diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index e1703ded543aed7b2e52fda3ca97c3b99c66cfc0..4e198ca1f685de549b38ced1644d2b2008d18624 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -47,6 +47,12 @@ enum wb_reason {
 	WB_REASON_LAPTOP_TIMER,
 	WB_REASON_FREE_MORE_MEM,
 	WB_REASON_FS_FREE_SPACE,
+	/*
+	 * There is no bdi forker thread any more and works are done
+	 * by emergency worker, however, this is TPs userland visible
+	 * and we'll be exposing exactly the same information,
+	 * so it has a mismatch name.
+	 */
 	WB_REASON_FORKER_THREAD,
 
 	WB_REASON_MAX,