From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965033AbWFTIOH (ORCPT ); Tue, 20 Jun 2006 04:14:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965148AbWFTIOH (ORCPT ); Tue, 20 Jun 2006 04:14:07 -0400 Received: from cantor2.suse.de ([195.135.220.15]:59008 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S965033AbWFTIOF (ORCPT ); Tue, 20 Jun 2006 04:14:05 -0400 From: Andi Kleen To: Jes Sorensen Subject: Re: [patch] do_no_pfn Date: Tue, 20 Jun 2006 10:13:10 +0200 User-Agent: KMail/1.9.3 Cc: Robin Holt , linux-kernel@vger.kernel.org, Nick Piggin , Hugh Dickins , Carsten Otte , bjorn_helgaas@hp.com References: <20060619224952.GA17685@lnx-holt.americas.sgi.com> <4497AB46.4000402@sgi.com> In-Reply-To: <4497AB46.4000402@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200606201013.10353.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 20 June 2006 10:01, Jes Sorensen wrote: > Robin Holt wrote: > > On Mon, Jun 19, 2006 at 03:06:05PM +0200, Andi Kleen wrote: > >> The big question is - why do you have pages without struct page? > >> It seems ... wrong. > [snip] > > Are you saying the for the mspec pages we should extend the vmem_map, > > partially populate the regions for the mspec pages, mark those pages as > > uncached and reserved and then turn them over to the uncached allocator? > > Seems like we have done a lot of extra work to put a struct page behind > > a page which requires special handling. > > Note that Bjorn Helgas has a case where he needs this as well. > > We could fake the pages by giving them a struct page, but it really > makes no point as you say. I think it would be better if you gave them struct pages instead of messing up core vm with such strange hooks. Or alternatively code this in a different way. There are drivers who map IO memory into user space without needing hacks like that. Usually they just tweak the page tables directly on mmap. -Andi