If the swap partition name changes, Ubuntu will not be aware of it. You can see if Ubuntu is using swap by It should show swap usage at the top.
If swap is not being used, you can set it up easily. First, doto see what the name of your swap partition is. Then, do
or whatever the name of your swap partition is. Then, turn swapping on with
sudo mkswap /dev/sda3
Now check /proc/meminfo again to see if swap is working. If so, edit the file /etc/fstab to make the swap partition start at boot time. If you already have a swap line in there, just change it to the correct new swap partition name. If there isn't a swap line, add one. An fstab swap line should look like this:
sudo swapon /dev/sda3
Again, substitute the correct swap device name for /dev/sda3 if yours is different.
/dev/sda3 none swap sw 0 0