Patch series "mm/hugetlb: code refine and simplification", v4.

Following are some cleanups for hugetlb.  Simple testing with
tools/testing/selftests/vm/map_hugetlb passes.

This patch (of 7):

Per my understanding, we keep the regions ordered and would always
coalesce regions properly.  So the task to keep this property is just to
coalesce its neighbour.

Let's simplify this.
Signed-off-by: NWei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NBaoquan He <bhe@redhat.com>
Reviewed-by: NMike Kravetz <mike.kravetz@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: https://lkml.kernel.org/r/20200901014636.29737-1-richard.weiyang@linux.alibaba.com
Link: https://lkml.kernel.org/r/20200831022351.20916-1-richard.weiyang@linux.alibaba.com
Link: https://lkml.kernel.org/r/20200831022351.20916-2-richard.weiyang@linux.alibaba.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>