"kswapd0" is taking up some of my device's CPU time even though I don't have any swap. What's going on?
It might not be possible to disable kswapd0. Even if it's possible to disable it, you should not try. You see, kswapd0 does important work even if you don't have a swap file.

On the Ubuntu Stack Exchange website, psusi explains:


  Swap space is only used for data that is not backed by any other file. Data that is mapped from other files on disk (such as executable programs) is still swapped to their respective files even if you don't have a swap device.


You should visit psusi's original answer and vote it up.