Received: by 2002:ac0:8c9a:0:0:0:0:0 with SMTP id r26csp4057139ima; Mon, 4 Feb 2019 09:28:19 -0800 (PST) X-Google-Smtp-Source: AHgI3IbtlEYBVYdvkDYXTlCLErJdyrFz7shV9TDVjbOddrSd2FSQAHjpOrQxkf50qT1MVvqaCekV X-Received: by 2002:a63:b4c:: with SMTP id a12mr416988pgl.131.1549301299168; Mon, 04 Feb 2019 09:28:19 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1549301299; cv=none; d=google.com; s=arc-20160816; b=SWNnNP53DMsx/dxQITC5UAzLrnTb67B8dh8yEhoxcpNzN6RD2+BTLCOuBsYYGyB+9+ QL75e5ZxrQj0GNdUh3StfVS2/XOWMemnLUquBgg7vRl0/bfZiY2VtJ+DgCiBgq1RjeDj uZcNx+MFf1QigDcaUWEHnJEzaTbBF0e7ep6iEYk4olMktBCRmnGzpGjMLx33YIETutXm HmjjyMC1XBBUzln8Of6pmVJLMrCL8BfWXcX/JUxL0OO98lMZRt3+bFtxvKO+B3jq7jhe gGEc5WkrkjJts6bKxcSO1ecuLP18yOaf5NuzkNQ64XD88J3GvspUf5nFkt0DzGPpl1/s M1pw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:feedback-id:mime-version:user-agent :references:message-id:in-reply-to:subject:cc:to:from:date :dkim-signature; bh=rRIYgpkoOU9OXyNN7jqzPWMWewZIFQicQrnhsy101kA=; b=cYAcNOA3EZ4fRfmcKPpgIaOX5vdv+FRoFhwLjklODOEl7bBZL4p9QiTwpv5OH1cbDG m7Kd0VlhpVY4PPigesXRAIoYj1SSUgqHXeENRVAAi6/jL75Ggb7IE4iYxeWhJt/byzgR IagM0jo3K8CFPc03ro9Y52UjQHUEzED8yb10/hhXAFDjIHBYyI/Q0ezIVYCSOOeGb+yQ 8IdIqAn+PADrmkoiQLsWHZyeqGvFuhYzXiVvj4lVJeSfPv96LKN9x5YAr4OCcIrTPy4V gtNgwmJUfXQ/cxgXl0hCAz3tBlEfUvx7b5RdcYGkjX0MzJbap9kGpLPjm3ZCMQnslQuB pZ3Q== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@amazonses.com header.s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug header.b=fNHfgZqQ; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id y6si508155pfi.228.2019.02.04.09.28.03; Mon, 04 Feb 2019 09:28:19 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@amazonses.com header.s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug header.b=fNHfgZqQ; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729956AbfBDROV (ORCPT + 99 others); Mon, 4 Feb 2019 12:14:21 -0500 Received: from a9-99.smtp-out.amazonses.com ([54.240.9.99]:46080 "EHLO a9-99.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727810AbfBDROU (ORCPT ); Mon, 4 Feb 2019 12:14:20 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug; d=amazonses.com; t=1549300459; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References:MIME-Version:Content-Type:Feedback-ID; bh=rRIYgpkoOU9OXyNN7jqzPWMWewZIFQicQrnhsy101kA=; b=fNHfgZqQCAIPedvEn9/V09tGYqNz+41uFUDzEvPKPtLzF+oYs+UPyt9aF1iKxinD bh8DOvBrneM8djIV8FXwYLhmyfi1OX1or69dkUp1EME8XHHZE50Sl5/y2eNyzaDG0p9 sgutHg/yTiJ/yAYnzb5sp8+EcpQzIQIv6gS10zzU= Date: Mon, 4 Feb 2019 17:14:19 +0000 From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: john.hubbard@gmail.com cc: 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 In-Reply-To: <20190204052135.25784-1-jhubbard@nvidia.com> Message-ID: <01000168b980e880-a7d8e0db-84fb-4398-8269-149c66b701b4-000000@email.amazonses.com> References: <20190204052135.25784-1-jhubbard@nvidia.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-SES-Outgoing: 2019.02.04-54.240.9.99 Feedback-ID: 1.us-east-1.fQZZZ0Xtj2+TD7V5apTT/NrT6QKuPgzCT/IC7XYgDKI=:AmazonSES Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Special filesystems that do not actually do write back (like hugetlbfs), mmaped raw device files and anonymous allocations are fine.