PD_KILL
drflags |= PD_KILL;
drflags &= ~PD_KILL;
prison_deref(pr, PD_KILL | PD_DEREF | PD_LOCKED | PD_LIST_XLOCKED);
if (flags & PD_KILL) {
flags &= ~PD_KILL;
if (flags & PD_KILL) {
flags &= ~PD_KILL;