Comment 4 for bug 1493188

for some specific information on different ubuntu kernels:

-- latest kernel before 4.8 entered yakkety --
$ uname -r
4.4.0-9136-generic

$ grep overlay /lib/modules/4.4.0-9136-generic/modules.alias
alias overlayfs overlay
alias fs-overlayfs overlay
alias fs-overlay overlay

$ sudo modprobe -v overlayfs
insmod /lib/modules/4.4.0-9136-generic/kernel/fs/overlayfs/overlay.ko

$ lsmod | grep overlay
overlay

$ grep overlay /proc/filesystems
nodev overlayfs
nodev overlay

-- 4.8 kernel in yakkety --
$ uname -r
4.8.0-15-generic

$ grep overlay /lib/modules/4.8.0-15-generic/modules.alias
alias fs-overlay overlay

$ modprobe -v overlayfs
modprobe: FATAL: Module overlayfs not found in directory /lib/modules/4.8.0-15-generic

$ modprobe -v overlay
insmod /lib/modules/4.8.0-15-generic/kernel/fs/overlayfs/overlay.ko

$ grep overlay /proc/filesystems
nodev overlay

-- 3.13 kernel (trusty GA) --
$ uname -r
3.13.0-96-generic

$ grep overlay /lib/modules/3.13.0-96-generic/modules.alias
alias fs-overlayfs overlayfs

$ sudo modprobe -v overlay
modprobe: FATAL: Module overlay not found.

$ sudo modprobe -v overlayfs
insmod /lib/modules/3.13.0-96-generic/kernel/fs/overlayfs/overlayfs.ko

$ grep overlay /proc/filesystems
nodev overlayfs