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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 505A2C18E5B for ; Mon, 9 Mar 2020 20:38:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3759E20409 for ; Mon, 9 Mar 2020 20:38:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726168AbgCIUiH (ORCPT ); Mon, 9 Mar 2020 16:38:07 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:42716 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725992AbgCIUiH (ORCPT ); Mon, 9 Mar 2020 16:38:07 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]) by out02.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jBPA0-0000iR-U1; Mon, 09 Mar 2020 14:38:00 -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 1jBPA0-0000KM-14; Mon, 09 Mar 2020 14:38:00 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Bernd Edlinger Cc: Christian Brauner , Kees Cook , 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> <87tv2xz510.fsf@x220.int.ebiederm.org> <87mu8pz4ex.fsf@x220.int.ebiederm.org> Date: Mon, 09 Mar 2020 15:35:42 -0500 In-Reply-To: (Bernd Edlinger's message of "Mon, 9 Mar 2020 20:03:46 +0000") Message-ID: <87sgihxo4h.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=1jBPA0-0000KM-14;;;mid=<87sgihxo4h.fsf@x220.int.ebiederm.org>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+C9q7AJy/XzZqfp4+4zJkdcGkx/cUL5xE= 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 Bernd Edlinger writes: > On 3/9/20 8:58 PM, Eric W. Biederman wrote: >> >> Ok. I think this has it sorted: >> >> exec: Move exec_mmap right after de_thread in flush_old_exec >> >> I have read through the code in exec_mmap and I do not see anything >> that depends on sighand or the sighand lock, or on signals in anyway >> so this should be safe. >> >> This rearrangement of code has two significant benefits. It makes >> the determination of passing the point of no return by testing bprm->mm >> accurate. All failures prior to that point in flush_old_exec are >> either truly recoverable or they are fatal. >> >> Further 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. >> >> This consolidation allows the creation of a mutex to replace >> cred_guard_mutex that is not held over possible indefinite userspace >> waits. Which will allow removing deadlock scenarios from the kernel. >> >> Reviewed-by: Bernd Edlinger >> Signed-off-by: "Eric W. Biederman" >> >> >> I don't think I usually have this many typos. Sigh. >> > > OK. > > never mind, No no. I really appreciate all of the scrutiny. Frequently the issues that will produce typos or poor patch descriptions are also the issues that will produce sloppy patches as well. I was just frustrated with myself. Eric