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Violators will be prosecuted for from ; Thu, 3 Aug 2017 18:24:50 +0100 Date: Thu, 3 Aug 2017 20:24:43 +0300 From: Mike Rapoport Subject: Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone References: <1501136819-21857-1-git-send-email-rppt@linux.vnet.ibm.com> <20170731122204.GB4878@dhcp22.suse.cz> <20170731133247.GK29716@redhat.com> <20170731134507.GC4829@dhcp22.suse.cz> <20170802123440.GD17905@rapoport-lnx> <20170802155522.GB21775@redhat.com> <20170802162248.GA3476@dhcp22.suse.cz> <20170802164001.GF21775@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170802164001.GF21775@redhat.com> Message-Id: <20170803172442.GA1026@rapoport-lnx> Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli Cc: Michal Hocko , Andrew Morton , "Dr. David Alan Gilbert" , Pavel Emelyanov , linux-mm , lkml , stable@vger.kernel.org On Wed, Aug 02, 2017 at 06:40:01PM +0200, Andrea Arcangeli wrote: > On Wed, Aug 02, 2017 at 06:22:49PM +0200, Michal Hocko wrote: > > ESRCH refers to "no such process". Strictly speaking userfaultfd code is > > about a mm which is gone but that is a mere detail. In fact the owner of > > Well this whole issue about which retval, is about a mere detail in > the first place, so I don't think you can discount all other mere > details as irrelevant in the evaluation of a change to solve a mere > detail. > > > But as I've said, this might be really risky to change. My impression > > was that userfaultfd is not widely used yet and those can be fixed > > easily but if that is not the case then we have to live with the current > > ENOSPC. > > The only change would be for userfaultfd non cooperative mode, and > CRIU is the main user of that. So I think it is up to Mike to decide, > I'm fine either ways. I certainly agree ESRCH could be a slightly > better fit, I only wanted to clarify it's not a 100% match either. I'm Ok with updating the code and the man page as long as Michal takes the blame if anything but CRIU breaks :) Now, seriously, I believe there are not many users of non-cooperative uffd if at all and it is very unlikely anybody has it in production. I'll send a patch with s/ENOSPC/ESRCH in the next few days. -- Sincerely yours, Mike. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751879AbdHCRZ5 (ORCPT ); Thu, 3 Aug 2017 13:25:57 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:43563 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751743AbdHCRZ4 (ORCPT ); Thu, 3 Aug 2017 13:25:56 -0400 Date: Thu, 3 Aug 2017 20:24:43 +0300 From: Mike Rapoport To: Andrea Arcangeli Cc: Michal Hocko , Andrew Morton , "Dr. David Alan Gilbert" , Pavel Emelyanov , linux-mm , lkml , stable@vger.kernel.org Subject: Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone References: <1501136819-21857-1-git-send-email-rppt@linux.vnet.ibm.com> <20170731122204.GB4878@dhcp22.suse.cz> <20170731133247.GK29716@redhat.com> <20170731134507.GC4829@dhcp22.suse.cz> <20170802123440.GD17905@rapoport-lnx> <20170802155522.GB21775@redhat.com> <20170802162248.GA3476@dhcp22.suse.cz> <20170802164001.GF21775@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170802164001.GF21775@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 17080317-0016-0000-0000-000004DEF469 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17080317-0017-0000-0000-0000281610EA Message-Id: <20170803172442.GA1026@rapoport-lnx> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-08-03_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1706020000 definitions=main-1708030267 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 02, 2017 at 06:40:01PM +0200, Andrea Arcangeli wrote: > On Wed, Aug 02, 2017 at 06:22:49PM +0200, Michal Hocko wrote: > > ESRCH refers to "no such process". Strictly speaking userfaultfd code is > > about a mm which is gone but that is a mere detail. In fact the owner of > > Well this whole issue about which retval, is about a mere detail in > the first place, so I don't think you can discount all other mere > details as irrelevant in the evaluation of a change to solve a mere > detail. > > > But as I've said, this might be really risky to change. My impression > > was that userfaultfd is not widely used yet and those can be fixed > > easily but if that is not the case then we have to live with the current > > ENOSPC. > > The only change would be for userfaultfd non cooperative mode, and > CRIU is the main user of that. So I think it is up to Mike to decide, > I'm fine either ways. I certainly agree ESRCH could be a slightly > better fit, I only wanted to clarify it's not a 100% match either. I'm Ok with updating the code and the man page as long as Michal takes the blame if anything but CRIU breaks :) Now, seriously, I believe there are not many users of non-cooperative uffd if at all and it is very unlikely anybody has it in production. I'll send a patch with s/ENOSPC/ESRCH in the next few days. -- Sincerely yours, Mike.