It seems that O_DIRECT write sometimes leaks memory. The upstream fix can be found here: http://linux.bkbits.net:8080/linux-2.6/cset@4182a613oVsK0-8eCWpyYFrUf8rhLA
committed in stream E5 build 42.0.1. A test kernel with this patch is available from http://people.redhat.com/~jbaron/rhel4/
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 the 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-2006-0617.html
committed in stream U5 build 42.4. A test kernel with this patch is available from http://people.redhat.com/~jbaron/rhel4/
*** Bug 211335 has been marked as a duplicate of this bug. ***