[PATCH v4 5/6] mm: cma: add cma_alloc_frozen{_compound}()

[Kefeng Wang <wangkefeng.wang@huawei.com>]

Introduce cma_alloc_frozen{_compound}() helper to alloc pages without
incrementing their refcount, then convert hugetlb cma to use the
cma_alloc_frozen_compound() and cma_release_frozen() and remove the
unused cma_{alloc,free}_folio(), also move the cma_validate_zones()
into mm/internal.h since no outside user.

The set_pages_refcounted() is only called to set non-compound pages
after above changes, so remove the process about PageHead.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 include/linux/cma.h | 26 ++++++------------------
 mm/cma.c            | 48 +++++++++++++++++++++++++--------------------
 mm/hugetlb_cma.c    | 24 +++++++++++++----------
 mm/internal.h       | 12 +++++-------
 4 files changed, 52 insertions(+), 58 deletions(-)

diff --git a/include/linux/cma.h b/include/linux/cma.h
index e5745d2aec55..e2a690f7e77e 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -51,29 +51,15 @@ extern struct page *cma_alloc(struct cma *cma, unsigned long count, unsigned int
 			      bool no_warn);
 extern bool cma_release(struct cma *cma, const struct page *pages, unsigned long count);
 
+struct page *cma_alloc_frozen(struct cma *cma, unsigned long count,
+		unsigned int align, bool no_warn);
+struct page *cma_alloc_frozen_compound(struct cma *cma, unsigned int order);
+bool cma_release_frozen(struct cma *cma, const struct page *pages,
+		unsigned long count);
+
 extern int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data);
 extern bool cma_intersects(struct cma *cma, unsigned long start, unsigned long end);
 
 extern void cma_reserve_pages_on_error(struct cma *cma);
 
-#ifdef CONFIG_CMA
-struct folio *cma_alloc_folio(struct cma *cma, int order, gfp_t gfp);
-bool cma_free_folio(struct cma *cma, const struct folio *folio);
-bool cma_validate_zones(struct cma *cma);
-#else
-static inline struct folio *cma_alloc_folio(struct cma *cma, int order, gfp_t gfp)
-{
-	return NULL;
-}
-
-static inline bool cma_free_folio(struct cma *cma, const struct folio *folio)
-{
-	return false;
-}
-static inline bool cma_validate_zones(struct cma *cma)
-{
-	return false;
-}
-#endif
-
 #endif
diff --git a/mm/cma.c b/mm/cma.c
index 7f050cf24383..1aa1d821fbe9 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -856,8 +856,8 @@ static int cma_range_alloc(struct cma *cma, struct cma_memrange *cmr,
 	return ret;
 }
 
-static struct page *__cma_alloc(struct cma *cma, unsigned long count,
-		       unsigned int align, gfp_t gfp)
+static struct page *__cma_alloc_frozen(struct cma *cma,
+		unsigned long count, unsigned int align, gfp_t gfp)
 {
 	struct page *page = NULL;
 	int ret = -ENOMEM, r;
@@ -904,7 +904,6 @@ static struct page *__cma_alloc(struct cma *cma, unsigned long count,
 	trace_cma_alloc_finish(name, page ? page_to_pfn(page) : 0,
 			       page, count, align, ret);
 	if (page) {
-		set_pages_refcounted(page, count);
 		count_vm_event(CMA_ALLOC_SUCCESS);
 		cma_sysfs_account_success_pages(cma, count);
 	} else {
@@ -915,6 +914,21 @@ static struct page *__cma_alloc(struct cma *cma, unsigned long count,
 	return page;
 }
 
+struct page *cma_alloc_frozen(struct cma *cma, unsigned long count,
+		unsigned int align, bool no_warn)
+{
+	gfp_t gfp = GFP_KERNEL | (no_warn ? __GFP_NOWARN : 0);
+
+	return __cma_alloc_frozen(cma, count, align, gfp);
+}
+
+struct page *cma_alloc_frozen_compound(struct cma *cma, unsigned int order)
+{
+	gfp_t gfp = GFP_KERNEL | __GFP_COMP | __GFP_NOWARN;
+
+	return __cma_alloc_frozen(cma, 1 << order, order, gfp);
+}
+
 /**
  * cma_alloc() - allocate pages from contiguous area
  * @cma:   Contiguous memory region for which the allocation is performed.
@@ -927,24 +941,18 @@ static struct page *__cma_alloc(struct cma *cma, unsigned long count,
  */
 struct page *cma_alloc(struct cma *cma, unsigned long count,
 		       unsigned int align, bool no_warn)
-{
-	return __cma_alloc(cma, count, align, GFP_KERNEL | (no_warn ? __GFP_NOWARN : 0));
-}
-
-struct folio *cma_alloc_folio(struct cma *cma, int order, gfp_t gfp)
 {
 	struct page *page;
 
-	if (WARN_ON(!order || !(gfp & __GFP_COMP)))
-		return NULL;
-
-	page = __cma_alloc(cma, 1 << order, order, gfp);
+	page = cma_alloc_frozen(cma, count, align, no_warn);
+	if (page)
+		set_pages_refcounted(page, count);
 
-	return page ? page_folio(page) : NULL;
+	return page;
 }
 
 static bool __cma_release(struct cma *cma, const struct page *pages,
-			  unsigned long count, bool compound)
+			  unsigned long count, bool frozen)
 {
 	unsigned long pfn, end;
 	int r;
@@ -974,8 +982,8 @@ static bool __cma_release(struct cma *cma, const struct page *pages,
 		return false;
 	}
 
-	if (compound)
-		__free_pages((struct page *)pages, compound_order(pages));
+	if (frozen)
+		free_contig_frozen_range(pfn, count);
 	else
 		free_contig_range(pfn, count);
 
@@ -1002,12 +1010,10 @@ bool cma_release(struct cma *cma, const struct page *pages,
 	return __cma_release(cma, pages, count, false);
 }
 
-bool cma_free_folio(struct cma *cma, const struct folio *folio)
+bool cma_release_frozen(struct cma *cma, const struct page *pages,
+		unsigned long count)
 {
-	if (WARN_ON(!folio_test_large(folio)))
-		return false;
-
-	return __cma_release(cma, &folio->page, folio_nr_pages(folio), true);
+	return __cma_release(cma, pages, count, true);
 }
 
 int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data)
diff --git a/mm/hugetlb_cma.c b/mm/hugetlb_cma.c
index e8e4dc7182d5..0a57d3776c8d 100644
--- a/mm/hugetlb_cma.c
+++ b/mm/hugetlb_cma.c
@@ -20,35 +20,39 @@ static unsigned long hugetlb_cma_size __initdata;
 
 void hugetlb_cma_free_folio(struct folio *folio)
 {
-	int nid = folio_nid(folio);
+	folio_ref_dec(folio);
 
-	WARN_ON_ONCE(!cma_free_folio(hugetlb_cma[nid], folio));
+	WARN_ON_ONCE(!cma_release_frozen(hugetlb_cma[folio_nid(folio)],
+					 &folio->page, folio_nr_pages(folio)));
 }
 
-
 struct folio *hugetlb_cma_alloc_folio(int order, gfp_t gfp_mask,
 				      int nid, nodemask_t *nodemask)
 {
 	int node;
-	struct folio *folio = NULL;
+	struct folio *folio;
+	struct page *page = NULL;
 
 	if (hugetlb_cma[nid])
-		folio = cma_alloc_folio(hugetlb_cma[nid], order, gfp_mask);
+		page = cma_alloc_frozen_compound(hugetlb_cma[nid], order);
 
-	if (!folio && !(gfp_mask & __GFP_THISNODE)) {
+	if (!page && !(gfp_mask & __GFP_THISNODE)) {
 		for_each_node_mask(node, *nodemask) {
 			if (node == nid || !hugetlb_cma[node])
 				continue;
 
-			folio = cma_alloc_folio(hugetlb_cma[node], order, gfp_mask);
-			if (folio)
+			page = cma_alloc_frozen_compound(hugetlb_cma[nid], order);
+			if (page)
 				break;
 		}
 	}
 
-	if (folio)
-		folio_set_hugetlb_cma(folio);
+	if (!page)
+		return NULL;
 
+	set_page_refcounted(page);
+	folio = page_folio(page);
+	folio_set_hugetlb_cma(folio);
 	return folio;
 }
 
diff --git a/mm/internal.h b/mm/internal.h
index ec1e47a9044f..dd22b1d8ff90 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -515,13 +515,6 @@ static inline void set_page_refcounted(struct page *page)
 
 static inline void set_pages_refcounted(struct page *page, unsigned long nr_pages)
 {
-	unsigned long pfn = page_to_pfn(page);
-
-	if (PageHead(page)) {
-		set_page_refcounted(page);
-		return;
-	}
-
 	for (; nr_pages--; pfn++)
 		set_page_refcounted(pfn_to_page(pfn));
 }
@@ -952,9 +945,14 @@ void init_cma_reserved_pageblock(struct page *page);
 struct cma;
 
 #ifdef CONFIG_CMA
+bool cma_validate_zones(struct cma *cma);
 void *cma_reserve_early(struct cma *cma, unsigned long size);
 void init_cma_pageblock(struct page *page);
 #else
+static inline bool cma_validate_zones(struct cma *cma)
+{
+	return false;
+}
 static inline void *cma_reserve_early(struct cma *cma, unsigned long size)
 {
 	return NULL;
-- 
2.27.0