If I read it correctly, your first
free command indicated that you were not using any of your currently allocated swap space. (Which is, I presume, something to check before doing a
swapoff.
)
Anyhow, rather than resizing the LV(s), why not just create a file in / and add it to the swap pool? And track your swap usage: With 4GB RAM, especially if you're on a server, you're unlikely to need any swap at all...