Comment 21 for bug 1788321

ubuntu 16.04, hit the same issue as this. swapon -v shows these:

```
swapon: /my/swap: found swap signature: version 1d, page-size 4, same byte order
swapon: /my/swap: pagesize=4096, swapsize=13..., devsize=13....
swapon: /my/swap: swapon failed: Invalid argument
```