In the Linux kernel, the following vulnerability has been resolved: cgroup: Add missing cpusreadlock() to cgroupattachtaskall() syzbot is hitting percpurwsemassertheld(&cpuhotpluglock) warning at cpusetattach() [1], for commit 4f7e7236435ca0ab ("cgroup: Fix threadgrouprwsem <-> cpusreadlock() deadlock") missed that cpusetattach() is also called from cgroupattachtaskall(). Add cpusreadlock() like what cgroupprocswrite_start() does.