From: Zhang Qiao zhangqiao22@huawei.com
commit 05c7b7a92cc87ff8d7fde189d0fade250697573c 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: be367d099270 ("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 --- kernel/cgroup/cpuset.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2204,6 +2204,7 @@ static void cpuset_attach(struct cgroup_ cgroup_taskset_first(tset, &css); cs = css_cs(css);
+ cpus_read_lock(); percpu_down_write(&cpuset_rwsem);
/* prepare for attach */ @@ -2259,6 +2260,7 @@ static void cpuset_attach(struct cgroup_ wake_up(&cpuset_attach_wq);
percpu_up_write(&cpuset_rwsem); + cpus_read_unlock(); }
/* The various types of files and directories in a cpuset file system */