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cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug
commit05c7b7a92c
upstream. As previously discussed(https://lkml.org/lkml/2022/1/20/51), cpuset_attach() is affected with similar cpu hotplug race, as follow scenario: cpuset_attach() cpu hotplug --------------------------- ---------------------- down_write(cpuset_rwsem) guarantee_online_cpus() // (load cpus_attach) sched_cpu_deactivate set_cpu_active() // will change cpu_active_mask set_cpus_allowed_ptr(cpus_attach) __set_cpus_allowed_ptr_locked() // (if the intersection of cpus_attach and cpu_active_mask is empty, will return -EINVAL) up_write(cpuset_rwsem) To avoid races such as described above, protect cpuset_attach() call with cpu_hotplug_lock. Fixes:be367d0992
("cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time") Cc: stable@vger.kernel.org # v2.6.32+ Reported-by: Zhao Gongyi <zhaogongyi@huawei.com> Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com> Acked-by: Waiman Long <longman@redhat.com> Reviewed-by: Michal Koutný <mkoutny@suse.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -2212,6 +2212,7 @@ static void cpuset_attach(struct cgroup_taskset *tset)
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cgroup_taskset_first(tset, &css);
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cs = css_cs(css);
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cpus_read_lock();
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percpu_down_write(&cpuset_rwsem);
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/* prepare for attach */
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@ -2267,6 +2268,7 @@ static void cpuset_attach(struct cgroup_taskset *tset)
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wake_up(&cpuset_attach_wq);
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percpu_up_write(&cpuset_rwsem);
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cpus_read_unlock();
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}
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/* The various types of files and directories in a cpuset file system */
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