From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423181AbXBBHWE (ORCPT ); Fri, 2 Feb 2007 02:22:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1423180AbXBBHV4 (ORCPT ); Fri, 2 Feb 2007 02:21:56 -0500 Received: from mx1.suse.de ([195.135.220.2]:44773 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423173AbXBBHVe (ORCPT ); Fri, 2 Feb 2007 02:21:34 -0500 Date: Fri, 2 Feb 2007 08:21:33 +0100 From: Nick Piggin To: Neil Brown Cc: Linux Memory Management List , Linux Kernel Mailing List Subject: Re: [rfc][patch] mm: half-fix page tail zeroing on write problem Message-ID: <20070202072133.GA26431@wotan.suse.de> References: <20070202055142.GA5004@wotan.suse.de> <17858.55858.642522.861130@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <17858.55858.642522.861130@notabene.brown> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 02, 2007 at 05:29:06PM +1100, Neil Brown wrote: > On Friday February 2, npiggin@suse.de wrote: > > Hi, > > > > For no important reason, I've again looked at those zeroing patches that > > Neil did a while back. I've always thought that a simple > > `write(fd, NULL, size)` would cause the same sorts of problems. > > Yeh, but who in their right mind would do that??? > Oh, you did :-) Well that's the test-case. Obviously not many people do it, but that's all the more reason to be careful about correct behaviour. > I cannot see why you make a change to fault_in_pages_writeable. Is it > just for symmetry? Yes. > For the rest, it certainly makes sense to return an early -EFAULT if > you cannot fault in the page. I think so. Thanks, Nick