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由 Tejun Heo 提交于
cpuset is scheduled to be decoupled from cgroup_lock which will make hotplug handling race with task migration. cpus or mems will be allowed to go offline between ->can_attach() and ->attach(). If hotplug takes down all cpus or mems of a cpuset while attach is in progress, ->attach() may end up putting tasks into an empty cpuset. This patchset makes ->attach() schedule hotplug propagation if the cpuset is empty after attaching is complete. This will move the tasks to the nearest ancestor which can execute and the end result would be as if hotplug handling happened after the tasks finished attaching. cpuset_write_resmask() now also flushes cpuset_propagate_hotplug_wq to wait for propagations scheduled directly by cpuset_attach(). This currently doesn't make any functional difference as everything is protected by cgroup_mutex but enables decoupling the locking. Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com>
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