Ext4 does not work with delayed allocation in this kernel, this is known mainstream bug. Can you please try to reproduce it with 'nodelalloc' mount option set in /etc/fstab? If you will able to reproduce the bug with 'nodelalloc' turned on, please report the kernel oops to OpenVZ bug #1510. Upstream bug references: http://bugzilla.openvz.org/show_bug.cgi?id=1509 http://bugzilla.openvz.org/show_bug.cgi?id=1510 -- Thanks, Kir.