Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755474AbaKSKJz (ORCPT ); Wed, 19 Nov 2014 05:09:55 -0500 Received: from e06smtp10.uk.ibm.com ([195.75.94.106]:48527 "EHLO e06smtp10.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755325AbaKSKJw (ORCPT ); Wed, 19 Nov 2014 05:09:52 -0500 Date: Wed, 19 Nov 2014 11:09:46 +0100 From: Heiko Carstens To: Kirill Tkhai , Peter Zijlstra , Ingo Molnar Cc: Josh Boyer , linux-kernel@vger.kernel.org Subject: rcu warning caused by [sched: Fix race between task_group and sched_task_group] Message-ID: <20141119100946.GB4163@osiris> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14111910-0041-0000-0000-0000022CC51C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Kirill, the problem below has already been reported here: https://lkml.org/lkml/2014/11/11/505 but seems there is still no fix available upstream? Would be good to have it soon, since this basically renders lockdep unusable. [ 0.173906] =============================== [ 0.173907] [ INFO: suspicious RCU usage. ] [ 0.173909] 3.18.0-rc5 #15 Not tainted [ 0.173909] ------------------------------- [ 0.173910] kernel/sched/core.c:7449 suspicious rcu_dereference_check() usage! [ 0.173912] other info that might help us debug this: [ 0.173913] rcu_scheduler_active = 1, debug_locks = 0 [ 0.173914] 2 locks held by swapper/0/0: [ 0.173915] #0: (&p->pi_lock){......}, at: [<000000000017baae>] task_rq_lock+0x4e/0xf8 [ 0.173925] #1: (&rq->lock){......}, at: [<000000000017bad6>] task_rq_lock+0x76/0xf8 [ 0.173928] [ 0.173930] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.18.0-rc5 #15 [ 0.173931] 0000000000b9fb70 0000000000b9fb80 0000000000000002 0000000000000000 0000000000b9fc10 0000000000b9fb88 0000000000b9fb88 0000000000112638 0000000000000000 00000000009d5b8c 00000000009be240 000000000000000b 0000000000b9fbd0 0000000000b9fb70 0000000000000000 0000000000000000 0000000000000000 0000000000112638 0000000000b9fb70 0000000000b9fbd0 [ 0.173944] Call Trace: [ 0.173947] ([<000000000011251c>] show_trace+0xf4/0x158) [ 0.173949] [<00000000001125ea>] show_stack+0x6a/0xe8 [ 0.173952] [<0000000000807ac2>] dump_stack+0x82/0xb0 [ 0.173955] [<000000000018700a>] sched_move_task+0x20a/0x210 [ 0.173959] [<0000000000203bf0>] cgroup_post_fork+0x60/0x148 [ 0.173963] [<000000000014c5b8>] copy_process.part.46+0xfe8/0x1bc8 [ 0.173964] [<000000000014d39c>] do_fork+0x104/0x7d8 [ 0.173965] [<000000000014dab6>] kernel_thread+0x46/0x58 [ 0.173968] [<00000000007fe890>] rest_init+0x38/0x170 [ 0.173971] [<0000000000c45b40>] start_kernel+0x460/0x470 [ 0.173972] [<0000000000100020>] _stext+0x20/0x80 [ 0.173973] INFO: lockdep is turned off. caused by (bisected): commit eeb61e53ea19be0c4015b00b2e8b3b2185436f2b Author: Kirill Tkhai Date: Mon Oct 27 14:18:25 2014 +0400 sched: Fix race between task_group and sched_task_group -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/