if ((options == (__WCLONE|__WALL)) && (current->uid = 0))
retval = -EINVAL;
Wait... Wait... A casual reading by any expert should result in the question "why is this code setting current->uid to 0?"
After all, in case said expert has forgotten the difference between = and ==, this little bit of code all by itself has two correct reminders about what those operators actually do.