+ if (!thread_group_empty(current))
+ return -EINVAL;
+ }
+ if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
+ if (atomic_read(¤t->sighand->count) > 1)
+ return -EINVAL;
+ }
+ if (unshare_flags & CLONE_VM) {
+ if (!current_is_single_threaded())