● gdm.service - GNOME Display Manager
   Loaded: loaded (/lib/systemd/system/gdm.service; enabled; vendor preset: disabled)
   Active: active (running) since Sun 2018-12-23 22:13:22 IST; 1min 40s ago
 Main PID: 4219 (gdm)
   Memory: 12.6M
   CGroup: /system.slice/gdm.service
           └─4219 /usr/sbin/gdm

Dec 23 22:14:02 localhost.localdomain gdm[4219]: Child process -8199 was already dead.
Dec 23 22:14:02 localhost.localdomain gdm[4219]: Child process 8196 was already dead.
Dec 23 22:14:02 localhost.localdomain gdm[4219]: Unable to kill session worker process
Dec 23 22:14:02 localhost.localdomain gdm-launch-environment][8202]: pam_systemd(gdm-launch-environment:session): Unknown parameter 'kill-session-processes=1', ignoring
Dec 23 22:14:02 localhost.localdomain gdm-launch-environment][8202]: pam_systemd(gdm-launch-environment:session): Failed to create session: Start job for unit user@115.service failed with 'dependency'
Dec 23 22:14:03 localhost.localdomain gdm[4219]: Could not start command '/usr/libexec/gdm-session-worker': Too many open files
Dec 23 22:14:03 localhost.localdomain gdm[4219]: GLib: g_child_watch_add_full: assertion 'pid > 0' failed
Dec 23 22:14:03 localhost.localdomain gdm[4219]: Child process -8205 was already dead.
Dec 23 22:14:03 localhost.localdomain gdm[4219]: Child process 8202 was already dead.
Dec 23 22:14:03 localhost.localdomain gdm[4219]: Unable to kill session worker process