diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 52add1825525eaa13674a3be317ddf30b44ab1e8..fa05e6d397833bd1f2910ca07f008679a16c48a3 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1834,13 +1834,12 @@ static void collapse_file(struct mm_struct *mm,
 		}
 
 		if (page_mapped(page))
-			unmap_mapping_pages(mapping, index, 1, false);
+			try_to_unmap(page, TTU_IGNORE_MLOCK | TTU_BATCH_FLUSH);
 
 		xas_lock_irq(&xas);
 		xas_set(&xas, index);
 
 		VM_BUG_ON_PAGE(page != xas_load(&xas), page);
-		VM_BUG_ON_PAGE(page_mapped(page), page);
 
 		/*
 		 * The page is expected to have page_count() == 3:
@@ -1904,6 +1903,13 @@ static void collapse_file(struct mm_struct *mm,
 	xas_unlock_irq(&xas);
 xa_unlocked:
 
+	/*
+	 * If collapse is successful, flush must be done now before copying.
+	 * If collapse is unsuccessful, does flush actually need to be done?
+	 * Do it anyway, to clear the state.
+	 */
+	try_to_unmap_flush();
+
 	if (result == SCAN_SUCCEED) {
 		struct page *page, *tmp;