[    7.502506] systemd-logind[1008]: Failed to start user service: Unknown unit: user@112.service
[    7.506792] systemd-logind[1008]: New session c1 of user lightdm.
[    7.506813] systemd-logind[1008]: Linked /tmp/.X11-unix/X0 to /run/user/112/X11-display.
[    7.881530] wlan0: authenticate with 38:22:9d:2e:80:f0
[    7.885930] wlan0: send auth to 38:22:9d:2e:80:f0 (try 1/3)
[    7.887351] wlan0: authenticated
[    7.889837] wlan0: associate with 38:22:9d:2e:80:f0 (try 1/3)
[    7.892191] wlan0: RX AssocResp from 38:22:9d:2e:80:f0 (capab=0x411 status=0 aid=4)
[    7.892277] wlan0: associated
[    7.892308] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[    9.301758] r8169 0000:02:00.1 eth0: link up
[    9.301767] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[   14.593027] systemd-logind[1008]: Failed to start unit user@1000.service: Unknown unit: user@1000.service
[   14.593035] systemd-logind[1008]: Failed to start user service: Unknown unit: user@1000.service
[   14.597138] systemd-logind[1008]: New session c2 of user diaolin.
[   14.597158] systemd-logind[1008]: Linked /tmp/.X11-unix/X0 to /run/user/1000/X11-display.
[   36.659336] audit_printk_skb: 45 callbacks suppressed
[   36.659340] audit: type=1400 audit(1423493218.287:30): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/lib/cups/backend/cups-pdf" pid=3295 comm="apparmor_parser"
[   36.659348] audit: type=1400 audit(1423493218.287:31): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=3295 comm="apparmor_parser"
[   36.673287] audit: type=1400 audit(1423493218.303:32): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="third_party" pid=3295 comm="apparmor_parser"
[  711.414926] systemd-logind[1008]: Failed to start unit user@0.service: Unknown unit: user@0.service
[  711.414934] systemd-logind[1008]: Failed to start user service: Unknown unit: user@0.service
[  711.420466] systemd-logind[1008]: New session 1 of user root.
[ 1993.037793] systemd-logind[1008]: New session 3 of user root.