Clients since 2.6.18 DO NOT need any patches.
PATCH SERIES FOR SERVER KERNELS:
-2.6-rhel6.series 2.6.32-431.17.1.el6
-3.0-sles11sp3.series 3.0.101-0.21
+2.6-rhel6.series 2.6.32-431.23.3.el6
+3.0-sles11sp3.series 3.0.101-0.31
See lustre/ChangeLog for supported client kernel versions.