From patchwork Fri Dec 22 03:17:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 13502865 Received: from 69-171-232-180.mail-mxout.facebook.com (69-171-232-180.mail-mxout.facebook.com [69.171.232.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 94A146111 for ; Fri, 22 Dec 2023 03:17:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=linux.dev Received: by devbig309.ftw3.facebook.com (Postfix, from userid 128203) id A68632BD9931B; Thu, 21 Dec 2023 19:17:29 -0800 (PST) From: Yonghong Song To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , kernel-team@fb.com, Martin KaFai Lau Subject: [PATCH bpf-next v6 0/8] bpf: Reduce memory usage for bpf_global_percpu_ma Date: Thu, 21 Dec 2023 19:17:29 -0800 Message-Id: <20231222031729.1287957-1-yonghong.song@linux.dev> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Currently when a bpf program intends to allocate memory for percpu kptr, the verifier will call bpf_mem_alloc_init() to prefill all supported unit sizes and this caused memory consumption very big for large number of cpus. For example, for 128-cpu system, the total memory consumption with initial prefill is ~175MB. Things will become worse for systems with even more cpus. Patch 1 avoids unnecessary extra percpu memory allocation. Patch 2 adds objcg to bpf_mem_alloc at init stage so objcg can be associated with root cgroup and objcg can be passed to later bpf_mem_alloc_percpu_unit_init(). Patch 3 addresses memory consumption issue by avoiding to prefill with all unit sizes, i.e. only prefilling with user specified size. Patch 4 further reduces memory consumption by limiting the number of prefill entries for percpu memory allocation. Patch 5 has much smaller low/high watermarks for percpu allocation to reduce memory consumption. Patch 6 rejects percpu memory allocation with bpf_global_percpu_ma when allocation size is greater than 512 bytes. Patch 7 fixed test_bpf_ma test due to Patch 5. Patch 8 added one test to show the verification failure log message. Changelogs: v5 -> v6: . Change bpf_mem_alloc_percpu_init() to add objcg as one of parameters. For bpf_global_percpu_ma, the objcg is NULL, corresponding root memcg. v4 -> v5: . Do not do bpf_global_percpu_ma initialization at init stage, instead doing initialization when the verifier knows it is going to be used by bpf prog. . Using much smaller low/high watermarks for percpu allocation. v3 -> v4: . Add objcg to bpf_mem_alloc during init stage. . Initialize objcg at init stage but use it in bpf_mem_alloc_percpu_unit_init(). . Remove check_obj_size() in bpf_mem_alloc_percpu_unit_init(). v2 -> v3: . Clear the bpf_mem_cache if prefill fails. . Change test_bpf_ma percpu allocation tests to use bucket_size as allocation size instead of bucket_size - 8. . Remove __GFP_ZERO flag from __alloc_percpu_gfp() call. v1 -> v2: . Avoid unnecessary extra percpu memory allocation. . Add a separate function to do bpf_global_percpu_ma initialization . promote. . Promote function static 'sizes' array to file static. . Add comments to explain to refill only one item for percpu alloc. Yonghong Song (8): bpf: Avoid unnecessary extra percpu memory allocation bpf: Add objcg to bpf_mem_alloc bpf: Allow per unit prefill for non-fix-size percpu memory allocator bpf: Refill only one percpu element in memalloc bpf: Use smaller low/high marks for percpu allocation bpf: Limit up to 512 bytes for bpf_global_percpu_ma allocation selftests/bpf: Cope with 512 bytes limit with bpf_global_percpu_ma selftests/bpf: Add a selftest with > 512-byte percpu allocation size include/linux/bpf_mem_alloc.h | 8 ++ kernel/bpf/memalloc.c | 93 ++++++++++++++++--- kernel/bpf/verifier.c | 45 ++++++--- .../selftests/bpf/prog_tests/test_bpf_ma.c | 20 ++-- .../selftests/bpf/progs/percpu_alloc_fail.c | 18 ++++ .../testing/selftests/bpf/progs/test_bpf_ma.c | 66 ++++++------- 6 files changed, 184 insertions(+), 66 deletions(-)