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=-1.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 9C41BC282C4 for ; Tue, 12 Feb 2019 16:36:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3D9C420855 for ; Tue, 12 Feb 2019 16:36:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazonses.com header.i=@amazonses.com header.b="ij6cI5fI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3D9C420855 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DF7018E0005; Tue, 12 Feb 2019 11:36:37 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DA6E38E0001; Tue, 12 Feb 2019 11:36:37 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CBEFA8E0005; Tue, 12 Feb 2019 11:36:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) by kanga.kvack.org (Postfix) with ESMTP id 9C35B8E0001 for ; Tue, 12 Feb 2019 11:36:37 -0500 (EST) Received: by mail-qk1-f198.google.com with SMTP id v67so16042252qkl.22 for ; Tue, 12 Feb 2019 08:36:37 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:from:to:cc:subject :in-reply-to:message-id:references:user-agent:mime-version :feedback-id; bh=98BSrrPqdO2vLypKZPM3TMscNVA1xtajyssG0F2CG4A=; b=lgLLnKQ+kR+TKB2C+E2XsbJfekajvpMLXeBCzrnueRDkwqNS+AuSsswJgoUFWuPMfq c/VgwpirCWILXngRvl1U62vW/VkZHvRGwurHLIdHwjSaIPuMKhXCmCpFajL661D+98+a pHE30uL0p4w7CsZ0LFBG/dtkNmxz+P5CsOxejAzBrsNmGg4kioRU8a4njf8bWZJkpH/J 6vFypH7sjdnEbj06qo+GB6Q/QfthedyRvu7xh5JtFlHUF7miGCb6tQLHV18Z7VJytEN5 Ij4vSt7EvY4y2lC974oExj4dwMhhbiUoMIYqM6ZGZNO46v05xFdOlDz5bvnNlEj7G71+ KUuQ== X-Gm-Message-State: AHQUAuY/MDPhQKScK17jEEZ1eR6jvtBXmVM/EcxKR0AUflA903IYwBtZ UIsvnPF68HIcDfl7gmOrt05biGn4IeGahTVOhpe9IAshYYZIsyDY7AQn+bS1G2wNiMcACCS/Fyc Stu7DGV5fI9mXMi3ibOb4cf0DN53JyHqNOPJxS3cYs6Y0Kxqvlgqg6IiLbv83k7M= X-Received: by 2002:a0c:ae1a:: with SMTP id y26mr3360228qvc.234.1549989397402; Tue, 12 Feb 2019 08:36:37 -0800 (PST) X-Google-Smtp-Source: AHgI3IaOZwZ29M4JyBRPN8EEWIlIgdTHvUi79n+4MLxhPX3mL6Kj3/Jy1xbkx/yEwV7zqJJ2wyTQ X-Received: by 2002:a0c:ae1a:: with SMTP id y26mr3360197qvc.234.1549989396945; Tue, 12 Feb 2019 08:36:36 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1549989396; cv=none; d=google.com; s=arc-20160816; b=M8xeshWXHmPBj12UHcFsOEjpAn6xsFDneykzAlELOWCVETbtj8ffoaraDx80DR4DZa xXiMEuohle0cdDNUzCDb+mXpLZYV4FmZvGOEPg3RfCjgzbuQd9EwTEEVPci/Xzg79Avu lGy9CCP0Np+ljtu0qGN8bRlVgHiil4uItmpjDMYXZRzdX3u/Y2KAXsx4praK6ufHb2/1 1zmRnvq4F+qOBH5nKYSqLpio2UZ8YHh+lFjiqkXpu6CuJp19y7SCqMeYHAfteJtLkNQS sLya3zOSQj3C4ILvYOyDeCHgZYr1EeCbmeMsMuFoLEvMBLx+AReFmSbVzjsVx9er9AR/ KPIA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=feedback-id:mime-version:user-agent:references:message-id :in-reply-to:subject:cc:to:from:date:dkim-signature; bh=98BSrrPqdO2vLypKZPM3TMscNVA1xtajyssG0F2CG4A=; b=GSue/3QzyHWq6cfAnpcoxCUvEl9dsVRRqdgng2XhPcKGC++AG4wUyENbG+k2IMP2SI 7/Eq4Ga7cBpwXZNoawlmaE/dQYwBmUEGyCRKSj5AnKRjX4Rx0UDxZhSKaP2N/qX8V+FV e9BCYxc1AaAjQIehfYjEH6xGx5QK4tLKHyM4lGl6f9Oiydu/IYEki+Y0hFlL9sLKNWEN nJJv2RNJp/qbpwS1acPqmUsI90oe5NLaaGsfxcDiKS8WNyBwv3l9oAJ6ivb2a7ocTWTI C3hX7hKhNL3czdGrwIetjQTekr7JJ7Dp+F1GNionMYMOQqdOscw/vROgjwSlK35Sn6Vc Qnmg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@amazonses.com header.s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug header.b=ij6cI5fI; spf=pass (google.com: domain of 01000168e2913f2e-56010847-a10b-407e-b4eb-7730164267de-000000@amazonses.com designates 54.240.9.36 as permitted sender) smtp.mailfrom=01000168e2913f2e-56010847-a10b-407e-b4eb-7730164267de-000000@amazonses.com Received: from a9-36.smtp-out.amazonses.com (a9-36.smtp-out.amazonses.com. [54.240.9.36]) by mx.google.com with ESMTPS id w4si2734260qtw.380.2019.02.12.08.36.36 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 12 Feb 2019 08:36:36 -0800 (PST) Received-SPF: pass (google.com: domain of 01000168e2913f2e-56010847-a10b-407e-b4eb-7730164267de-000000@amazonses.com designates 54.240.9.36 as permitted sender) client-ip=54.240.9.36; Authentication-Results: mx.google.com; dkim=pass header.i=@amazonses.com header.s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug header.b=ij6cI5fI; spf=pass (google.com: domain of 01000168e2913f2e-56010847-a10b-407e-b4eb-7730164267de-000000@amazonses.com designates 54.240.9.36 as permitted sender) smtp.mailfrom=01000168e2913f2e-56010847-a10b-407e-b4eb-7730164267de-000000@amazonses.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug; d=amazonses.com; t=1549989396; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References:MIME-Version:Content-Type:Feedback-ID; bh=98BSrrPqdO2vLypKZPM3TMscNVA1xtajyssG0F2CG4A=; b=ij6cI5fIk1W9Uqxy4H/82RA/mSETWX5OjNOJ6+Fe1YaAP8sfIOf7a4Kx6reL6Jae Uz3CSh53BZI3D7nIFYvBFyUyK3A909rmd8oA+f3lMBCIjbdEn/jXPbE/3cr1PAtj++y BtFdzXKLU04EjRLWjSCEUtCrAo/sa65SJir7bjMc= Date: Tue, 12 Feb 2019 16:36:36 +0000 From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Dan Williams cc: Jason Gunthorpe , Matthew Wilcox , Ira Weiny , Jan Kara , Dave Chinner , Doug Ledford , lsf-pc@lists.linux-foundation.org, linux-rdma , Linux MM , Linux Kernel Mailing List , John Hubbard , Jerome Glisse , Michal Hocko Subject: Re: [LSF/MM TOPIC] Discuss least bad options for resolving longterm-GUP usage by RDMA In-Reply-To: Message-ID: <01000168e2913f2e-56010847-a10b-407e-b4eb-7730164267de-000000@email.amazonses.com> References: <20190208044302.GA20493@dastard> <20190208111028.GD6353@quack2.suse.cz> <20190211102402.GF19029@quack2.suse.cz> <20190211180654.GB24692@ziepe.ca> <20190211181921.GA5526@iweiny-DESK2.sc.intel.com> <20190211182649.GD24692@ziepe.ca> <20190211184040.GF12668@bombadil.infradead.org> <20190211204945.GF24692@ziepe.ca> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-SES-Outgoing: 2019.02.12-54.240.9.36 Feedback-ID: 1.us-east-1.fQZZZ0Xtj2+TD7V5apTT/NrT6QKuPgzCT/IC7XYgDKI=:AmazonSES X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, 11 Feb 2019, Dan Williams wrote: > An mmap write after a fault due to a hole punch is free to trigger > SIGBUS if the subsequent page allocation fails. So no, I don't see > them as the same unless you're allowing for the holder of the MR to > receive a re-fault failure. Order 0 page allocation failures are generally not possible in that path. System will reclaim and OOM before that happens.