mm/hugetlb: convert dissolve_free_huge_page() to folios

Removes compound_head() call by using a folio rather than a head page.

Link: https://lkml.kernel.org/r/20221129225039.82257-4-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tarun Sahu <tsahu@linux.ibm.com>
Cc: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb.c

@@ -2128,21 +2128,21 @@ static struct page *remove_pool_huge_page(struct hstate *h,
 int dissolve_free_huge_page(struct page *page)
 {
 	int rc = -EBUSY;
+	struct folio *folio = page_folio(page);
 
 retry:
 	/* Not to disrupt normal path by vainly holding hugetlb_lock */
-	if (!PageHuge(page))
+	if (!folio_test_hugetlb(folio))
 		return 0;
 
 	spin_lock_irq(&hugetlb_lock);
-	if (!PageHuge(page)) {
+	if (!folio_test_hugetlb(folio)) {
 		rc = 0;
 		goto out;
 	}
 
-	if (!page_count(page)) {
-		struct page *head = compound_head(page);
-		struct hstate *h = page_hstate(head);
+	if (!folio_ref_count(folio)) {
+		struct hstate *h = folio_hstate(folio);
 		if (!available_huge_pages(h))
 			goto out;
 
@@ -2150,7 +2150,7 @@ int dissolve_free_huge_page(struct page *page)
 		 * We should make sure that the page is already on the free list
 		 * when it is dissolved.
 		 */
-		if (unlikely(!HPageFreed(head))) {
+		if (unlikely(!folio_test_hugetlb_freed(folio))) {
 			spin_unlock_irq(&hugetlb_lock);
 			cond_resched();
 
@@ -2165,7 +2165,7 @@ int dissolve_free_huge_page(struct page *page)
 			goto retry;
 		}
 
-		remove_hugetlb_page(h, head, false);
+		remove_hugetlb_page(h, &folio->page, false);
 		h->max_huge_pages--;
 		spin_unlock_irq(&hugetlb_lock);
 
@@ -2177,12 +2177,12 @@ int dissolve_free_huge_page(struct page *page)
 		 * Attempt to allocate vmemmmap here so that we can take
 		 * appropriate action on failure.
 		 */
-		rc = hugetlb_vmemmap_restore(h, head);
+		rc = hugetlb_vmemmap_restore(h, &folio->page);
 		if (!rc) {
-			update_and_free_page(h, head, false);
+			update_and_free_page(h, &folio->page, false);
 		} else {
 			spin_lock_irq(&hugetlb_lock);
-			add_hugetlb_page(h, head, false);
+			add_hugetlb_page(h, &folio->page, false);
 			h->max_huge_pages++;
 			spin_unlock_irq(&hugetlb_lock);
 		}