From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751811AbdIULEi (ORCPT ); Thu, 21 Sep 2017 07:04:38 -0400 Received: from merlin.infradead.org ([205.233.59.134]:34582 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751701AbdIULEf (ORCPT ); Thu, 21 Sep 2017 07:04:35 -0400 Date: Thu, 21 Sep 2017 13:04:29 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: Thomas Gleixner , LKML , Ingo Molnar , "H. Peter Anvin" Subject: Re: [LOCKDEP SPLAT 4.14-rc1] Conflict between smpboot thread create completions and get_online_cpus Message-ID: <20170921110429.2qx7jn32f6nqnuwf@hirez.programming.kicks-ass.net> References: <20170918152459.35c233d2@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170918152459.35c233d2@gandalf.local.home> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 18, 2017 at 03:24:59PM -0400, Steven Rostedt wrote: > And adding some debugging where the lockdep splat happened: > > watchdog-27 3.... 764857us : cpus_read_lock+0x5/0xc0: lock cpu > watchdog-27 3.... 764858us : > => x86_release_hardware+0x8f/0xa0 > => hw_perf_event_destroy+0xe/0x20 > => _free_event+0xca/0x3d0 > => put_event+0x14/0x20 > => perf_event_release_kernel+0x236/0x330 > => watchdog_nmi_disable+0x49/0x70 > => watchdog_disable+0x4d/0x60 > => smpboot_thread_fn+0x138/0x280 > => kthread+0x152/0x190 > => ret_from_fork+0x2a/0x40 > watchdog-27 3.... 764917us : cpus_read_unlock+0x5/0xa0: unlock cpu > watchdog-27 3d..1 764918us : lock_commit_crosslock+0xc1/0x5b0: xhlock=132 Yeah, known issue. Thomas has already been prodding at the watchdog stuff.