Merge tag 'cgroup-for-6.0-rc2-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull another cgroup fix from Tejun Heo:
 "Commit 4f7e7236 ("cgroup: Fix threadgroup_rwsem <->
  cpus_read_lock() deadlock") required the cgroup
  core to grab cpus_read_lock() before invoking ->attach().

  Unfortunately, it missed adding cpus_read_lock() in
  cgroup_attach_task_all(). Fix it"

* tag 'cgroup-for-6.0-rc2-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: Add missing cpus_read_lock() to cgroup_attach_task_all()