>I would advise to stay away from 2.6.31 and 2.6.32 for UML. Too much has
>been changing in mainstream with regard to interfaces and bugfixing for
>block handling operations. Also ext4 support is buggy.

I have been working with and I had the same issue on compiling. Once I compiled dynamic  (I did not check the option UML  Force static link), I did not got any seg fault. The ext filesystem is an issue but it does not affect me much.