mm/memory-failure.c: dissolve truncated hugetlb page

If me_huge_page meets a truncated but not yet freed hugepage, it won't be
dissolved even if we hold the last refcnt. It's because the hugepage has
NULL page_mapping while it's not anonymous hugepage too. Thus we lose the
last chance to dissolve it into buddy to save healthy subpages. Remove
PageAnon check to handle these hugepages too.

Link: https://lkml.kernel.org/r/20220414114941.11223-3-linmiaohe@huawei.comSigned-off-by: NMiaohe Lin <linmiaohe@huawei.com>
Acked-by: NNaoya Horiguchi <naoya.horiguchi@nec.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>

mm/memory-failure.c

@@ -1040,11 +1040,10 @@ static int me_huge_page(struct page_state *ps, struct page *p)
 		res = MF_FAILED;
 		unlock_page(hpage);
 		/*
-		 * migration entry prevents later access on error anonymous
-		 * hugepage, so we can free and dissolve it into buddy to
-		 * save healthy subpages.
+		 * migration entry prevents later access on error hugepage,
+		 * so we can free and dissolve it into buddy to save healthy
+		 * subpages.
 		 */
-		if (PageAnon(hpage))
 		put_page(hpage);
 		if (__page_handle_poison(p)) {
 			page_ref_inc(p);