From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755029Ab0CYPgr (ORCPT ); Thu, 25 Mar 2010 11:36:47 -0400 Received: from mail-out2.uio.no ([129.240.10.58]:52861 "EHLO mail-out2.uio.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754930Ab0CYPgp (ORCPT ); Thu, 25 Mar 2010 11:36:45 -0400 Subject: Re: INFO: suspicious rcu_dereference_check() From: Trond Myklebust To: Zdenek Kabelac Cc: Linux Kernel Mailing List , linux-nfs@vger.kernel.org In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Date: Thu, 25 Mar 2010 11:36:40 -0400 Message-ID: <1269531400.3648.1.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 (2.28.3-1.fc12) Content-Transfer-Encoding: 7bit X-UiO-Ratelimit-Test: rcpts/h 3 msgs/h 1 sum rcpts/h 7 sum msgs/h 2 total rcpts 2617 max rcpts/h 27 ratelimit 0 X-UiO-Spam-info: not spam, SpamAssassin (score=-5.0, required=5.0, autolearn=disabled, UIO_MAIL_IS_INTERNAL=-5, uiobl=NO, uiouri=NO) X-UiO-Scanned: 6093171428F2035B21F7339EE267ECAF1190779A X-UiO-SPAM-Test: remote_host: 68.40.206.115 spam_score: -49 maxlevel 80 minaction 2 bait 0 mail/h: 1 total 260 max/h 7 blacklist 0 greylist 0 ratelimit 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2010-03-25 at 11:48 +0100, Zdenek Kabelac wrote: > Hi > > I've enabled rcu correctness for my todays 2.6.34-rc2 kernel. > > I'm getting this INFO: from my kvm guest (which uses host's nfs > exported directory.) > This > > =================================================== > [ INFO: suspicious rcu_dereference_check() usage. ] > --------------------------------------------------- > fs/nfs/delegation.c:348 invoked rcu_dereference_check() without protection! > > other info that might help us debug this: > > > rcu_scheduler_active = 1, debug_locks = 0 > 2 locks held by rm/1820: > #0: (&sb->s_type->i_mutex_key#13/1){+.+.+.}, at: > [] do_unlinkat+0x9b/0x1c0 > #1: (&sb->s_type->i_mutex_key#13){+.+.+.}, at: [] > vfs_unlink+0x56/0xf0 > > stack backtrace: > Pid: 1820, comm: rm Not tainted 2.6.34-rc2-00186-ge79a302 #60 > Call Trace: > [] lockdep_rcu_dereference+0xbb/0xc0 > [] nfs_inode_return_delegation+0x101/0x110 [nfs] > [] nfs_unlink+0xad/0x2a0 [nfs] > [] vfs_unlink+0x9a/0xf0 > [] ? mnt_want_write+0x65/0xb0 > [] do_unlinkat+0x183/0x1c0 > [] ? retint_swapgs+0xe/0x13 > [] ? trace_hardirqs_on_caller+0x155/0x1a0 > [] ? trace_hardirqs_on_thunk+0x3a/0x3f > [] sys_unlinkat+0x22/0x40 > [] sysenter_dispatch+0x7/0x2c > It is a 100% bogus warning. There are tentative patches floating around to fix the above warning, but they haven't been merged yet. In the meantime, please ignore... Cheers Trond