From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:46432 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726442AbgBRQCs (ORCPT ); Tue, 18 Feb 2020 11:02:48 -0500 Date: Tue, 18 Feb 2020 16:02:42 +0000 From: Will Deacon Subject: Re: [PATCH v2 01/42] mm:gup/writeback: add callbacks for inaccessible pages Message-ID: <20200218160242.GB1133@willie-the-truck> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200218154610.GB27565@linux.intel.com> Sender: linux-s390-owner@vger.kernel.org List-ID: To: Sean Christopherson Cc: David Hildenbrand , Christian Borntraeger , 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 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). Will