The following is mostly copied from an Arch Linux bug report, available here:
https://bugs.archlinux.org/task/41518
I was in my regular user session and was kicked and banned from said session seemingly without warning; rebooting allowed me to log in again, but that's not the issue. The log file showing the actual issue, which looks to be related to an nfs kernel module.
uname -a:
Linux orchid 3.15.8.201408040708-2-grsec #1 SMP PREEMPT Mon Aug 4 19:07:55 EDT 2014 x86_64 GNU/Linux
The log from the bug report is also available here:
http://hastebin.com/raw/ejujoyarix