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=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 9F8B2C48BCD for ; Wed, 9 Jun 2021 21:05:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6B43E613EF for ; Wed, 9 Jun 2021 21:05:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229548AbhFIVHf (ORCPT ); Wed, 9 Jun 2021 17:07:35 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:46516 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229536AbhFIVHe (ORCPT ); Wed, 9 Jun 2021 17:07:34 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]) by out02.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1lr5ON-0049fj-1f; Wed, 09 Jun 2021 15:05:39 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=email.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1lr5OL-000F8v-4H; Wed, 09 Jun 2021 15:05:38 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Olivier Langlois Cc: Linus Torvalds , Linux Kernel Mailing List , linux-fsdevel , io-uring , Alexander Viro , Jens Axboe , "Pavel Begunkov\>" , Oleg Nesterov References: <192c9697e379bf084636a8213108be6c3b948d0b.camel@trillion01.com> <9692dbb420eef43a9775f425cb8f6f33c9ba2db9.camel@trillion01.com> <87h7i694ij.fsf_-_@disp2133> <198e912402486f66214146d4eabad8cb3f010a8e.camel@trillion01.com> Date: Wed, 09 Jun 2021 16:05:29 -0500 In-Reply-To: <198e912402486f66214146d4eabad8cb3f010a8e.camel@trillion01.com> (Olivier Langlois's message of "Wed, 09 Jun 2021 17:02:05 -0400") Message-ID: <87eeda7nqe.fsf@disp2133> 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=1lr5OL-000F8v-4H;;;mid=<87eeda7nqe.fsf@disp2133>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/SZKsQtgDKCsReGzr60p+CHQwK8l82Kxw= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [RFC] coredump: Do not interrupt dump for TIF_NOTIFY_SIGNAL X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Olivier Langlois writes: > On Wed, 2021-06-09 at 13:33 -0700, Linus Torvalds wrote: >> Now, the fact that we haven't cleared TIF_NOTIFY_SIGNAL for the first >> signal is clearly the immediate cause of this, but at the same time I >> really get the feeling that that coredump aborting code should always >> had used fatal_signal_pending(). > > I need clarify what does happen with the io_uring situation. If > somehow, TIF_NOTIFY_SIGNAL wasn't cleared, I would get all the time a 0 > byte size core dump because do_coredump() does check if the dump is > interrupted before writing a single byte. > > io_uring is quite a strange animal. AFAIK, the common pattern to use a > wait_queue is to insert a task into it and then put that task to sleep > until the waited event occur. > > io_uring place tasks into wait queues and then let the the task return > to user space to do some other stuff (like core dumping). I would guess > that it is the main reason for it using the task_work feature. > > So the TIF_NOTIFY_SIGNAL does get set WHILE the core dump is written. Did you mean? So the TIF_NOTIFY_SIGNAL does _not_ get set WHILE the core dump is written. Eric