Allow struct folio to store hugetlb metadata that is contained in the private field of the first tail page. On 32-bit, _private_1 aligns with page[1].private. Link: https://lkml.kernel.org/r/20220922154207.1575343-3-sidhartha.kumar@oracle.com Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Colin Cross <ccross@google.com> Cc: David Howells <dhowells@redhat.com> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Hugh Dickins <hughd@google.com> Cc: kernel test robot <lkp@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Peter Xu <peterx@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>