Issue

• Upgrading to systemd-219-42.el7_4.4 or systemd-219-42.el7_4.5 without rebooting leads to transient files to be created in /run/systemd/sessions, consuming space over time

  # ll /run/systemd/sessions/
  total 35
  ...
  -rw-r--r--. 1 root root 240 Jan 18 09:41 36
  -rw-r--r--. 1 root root 240 Jan 18 09:41 37
  -rw-r--r--. 1 root root 240 Jan 18 09:41 38
  -rw-r--r--. 1 root root 240 Jan 18 09:41 39
  -rw-r--r--. 1 root root 284 Jan 18 09:48 40
  prw-------. 1 root root   0 Jan 18 09:48 40.ref
  

• After rebooting the system, the issue disappears

  # ll /run/systemd/sessions/
  total 2
  -rw-r--r--. 1 root root 284 Jan 18 09:58 2
  prw-------. 1 root root   0 Jan 18 09:58 2.ref