[PATCH v5 08/17] mm: Use page->deferred_list

[Matthew Wilcox <willy@infradead.org>]

From: Matthew Wilcox <mawilcox@microsoft.com>

Now that we can represent the location of 'deferred_list' in C instead
of comments, make use of that ability.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/huge_memory.c | 7 ++-----
 mm/page_alloc.c  | 2 +-
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a3a1815f8e11..cb0954a6de88 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -483,11 +483,8 @@ pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
 
 static inline struct list_head *page_deferred_list(struct page *page)
 {
-	/*
-	 * ->lru in the tail pages is occupied by compound_head.
-	 * Let's use ->mapping + ->index in the second tail page as list_head.
-	 */
-	return (struct list_head *)&page[2].mapping;
+	/* ->lru in the tail pages is occupied by compound_head. */
+	return &page[2].deferred_list;
 }
 
 void prep_transhuge_page(struct page *page)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index da3eb2236ba1..1a0149c4f672 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -933,7 +933,7 @@ static int free_tail_pages_check(struct page *head_page, struct page *page)
 	case 2:
 		/*
 		 * the second tail page: ->mapping is
-		 * page_deferred_list().next -- ignore value.
+		 * deferred_list.next -- ignore value.
 		 */
 		break;
 	default:
-- 
2.17.0