From: Hugh Dickins <hugh@veritas.com>

Before some real vma_merge work in mmap.c in the next patch, a patch of
miscellaneous cleanups to cut down the noise:

- remove rb_parent arg from vma_merge: mm->mmap can do that case
- scatter pgoff_t around to ingratiate myself with the boss
- reorder is_mergeable_vma tests, vm_ops->close is least likely
- can_vma_merge_before take combined pgoff+pglen arg (from Andrea)
- rearrange do_mmap_pgoff's ever-confusing anonymous flags switch
- comment do_mmap_pgoff's mysterious (vm_flags & VM_SHARED) test
- fix ISO C90 warning on browse_rb if building with DEBUG_MM_RB
- stop that long MNT_NOEXEC line wrapping

Yes, buried in amidst these is indeed one pgoff replaced by "next->vm_pgoff -
pglen" (reverting a mod of mine which took pgoff supplied by user too
seriously in the anon case), and another pgoff replaced by 0 (reverting
anon_vma mod which crept in with NUMA API): neither of them really matters,
except perhaps in /proc/pid/maps.