Here are what modprobe lustre and dmesg give :
WARNING: Error inserting libcfs (/lib/modules/2.6.18-ovz028stab053.5/kernel/net/lustre/libcfs.ko): Invalid module format
WARNING: Error inserting lvfs (/lib/modules/2.6.18-ovz028stab053.5/kernel/fs/lustre/lvfs.ko): Invalid module format
WARNING: Error inserting lnet (/lib/modules/2.6.18-ovz028stab053.5/kernel/net/lustre/lnet.ko): Invalid module format
WARNING: Error inserting obdclass (/lib/modules/2.6.18-ovz028stab053.5/kernel/fs/lustre/obdclass.ko): Invalid module format
WARNING: Error inserting ptlrpc (/lib/modules/2.6.18-ovz028stab053.5/kernel/fs/lustre/ptlrpc.ko): Invalid module format
WARNING: Error inserting mdc (/lib/modules/2.6.18-ovz028stab053.5/kernel/fs/lustre/mdc.ko): Invalid module format
WARNING: Error inserting lov (/lib/modules/2.6.18-ovz028stab053.5/kernel/fs/lustre/lov.ko): Invalid module format
FATAL: Error inserting lustre (/lib/modules/2.6.18-ovz028stab053.5/kernel/fs/lustre/lustre.ko): Invalid module format
libcfs: version magic '2.6.18-ovz028stab053.5 SMP mod_unload 686 REGPARM 4KSTACKS gcc-3.4' should be '2.6.18-ovz028stab053.5 mod_unload 686 4KSTACKS gcc-3.4'
lvfs: version magic '2.6.18-ovz028stab053.5 SMP mod_unload 686 REGPARM 4KSTACKS gcc-3.4' should be '2.6.18-ovz028stab053.5 mod_unload 686 4KSTACKS gcc-3.4'
lnet: version magic '2.6.18-ovz028stab053.5 SMP mod_unload 686 REGPARM 4KSTACKS gcc-3.4' should be '2.6.18-ovz028stab053.5 mod_unload 686 4KSTACKS gcc-3.4'
obdclass: version magic '2.6.18-ovz028stab053.5 SMP mod_unload 686 REGPARM 4KSTACKS gcc-3.4' should be '2.6.18-ovz028stab053.5 mod_unload 686 4KSTACKS gcc-3.4'
ptlrpc: version magic '2.6.18-ovz028stab053.5 SMP mod_unload 686 REGPARM 4KSTACKS gcc-3.4' should be '2.6.18-ovz028stab053.5 mod_unload 686 4KSTACKS gcc-3.4'
mdc: version magic '2.6.18-ovz028stab053.5 SMP mod_unload 686 REGPARM 4KSTACKS gcc-3.4' should be '2.6.18-ovz028stab053.5 mod_unload 686 4KSTACKS gcc-3.4'
lov: version magic '2.6.18-ovz028stab053.5 SMP mod_unload 686 REGPARM 4KSTACKS gcc-3.4' should be '2.6.18-ovz028stab053.5 mod_unload 686 4KSTACKS gcc-3.4'
lustre: version magic '2.6.18-ovz028stab053.5 SMP mod_unload 686 REGPARM 4KSTACKS gcc-3.4' should be '2.6.18-ovz028stab053.5 mod_unload 686 4KSTACKS gcc-3.4'