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=-5.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 08185C433C1 for ; Fri, 26 Mar 2021 14:54:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C624F60C40 for ; Fri, 26 Mar 2021 14:54:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229945AbhCZOxi (ORCPT ); Fri, 26 Mar 2021 10:53:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56634 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230016AbhCZOxJ (ORCPT ); Fri, 26 Mar 2021 10:53:09 -0400 Received: from mail-io1-xd2a.google.com (mail-io1-xd2a.google.com [IPv6:2607:f8b0:4864:20::d2a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF76FC0613AA for ; Fri, 26 Mar 2021 07:53:08 -0700 (PDT) Received: by mail-io1-xd2a.google.com with SMTP id j26so5621435iog.13 for ; Fri, 26 Mar 2021 07:53:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=NXuRAzdKEe7N5IQQl9xMaaIUvBWdEBQEbrAPEIQ9aXQ=; b=L1c239beA0XBmspjlf3y3HTn9Z9nSwHses5P2ve269y9Unj7cktKPCwBrhu49QIUl5 Av2iihOObkQ6ymlCFAaKtP03ouqEoNUoXf2erXD6Gtk9xvhyXuNZPmLY+qUSIs3fxyyu lV6CdQmVAX74ip4lNGNqKf+tgzhu2XAstjvYIL37jlTQAKHqi3VhxeWVQYbTaFdcgrGq jOipfo5X6XpEA/FvCHObZ1DYHbACLIRfWRYgSzVOI1Ke0vHIu0QQKAen8sdiX2oqkkwi /KPaHiffO323G8N79uYVv8MjciAsxrcCOs1ELgEphitmKlMeRzYFJSpvtH4TrD6kUGMH FDiw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=NXuRAzdKEe7N5IQQl9xMaaIUvBWdEBQEbrAPEIQ9aXQ=; b=iS+9hhs8PmgYFx1KuXrxfEtq22y2f3lgBANnToYhCWif0Ql/d6O5fJnimqRJG7XWuu nY1KT7UpvfgtaGdSmmbzG7eQdxwSupEUPqP4kaAFXNwdxssf3O3Secaxuga7MjD0cEeS T6xTDLh3wbRXTc4YiVmyJf4z9oC+l1sABKypF/ClG01Bg5q/MGMDrH59vxfHDRjZJ3XB dsyJAR/B+OimELHGYgHTMkeKAA3HgHOpGmEYc4uEu55b0BIPcnDPyHxUpW+FpcM1bDiG z5zlvS9BsBhVQLlGLrjJeDJLOABje/mQIj9VqMYUxebFDSGEsHk9ODFsS66Cm9lJwBGW 7vpA== X-Gm-Message-State: AOAM530/4kK0t5VH12CxO4BzUR9M38H8B0up80DpAePSuBaGs135L7AN 5CknI2GFoRKkgxQORvq8EDMaMA== X-Google-Smtp-Source: ABdhPJzfj750MvDj2ov6f4RiA0vpzH3d69CrBQeQA14UDCb365lt5hu9mqMYknwSLlqfJSAuDJDQSQ== X-Received: by 2002:a02:cc1a:: with SMTP id n26mr12397597jap.21.1616770388203; Fri, 26 Mar 2021 07:53:08 -0700 (PDT) Received: from [192.168.1.30] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id v17sm4394179ios.46.2021.03.26.07.53.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Mar 2021 07:53:07 -0700 (PDT) Subject: Re: [PATCH 0/6] Allow signals for IO threads To: Stefan Metzmacher , io-uring@vger.kernel.org Cc: torvalds@linux-foundation.org, ebiederm@xmission.com, oleg@redhat.com, linux-kernel@vger.kernel.org References: <20210326003928.978750-1-axboe@kernel.dk> <8efd9977-003b-be65-8ae2-4b04d8dd1224@samba.org> <0c91d9e7-82cd-bec2-19ae-cc592ec757c6@kernel.dk> <66fa3cfc-4161-76fe-272e-160097f32a53@kernel.dk> <67a83ad5-1a94-39e5-34c7-6b2192eb7edb@samba.org> From: Jens Axboe Message-ID: <0396df33-7f91-90c8-6c0d-8a3afd3fff3c@kernel.dk> Date: Fri, 26 Mar 2021 08:53:07 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 3/26/21 8:45 AM, Stefan Metzmacher wrote: > Am 26.03.21 um 15:43 schrieb Stefan Metzmacher: >> Am 26.03.21 um 15:38 schrieb Jens Axboe: >>> On 3/26/21 7:59 AM, Jens Axboe wrote: >>>> On 3/26/21 7:54 AM, Jens Axboe wrote: >>>>>> The KILL after STOP deadlock still exists. >>>>> >>>>> In which tree? Sounds like you're still on the old one with that >>>>> incremental you sent, which wasn't complete. >>>>> >>>>>> Does io_wq_manager() exits without cleaning up on SIGKILL? >>>>> >>>>> No, it should kill up in all cases. I'll try your stop + kill, I just >>>>> tested both of them separately and didn't observe anything. I also ran >>>>> your io_uring-cp example (and found a bug in the example, fixed and >>>>> pushed), fwiw. >>>> >>>> I can reproduce this one! I'll take a closer look. >>> >>> OK, that one is actually pretty straight forward - we rely on cleaning >>> up on exit, but for fatal cases, get_signal() will call do_exit() for us >>> and never return. So we might need a special case in there to deal with >>> that, or some other way of ensuring that fatal signal gets processed >>> correctly for IO threads. >> >> And if (fatal_signal_pending(current)) doesn't prevent get_signal() from being called? > > Ah, we're still in the first get_signal() from SIGSTOP, correct? Yes exactly, we're waiting in there being stopped. So we either need to check to something ala: relock: + if (current->flags & PF_IO_WORKER && fatal_signal_pending(current)) + return false; to catch it upfront and from the relock case, or add: fatal: + if (current->flags & PF_IO_WORKER) + return false; to catch it in the fatal section. -- Jens Axboe