$ cat /proc/swaps
Filename            Type        Size        Used    Priority
/swapfile           file        2097148     0       -2

$ sudo swapon /dev/sdb5

$ cat /proc/swaps
Filename            Type        Size        Used    Priority
/swapfile           file        2097148     0       -2
/dev/sdb5           partition   16831484    0       -3

$ sudo swapoff /swapfile

$ cat /proc/swaps
Filename            Type        Size        Used    Priority
/dev/sdb5           partition   16831484    0       -2