Executive brief
The Linux kernel's cpuset (control group processor set) subsystem contains a logic error that triggers a kernel warning when disabling remote partitions after CPU hotplug events. While primarily a reliability issue rather than a security vulnerability, this can disrupt system stability and prevent proper partition management in containerized or virtualized environments.
Technical details
This is a logic error (not an exploitable vulnerability) in the cpuset cgroup subsystem that occurs when CPU hotplug events offline CPUs, clearing subpartitions_cpus and forcing partitions to share CPUs with the top_cpuset. The warning at remote_partition_disable+0xf7/0x110 fires incorrectly because the code checks if effective_xcpus is a subset of subpartitions_cpus without first verifying that subpartitions_cpus is non-empty. The fix involves two changes: (1) only emit the warning if subpartitions_cpus is not empty, and (2) invalidate partitions during CPU hotplug when subpartitions_cpus becomes empty. No remote exploitation is possible; this affects only the kernel's internal cgroup management.
Affected products
- Linux Linux kernel <UNKNOWN>
Timeline
- 2026-01-14: disclosed