I'm doing some file processing that seems to require an enormous swap file: even 20Gb isn't enough. What's the theoretical maximum? Running
swapon on a 1Tb file resulted in:
swapon: /mnt/big/swap.swap: swapon failed: Invalid argument
The system in question is an Ubuntu VM running on OpenStack, and the drive is NFS mounted. Answers that are broader than this are fine, too though.