[PATCH v3 4/5] hugetlb: convert PageHugeTemporary() to HPageTemporary flag

[Mike Kravetz <mike.kravetz@xxxxxxxxxx>]

Use new hugetlb specific HPageTemporary flag to replace the
PageHugeTemporary() interfaces.  PageHugeTemporary does contain
a PageHuge() check.  However, this interface is only used within
hugetlb code where we know we are dealing with a hugetlb page.
Therefore, the check can be eliminated.

Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
---
 include/linux/hugetlb.h |  6 ++++++
 mm/hugetlb.c            | 36 +++++++-----------------------------
 2 files changed, 13 insertions(+), 29 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index cd1960541f2a..3c86c3a0e144 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -483,10 +483,15 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
  * HPG_migratable  - Set after a newly allocated page is added to the page
  *	cache and/or page tables.  Indicates the page is a candidate for
  *	migration.
+ * HPG_temporary - - Set on a page that is temporarily allocated from the buddy
+ *	allocator.  Typically used for migration target pages when no pages
+ *	are available in the pool.  The hugetlb free page path will
+ *	immediately free pages with this flag set to the buddy allocator.
  */
 enum hugetlb_page_flags {
 	HPG_restore_reserve = 0,
 	HPG_migratable,
+	HPG_temporary,
 	__NR_HPAGEFLAGS,
 };
 
@@ -530,6 +535,7 @@ static inline void ClearHPage##uname(struct page *page)		\
  */
 HPAGEFLAG(RestoreReserve, restore_reserve)
 HPAGEFLAG(Migratable, migratable)
+HPAGEFLAG(Temporary, temporary)
 
 #ifdef CONFIG_HUGETLB_PAGE
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 4da1a29ac5e2..70ffa1027988 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1353,28 +1353,6 @@ struct hstate *size_to_hstate(unsigned long size)
 	return NULL;
 }
 
-/*
- * Internal hugetlb specific page flag. Do not use outside of the hugetlb
- * code
- */
-static inline bool PageHugeTemporary(struct page *page)
-{
-	if (!PageHuge(page))
-		return false;
-
-	return (unsigned long)page[2].mapping == -1U;
-}
-
-static inline void SetPageHugeTemporary(struct page *page)
-{
-	page[2].mapping = (void *)-1U;
-}
-
-static inline void ClearPageHugeTemporary(struct page *page)
-{
-	page[2].mapping = NULL;
-}
-
 static void __free_huge_page(struct page *page)
 {
 	/*
@@ -1422,9 +1400,9 @@ static void __free_huge_page(struct page *page)
 	if (restore_reserve)
 		h->resv_huge_pages++;
 
-	if (PageHugeTemporary(page)) {
+	if (HPageTemporary(page)) {
 		list_del(&page->lru);
-		ClearPageHugeTemporary(page);
+		ClearHPageTemporary(page);
 		update_and_free_page(h, page);
 	} else if (h->surplus_huge_pages_node[nid]) {
 		/* remove the page from active list */
@@ -1860,7 +1838,7 @@ 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) {
-		SetPageHugeTemporary(page);
+		SetHPageTemporary(page);
 		spin_unlock(&hugetlb_lock);
 		put_page(page);
 		return NULL;
@@ -1891,7 +1869,7 @@ static struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask,
 	 * We do not account these pages as surplus because they are only
 	 * temporary and will be released properly on the last reference
 	 */
-	SetPageHugeTemporary(page);
+	SetHPageTemporary(page);
 
 	return page;
 }
@@ -5612,12 +5590,12 @@ void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason)
 	 * here as well otherwise the global surplus count will not match
 	 * the per-node's.
 	 */
-	if (PageHugeTemporary(newpage)) {
+	if (HPageTemporary(newpage)) {
 		int old_nid = page_to_nid(oldpage);
 		int new_nid = page_to_nid(newpage);
 
-		SetPageHugeTemporary(oldpage);
-		ClearPageHugeTemporary(newpage);
+		SetHPageTemporary(oldpage);
+		ClearHPageTemporary(newpage);
 
 		spin_lock(&hugetlb_lock);
 		if (h->surplus_huge_pages_node[old_nid]) {
-- 
2.29.2