From: Zwane Mwaikambo <zwane@linuxpower.ca>

hugetlbfs was accessing super_block->s_fs_info after free'ing it.  This was
because it was being free'd prematurely.  I have deferred free until
->put_super().  I have also removed hugetlbfs_kill_super since it now is
simply a kill_litter_super.