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=-8.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 5A0B9C433DF for ; Tue, 25 Aug 2020 02:07:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F8C0204EC for ; Tue, 25 Aug 2020 02:07:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="mdh8z5wV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727970AbgHYCHG (ORCPT ); Mon, 24 Aug 2020 22:07:06 -0400 Received: from hqnvemgate25.nvidia.com ([216.228.121.64]:19949 "EHLO hqnvemgate25.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725838AbgHYCHD (ORCPT ); Mon, 24 Aug 2020 22:07:03 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate25.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 24 Aug 2020 19:06:01 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Mon, 24 Aug 2020 19:07:02 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Mon, 24 Aug 2020 19:07:02 -0700 Received: from [10.2.53.36] (172.20.13.39) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 25 Aug 2020 02:07:02 +0000 Subject: Re: [PATCH 0/5] bio: Direct IO: convert to pin_user_pages_fast() To: Al Viro CC: Andrew Morton , Christoph Hellwig , Ilya Dryomov , Jens Axboe , Jeff Layton , , , , , , LKML References: <20200822042059.1805541-1-jhubbard@nvidia.com> <20200825015428.GU1236603@ZenIV.linux.org.uk> From: John Hubbard Message-ID: <3072d5a0-43c7-3396-c57f-6af83621b71c@nvidia.com> Date: Mon, 24 Aug 2020 19:07:02 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200825015428.GU1236603@ZenIV.linux.org.uk> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1598321161; bh=ZcHTDdlQwnmvisGnEHrOUys0m6Em61G2G45Wkp1xa+Q=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=mdh8z5wVjPjjZG/Qd901xbUylV66hUTuhC/mmJizUuB3/wXCvErWnYXXGHx752ILn 9+B+sTaebyJsi4SIejtp2bODRqvR+7RWhoWQKPjy0/Xk1gPrc/LmIJHdgdkwT3TZ4Y Fk/zImUHa4mn3V1Ft5+fd5Nvy0ubeYnI8qFt+iSOHYg1Wy/8dADqtMYqVYluSHB+1q mBg+WEOxM/3khAkFM5rRSzk9JdhnXH43GgU0IWm9TFqvJN+54tUvrJvYijAPyu0ol5 5WX57bf2/aui+PnN69IJrg27/PcHZUUS/2sNzQ9aHTCK4OOE8fX9e7jvUMjaoxFfNX xUO7HzHVFxbPw== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/24/20 6:54 PM, Al Viro wrote: > On Fri, Aug 21, 2020 at 09:20:54PM -0700, John Hubbard wrote: >=20 >> Direct IO behavior: >> >> ITER_IOVEC: >> pin_user_pages_fast(); >> break; >> >> ITER_KVEC: // already elevated page refcount, leave alone >> ITER_BVEC: // already elevated page refcount, leave alone >> ITER_PIPE: // just, no :) >=20 > Why? What's wrong with splice to O_DIRECT file? >=20 Oh! I'll take a look. Is this the fs/splice.c stuff? I ruled this out earl= y mainly based on Christoph's comment in [1] ("ITER_PIPE is rejected =D1=96n = the direct I/O path"), but if it's supportable then I'll hook it up. (As you can see, I'm still very much coming up to speed on the various thin= gs that invoke iov_iter_get_pages*().) [1] https://lore.kernel.org/kvm/20190724061750.GA19397@infradead.org/ thanks, --=20 John Hubbard NVIDIA