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Sat, 14 Nov 2026 22:45:14 -0800 (PST) Received: from LAPTOP-AVI.lan ([2a06:c701:474b:1700:dc0a:bc51:e26f:5cf8]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-49c6020bb0fsm14073284f8f.34.2026.11.14.22.45.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 Nov 2026 22:45:13 -0800 (PST) From: Avi Weiss To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, shuah@kernel.org, emil@etsalapatis.com, houtao1@huawei.com, linux-kselftest@vger.kernel.org, Avi Weiss Subject: [PATCH bpf 0/2] bpf: Clear invalid cpumask bits after population Date: Sun, 15 Nov 2026 08:45:10 +0200 Message-ID: X-Mailer: git-send-email 2.43.0 X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit bpf_cpumask_populate() copies the final bitmap word without clearing bits beyond nr_cpu_ids. On configurations where cpumask operations scan a whole word, those bits can inflate the reported mask weight. Patch 1 clears the unused tail bits. Patch 2 checks the resulting weight in the existing populate selftest. Tested on 97d73c825122 (x86_64, CONFIG_NR_CPUS=64, 4 possible CPUs): - Unpatched: cpumask/test_populate FAIL (err=5). - Patched: cpumask/test_populate PASS. - Patched: cpumask selftests 36/36 subtests PASS. Not run: allmodconfig, allyesconfig, the full BPF selftest suite, cross-architecture builds or a dedicated performance benchmark. The changes have not been rebuilt on top of the target BPF fixes tip. Avi Weiss (2): bpf: Clear invalid tail bits when populating a cpumask selftests/bpf: Check cpumask weight after population kernel/bpf/cpumask.c | 2 +- tools/testing/selftests/bpf/progs/cpumask_success.c | 3 +++ 2 files changed, 4 insertions(+), 1 deletion(-) base-commit: 4b4eb7f44ee05754339d07e9df649809f45d14c5 -- 2.43.0