mm/hugetlb: change hugetlb allocation functions to return a folio

Many hugetlb allocation helper functions have now been converting to
folios, update their higher level callers to be compatible with folios. 
alloc_pool_huge_page is reorganized to avoid a smatch warning reporting
the folio variable is uninitialized.

[sidhartha.kumar@oracle.com: update alloc_and_dissolve_hugetlb_folio comments]
  Link: https://lkml.kernel.org/r/20221206233512.146535-1-sidhartha.kumar@oracle.com
Link: https://lkml.kernel.org/r/20221129225039.82257-11-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reported-by: Wei Chen <harperchen1110@gmail.com>
Suggested-by: John Hubbard <jhubbard@nvidia.com>
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.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: Tarun Sahu <tsahu@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb.c

@@ -1378,23 +1378,23 @@ static void free_gigantic_folio(struct folio *folio, unsigned int order)
 }
 
 #ifdef CONFIG_CONTIG_ALLOC
-static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
+static struct folio *alloc_gigantic_folio(struct hstate *h, gfp_t gfp_mask,
 		int nid, nodemask_t *nodemask)
 {
+	struct page *page;
 	unsigned long nr_pages = pages_per_huge_page(h);
 	if (nid == NUMA_NO_NODE)
 		nid = numa_mem_id();
 
 #ifdef CONFIG_CMA
 	{
-		struct page *page;
 		int node;
 
 		if (hugetlb_cma[nid]) {
 			page = cma_alloc(hugetlb_cma[nid], nr_pages,
 					huge_page_order(h), true);
 			if (page)
-				return page;
+				return page_folio(page);
 		}
 
 		if (!(gfp_mask & __GFP_THISNODE)) {
@@ -1405,17 +1405,18 @@ static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
 				page = cma_alloc(hugetlb_cma[node], nr_pages,
 						huge_page_order(h), true);
 				if (page)
-					return page;
+					return page_folio(page);
 			}
 		}
 	}
 #endif
 
-	return alloc_contig_pages(nr_pages, gfp_mask, nid, nodemask);
+	page = alloc_contig_pages(nr_pages, gfp_mask, nid, nodemask);
+	return page ? page_folio(page) : NULL;
 }
 
 #else /* !CONFIG_CONTIG_ALLOC */
-static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
+static struct folio *alloc_gigantic_folio(struct hstate *h, gfp_t gfp_mask,
 					int nid, nodemask_t *nodemask)
 {
 	return NULL;
@@ -1423,7 +1424,7 @@ static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
 #endif /* CONFIG_CONTIG_ALLOC */
 
 #else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */
-static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
+static struct folio *alloc_gigantic_folio(struct hstate *h, gfp_t gfp_mask,
 					int nid, nodemask_t *nodemask)
 {
 	return NULL;
@@ -1950,7 +1951,7 @@ pgoff_t hugetlb_basepage_index(struct page *page)
 	return (index << compound_order(page_head)) + compound_idx;
 }
 
-static struct page *alloc_buddy_huge_page(struct hstate *h,
+static struct folio *alloc_buddy_hugetlb_folio(struct hstate *h,
 		gfp_t gfp_mask, int nid, nodemask_t *nmask,
 		nodemask_t *node_alloc_noretry)
 {
@@ -1988,11 +1989,6 @@ static struct page *alloc_buddy_huge_page(struct hstate *h,
 		page = NULL;
 	}
 
-	if (page)
-		__count_vm_event(HTLB_BUDDY_PGALLOC);
-	else
-		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
-
 	/*
 	 * If we did not specify __GFP_RETRY_MAYFAIL, but still got a page this
 	 * indicates an overall state change.  Clear bit so that we resume
@@ -2009,7 +2005,13 @@ static struct page *alloc_buddy_huge_page(struct hstate *h,
 	if (node_alloc_noretry && !page && alloc_try_hard)
 		node_set(nid, *node_alloc_noretry);
 
-	return page;
+	if (!page) {
+		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
+		return NULL;
+	}
+
+	__count_vm_event(HTLB_BUDDY_PGALLOC);
+	return page_folio(page);
 }
 
 /*
@@ -2019,23 +2021,21 @@ static struct page *alloc_buddy_huge_page(struct hstate *h,
  * Note that returned page is 'frozen':  ref count of head page and all tail
  * pages is zero.
  */
-static struct page *alloc_fresh_huge_page(struct hstate *h,
+static struct folio *alloc_fresh_hugetlb_folio(struct hstate *h,
 		gfp_t gfp_mask, int nid, nodemask_t *nmask,
 		nodemask_t *node_alloc_noretry)
 {
-	struct page *page;
 	struct folio *folio;
 	bool retry = false;
 
 retry:
 	if (hstate_is_gigantic(h))
-		page = alloc_gigantic_page(h, gfp_mask, nid, nmask);
+		folio = alloc_gigantic_folio(h, gfp_mask, nid, nmask);
 	else
-		page = alloc_buddy_huge_page(h, gfp_mask,
+		folio = alloc_buddy_hugetlb_folio(h, gfp_mask,
 				nid, nmask, node_alloc_noretry);
-	if (!page)
+	if (!folio)
 		return NULL;
-	folio = page_folio(page);
 	if (hstate_is_gigantic(h)) {
 		if (!prep_compound_gigantic_folio(folio, huge_page_order(h))) {
 			/*
@@ -2052,7 +2052,7 @@ static struct page *alloc_fresh_huge_page(struct hstate *h,
 	}
 	prep_new_hugetlb_folio(h, folio, folio_nid(folio));
 
-	return page;
+	return folio;
 }
 
 /*
@@ -2062,23 +2062,20 @@ static struct page *alloc_fresh_huge_page(struct hstate *h,
 static int alloc_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
 				nodemask_t *node_alloc_noretry)
 {
-	struct page *page;
+	struct folio *folio;
 	int nr_nodes, node;
 	gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
 
 	for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
-		page = alloc_fresh_huge_page(h, gfp_mask, node, nodes_allowed,
-						node_alloc_noretry);
-		if (page)
-			break;
+		folio = alloc_fresh_hugetlb_folio(h, gfp_mask, node,
+					nodes_allowed, node_alloc_noretry);
+		if (folio) {
+			free_huge_page(&folio->page); /* free it into the hugepage allocator */
+			return 1;
+		}
 	}
 
-	if (!page)
-		return 0;
-
-	free_huge_page(page); /* free it into the hugepage allocator */
-
-	return 1;
+	return 0;
 }
 
 /*
@@ -2237,7 +2234,7 @@ int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
 static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
 						int nid, nodemask_t *nmask)
 {
-	struct page *page = NULL;
+	struct folio *folio = NULL;
 
 	if (hstate_is_gigantic(h))
 		return NULL;
@@ -2247,8 +2244,8 @@ static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
 		goto out_unlock;
 	spin_unlock_irq(&hugetlb_lock);
 
-	page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask, NULL);
-	if (!page)
+	folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask, NULL);
+	if (!folio)
 		return NULL;
 
 	spin_lock_irq(&hugetlb_lock);
@@ -2260,43 +2257,42 @@ static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
 	 * codeflow
 	 */
 	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
-		SetHPageTemporary(page);
+		folio_set_hugetlb_temporary(folio);
 		spin_unlock_irq(&hugetlb_lock);
-		free_huge_page(page);
+		free_huge_page(&folio->page);
 		return NULL;
 	}
 
 	h->surplus_huge_pages++;
-	h->surplus_huge_pages_node[page_to_nid(page)]++;
+	h->surplus_huge_pages_node[folio_nid(folio)]++;
 
 out_unlock:
 	spin_unlock_irq(&hugetlb_lock);
 
-	return page;
+	return &folio->page;
 }
 
 static struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask,
 				     int nid, nodemask_t *nmask)
 {
-	struct page *page;
+	struct folio *folio;
 
 	if (hstate_is_gigantic(h))
 		return NULL;
 
-	page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask, NULL);
-	if (!page)
+	folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask, NULL);
+	if (!folio)
 		return NULL;
 
 	/* fresh huge pages are frozen */
-	set_page_refcounted(page);
-
+	folio_ref_unfreeze(folio, 1);
 	/*
 	 * We do not account these pages as surplus because they are only
 	 * temporary and will be released properly on the last reference
 	 */
-	SetHPageTemporary(page);
+	folio_set_hugetlb_temporary(folio);
 
-	return page;
+	return &folio->page;
 }
 
 /*
@@ -2745,54 +2741,52 @@ void restore_reserve_on_error(struct hstate *h, struct vm_area_struct *vma,
 }
 
 /*
- * alloc_and_dissolve_huge_page - Allocate a new page and dissolve the old one
+ * alloc_and_dissolve_hugetlb_folio - Allocate a new folio and dissolve
+ * the old one
  * @h: struct hstate old page belongs to
- * @old_page: Old page to dissolve
+ * @old_folio: Old folio to dissolve
  * @list: List to isolate the page in case we need to
  * Returns 0 on success, otherwise negated error.
  */
-static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
-					struct list_head *list)
+static int alloc_and_dissolve_hugetlb_folio(struct hstate *h,
+			struct folio *old_folio, struct list_head *list)
 {
 	gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
-	struct folio *old_folio = page_folio(old_page);
 	int nid = folio_nid(old_folio);
-	struct page *new_page;
 	struct folio *new_folio;
 	int ret = 0;
 
 	/*
-	 * Before dissolving the page, we need to allocate a new one for the
-	 * pool to remain stable.  Here, we allocate the page and 'prep' it
+	 * Before dissolving the folio, we need to allocate a new one for the
+	 * pool to remain stable.  Here, we allocate the folio and 'prep' it
 	 * by doing everything but actually updating counters and adding to
 	 * the pool.  This simplifies and let us do most of the processing
 	 * under the lock.
 	 */
-	new_page = alloc_buddy_huge_page(h, gfp_mask, nid, NULL, NULL);
-	if (!new_page)
+	new_folio = alloc_buddy_hugetlb_folio(h, gfp_mask, nid, NULL, NULL);
+	if (!new_folio)
 		return -ENOMEM;
-	new_folio = page_folio(new_page);
 	__prep_new_hugetlb_folio(h, new_folio);
 
 retry:
 	spin_lock_irq(&hugetlb_lock);
 	if (!folio_test_hugetlb(old_folio)) {
 		/*
-		 * Freed from under us. Drop new_page too.
+		 * Freed from under us. Drop new_folio too.
 		 */
 		goto free_new;
 	} else if (folio_ref_count(old_folio)) {
 		/*
-		 * Someone has grabbed the page, try to isolate it here.
+		 * Someone has grabbed the folio, try to isolate it here.
 		 * Fail with -EBUSY if not possible.
 		 */
 		spin_unlock_irq(&hugetlb_lock);
-		ret = isolate_hugetlb(old_page, list);
+		ret = isolate_hugetlb(&old_folio->page, list);
 		spin_lock_irq(&hugetlb_lock);
 		goto free_new;
 	} else if (!folio_test_hugetlb_freed(old_folio)) {
 		/*
-		 * Page's refcount is 0 but it has not been enqueued in the
+		 * Folio's refcount is 0 but it has not been enqueued in the
 		 * freelist yet. Race window is small, so we can succeed here if
 		 * we retry.
 		 */
@@ -2801,7 +2795,7 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
 		goto retry;
 	} else {
 		/*
-		 * Ok, old_page is still a genuine free hugepage. Remove it from
+		 * Ok, old_folio is still a genuine free hugepage. Remove it from
 		 * the freelist and decrease the counters. These will be
 		 * incremented again when calling __prep_account_new_huge_page()
 		 * and enqueue_hugetlb_folio() for new_folio. The counters will
@@ -2810,14 +2804,14 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
 		remove_hugetlb_folio(h, old_folio, false);
 
 		/*
-		 * Ref count on new page is already zero as it was dropped
+		 * Ref count on new_folio is already zero as it was dropped
 		 * earlier.  It can be directly added to the pool free list.
 		 */
 		__prep_account_new_huge_page(h, nid);
 		enqueue_hugetlb_folio(h, new_folio);
 
 		/*
-		 * Pages have been replaced, we can safely free the old one.
+		 * Folio has been replaced, we can safely free the old one.
 		 */
 		spin_unlock_irq(&hugetlb_lock);
 		update_and_free_hugetlb_folio(h, old_folio, false);
@@ -2827,7 +2821,7 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
 
 free_new:
 	spin_unlock_irq(&hugetlb_lock);
-	/* Page has a zero ref count, but needs a ref to be freed */
+	/* Folio has a zero ref count, but needs a ref to be freed */
 	folio_ref_unfreeze(new_folio, 1);
 	update_and_free_hugetlb_folio(h, new_folio, false);
 
@@ -2865,7 +2859,7 @@ int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list)
 	if (folio_ref_count(folio) && !isolate_hugetlb(&folio->page, list))
 		ret = 0;
 	else if (!folio_ref_count(folio))
-		ret = alloc_and_dissolve_huge_page(h, &folio->page, list);
+		ret = alloc_and_dissolve_hugetlb_folio(h, folio, list);
 
 	return ret;
 }
@@ -3083,14 +3077,14 @@ static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid)
 			if (!alloc_bootmem_huge_page(h, nid))
 				break;
 		} else {
-			struct page *page;
+			struct folio *folio;
 			gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
 
-			page = alloc_fresh_huge_page(h, gfp_mask, nid,
+			folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid,
 					&node_states[N_MEMORY], NULL);
-			if (!page)
+			if (!folio)
 				break;
-			free_huge_page(page); /* free it into the hugepage allocator */
+			free_huge_page(&folio->page); /* free it into the hugepage allocator */
 		}
 		cond_resched();
 	}