Re: [PATCH] mm: Check NULL pointer Dereference in mm/filemap.c

From: Andrew Morton
Date: Tue Jul 27 2010 - 19:11:00 EST

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.

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