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=-10.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 8806BC433DB for ; Fri, 26 Mar 2021 15:13:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 59B8861937 for ; Fri, 26 Mar 2021 15:13:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230386AbhCZPMd (ORCPT ); Fri, 26 Mar 2021 11:12:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60866 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231210AbhCZPMU (ORCPT ); Fri, 26 Mar 2021 11:12:20 -0400 Received: from mail-il1-x132.google.com (mail-il1-x132.google.com [IPv6:2607:f8b0:4864:20::132]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08565C0613AA for ; Fri, 26 Mar 2021 08:12:18 -0700 (PDT) Received: by mail-il1-x132.google.com with SMTP id r8so5293881ilo.8 for ; Fri, 26 Mar 2021 08:12:18 -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=/B+rkG+QASXJ+f3N/V701sPdc66lQcXE98p293DZ/Ro=; b=yGKGzQKQ3J4aDN0SiM1Cc94ZusrO3ZOe0UiL+VrtoUWKJ50JIaoAB2NKGPnZdyYNlI zXTTsKQq2m5K63jZTsyIgizRhkdfQqQ79zvRo+2JP7UtU40wvy/mE81lMlPUj4P6dVNP 4lIf1p5//fuMAYIFIfo7dztwwMBhUoDryZPB7qIvTSr1kw0vRpx1y2klINt/aXkin7P5 Z4xH0KXqgx68CIuGBGiUtS77Ey7FU/BEGEWDvASuivjKvTSLvjfYwvqEgdNsrFNY83r1 vWLbbOto37SyiH7VIOpiymGTSrn178cLrPeq6YCqAuNBqKqU8UFyU5H5ANdZ5kNsDEV2 INEw== 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=/B+rkG+QASXJ+f3N/V701sPdc66lQcXE98p293DZ/Ro=; b=YY6gyp2xKILxFLnJX2He4x2EZqgSHzqxh6nPLXzNV0jvTF/Gpwb0uHZ1dSlFpCJo3L 2oziC/U3QcHxdqpKO3S1516WWCeTxC6ARyewAcPdiJzPgRcVxuqb9onzqM7goQahh7XB 8nbzgXYu44LXQXkkplYDpFQcd6NDAa37sYY8ywYK/C+HeZomkiyu6oPUSAVj+r2jmiTx vxyDZ67MXRFCF3q3WBtgu/0tKUVhhXtFrYx5FBgYmnri9n/rSFOF/VvSpjNaXa3YNw9T zJ2twSOW0TR4M7Nwk8ggYeyVbYHKIfA0vUpPSyHQkOTndAVqOuxjsNSSQzpIfEJycS9J ge+w== X-Gm-Message-State: AOAM530XnVVd9nDyI0SblaFLdYopTjt9cHdjoIWtd9wXPdEhnarC4s5x 84joKe8tz0so5X3mrXPAvagi4Q== X-Google-Smtp-Source: ABdhPJyN604lOiqV3+3XwW5ECVqjzT6kq4SSE/vnPAIv78cRziMv0b73uD1e2aVKi2nJj17lkqmnPg== X-Received: by 2002:a05:6e02:f07:: with SMTP id x7mr5614797ilj.242.1616771537478; Fri, 26 Mar 2021 08:12:17 -0700 (PDT) Received: from [192.168.1.30] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id q21sm4377742ioh.41.2021.03.26.08.12.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Mar 2021 08:12:17 -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> <0396df33-7f91-90c8-6c0d-8a3afd3fff3c@kernel.dk> <1304f480-a8db-44cf-5d89-aa9b99efdcd7@kernel.dk> <6a171373-e901-ae97-41fd-29445c3fe89e@samba.org> <018c3185-bd13-1085-e738-9b5010252215@samba.org> From: Jens Axboe Message-ID: <26b06a25-9be9-102e-09f5-b2cb7c0fbc5e@kernel.dk> Date: Fri, 26 Mar 2021 09:12:16 -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: <018c3185-bd13-1085-e738-9b5010252215@samba.org> 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 9:11 AM, Stefan Metzmacher wrote: > Am 26.03.21 um 16:10 schrieb Jens Axboe: >> On 3/26/21 9:08 AM, Stefan Metzmacher wrote: >>> Am 26.03.21 um 15:55 schrieb Jens Axboe: >>>> On 3/26/21 8:53 AM, Jens Axboe wrote: >>>>> 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. >>>> >>>> Can you try this? Not crazy about adding a special case, but I don't >>>> think there's any way around this one. And should be pretty cheap, as >>>> we're already pulling in ->flags right above anyway. >>>> >>>> diff --git a/kernel/signal.c b/kernel/signal.c >>>> index 5ad8566534e7..5b75fbe3d2d6 100644 >>>> --- a/kernel/signal.c >>>> +++ b/kernel/signal.c >>>> @@ -2752,6 +2752,15 @@ bool get_signal(struct ksignal *ksig) >>>> */ >>>> current->flags |= PF_SIGNALED; >>>> >>>> + /* >>>> + * PF_IO_WORKER threads will catch and exit on fatal signals >>>> + * themselves. They have cleanup that must be performed, so >>>> + * we cannot call do_exit() on their behalf. coredumps also >>>> + * do not apply to them. >>>> + */ >>>> + if (current->flags & PF_IO_WORKER) >>>> + return false; >>>> + >>>> if (sig_kernel_coredump(signr)) { >>>> if (print_fatal_signals) >>>> print_fatal_signal(ksig->info.si_signo); >>>> >>> >>> I guess not before next week, but if it resolves the problem for you, >>> I guess it would be good to get this into rc5. >> >> It does, I pushed out a new branch. I'll send out a v2 series in a bit. > > Great, thanks! > > Any chance to get the "cmdline" hiding included? I'll take a look at your response there, haven't yet. Wanted to get this one sorted first. -- Jens Axboe