From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753349Ab2HKSCh (ORCPT ); Sat, 11 Aug 2012 14:02:37 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:57025 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751185Ab2HKSCf (ORCPT ); Sat, 11 Aug 2012 14:02:35 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Fengguang Wu Cc: Serge Hallyn , linux-kernel@vger.kernel.org References: <20120811091920.GA8117@localhost> Date: Sat, 11 Aug 2012 11:02:28 -0700 In-Reply-To: <20120811091920.GA8117@localhost> (Fengguang Wu's message of "Sat, 11 Aug 2012 17:19:20 +0800") Message-ID: <87ehnd1f4b.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=98.207.153.68;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+AR7TIbhF4fv/CJnkCcyvl7oZ7YcTnkB8= X-SA-Exim-Connect-IP: 98.207.153.68 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Fengguang Wu X-Spam-Relay-Country: Subject: Re: suspicious RCU usage in copy_namespaces() X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Fri, 06 Aug 2010 16:31:04 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Fengguang Wu writes: > Hi Eric, > > The below warning shows up since commit Thanks. I am believe the usage is actually correct but I will dig some more and see what it takes to convince the tools of that. Eric > > tree: git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git userns-always-map-user-v45 > head: 38a0b1b84f5f613ff4e01fffda27f87d4cb2b649 > commit: 928ccdb582292cec4552bbf5831f7d374ff60269 userns: Allow unprivileged users to create new namespaces > > [ 0.053560] =============================== > [ 0.054000] [ INFO: suspicious RCU usage. ] > [ 0.055001] 3.6.0-rc1-00116-g48de0c9 #176 Not tainted > [ 0.055999] ------------------------------- > [ 0.057001] /c/kernel-tests/src/linux/kernel/nsproxy.c:126 suspicious rcu_dereference_check() usage! > [ 0.057999] > [ 0.057999] other info that might help us debug this: > [ 0.057999] > [ 0.058999] > [ 0.058999] rcu_scheduler_active = 1, debug_locks = 1 > [ 0.059998] no locks held by swapper/0. > [ 0.060998] > [ 0.060998] stack backtrace: > [ 0.061999] Pid: 0, comm: swapper Not tainted 3.6.0-rc1-00116-g48de0c9 #176 > [ 0.062999] Call Trace: > [ 0.063532] [] lockdep_rcu_suspicious+0xba/0xc3 > [ 0.064004] [] copy_namespaces+0x59/0x1fd > [ 0.066002] [] copy_process.part.49+0xec6/0xf02 > [ 0.067002] [] ? kvm_clock_read+0x18/0x26 > [ 0.068004] [] ? start_kernel+0x304/0x304 > [ 0.069000] [] do_fork+0xc6/0x23d > [ 0.070000] [] ? trace_hardirqs_off+0xb/0xd > [ 0.071001] [] ? local_clock+0x36/0x4e > [ 0.072003] [] ? _raw_spin_unlock_irqrestore+0x39/0x4f > [ 0.073053] [] ? start_kernel+0x304/0x304 > [ 0.074002] [] kernel_thread+0x72/0x7a > [ 0.074999] [] ? start_kernel+0x304/0x304 > [ 0.076001] [] ? common_interrupt+0x3c/0x3c > [ 0.077000] [] rest_init+0x1a/0x112 > [ 0.077999] [] start_kernel+0x2ff/0x304 > [ 0.079000] [] i386_start_kernel+0x78/0x7d > [ 0.080376] Performance Events: unsupported Netburst CPU model 6 no PMU driver, software events only. > [ 0.086440] device: 'platform': device_add > > Thanks, > Fengguang