Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261876AbVEPVJV (ORCPT ); Mon, 16 May 2005 17:09:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261882AbVEPVHy (ORCPT ); Mon, 16 May 2005 17:07:54 -0400 Received: from dvhart.com ([64.146.134.43]:58529 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id S261876AbVEPVGX (ORCPT ); Mon, 16 May 2005 17:06:23 -0400 Date: Mon, 16 May 2005 14:06:14 -0700 From: "Martin J. Bligh" Reply-To: "Martin J. Bligh" To: christoph , Dave Hansen Cc: linux-mm , shai@scalex86.org, Linux Kernel Mailing List Subject: Re: [PATCH] Factor in buddy allocator alignment requirements in node memory alignment Message-ID: <737010000.1116277574@flay> In-Reply-To: References: <1116274451.1005.106.camel@localhost> <1116276439.1005.110.camel@localhost> X-Mailer: Mulberry/2.1.2 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1266 Lines: 33 --On Monday, May 16, 2005 12:55:39 -0700 christoph wrote: > On Mon, 16 May 2005, Dave Hansen wrote: > >> > Because the buddy allocator is complaining about wrongly allocated zones! >> >> Just because it complains doesn't mean that anything is actually >> wrong :) >> >> Do you know which pieces of code actually break if the alignment doesn't >> meet what that warning says? > > I have seen nothing break but 4 MB allocations f.e. will not be allocated > on a 4MB boundary with a 2 MB zone alignment. The page allocator always > returnes properly aligned pages but 4MB allocations are an exception? > > Some present or future hardware device or some other code may find that > surprising and crash. Now that it's fixed it is meant to notice that the start of the zone is not aligned, and not key off that, but the aligment itself ... the start and end roundoff bits shouldn't throw the rest out of alignment, as long as we do the calculation sensibly for how we regroup buddies. M. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/