From: Johannes Buchner <buchner.johannes@gmx.at>

the parameter wbc=NULL caused a NULL pointer dereference in
reiser4_sync_inodes.

introduced in patch reiser4-vfs-add-super_operationssync_inodes
Index: linux/fs/reiser4/super_ops.c
===================================================================
--- linux.orig/fs/reiser4/super_ops.c
+++ linux/fs/reiser4/super_ops.c
@@ -395,7 +395,7 @@ static void reiser4_sync_inodes(struct s
 	reiser4_context *ctx;
 	long to_write;
 
-	if (wbc->for_kupdate)
+	if (wbc == NULL || wbc->for_kupdate)
 		/* reiser4 has its own means of periodical write-out */
 		return;