sudo systemctl status swapfile.swap
[sudo] password for francisv: 
● swapfile.swap - /swapfile
   Loaded: loaded (/etc/fstab; generated; vendor preset: enabled)
   Active: failed (Result: exit-code) since Mon 2017-11-06 13:58:05 CET; 15min ago
     What: /swapfile
     Docs: man:fstab(5)
           man:systemd-fstab-generator(8)

nov. 06 13:58:05 francisv-iMac systemd[1]: Activating swap /swapfile...
nov. 06 13:58:05 francisv-iMac swapon[747]: swapon: /swapfile: read swap header failed
nov. 06 13:58:05 francisv-iMac systemd[1]: swapfile.swap: Swap process exited, code=exited status=255
nov. 06 13:58:05 francisv-iMac systemd[1]: Failed to activate swap /swapfile.
nov. 06 13:58:05 francisv-iMac systemd[1]: swapfile.swap: Unit entered failed state.