From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757981Ab1ELQGa (ORCPT ); Thu, 12 May 2011 12:06:30 -0400 Received: from lennier.cc.vt.edu ([198.82.162.213]:38228 "EHLO lennier.cc.vt.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757308Ab1ELQG2 (ORCPT ); Thu, 12 May 2011 12:06:28 -0400 X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.3-dev To: paulmck@linux.vnet.ibm.com Cc: Andrew Morton , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: 2.6.39-rc6-mmotm0506 - lockdep splat in RCU code on page fault In-Reply-To: Your message of "Thu, 12 May 2011 02:47:05 PDT." <20110512094704.GL2258@linux.vnet.ibm.com> From: Valdis.Kletnieks@vt.edu References: <6921.1304989476@localhost> <20110510082029.GF2258@linux.vnet.ibm.com> <34783.1305155494@localhost> <20110512094704.GL2258@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1305216324_4101P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Thu, 12 May 2011 12:05:24 -0400 Message-ID: <5817.1305216324@localhost> X-Mirapoint-Received-SPF: 198.82.161.152 auth3.smtp.vt.edu Valdis.Kletnieks@vt.edu 2 pass X-Mirapoint-IP-Reputation: reputation=neutral-1, source=Fixed, refid=n/a, actions=MAILHURDLE SPF TAG X-Junkmail-Status: score=10/50, host=zidane.cc.vt.edu X-Junkmail-Signature-Raw: score=unknown, refid=str=0001.0A020208.4DCC0546.00FE,ss=1,fgs=0, ip=0.0.0.0, so=2010-07-22 22:03:31, dmn=2009-09-10 00:05:08, mode=single engine X-Junkmail-IWF: false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --==_Exmh_1305216324_4101P Content-Type: text/plain; charset=us-ascii On Thu, 12 May 2011 02:47:05 PDT, "Paul E. McKenney" said: > On Wed, May 11, 2011 at 07:11:34PM -0400, Valdis.Kletnieks@vt.edu wrote: > > My source has this: > > > > raw_spin_lock_irqsave(&rnp->lock, flags); > > rnp->wakemask |= rdp->grpmask; > > invoke_rcu_node_kthread(rnp); > > raw_spin_unlock_irqrestore(&rnp->lock, flags); > > > > the last 2 lines swapped from what you diffed against. I can easily work around > > that, except it's unclear what the implications of the invoke_rcu moving outside > > of the irq save/restore pair (or if it being inside is the actual root cause)... > > Odd... > > This looks to me like a recent -next -- I do not believe that straight > mmotm has rcu_cpu_kthread_timer() in it. The patch should apply to the > last few days' -next kernels. Ah. Found it. Your tree and current linux-next include this commit: commit 1217ed1ba5c67393293dfb0f03c353b118dadeb4 tree a765356c8418e134de85fd05d9fe6eda41de859c tree | snapshot parent 29ce831000081dd757d3116bf774aafffc4b6b20 commit | diff rcu: permit rcu_read_unlock() to be called while holding runqueue locks which includes this chunk: @@ -1546,8 +1531,8 @@ static void rcu_cpu_kthread_timer(unsigned long arg) raw_spin_lock_irqsave(&rnp->lock, flags); rnp->wakemask |= rdp->grpmask; - invoke_rcu_node_kthread(rnp); raw_spin_unlock_irqrestore(&rnp->lock, flags); + invoke_rcu_node_kthread(rnp); } but that was committed 4 days ago, and Andrew pulled linux-next for the -mmotm 6 days ago, so it's not in there. The *rest* of your recent commits appear to be in there though. So that explains the patch failure to apply. --==_Exmh_1305216324_4101P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFNzAVEcC3lWbTT17ARAq37AJ99BJDiC8la1nOfutkD43yaFULQKQCfUAbR cLdUqxD+99QEOdSi1qrgUBY= =p+Ll -----END PGP SIGNATURE----- --==_Exmh_1305216324_4101P--