This bug has been copied from bug #634850 and has been proposed to be backported to 5.5 z-stream (EUS).
in kernel 2.6.18-194.20.1.el5 linux-2.6-misc-fix-race-in-pid-generation-causing-immediate-reuse.patch
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2010-0839.html
Technical note added. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. New Contents: A race in the PID generation caused PIDs to be reused immediately. This caused problems such as signaling or killing wrong processes accidentally, resulting in various application faults. With this update, the reuse of PIDs is detected and is no longer allowed.