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=-1.0 required=3.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 DF0FCC43142 for ; Thu, 2 Aug 2018 08:28:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 89CD32146F for ; Thu, 2 Aug 2018 08:28:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 89CD32146F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gmx.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731912AbeHBKSb (ORCPT ); Thu, 2 Aug 2018 06:18:31 -0400 Received: from mout.gmx.net ([212.227.15.19]:46681 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729735AbeHBKSa (ORCPT ); Thu, 2 Aug 2018 06:18:30 -0400 Received: from homer.simpson.net ([185.191.216.67]) by mail.gmx.com (mrgmx002 [212.227.17.190]) with ESMTPSA (Nemesis) id 0MgcTf-1fYj3A365X-00O0d9; Thu, 02 Aug 2018 10:27:59 +0200 Message-ID: <1533198478.11791.10.camel@gmx.de> Subject: Re: cpu stopper threads and setaffinity leads to deadlock From: Mike Galbraith To: Peter Zijlstra , Sodagudi Prasad Cc: mingo@kernel.org, gregkh@linuxfoundation.org, bigeasy@linutronix.de, tglx@linutronix.de, isaacm@codeaurora.org, linux-kernel@vger.kernel.org Date: Thu, 02 Aug 2018 10:27:58 +0200 In-Reply-To: <20180802081252.GG2494@hirez.programming.kicks-ass.net> References: <24eebe1d874cb8e3b9a18087554544fa@codeaurora.org> <20180802081252.GG2494@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-Provags-ID: V03:K1:3UosMcJ79z03EPQNxMZV/lsJr5ao+AvOrp2jIh+kMPdNz8GwZic RwSjh3dsOpY0lKUzuXAS4lJy0MLOk4ow4+zAxe+cHVnMAeKSx3RWdI0M0Eo0O4uOJBeSV6T 5lrW4S2NbYyFbb8nE/eCeXY/PmQUMX3Jl6HwEXMFw05Txmh/PvnrBkBIKLcdAuOY3rbbB+u 1NB8NdTsySJTzh1Ii7RdA== X-UI-Out-Filterresults: notjunk:1;V01:K0:8lYunZ92zM8=:8wMiaBFTDcUrYAcbO+oSYf +P5XHoijKouulx2SHwDgEfDZd2iT2M7QTPR4YZbspQLQfKxa2Ob+1/UbryJDmddxwb+yu0rsj a3qtdTlSJNUP+SPUXyH0wWfX4Jn70MMhhRWQiilmcEq+K+mu647xKDGw1+xijy3HeKR98s5T+ XQL1wjA0sjSk5r9ucXnZ1vKRjoUQ0Y3NitylVJUdqTBsAaY2+UJ5+rwyD9p3V21KMlk29Jxbl GZHSTSkBGxVXGuy8yWNk90WAkhpquztJGi/qxdG5jF59HhSm78XEPS7EXIaQQykWKsjAE21HZ Bt5i+HAqWfKZXpHr+7OLFjDKZQnhyuvMG6dr2+cYS9sTvBRWmHtfdm2BxHR3EWN6qvCRtHxa3 gvOVILI/uXkFIlDreHPgDfLZHPE81CDBqn9QT1ToNKfO01BrSNHa6Bgk4HZMyesZPAfmSNQO1 5VgsrALcMmD2OtNQOITHFBJTaROq5pkmUOB+0p9OLG62uTpwqEKK7beSmBV5U/aaZsKYQ/7Ow fbx1C6ElDnodg7YA59lq+UEC2az2xmqvtrxk1IGLGNBNlcb6ArjulZF9lZ6dn8tLzGyqUx0DG 7FhnRBS6+9nXVkjOGablsX9d8TgbveY/VF2xwqHubeWZfbdu85SiLqTFmR4YYhQ6RW1oSMf7O Ieg2MhyD4VtFEjYSlwq2a5ggiJv9e31wBmosXA1qJQwZaosZlIL+YAZm7Go6kl+mMUdBtzraS EXTatkm1qfv3nivV2M9kmU79ol6hvmBRw2gOOX/Q7xLZRxR3eyF3Wf9KRLC5e5TbGz16ZJjKS VACnOpX Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2018-08-02 at 10:12 +0200, Peter Zijlstra wrote: > On Wed, Aug 01, 2018 at 06:34:40PM -0700, Sodagudi Prasad wrote: > > diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c > > index e190d1e..f932e1e 100644 > > --- a/kernel/stop_machine.c > > +++ b/kernel/stop_machine.c > > @@ -87,9 +87,9 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct > > cpu_stop_work *work) > > __cpu_stop_queue_work(stopper, work, &wakeq); > > else if (work->done) > > cpu_stop_signal_done(work->done); > > - raw_spin_unlock_irqrestore(&stopper->lock, flags); > > > > wake_up_q(&wakeq); > > + raw_spin_unlock_irqrestore(&stopper->lock, flags); > > > > That puts the wakeup back under stopper lock, which causes another > deadlock iirc. Yup, one you fixed. 0b26351b910fb (Peter Zijlstra 2018-04-20 11:50:05 +0200 92) wake_up_q(&wakeq);