple opinions on what the best policy is. As it's highly workload-dependent and specific to a concrete way of organizing workloads, the structure of the cgroup tree etc, a customizable bpf-based implementation is preferable over a in-kernel implementation with a dozen on sysctls. 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. [1]: https://lwn.net/ml/linux-kernel/20230810081319.65668-1-zhouchuyi@bytedance.com/ [2]: https://lore.kernel.org/lkml/20171130152824.1591-1-guro@fb.com/ [3]: https://github.com/facebookincubator/oomd [4]: https://www.freedesktop.org/software/systemd/man/latest/systemd-oomd.service.html ---- v1: 1) Both OOM and PSI parts are now implemented using bpf struct ops, providing a path the future extensions (suggested by Kumar Kartikeya Dwivedi, Song Liu and Matt Bobrowski) 2) It's possible to create PSI triggers from BPF, no need for an additional userspace agent. (suggested by Suren Baghdasaryan) Also there is now a callback for the cgroup release event. 3) Added an ability to block on oom_lock instead of bailing out (suggested by Michal Hocko) 4) Added bpf_task_is_oom_victim (suggested by Michal Hocko) 5) PSI callbacks are scheduled using a separate workqueue (suggested by Suren Baghdasaryan) RFC: https://lwn.net/ml/all/20250428033617.3797686-1-roman.gushchin@linux.dev/ Roman Gushchin (14): mm: introduce bpf struct ops for OOM handling bpf: mark struct oom_control's memcg field as TRUSTED_OR_NULL mm: introduce bpf_oom_kill_process() bpf kfunc mm: introduce bpf kfuncs to deal with memcg pointers mm: introduce bpf_get_root_mem_cgroup() bpf kfunc mm: introduce bpf_out_of_memory() bpf kfunc mm: allow specifying custom oom constraint for bpf triggers mm: introduce bpf_task_is_oom_victim() kfunc bpf: selftests: introduce read_cgroup_file() helper bpf: selftests: bpf OOM handler test sched: psi: refactor psi_trigger_create() sched: psi: implement psi trigger handling using bpf sched: psi: implement bpf_psi_create_trigger() kfunc bpf: selftests: psi struct ops test include/linux/bpf_oom.h | 49 +++ include/linux/bpf_psi.h | 71 ++++ include/linux/memcontrol.h | 2 + include/linux/oom.h | 12 + include/linux/psi.h | 15 +- include/linux/psi_types.h | 72 +++- kernel/bpf/verifier.c | 5 + kernel/cgroup/cgroup.c | 14 +- kernel/sched/bpf_psi.c | 337 ++++++++++++++++++ kernel/sched/build_utility.c | 4 + kernel/sched/psi.c | 130 +++++-- mm/Makefile | 4 + mm/bpf_memcontrol.c | 166 +++++++++ mm/bpf_oom.c | 157 ++++++++ mm/oom_kill.c | 182 +++++++++- tools/testing/selftests/bpf/cgroup_helpers.c | 39 ++ tools/testing/selftests/bpf/cgroup_helpers.h | 2 + .../selftests/bpf/prog_tests/test_oom.c | 229 ++++++++++++ .../selftests/bpf/prog_tests/test_psi.c | 224 ++++++++++++ tools/testing/selftests/bpf/progs/test_oom.c | 108 ++++++ tools/testing/selftests/bpf/progs/test_psi.c | 76 ++++ 21 files changed, 1845 insertions(+), 53 deletions(-) create mode 100644 include/linux/bpf_oom.h create mode 100644 include/linux/bpf_psi.h create mode 100644 kernel/sched/bpf_psi.c create mode 100644 mm/bpf_memcontrol.c create mode 100644 mm/bpf_oom.c create mode 100644 tools/testing/selftests/bpf/prog_tests/test_oom.c create mode 100644 tools/testing/selftests/bpf/prog_tests/test_psi.c create mode 100644 tools/testing/selftests/bpf/progs/test_oom.c create mode 100644 tools/testing/selftests/bpf/progs/test_psi.c -- 2.50.1