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Fri, 23 Oct 2026 20:01:01 +0000 (UTC) Received: from llong-thinkpadp16vgen1.redhat.corp (headnet04.pony-001.prod.iad2.dc.redhat.com [10.2.32.116]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 5CDAB1956088; Fri, 23 Oct 2026 20:00:59 +0000 (UTC) From: Waiman Long To: Ridong Chen , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Shuah Khan Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Guopeng Zhang , Waiman Long Subject: [PATCH-next v2 07/10] cgroup/cpuset: Make sure compute_partition_effective_cpumask() is only called for valid partition Date: Fri, 23 Oct 2026 16:00:33 -0400 Message-ID: <20261023200036.60560-8-longman@redhat.com> In-Reply-To: <20261023200036.60560-1-longman@redhat.com> References: <20261023200036.60560-1-longman@redhat.com> X-Mailing-List: linux-kernel@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 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 With visual inspection to make sure that compute_partition_effective_cpumask() is only called for valid partition root, it was found that the function can be called for an invalidated partition near the end of cpuset_hotplug_update_tasks(). When partcmd is set, update_parent_effective_cpumask() is called to either invalidate a valid partition or with partcmd_update to check if an invalid partition can be switched back to valid. In both cases, cpuset_force_rebuild() should be invoked. However, compute_partition_effective_cpumask() should only be called when an invalid partition is switched back to valid. When a partition is invalidated, compute_effective_cpumask() should be called instead. Also add a WARN_ON_ONCE() in compute_partition_effective_cpumask() to ensure that a valid partition root is passed in. Fixes: 72c6303acfa1 ("cgroup/cpuset: Take isolated CPUs out of workqueue unbound cpumask") Signed-off-by: Waiman Long --- kernel/cgroup/cpuset.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index d995f1ec5259..2c3a148fa40b 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2116,6 +2116,8 @@ static void compute_partition_effective_cpumask(struct cpuset *cs, struct cpuset *child; bool populated = partition_is_populated(cs, NULL); + WARN_ON_ONCE(!is_partition_valid(cs)); + /* * Check child partition roots to see if they should be * invalidated when @@ -4023,9 +4025,12 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) if (partcmd >= 0) { update_parent_effective_cpumask(cs, partcmd, NULL, tmp); - if ((partcmd == partcmd_invalidate) || is_partition_valid(cs)) { + if (is_partition_valid(cs)) { compute_partition_effective_cpumask(cs, &new_cpus); cpuset_force_rebuild(); + } else if (partcmd == partcmd_invalidate) { + compute_effective_cpumask(&new_cpus, cs, parent); + cpuset_force_rebuild(); } } -- 2.56.0