From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 45491900001 for ; Fri, 13 May 2011 03:18:56 -0400 (EDT) Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e2.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id p4D6x6PM022794 for ; Fri, 13 May 2011 02:59:06 -0400 Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p4D7IqZA084596 for ; Fri, 13 May 2011 03:18:52 -0400 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p4D7IpJs020336 for ; Fri, 13 May 2011 03:18:52 -0400 Date: Fri, 13 May 2011 00:18:50 -0700 From: "Paul E. McKenney" Subject: Re: 2.6.39-rc6-mmotm0506 - lockdep splat in RCU code on page fault Message-ID: <20110513071850.GU2258@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <6921.1304989476@localhost> <20110510082029.GF2258@linux.vnet.ibm.com> <34783.1305155494@localhost> <20110512094704.GL2258@linux.vnet.ibm.com> <5817.1305216324@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5817.1305216324@localhost> Sender: owner-linux-mm@kvack.org List-ID: To: Valdis.Kletnieks@vt.edu Cc: Andrew Morton , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Thu, May 12, 2011 at 12:05:24PM -0400, Valdis.Kletnieks@vt.edu wrote: > 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. Whew!!! ;-) Thanx, Paul -- 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