Clients since 2.6.18 DO NOT need any patches.
PATCH SERIES FOR SERVER KERNELS:
-2.6-rhel6.series 2.6.32-431.29.2.el6 (RHEL 6.5)
-2.6-rhel6.series 2.6.32-504.30.3.el6 (RHEL 6.6)
-2.6-rhel6.series 2.6.32-573.26.1.el6 (RHEL 6.7)
-2.6-rhel6.8.series 2.6.32-642.15.1.el6 (RHEL 6.8)
-2.6-rhel6.8.series 2.6.32-696.16.1.el6 (RHEL 6.9)
-3.10-rhel7.series 3.10.0-693.11.6.el7 (RHEL 7.4)
-3.0-sles11sp3.series 3.0.101-0.47.71 (SLES11 SP3)
-3.0-sles11sp3.series 3.0.101-107 (SLES11 SP4)
-3.12-sles12.series 3.12.74-60.64.40 (SLES12 SP1)
-4.4-sles12.series 4.4.90-92.45 (SLES12 SP2)
-4.4-sles12sp3.series 4.4.103-6.38 (SLES12 SP3)
+3.10-rhel7.9.series 3.10.0-1160.88.1.el7 (RHEL 7.9)
+4.18-rhel8.4.series 4.18.0-305.25.1.el8 (RHEL 8.4)
+4.18-rhel8.5.series 4.18.0-348.23.1.el8 (RHEL 8.5)
+4.18-rhel8.6.series 4.18.0-372.32.1.el8 (RHEL 8.6)
+4.18-rhel8.7.series 4.18.0-425.10.1.el8 (RHEL 8.7)
+4.18-rhel8.8.series 4.18.0-477.27.1.el8 (RHEL 8.8)
+4.18-rhel8.9.series 4.18.0-513.18.1.el8 (RHEL 8.9)
+5.14-rhel9.1.series 5.14.0-162.23.1.el9 (RHEL 9.1)
+5.14-rhel9.2.series 5.14.0-284.30.1.el9 (RHEL 9.2)
+5.14-rhel9.3.series 5.14.0-362.18.1.el9 (RHEL 9.3)
See lustre/ChangeLog for supported client kernel versions.