You need to perform the following two commands with su access to expand out the swap

dd if=/dev/zero of=/swapfile bs=1k count=4096k

mkswap /swapfile


original was /dev/dm-1 with 2GB of space

[root@localhost oracle]# dd if=/dev/zero of=/swapfile bs=1k count=4096k

[oracle@localhost ~]$ df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                       65G   38G   25G  61% /
tmpfs                 3.5G  112K  3.5G   1% /dev/shm
/dev/sda1             485M  114M  346M  25% /boot
[oracle@localhost ~]$ free -m
Mem:          7119        610       6508          0         32        185
-/+ buffers/cache:        392       6726
Swap:         2015          0       2015
[oracle@localhost ~]$ sudo install -o root -g root -m 0600 /dev/null /swapfile
[oracle@localhost ~]$ dd if=/dev/zero of=/swapfile bs=1k count=4096k
dd: opening `/swapfile': Permission denied
[oracle@localhost ~]$ su
Password: 
[root@localhost oracle]# dd if=/dev/zero of=/swapfile bs=1k count=4096k
4194304+0 records in
4194304+0 records out
4294967296 bytes (4.3 GB) copied, 250.221 s, 17.2 MB/s
[root@localhost oracle]# mkswap /swapfile
mkswap: /swapfile: warning: don't erase bootbits sectors
        on whole disk. Use -f to force.
Setting up swapspace version 1, size = 4194300 KiB
no label, UUID=b25a189b-eff2-4db5-a798-c6f90fc55e40
[root@localhost oracle]# swapon /swapfile
[root@localhost oracle]# free -m
             total       used       free     shared    buffers     cached
Mem:          7119       3272       3847          0          9       2862
-/+ buffers/cache:        400       6719
Swap:         6111          0       6111
[root@localhost oracle]# 

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