From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f72.google.com (mail-lf0-f72.google.com [209.85.215.72]) by kanga.kvack.org (Postfix) with ESMTP id 1E5A96B0003 for ; Mon, 12 Mar 2018 05:47:19 -0400 (EDT) Received: by mail-lf0-f72.google.com with SMTP id p202-v6so5146856lfe.3 for ; Mon, 12 Mar 2018 02:47:19 -0700 (PDT) Received: from mail.kapsi.fi (mail.kapsi.fi. [2001:67c:1be8::25]) by mx.google.com with ESMTPS id r68si2587893ljb.247.2018.03.12.02.47.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 12 Mar 2018 02:47:17 -0700 (PDT) Date: Mon, 12 Mar 2018 11:46:44 +0200 (EET) From: Otto Ebeling In-Reply-To: <20180129135747.GG21609@dhcp22.suse.cz> Message-ID: References: <1394749328.5225281.1515598510696.JavaMail.zimbra@redhat.com> <87d12hbs6s.fsf@xmission.com> <20180129133151.GF21609@dhcp22.suse.cz> <20180129135747.GG21609@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Subject: Re: migrate_pages() of process with same UID in 4.15-rcX Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: "Eric W. Biederman" , Jan Stancek , otto ebeling , mtk manpages , linux-mm@kvack.org, w@1wt.eu, keescook@chromium.org, ltp@lists.linux.it, Linus Torvalds , Cristopher Lameter Hi, [sorry for the even later reply] I don't have a strong preference either way (between fs creds or real creds), having the same behavior as proc_mem_open sounds like a sensible option too. Whether moving pages between NUMA nodes is a read-only (PTRACE_MODE_READ) activity is debatable, but I'm no NUMA expert. My concern here was mainly about a) preventing layout discovery and b) consistency between move_pages and migrate_pages. Otto On Mon, 29 Jan 2018, Michal Hocko wrote: > [Fixup Christoph email - the thread starts here > http://lkml.kernel.org/r/1394749328.5225281.1515598510696.JavaMail.zimbra@redhat.com] > > On Mon 29-01-18 14:31:51, Michal Hocko wrote: >> [Sorry for a very late reply] >> >> On Wed 10-01-18 10:21:31, Eric W. Biederman wrote: >> [...] >>> All of that said. I am wondering if we should have used >>> PTRACE_MODE_READ_FSCREDS on these permission checks. >> >> If this is really about preventing the layout discovery then we should >> be in sync with proc_mem_open and that uses PTRACE_MODE_FSCREDS|PTRACE_MODE_READ >> Should we do the same thing here? >> -- >> Michal Hocko >> SUSE Labs > > -- > Michal Hocko > SUSE Labs >