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=-13.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 D71E9C43331 for ; Mon, 30 Mar 2020 09:02:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F38820658 for ; Mon, 30 Mar 2020 09:02:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="fExB7XpW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729731AbgC3JCC (ORCPT ); Mon, 30 Mar 2020 05:02:02 -0400 Received: from mail-qv1-f66.google.com ([209.85.219.66]:38732 "EHLO mail-qv1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729664AbgC3JCB (ORCPT ); Mon, 30 Mar 2020 05:02:01 -0400 Received: by mail-qv1-f66.google.com with SMTP id p60so8512016qva.5 for ; Mon, 30 Mar 2020 02:02:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=9yTXcAm8xTZZlLv27rN0g4+yu3w2ZB5Uvj+XDLCM2Es=; b=fExB7XpWILh9K7fynAxxQYw//W3hUVCDQMwbfAXNtfjIlXo3SFYHWvzyJMndxZwR2N KBUh16CiA3j7/aSrXYS+N6OdNeSuC1oS/Uq+PCamn/cxVCzDq4L19UOxgmDZuGvxqR4r ea/to9r1ZF4Afeq3u+BV0xWGPGN4iF72JAi+TyeSnoYywsNTLMhKd+cnuPOnzoqTyUxl vpskI2pFsUrdFHmeN2aw1AmtIK8w+8ku//sKSq87Gpj4Bvo/k8iPYvm/MlKdq1mCVqDw CmFSJJWeYm8p9pquqLeJT261L+OKUNCRxj+dI9qrwkjodlEQCva8BULWRLr9ilc38Y4D RqMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=9yTXcAm8xTZZlLv27rN0g4+yu3w2ZB5Uvj+XDLCM2Es=; b=Qm6sAMRj6GIaKEL7pkabXsXBR05PI9AKDFI2uRJXilDi6mM+ROeDXnAkj3Arbu9EoW UWw7th1FACZEttgA8IrpF6DgrBZCX+RvWN3H/C9mdWUgXj+EhdEqqRI/qsXSvzur5deS xX2+FAaTX8RLLoscpWAqGljK71DbBFqmO6Dt/T6OzWyWkDZubbhn5ZP7u/2zAiTVBOWw 0h4fN7p/1+KuGe/k8uOw64RxtIGVMCv/SS5+E+N2WyNzTfsVXNjJtGJ/yGokoOggSiQk rb5dVfbDIcgC4WYa4iijlKzXYFjuFt7QSssYQ9W7mZDkYInCu+fQoeyQ1xRV2oA80cF0 t+bw== X-Gm-Message-State: ANhLgQ259aiLl0kg5xKGQpBdvL0ZJwqSJrVUXkD7EF/2Lonv8l57euTq xBFAv9EQXTpfCU0IovT8jb1z8KLBJVgj0BV0T2JgRA== X-Google-Smtp-Source: ADFU+vvD/6dG6pRSGnJBnlqX4CdrzrUlbYE8lR5UYGUsPdMEkb/7J9W7tnn/t8sOcJdinRhiUqQ0ut4pNbnUOVLK7N8= X-Received: by 2002:ad4:49d1:: with SMTP id j17mr11017654qvy.80.1585558920517; Mon, 30 Mar 2020 02:02:00 -0700 (PDT) MIME-Version: 1.0 References: <20200327223646.20779-1-gpiccoli@canonical.com> <7fe65aef-94e1-b51a-0434-b1fe9d402d7b@i-love.sakura.ne.jp> In-Reply-To: From: Dmitry Vyukov Date: Mon, 30 Mar 2020 11:01:49 +0200 Message-ID: Subject: Re: [PATCH V3] kernel/hung_task.c: Introduce sysctl to print all traces when a hung task is detected To: Guilherme Piccoli Cc: Tetsuo Handa , LKML , syzkaller , kernelci@groups.io, CKI Project , kbuild test robot , workflows@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: workflows-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: workflows@vger.kernel.org On Mon, Mar 30, 2020 at 10:49 AM Dmitry Vyukov wrote: > > On Mon, Mar 30, 2020 at 2:43 AM Guilherme Piccoli > wrote: > > > > Hi Tetsuo and Dmitry, thanks for noticing this Tetsuo. And sorry for > > not looping you in the patch Dmitry, I wasn't aware that you were > > working with testing. By the way, I suggest people interested in linux > > testing to create a ML; I'd be glad to have looped such list, but I > > couldn't find information about a group dealing with testing. > > > > So Tetsuo, you got it right: just change it to > > "sysctl.kernel.hung_task_all_cpu_backtrace=1" and that should work > > fine, once Vlastimil's patch gets merged (and I hope it happens soon). > > Cheers, > > > > > > Guilherme > > +LKML, workflows, syzkaller, kernelci, cki, kbuild > > Tetsuo, thanks for notifying again. > > Yes, kernel devs breaking all testing happens from time to time and > currently there is no good way to address this. > Other things I remember is the introduction of CONFIG_DEBUG_MEMORY, > which defaults to =n and disables KASAN, which in turn produced an > explosion of assorted crashes caused by memory corruptions; also > periodic changes in kernel crash messages which I assume all testing > systems parse and need to understand. > > Is there already a mailing list for this? Or should we create one? > I.e. announce and changes that may need actions from all testing > systems. > Another thing that may benefit from announcements is addition of new > useful debugging configs. Currently they are introduced silently and > don't reach the target audience. I've fixed this up: https://github.com/google/syzkaller/commit/c8d1cc20df5ca5d9ea437054720fa3cfdfa1f578 But what would be even better is some kind of canned configs/settings for testing systems so that I enable it once and then such changes magically auto-happen for me. Imposing work on N testing systems maintainers is not good. And there really is no good point in the current kernel dev process for this. Announcing unmerged changes is too early (as this patch showed). And once it's in linux-next it's already too late.. And I don't want to be inventing a new unique kernel configuration for testing. I don't think it's the right way to approach this. Whatever is "the testing configuration", whatever kernel developers want to see in task hang reports, I just want the system to provide that.