From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754989Ab0C2RO5 (ORCPT ); Mon, 29 Mar 2010 13:14:57 -0400 Received: from mail-out1.uio.no ([129.240.10.57]:45246 "EHLO mail-out1.uio.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752231Ab0C2ROz (ORCPT ); Mon, 29 Mar 2010 13:14:55 -0400 Subject: Re: INFO: suspicious rcu_dereference_check() From: Trond Myklebust To: paulmck@linux.vnet.ibm.com, David Howells Cc: Zdenek Kabelac , Linux Kernel Mailing List , linux-nfs@vger.kernel.org In-Reply-To: <20100329152557.GD2569@linux.vnet.ibm.com> References: <1269531400.3648.1.camel@localhost.localdomain> <20100329152557.GD2569@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Date: Mon, 29 Mar 2010 13:14:43 -0400 Message-ID: <1269882883.3181.25.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 6 msgs/h 2 sum rcpts/h 6 sum msgs/h 2 total rcpts 2675 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: DE305CE38DD03C29A481CA60CC616599419C7CE9 X-UiO-SPAM-Test: remote_host: 68.40.206.115 spam_score: -49 maxlevel 80 minaction 2 bait 0 mail/h: 2 total 279 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 Mon, 2010-03-29 at 08:25 -0700, Paul E. McKenney wrote: > On Thu, Mar 25, 2010 at 11:36:40AM -0400, Trond Myklebust wrote: > > 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... > > Did you want to carry these patches, or would you rather that I do so? > > (And sorry for the slow response, was on holiday last week.) > > Thanx, Paul Hi Paul, I don't mind whether you or I push them to Linus, but IIRC you had a couple of comments about the last patchset I saw from David, so I was expecting to see either a reply from him or patch update. Did I miss that reply? (Ccing: David) Cheers Trond