From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 6EBDD6B0026 for ; Thu, 12 May 2011 12:06:13 -0400 (EDT) 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> Sender: owner-linux-mm@kvack.org List-ID: To: paulmck@linux.vnet.ibm.com Cc: Andrew Morton , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.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-- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org