Adding a swap volume on LVM.
# add a logical volume for swap
lvcreate -L 2G VolGroup00 -n lvolswap
# make swap
mkswap /dev/VolGroup00/lvolswap
# activate swap
swapon /dev/VolGroup00/lvolswap
After that add following line to /etc/fstab.
/dev/mapper/VolGroup00-lvolswap none swap sw 0 0
Now it works!
root@raspberrypi:/home/pi# free -h
total used free shared buff/cache available
Mem: 926M 499M 46M 53M 379M 314M
Swap: 2.0G 390M 1.6G