[arch-general] what is happening here?

[ 491.146655] INFO: task systemd-udevd:128 blocked for more than 120 seconds. [ 491.147874] Tainted: G C 4.13.12-1-ARCH #1 [ 491.149295] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. --