if you get swapon failed: Operation not permitted Error even if you run as root it is because in your VPS swap creation is not allowed follow below steps to Create Fake Swap in OpenVZ VPS
[root@server] free -m total used free Mem: 4096 104 3991 -/+ buffers/cache: 104 3991
Swap: 0 0 0
create shell script file add lines like below
[root@server] vi fakeswap.sh
#!/bin/bash
SWAP=”${1:-512}”
NEW=”$[SWAP*1024]”; TEMP=”${NEW//?/ }”; OLD=”${TEMP:1}0″
umount /proc/meminfo 2> /dev/null
sed “/^Swap\(Total\|Free\):/s,$OLD,$NEW,” /proc/meminfo > /etc/fake_meminfo
mount –bind /etc/fake_meminfo /proc/meminfo
free -m
[root@server] chmod +x fakeswap.sh
[root@server] sh fakeswap.sh [root@server] free -m total used free Mem: 4096 104 3991 -/+ buffers/cache: 104 3991 Swap: 512 0 512 to create 1024MB Swap run like below [root@server] sh fakeswap.sh 1024 [root@server] free -m total used free Mem: 4096 104 3991 -/+ buffers/cache: 104 3991 Swap: 1024 0 1024 – See more at: http://linux-problem-solver.blogspot.sg/2013/08/create-fake-swap-in-openvz-vps-if-you-get-swapon-failed-operation-not-permitted-error.html#sthash.Eeknzpcf.dpuf