I attempted to upgrade a Mandriva 2010.2 system with the Mageia 2 alpha 2 x86 DVD and was unsuccessful. The Mandriva system had the /var partition formatted as nilfs2, and when the Mageia installer attempted to point that partition, it  warned that "an error occurred. Mounting partition UUID=xyz in directory /mnt/var failed" In the log, after a bunch of "running /sbin/insmod..." commands came
the lonely error message: "missing module nilfs2".

Everything to that point seemed to work, so the solution may be as simple as including the nilfs2.ko module in the installer.

nilfs2 is marked as experimental in the kernel, but Mageia ships the kernel module so it's reasonable to expect that someone may use it in such a way.