moby: ServeAPI error: is a directory

New docker nodes that I bring up are getting this error. Any suggestions or ideas?

I’ve tried it now on two completely fresh boxes. This is Docker 1.7.1

Note: because Linode uses custom kernels, I’ve always fallen back to devicemapper since aufs support isn’t possible without a bootloader.

root@localhost:~# docker -d
WARN[0000] Udev sync is not supported. This will lead to unexpected behavior, data loss and errors. For more information, see https://docs.docker.com/reference/commandline/cli/#daemon-storage-driver-option
ERRO[0000] ServeAPI error: is a directory
INFO[0000] [graphdriver] using prior storage driver "devicemapper"
WARN[0000] Running modprobe bridge nf_nat failed with message: , error: exit status 1
WARN[0000] Your kernel does not support swap memory limit.
INFO[0000] Loading containers: start.
......ERRO[0000] Error unmounting device 90562e5df6b554a1bc41196f6c24f1d9bdd452818377913773b475d940839897: UnmountDevice: device not-mounted id 90562e5df6b554a1bc41196f6c24f1d9bdd452818377913773b475d940839897
ERRO[0000] error locating network id f4428f1834021aaba328334c1dd2d56279cf04f9c88215658111e15ce84d725a: network f4428f1834021aaba328334c1dd2d56279cf04f9c88215658111e15ce84d725a not found
ERRO[0000] Error unmounting device 90562e5df6b554a1bc41196f6c24f1d9bdd452818377913773b475d940839897: UnmountDevice: device not-mounted id 90562e5df6b554a1bc41196f6c24f1d9bdd452818377913773b475d940839897

INFO[0000] Loading containers: done.
INFO[0000] Daemon has completed initialization
INFO[0000] Docker daemon                                 commit=786b29d execdriver=native-0.2 graphdriver=devicemapper version=1.7.1
ERRO[0001] Error during graph storage driver.Cleanup(): device or resource busy
ERRO[0001] remove /var/run/docker.pid: no such file or directory
FATA[0001] Shutting down due to ServeAPI error: is a directory