This Oops affects 3.5 kernels and older, and is due to lookup_one_len()
calling down to the dentry revalidation code with a NULL pointer
to struct nameidata.
It is fixed upstream by commit 0b728e1911c (stop passing nameidata *
to ->d_revalidate())
Reported-by: Richard Ems <richard.ems@cape-horn-eng.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>