From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030296AbVKWBHR (ORCPT ); Tue, 22 Nov 2005 20:07:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030297AbVKWBHR (ORCPT ); Tue, 22 Nov 2005 20:07:17 -0500 Received: from smtp012.mail.yahoo.com ([216.136.173.32]:14468 "HELO smtp012.mail.yahoo.com") by vger.kernel.org with SMTP id S1030296AbVKWBHP (ORCPT ); Tue, 22 Nov 2005 20:07:15 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=FEDy7LqoMtVqQMrKJ96gf+EJJZ7ycT/rs7qyufJLYYK8U6iH/v7LHEcXXVamLn7MsS1GRfaVIlFhsOV9qWJQzlxewoLXTRehVl9lx78JU188S99xER8tsQO1Ih/DsAlDvUwCC9XyAwiAIkFdvGxdO0J5qEHvr8o+/Vtl86/E2eI= ; Message-ID: <4383CF6C.4060001@yahoo.com.au> Date: Wed, 23 Nov 2005 13:09:48 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Dave Hansen CC: Linux Kernel Mailing List , Andrew Morton , Linux Memory Management Subject: Re: [patch 6/12] mm: remove bad_range References: <20051121123906.14370.3039.sendpatchset@didi.local0.net> <20051121124126.14370.50844.sendpatchset@didi.local0.net> <1132662725.6696.45.camel@localhost> In-Reply-To: <1132662725.6696.45.camel@localhost> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Dave Hansen wrote: > > I seem to also remember a case with this bad_range() check was useful > for zones that don't have their boundaries aligned on a MAX_ORDER > boundary. Would this change break such a zone? Do we care? > Hmm, I guess that would be covered by the: if (page_to_pfn(page) >= zone->zone_start_pfn + zone->spanned_pages) return 1; if (page_to_pfn(page) < zone->zone_start_pfn) return 1; checks in bad_range. ISTR some "warning: zone not aligned, kernel *will* crash" message got printed in that case. I always thought that zones were supposed to be MAX_ORDER aligned, but I can see how that restriction might be relaxed with these checks in place. This commit introduced the change: http://www.kernel.org/git/?p=linux/kernel/git/torvalds/old-2.6-bkcvs.git;a=commitdiff;h=d60c9dbc4589766ef5fe88f082052ccd4ecaea59 I think this basically says that architectures who care need to define CONFIG_HOLES_IN_ZONE and handle this in pfn_valid. Unless this is a very common requirement and such a solution would have too much performance cost? Anyone? -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com