mm/thp: fix node page state in split_huge_page_to_list()

Make sure split_huge_page_to_list() handles the state of shmem THP and
file THP properly.

Link: http://lkml.kernel.org/r/[email protected]
Fixes: 60fbf0a ("mm,thp: stats for file backed THP")
Signed-off-by: Kirill A. Shutemov <[email protected]>
Signed-off-by: Song Liu <[email protected]>
Tested-by: Song Liu <[email protected]>
Acked-by: Yang Shi <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Srikar Dronamraju <[email protected]>
Cc: William Kucharski <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: kiryl

mm/huge_memory.c

@@ -2789,8 +2789,13 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 			ds_queue->split_queue_len--;
 			list_del(page_deferred_list(head));
 		}
-		if (mapping)
-			__dec_node_page_state(page, NR_SHMEM_THPS);
+		if (mapping) {
+			if (PageSwapBacked(page))
+				__dec_node_page_state(page, NR_SHMEM_THPS);
+			else
+				__dec_node_page_state(page, NR_FILE_THPS);
+		}
+
 		spin_unlock(&ds_queue->split_queue_lock);
 		__split_huge_page(page, list, end, flags);
 		if (PageSwapCache(head)) {