On Mon, 26 Jul 2010 16:25:42 +0800 wzt.wzt@xxxxxxxxx wrote: > mapping->a_ops->direct_IO() is not checked, if it's a NULL pointer, > that will casue an oops. pagecache_write_begin/end is exported to > other functions, so they need to check null pointer before use them. > The patch checks a lot more things than ->directIO! It would be best to not add this overhead if possible. Did you actually observe an oops? If so, please fully describe it. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>