utmp_wall() and utmp_put_dead_process() called setutxent() directly instead of the stub in utmp-wtmp.h and never called endutxent(). This would leave /run/utmp left open by PID 1 or journald. This can be reproduced by e.g. lsof /run/utmp and systemd-cat -p 0 echo test. For utmp_put_dead_process() it would only leave it open if it returned early before calling write_utmp_wtmp()