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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 19C19C282CC for ; Mon, 4 Feb 2019 23:35:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E485C20821 for ; Mon, 4 Feb 2019 23:35:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727129AbfBDXfg (ORCPT ); Mon, 4 Feb 2019 18:35:36 -0500 Received: from mga06.intel.com ([134.134.136.31]:59687 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726083AbfBDXff (ORCPT ); Mon, 4 Feb 2019 18:35:35 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Feb 2019 15:35:35 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,560,1539673200"; d="scan'208";a="113707140" Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by orsmga006.jf.intel.com with ESMTP; 04 Feb 2019 15:35:34 -0800 Date: Mon, 4 Feb 2019 15:35:14 -0800 From: Ira Weiny To: Christopher Lameter Cc: john.hubbard@gmail.com, Andrew Morton , linux-mm@kvack.org, Al Viro , Christian Benvenuti , Christoph Hellwig , Dan Williams , Dave Chinner , Dennis Dalessandro , Doug Ledford , Jan Kara , Jason Gunthorpe , Jerome Glisse , Matthew Wilcox , Michal Hocko , Mike Rapoport , Mike Marciniszyn , Ralph Campbell , Tom Talpey , LKML , linux-fsdevel@vger.kernel.org, John Hubbard Subject: Re: [PATCH 0/6] RFC v2: mm: gup/dma tracking Message-ID: <20190204233513.GA7917@iweiny-DESK2.sc.intel.com> References: <20190204052135.25784-1-jhubbard@nvidia.com> <01000168b980e880-a7d8e0db-84fb-4398-8269-149c66b701b4-000000@email.amazonses.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01000168b980e880-a7d8e0db-84fb-4398-8269-149c66b701b4-000000@email.amazonses.com> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 04, 2019 at 05:14:19PM +0000, Christopher Lameter wrote: > Frankly I still think this does not solve anything. > > Concurrent write access from two sources to a single page is simply wrong. > You cannot make this right by allowing long term RDMA pins in a filesystem > and thus the filesystem can never update part of its files on disk. > > Can we just disable RDMA to regular filesystems? Regular filesystems > should have full control of the write back and dirty status of their > pages. That may be a solution to the corruption/crashes but it is not a solution which users want to see. RDMA directly to file systems (specifically DAX) is a use case we have seen customers ask for. I think this is the correct path toward supporting this use case. Ira