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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 690B1C4363A for ; Tue, 27 Oct 2020 09:55:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 72B3921D24 for ; Tue, 27 Oct 2020 09:55:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 72B3921D24 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D19786B0062; Tue, 27 Oct 2020 05:55:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CCA586B006C; Tue, 27 Oct 2020 05:55:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B90886B006E; Tue, 27 Oct 2020 05:55:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0048.hostedemail.com [216.40.44.48]) by kanga.kvack.org (Postfix) with ESMTP id 88F846B0062 for ; Tue, 27 Oct 2020 05:55:49 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 2762DB9F4 for ; Tue, 27 Oct 2020 09:55:49 +0000 (UTC) X-FDA: 77417248818.01.range40_2217c3f2727b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin01.hostedemail.com (Postfix) with ESMTP id 05E5E1004CB0F for ; Tue, 27 Oct 2020 09:55:48 +0000 (UTC) X-HE-Tag: range40_2217c3f2727b X-Filterd-Recvd-Size: 1870 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Tue, 27 Oct 2020 09:55:48 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id D8C2068B02; Tue, 27 Oct 2020 10:55:45 +0100 (CET) Date: Tue, 27 Oct 2020 10:55:45 +0100 From: Christoph Hellwig To: Jan Kara Cc: John Hubbard , Jason Gunthorpe , linux-kernel@vger.kernel.org, Andrea Arcangeli , Andrew Morton , Christoph Hellwig , Hugh Dickins , Jann Horn , Kirill Shutemov , Kirill Tkhai , Linux-MM , Michal Hocko , Oleg Nesterov , Peter Xu Subject: Re: [PATCH 1/2] mm: reorganize internal_get_user_pages_fast() Message-ID: <20201027095545.GA30382@lst.de> References: <1-v1-281e425c752f+2df-gup_fork_jgg@nvidia.com> <16c50bb0-431d-5bfb-7b80-a8af0b4da90f@nvidia.com> <20201027093301.GA16090@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201027093301.GA16090@quack2.suse.cz> User-Agent: Mutt/1.5.17 (2007-11-01) 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 Tue, Oct 27, 2020 at 10:33:01AM +0100, Jan Kara wrote: > Actually there are callers that care about partial success. See e.g. > iov_iter_get_pages() usage in fs/direct_io.c:dio_refill_pages() or > bio_iov_iter_get_pages(). These places handle partial success just fine and > not allowing partial success from GUP could regress things... But most users do indeed not care. Maybe an explicit FOLL_PARTIAL to opt into partial handling could clean up a lot of the mess. Maybe just for pin_user_pages for now.