From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE873C0650F for ; Tue, 30 Jul 2019 15:51:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C25CD20644 for ; Tue, 30 Jul 2019 15:51:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732655AbfG3Pvl (ORCPT ); Tue, 30 Jul 2019 11:51:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54784 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725974AbfG3Pvl (ORCPT ); Tue, 30 Jul 2019 11:51:41 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BBA843E2D3; Tue, 30 Jul 2019 15:51:40 +0000 (UTC) Received: from redhat.com (ovpn-112-36.rdu2.redhat.com [10.10.112.36]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DFACB608A5; Tue, 30 Jul 2019 15:51:37 +0000 (UTC) Date: Tue, 30 Jul 2019 11:51:34 -0400 From: Jerome Glisse To: Christoph Hellwig Cc: Jason Gunthorpe , Ben Skeggs , Ralph Campbell , Bharata B Rao , Andrew Morton , linux-mm@kvack.org, nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 9/9] mm: remove the MIGRATE_PFN_WRITE flag Message-ID: <20190730155134.GA10366@redhat.com> References: <20190729142843.22320-1-hch@lst.de> <20190729142843.22320-10-hch@lst.de> <20190729233044.GA7171@redhat.com> <20190730054633.GA28515@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190730054633.GA28515@lst.de> User-Agent: Mutt/1.12.0 (2019-05-25) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 30 Jul 2019 15:51:41 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 30, 2019 at 07:46:33AM +0200, Christoph Hellwig wrote: > On Mon, Jul 29, 2019 at 07:30:44PM -0400, Jerome Glisse wrote: > > On Mon, Jul 29, 2019 at 05:28:43PM +0300, Christoph Hellwig wrote: > > > The MIGRATE_PFN_WRITE is only used locally in migrate_vma_collect_pmd, > > > where it can be replaced with a simple boolean local variable. > > > > > > Signed-off-by: Christoph Hellwig > > > > NAK that flag is useful, for instance a anonymous vma might have > > some of its page read only even if the vma has write permission. > > > > It seems that the code in nouveau is wrong (probably lost that > > in various rebase/rework) as this flag should be use to decide > > wether to map the device memory with write permission or not. > > > > I am traveling right now, i will investigate what happened to > > nouveau code. > > We can add it back when needed pretty easily. Much of this has bitrotted > way to fast, and the pending ppc kvmhmm code doesn't need it either. Not using is a serious bug, i will investigate this friday. Cheers, Jérôme