Ji Fa

**Name of the Vulnerable Software and Affected Versions** Linux kernel (affected versions not specified) **Description** A warning was found in the Linux kernel related to the cgroup/cpuset functionality. The issue is caused by the `kernfs break active protection` function when writing to `cpuset.cpus` and the cgroup is removed concurrently. This warning can lead to a deadlock due to a circular locking dependency involving `cgroup mutex`. The commit 3a5a6d0c2b03 made `cpuset hotplug workfn` asynchronous, which involves calling `flush work()` and can create a multiple processes circular locking dependency. To avoid deadlock, the commit 76bb5ab8f6e3 added `kernfs break active protection` in `cpuset write resmask`. However, after the commit 2125c0034c5d, `cpuset write resmask` no longer needs to wait for the hotplug to finish, making concurrent hotplug and cpuset operations no longer possible and thus removing the deadlock. **Recommendations** To fix this warning, remove the `kernfs break active protection` operation in `cpuset write resmask`.