hugetlb: check for hugetlb folio before vmemmap_restore

In commit d8f5f7e4 ("hugetlb: set hugetlb page flag before
optimizing vmemmap") checks were added to print a warning if
hugetlb_vmemmap_restore was called on a non-hugetlb page.

This was mostly due to ordering issues in the hugetlb page set up and tear
down sequencees.  One place missed was the routine
dissolve_free_huge_page.

Naoya Horiguchi noted: "I saw that VM_WARN_ON_ONCE() in
hugetlb_vmemmap_restore is triggered when memory_failure() is called on a
free hugetlb page with vmemmap optimization disabled (the warning is not
triggered if vmemmap optimization is enabled).  I think that we need check
folio_test_hugetlb() before dissolve_free_huge_page() calls
hugetlb_vmemmap_restore_folio()."

Perform the check as suggested by Naoya.

Link: https://lkml.kernel.org/r/20231017032140.GA3680@monkey
Fixes: d8f5f7e4 ("hugetlb: set hugetlb page flag before optimizing vmemmap")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Suggested-by: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Tested-by: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Barry Song <song.bao.hua@hisilicon.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb.c

@@ -2322,17 +2322,23 @@ int dissolve_free_huge_page(struct page *page)
 		 * need to adjust max_huge_pages if the page is not freed.
 		 * Attempt to allocate vmemmmap here so that we can take
 		 * appropriate action on failure.
+		 *
+		 * The folio_test_hugetlb check here is because
+		 * remove_hugetlb_folio will clear hugetlb folio flag for
+		 * non-vmemmap optimized hugetlb folios.
 		 */
-		rc = hugetlb_vmemmap_restore(h, &folio->page);
-		if (!rc) {
-			update_and_free_hugetlb_folio(h, folio, false);
-		} else {
-			spin_lock_irq(&hugetlb_lock);
-			add_hugetlb_folio(h, folio, false);
-			h->max_huge_pages++;
-			spin_unlock_irq(&hugetlb_lock);
-		}
+		if (folio_test_hugetlb(folio)) {
+			rc = hugetlb_vmemmap_restore(h, &folio->page);
+			if (rc) {
+				spin_lock_irq(&hugetlb_lock);
+				add_hugetlb_folio(h, folio, false);
+				h->max_huge_pages++;
+				goto out;
+			}
+		} else
+			rc = 0;
 
+		update_and_free_hugetlb_folio(h, folio, false);
 		return rc;
 	}
 out: