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=-2.2 required=3.0 tests=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 C35D2C3404B for ; Tue, 18 Feb 2020 21:35:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9247D21D56 for ; Tue, 18 Feb 2020 21:35:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9247D21D56 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2EDE56B0005; Tue, 18 Feb 2020 16:35:51 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2787E6B0006; Tue, 18 Feb 2020 16:35:51 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1417C6B0007; Tue, 18 Feb 2020 16:35:51 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0253.hostedemail.com [216.40.44.253]) by kanga.kvack.org (Postfix) with ESMTP id EBD5E6B0005 for ; Tue, 18 Feb 2020 16:35:50 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id C33642C68 for ; Tue, 18 Feb 2020 21:35:50 +0000 (UTC) X-FDA: 76504555260.25.point56_6d2aa0542a129 X-HE-Tag: point56_6d2aa0542a129 X-Filterd-Recvd-Size: 3235 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Tue, 18 Feb 2020 21:35:49 +0000 (UTC) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Feb 2020 13:35:48 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,458,1574150400"; d="scan'208";a="382589447" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202]) by orsmga004.jf.intel.com with ESMTP; 18 Feb 2020 13:35:48 -0800 Date: Tue, 18 Feb 2020 13:35:48 -0800 From: Sean Christopherson To: Christian Borntraeger Cc: Will Deacon , David Hildenbrand , Janosch Frank , Andrew Morton , KVM , Cornelia Huck , Thomas Huth , Ulrich Weigand , Claudio Imbrenda , linux-s390 , Michael Mueller , Vasily Gorbik , Andrea Arcangeli , linux-mm@kvack.org Subject: Re: [PATCH v2 01/42] mm:gup/writeback: add callbacks for inaccessible pages Message-ID: <20200218213548.GI28156@linux.intel.com> References: <20200214222658.12946-1-borntraeger@de.ibm.com> <20200214222658.12946-2-borntraeger@de.ibm.com> <107a8a72-b745-26f2-5805-c4d99ce77b35@redhat.com> <20200218154610.GB27565@linux.intel.com> <20200218160242.GB1133@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) 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, Feb 18, 2020 at 05:15:57PM +0100, Christian Borntraeger wrote: > > > On 18.02.20 17:02, Will Deacon wrote: > > On Tue, Feb 18, 2020 at 07:46:10AM -0800, Sean Christopherson wrote: > >> On Tue, Feb 18, 2020 at 09:27:20AM +0100, David Hildenbrand wrote: > >>> On 17.02.20 12:10, Christian Borntraeger wrote: > >>>> So yes, if everything is setup properly this should not fail in real life > >>>> and only we have a kernel (or firmware) bug. > >>>> > >>> > >>> Then, without feedback from other possible users, this should be a void > >>> function. So either introduce error handling or convert it to a void for > >>> now (and add e.g., BUG_ON and a comment inside the s390x implementation). > >> > >> My preference would also be for a void function (versus ignoring an int > >> return). > > > > The gup code could certainly handle the error value, although the writeback > > is a lot less clear (so a BUG_ON() would seem to be sufficient for now). > > Sean, David. Can we agree on merging patch 39? I'm a-ok with adding error checking, ignoring the return value is the only option I don't like :-)