mm/hugetlb: have CONFIG_HUGETLB_PAGE select CONFIG_XARRAY_MULTI

After commit a08c719 "mm/filemap: remove hugetlb special casing in
filemap.c", hugetlb pages are stored in the page cache in base page sized
indexes.  This leads to multi index stores in the xarray which is only
supporting through CONFIG_XARRAY_MULTI.  The other page cache user of
multi index stores ,THP, selects XARRAY_MULTI.  Have CONFIG_HUGETLB_PAGE
follow this behavior as well to avoid the BUG() with a CONFIG_HUGETLB_PAGE
&& !CONFIG_XARRAY_MULTI config.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: a08c719 ("mm/filemap: remove hugetlb special casing in filemap.c")
Signed-off-by: Sidhartha Kumar <[email protected]>
Reported-by: Al Viro <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Muchun Song <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: sidkumar99

fs/Kconfig

@@ -268,6 +268,7 @@ config HUGETLBFS
 
 config HUGETLB_PAGE
 	def_bool HUGETLBFS
+	select XARRAY_MULTI
 
 config HUGETLB_PAGE_OPTIMIZE_VMEMMAP
 	def_bool HUGETLB_PAGE