Linode does not support AUFS below is their official support response:
“Hello,Our kernels do not currently include AUFS support–you may create your own kernel with AUFS support as you mentioned.Please let us know should you have any additional questions.”
here is blog post about how to do it Customizing a Linode kernel | PyTux
I find it bit complex solution so switched to Digital Ocean which does support AUFS out of the box.