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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 4AC51C10DCE for ; Tue, 10 Mar 2020 21:11:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 08292222C3 for ; Tue, 10 Mar 2020 21:11:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726271AbgCJVL3 (ORCPT ); Tue, 10 Mar 2020 17:11:29 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:44262 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726100AbgCJVL3 (ORCPT ); Tue, 10 Mar 2020 17:11:29 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]) by out03.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jBm9u-0000b5-VI; Tue, 10 Mar 2020 15:11:27 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=x220.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1jBm9u-0007sT-8M; Tue, 10 Mar 2020 15:11:26 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Kees Cook Cc: Bernd Edlinger , Christian Brauner , Jann Horn , Jonathan Corbet , Alexander Viro , Andrew Morton , Alexey Dobriyan , Thomas Gleixner , Oleg Nesterov , Frederic Weisbecker , Andrei Vagin , Ingo Molnar , "Peter Zijlstra \(Intel\)" , Yuyang Du , David Hildenbrand , Sebastian Andrzej Siewior , Anshuman Khandual , David Howells , James Morris , Greg Kroah-Hartman , Shakeel Butt , Jason Gunthorpe , Christian Kellner , Andrea Arcangeli , Aleksa Sarai , "Dmitry V. Levin" , "linux-doc\@vger.kernel.org" , "linux-kernel\@vger.kernel.org" , "linux-fsdevel\@vger.kernel.org" , "linux-mm\@kvack.org" , "stable\@vger.kernel.org" , "linux-api\@vger.kernel.org" References: <87v9nlii0b.fsf@x220.int.ebiederm.org> <87a74xi4kz.fsf@x220.int.ebiederm.org> <87r1y8dqqz.fsf@x220.int.ebiederm.org> <87tv32cxmf.fsf_-_@x220.int.ebiederm.org> <87v9ne5y4y.fsf_-_@x220.int.ebiederm.org> <875zfe5xzb.fsf_-_@x220.int.ebiederm.org> <202003101344.8777D43A44@keescook> Date: Tue, 10 Mar 2020 16:09:07 -0500 In-Reply-To: <202003101344.8777D43A44@keescook> (Kees Cook's message of "Tue, 10 Mar 2020 13:47:51 -0700") Message-ID: <87r1xzrk7g.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1jBm9u-0007sT-8M;;;mid=<87r1xzrk7g.fsf@x220.int.ebiederm.org>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1869cHHJ7TMyCuGI2yA9NNHqGaU0S/DZQI= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [PATCH v2 4/5] exec: Move exec_mmap right after de_thread in flush_old_exec X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-api-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org Kees Cook writes: > On Sun, Mar 08, 2020 at 04:38:00PM -0500, Eric W. Biederman wrote: >> Futher this consolidates all of the possible indefinite waits for >> userspace together at the top of flush_old_exec. The possible wait >> for a ptracer on PTRACE_EVENT_EXIT, the possible wait for a page fault >> to be resolved in clear_child_tid, and the possible wait for a page >> fault in exit_robust_list. > > I forgot to mention, just as a point of clarity, there are lots of > other page faults possible, but they're _before_ flush_old_exec() > (i.e. all the copy_strings() calls). Is it worth clarifying this to > "before or at the top of flush_old_exec()" or do you mean something > else? (And as always: perhaps expand flush_old_exec()'s comment to > describe the newly intended state.) Yes. Before or at the start of flush_old_exec where the mutex is taken. That is the point. I will see if I can come up with and appropriate comment. Eric