mm-hugetlbfs-fix-bugs-in-fallocate-hole-punch-of-areas-with-holes-v3

mm-hugetlbfs-fix-bugs-in-fallocate-hole-punch-of-areas-with-holes-v3

Orabug: 22220400

V3:
  Add more descriptive comments and minor improvements as suggested by
  Naoya Horiguchi
v2:
  Make remove_inode_hugepages simpler after verifying truncate can not
  race with page faults here.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Hillf Danton" <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit d4d7420e86e29267ff2e20226cbcadcf7e6eab8c)
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>