Bug 996295

I've been seeing this every boot as well for a while:

[root@tlondon systemd]# journalctl -b | grep systemd-udevd
Aug 20 06:01:58 tlondon.localhost.org systemd-udevd[142]: starting version 206
Aug 20 06:02:04 tlondon.localhost.org systemd-udevd[322]: starting version 206
Aug 20 06:02:05 tlondon.localhost.org systemd-udevd[338]: error opening ATTR{/sys/devices/pci0000:00/0000:00:1a.1/usb4/4-1/4-1:1.0/power/control} for writing: No such file or directory
Aug 20 06:02:07 tlondon.localhost.org systemd-udevd[329]: renamed network interface wlan0 to wlp3s0
Aug 20 06:02:46 tlondon.localhost.org systemd-udevd[322]: worker [330] /devices/system/cpu/cpu0 timeout; kill it
Aug 20 06:02:46 tlondon.localhost.org systemd-udevd[322]: seq 1890 '/devices/system/cpu/cpu0' killed
Aug 20 06:02:46 tlondon.localhost.org systemd-udevd[322]: worker [336] /devices/system/cpu/cpu1 timeout; kill it
Aug 20 06:02:46 tlondon.localhost.org systemd-udevd[322]: seq 1891 '/devices/system/cpu/cpu1' killed
Aug 20 06:02:46 tlondon.localhost.org systemd-udevd[322]: worker [336] terminated by signal 9 (Killed)
Aug 20 06:04:06 tlondon.localhost.org systemd-udevd[322]: worker [330] terminated by signal 9 (Killed)
[root@tlondon systemd]# 

Boot appears to hang for up to 10-20 seconds until this spews out.

More info I can provide?

Might be this, not sure:
  https://bugzilla.redhat.com/show_bug.cgi?id=997149#c5

This bug appears to have been reported against 'rawhide' during the Fedora 20 development cycle.
Changing version to '20'.

More information and reason for this action is here:
https://fedoraproject.org/wiki/BugZappers/HouseKeeping/Fedora20

not sure if related because doesnt boot enough to look at logs but running kernels greater than 3.10.4-300.fc19.x86_64 the system fails to boot (tried kernel-3.11.7-300.fc20.x86_64 and kernel-3.13.0-0.rc0.git1.3.fc21.x86_64) 

running fedora 20 which now has systemd-208.4.fc20.x86_64

gives similar systemd errors to screen (nothing shows in logs when boot with 3.10.4-300.fc19 to check):

  'BUG: soft lockup: cpu stuck for xxs' where xx is some number of seconds

  'fixing recursive fault but reboot is needed'

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