Patch "mm: fix false-positive WARN_ON() in truncate/invalidate for hugetlb" has been added to the 4.8-stable tree

@@ -364,16 +364,13 @@ static inline struct page *read_mapping_
 }
 
 /*
- * Get the offset in PAGE_SIZE.
- * (TODO: hugepage should have ->index in PAGE_SIZE)
+ * Get index of the page with in radix-tree
+ * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)
  */
-static inline pgoff_t page_to_pgoff(struct page *page)
+static inline pgoff_t page_to_index(struct page *page)
 {
 	pgoff_t pgoff;
 
-	if (unlikely(PageHeadHuge(page)))
-		return page->index << compound_order(page);
-
 	if (likely(!PageTransTail(page)))
 		return page->index;
 

@@ -387,6 +384,18 @@ static inline pgoff_t page_to_pgoff(stru
 }
 
 /*
+ * Get the offset in PAGE_SIZE.
+ * (TODO: hugepage should have ->index in PAGE_SIZE)
+ */
+static inline pgoff_t page_to_pgoff(struct page *page)
+{
+	if (unlikely(PageHeadHuge(page)))
+		return page->index << compound_order(page);
+
+	return page_to_index(page);
+}
+
+/*
  * Return byte-offset into filesystem object for page.
  */
 static inline loff_t page_offset(struct page *page)

@@ -283,7 +283,7 @@ void truncate_inode_pages_range(struct a
 
 			if (!trylock_page(page))
 				continue;
-			WARN_ON(page_to_pgoff(page) != index);
+			WARN_ON(page_to_index(page) != index);
 			if (PageWriteback(page)) {
 				unlock_page(page);
 				continue;

@@ -371,7 +371,7 @@ void truncate_inode_pages_range(struct a
 			}
 
 			lock_page(page);
-			WARN_ON(page_to_pgoff(page) != index);
+			WARN_ON(page_to_index(page) != index);
 			wait_on_page_writeback(page);
 			truncate_inode_page(mapping, page);
 			unlock_page(page);

@@ -492,7 +492,7 @@ unsigned long invalidate_mapping_pages(s
 			if (!trylock_page(page))
 				continue;
 
-			WARN_ON(page_to_pgoff(page) != index);
+			WARN_ON(page_to_index(page) != index);
 
 			/* Middle of THP: skip */
 			if (PageTransTail(page)) {

@@ -612,7 +612,7 @@ int invalidate_inode_pages2_range(struct
 			}
 
 			lock_page(page);
-			WARN_ON(page_to_pgoff(page) != index);
+			WARN_ON(page_to_index(page) != index);
 			if (page->mapping != mapping) {
 				unlock_page(page);
 				continue;