From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751450AbWAWJUS (ORCPT ); Mon, 23 Jan 2006 04:20:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751454AbWAWJUS (ORCPT ); Mon, 23 Jan 2006 04:20:18 -0500 Received: from mail.suse.de ([195.135.220.2]:32229 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S1751450AbWAWJUQ (ORCPT ); Mon, 23 Jan 2006 04:20:16 -0500 Date: Mon, 23 Jan 2006 10:20:03 +0100 From: Nick Piggin To: Heiko Carstens Cc: Nick Piggin , Arjan van de Ven , Linux Kernel Mailing List , Linux Memory Management List Subject: Re: [rfc] split_page function to split higher order pages? Message-ID: <20060123092002.GA26399@wotan.suse.de> References: <20060121124053.GA911@wotan.suse.de> <1137853024.23974.0.camel@laptopd505.fenrus.org> <20060123054927.GA9960@wotan.suse.de> <20060123084715.GA9241@osiris.boeblingen.de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060123084715.GA9241@osiris.boeblingen.de.ibm.com> User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 23, 2006 at 09:47:15AM +0100, Heiko Carstens wrote: > > > > Just wondering what people think of the idea of using a helper > > > > function to split higher order pages instead of doing it manually? > > > > > > Maybe it's worth documenting that this is for kernel (or even > > > architecture) internal use only and that drivers really shouldn't be > > > doing this.. > > > > I guess it doesn't seem like something drivers would need to use > > (and none appear to do anything like it). > > And I thought this could/should be used together with vm_insert_page() that > drivers are supposed to use nowadays instead of remap_pfn_range(). > Why shouldn't drivers use this? > Actually fs/ramfs/file-nommu.c does use this (but it need not because !CONFIG_MMU page allocator already does something similar). But largely, no in-tree drivers use the facility so I think it would be good for the mm folk to consider the first use case if and when it comes up. So I've added a comment in split_page to that effect. Thanks, Nick