On Fri, Jan 21, 2022 at 06:12:10PM +0800, Zhang Qiao wrote: > 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: be367d099270 ("cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time") > Reported-by: Zhao Gongyi <zhaogongyi@xxxxxxxxxx> > Signed-off-by: Zhang Qiao <zhangqiao22@xxxxxxxxxx> Applied to cgroup/for-5.17-fixes w/ stable cc'd. Thanks and sorry about the delay. -- tejun
