From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933067Ab1IBBxi (ORCPT ); Thu, 1 Sep 2011 21:53:38 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:62669 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933019Ab1IBBxh (ORCPT ); Thu, 1 Sep 2011 21:53:37 -0400 Date: Fri, 2 Sep 2011 03:53:32 +0200 From: Frederic Weisbecker To: "Paul E. McKenney" Cc: Valdis.Kletnieks@vt.edu, linux-kernel@vger.kernel.org Subject: Re: linux-next RCU complaint during boot Message-ID: <20110902015330.GA28121@somewhere.redhat.com> References: <8867.1314894817@turing-police.cc.vt.edu> <20110902014424.GB2405@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110902014424.GB2405@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 01, 2011 at 06:44:24PM -0700, Paul E. McKenney wrote: > On Thu, Sep 01, 2011 at 12:33:37PM -0400, Valdis.Kletnieks@vt.edu wrote: > > Seen during boot of linux-next 20110831: > > > > [ 8.823047] ------------[ cut here ]------------ > > [ 8.823177] WARNING: at kernel/rcutree.c:1821 rcu_needs_cpu_quick_check+0x6e/0x204() > > [ 8.823314] Hardware name: Latitude E6500 > > [ 8.823418] Modules linked in: > > [ 8.823601] Pid: 0, comm: swapper Not tainted 3.1.0-rc4-next-20110831-dirty #11 > > [ 8.823724] Call Trace: > > [ 8.823824] [] warn_slowpath_common+0x7e/0x96 > > [ 8.824015] [] ? note_new_gpnum+0x32/0x96 > > [ 8.824034] [] warn_slowpath_null+0x15/0x17 > > [ 8.824034] [] rcu_needs_cpu_quick_check+0x6e/0x204 > > [ 8.824034] [] rcu_needs_cpu+0x9/0xd > > [ 8.824034] [] tick_nohz_stop_sched_tick+0x20a/0x420 > > [ 8.824034] [] irq_exit+0xd2/0xe0 > > [ 8.824034] [] smp_apic_timer_interrupt+0x8b/0x99 > > [ 8.824034] [] apic_timer_interrupt+0x70/0x80 > > [ 8.824034] [] ? notifier_call_chain+0x20/0x81 > > [ 8.824034] [] __atomic_notifier_call_chain+0x5e/0x90 > > [ 8.824034] [] ? notifier_call_chain+0x81/0x81 > > [ 8.824034] [] atomic_notifier_call_chain+0xf/0x11 > > [ 8.824034] [] cpu_idle+0xaf/0x102 > > [ 8.824034] [] rest_init+0xd0/0xd7 > > [ 8.824034] [] ? csum_partial_copy_generic+0x16c/0x16c > > [ 8.824034] [] start_kernel+0x375/0x380 > > [ 8.824034] [] x86_64_start_reservations+0xaf/0xb3 > > [ 8.824034] [] x86_64_start_kernel+0xf0/0xf7 > > [ 8.824034] ---[ end trace f6289633ba846f8f ]--- > > > > Any ideas? > > This is a bug where someone uses RCU at a time when RCU has been told > that the CPU is in dyntick-idle mode. Frederic Weisbecker has some > patches that should address this. Yep, see there: https://lkml.org/lkml/2011/8/20/81