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[34.127.51.67]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2df6a5a4997sm19710685ad.27.2026.09.23.21.27.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Sep 2026 21:27:33 -0700 (PDT) From: Hui Peng To: Waiman Long , Ridong Chen , Guopeng Zhang , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= Cc: Shuah Khan , Chen Ridong , cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Hui Peng , stable@vger.kernel.org Subject: [PATCH v4 3/3] cgroup/cpuset: check sibling effective_xcpus in cpus_excl_conflict() Date: Thu, 24 Sep 2026 04:27:29 +0000 Message-ID: <20260924042729.1908863-4-benquike@gmail.com> X-Mailer: git-send-email 2.56.0.rc1.310.g51773c2048-goog In-Reply-To: <20260924042729.1908863-1-benquike@gmail.com> References: <20260924042729.1908863-1-benquike@gmail.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In cpus_excl_conflict(), when a valid local partition A1 uses implicit exclusive CPUs (cpuset.cpus set without cpuset.cpus.exclusive, so sibling->exclusive_cpus is empty while sibling->effective_xcpus is populated), a sibling cgroup B1 can still set cpuset.cpus.exclusive on the same CPUs because cpus_excl_conflict() only checks sibling->exclusive_cpus. Fall back to sibling->effective_xcpus in cpus_excl_conflict() when sibling->exclusive_cpus is empty, and add a regression test case to tools/testing/selftests/cgroup/test_cpuset_prs.sh. Tested in QEMU on Linux 7.3.0-rc3 using tools/testing/selftests/cgroup/test_cpuset_prs.sh. Fixes: 2a3602030d80 ("cgroup/cpuset: Don't invalidate sibling partitions on cpuset.cpus conflict") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Hui Peng --- kernel/cgroup/cpuset.c | 5 ++++- tools/testing/selftests/cgroup/test_cpuset_prs.sh | 1 + 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 7c5b4a8f1f3a..f46a51f07938 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -713,7 +713,10 @@ static inline bool cpus_excl_conflict(struct cpuset *trial, struct cpuset *sibli return true; /* Exclusive_cpus cannot intersect */ - return cpumask_intersects(trial->exclusive_cpus, sibling->exclusive_cpus); + return cpumask_intersects(trial->exclusive_cpus, + cpumask_empty(sibling->exclusive_cpus) + ? sibling->effective_xcpus + : sibling->exclusive_cpus); } static inline bool mems_excl_conflict(struct cpuset *cs1, struct cpuset *cs2) diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/testing/selftests/cgroup/test_cpuset_prs.sh index f4d1822d4e21..f62155cf6162 100755 --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh @@ -445,6 +445,7 @@ TEST_MATRIX=( # Changes to cpuset.cpus.exclusive that violate exclusivity rule is rejected " C0-3 . . C4-5 X0-3 . . X3-5 1 A1:0-3|B1:4-5" + " C0-3:P1 . . C4-5 . . . X3-5 1 A1:0-3|B1:4-5 A1:P1|B1:P0" # cpuset.cpus.exclusive cannot be set to a superset of sibling's cpuset.cpus " C0-3 . . C4-5 X3-5 . . . 1 A1:0-3|B1:4-5" -- 2.49.0