Oracle: Unable to switch user to oracle

[root@iTest ~]# su - oracle
could not open session

Checked the 

ulimit -a 

or 

vi /etc/security/limits.conf

The soft or hard may have been overlocated. 

I was fooling with the parameters and insert 2000000 on both oracle hard nproc and nofile.

# End of file

#oracle hard nproc 16384

#oracle hard nofile 65536

oracle hard nproc 30000

oracle hard nofile 100000

Change it to lower number and run this as root.

sysctl -p