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由 Waiman Long 提交于
When external events like CPU offlining or user events like changing the cpu list of an ancestor cpuset happen, update_cpumasks_hier() will be called to update the effective cpus of each of the affected cpusets. That will then call update_parent_subparts_cpumask() if partitions are impacted. Currently, these events may cause update_parent_subparts_cpumask() to return error if none of the requested cpus are available or it will consume all the cpus in the parent partition root. Handling these errors is problematic as the states may become inconsistent. Instead of letting update_parent_subparts_cpumask() return error, a new error state (-1) is added to the partition_root_state flag to designate the fact that the partition is no longer valid. IOW, it is no longer a real partition root, but the CS_CPU_EXCLUSIVE flag will still be set as it can be changed back to a real one if favorable change happens later on. This new error state is set internally and user cannot write this new value to "cpuset.sched.partition". Signed-off-by: NWaiman Long <longman@redhat.com> Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: NTejun Heo <tj@kernel.org>
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