The software described in this documentation is either in Extended Support or Sustaining Support. See https://www.oracle.com/us/support/library/enterprise-linux-support-policies-069172.pdf for more information.
Oracle recommends that you upgrade the software described by this documentation as soon as possible.

2.2.22 Oracle RDBMS Server 11gR2 Preinstall Settings Not Visible After Installation

On an x86-64 system, if you install the pam.i386 package either manually or via a package dependency, and the oracle-rdbms-server-11gR2-preinstall package is also selected, this overwrites the settings for Oracle Database in /etc/security/limits.conf. This is most likely to occur during a Kickstart-automated installation that includes non-standard packages. To restore the settings, run the oracle-rdbms-server-11gR2-preinstall-verify script. (Bug ID 14212822)