Patch from Rohit Seth

It fixes the problem which Andrea noted in his initial review of the
hugetlb code:

"In short doing "addr = vma->vm_end" and then checking if vm_end + len
 is below vm_next->vm_start is broken, because there's no guarantee
 that "addr" will be a largepage aligned address.  the LPAGE_ALIGN in
 found_addr should be dropped becaue moving the addr ahead without
 checking that addr+len doesn't then fall into a vma, will generate
 do_munmaps and in turn userspace mem corruption."