From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id B0C8D6B0203 for ; Wed, 24 Mar 2010 17:20:18 -0400 (EDT) Date: Wed, 24 Mar 2010 22:19:24 +0100 From: Andrea Arcangeli Subject: Re: [PATCH 07/11] Memory compaction core Message-ID: <20100324211924.GH10659@random.random> References: <1269347146-7461-1-git-send-email-mel@csn.ul.ie> <1269347146-7461-8-git-send-email-mel@csn.ul.ie> <20100324133347.9b4b2789.akpm@linux-foundation.org> <20100324145946.372f3f31@bike.lwn.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100324145946.372f3f31@bike.lwn.net> Sender: owner-linux-mm@kvack.org To: Jonathan Corbet Cc: Andrew Morton , Mel Gorman , Christoph Lameter , Adam Litke , Avi Kivity , David Rientjes , Minchan Kim , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Hi Jonathan, On Wed, Mar 24, 2010 at 02:59:46PM -0600, Jonathan Corbet wrote: > On Wed, 24 Mar 2010 13:33:47 -0700 > Andrew Morton wrote: > > > > + VM_BUG_ON(cc == NULL); > > > > It's a bit strange to test this when we're about to oops anyway. The > > oops will tell us the same thing. > > ...except that we've seen a fair number of null pointer dereference > exploits that have told us something altogether different. Are we > *sure* we don't want to test for null pointers...? Examples? Maybe WARN_ON != oops, but VM_BUG_ON still an oops that is and without serial console it would go lost too. I personally don't see how it's needed. Plus those things are mostly for debug to check for invariant condition, how long it takes to sort it out isn't very relevant. So I'm on Andrew camp ;). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org