Hello. In my opinion there are two approaches: a) drop this backport (given other races present), b) swap the locks compatible with v4.19 as this patch proposes. On Mon, Mar 14, 2022 at 05:11:50PM +0800, Zhang Qiao <zhangqiao22@xxxxxxxxxx> wrote: > + /* > + * It should hold cpus lock because a cpu offline event can > + * cause set_cpus_allowed_ptr() failed. > + */ > + cpus_read_lock(); Maybe just a nit, the old kernels before commit c5c63b9a6a2e ("cgroup: Replace deprecated CPU-hotplug functions.") v5.15-rc1~159^2~5 would be more consistent with get_online_cpus() here (but they're equivalent functionally so the locking order is correct). Michal