From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx122.postini.com [74.125.245.122]) by kanga.kvack.org (Postfix) with SMTP id DF4956B0098 for ; Mon, 10 Sep 2012 22:50:49 -0400 (EDT) Received: from /spool/local by e28smtp05.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 11 Sep 2012 08:20:46 +0530 Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay01.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q8B2oeYS39911536 for ; Tue, 11 Sep 2012 08:20:40 +0530 Received: from d28av05.in.ibm.com (loopback [127.0.0.1]) by d28av05.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q8B2oeJd026326 for ; Tue, 11 Sep 2012 12:50:40 +1000 Message-ID: <504EA6FE.7070405@linux.vnet.ibm.com> Date: Tue, 11 Sep 2012 10:50:38 +0800 From: Michael Wang MIME-Version: 1.0 Subject: Re: [PATCH] slab: fix the DEADLOCK issue on l3 alien lock References: <5044692D.7080608@linux.vnet.ibm.com> <5046B9EE.7000804@linux.vnet.ibm.com> <0000013996b6f21d-d45be653-3111-4aef-b079-31dc673e6fd8-000000@email.amazonses.com> <504812E7.3000700@linux.vnet.ibm.com> <20120906222933.GR2448@linux.vnet.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Pekka Enberg Cc: paulmck@linux.vnet.ibm.com, Christoph Lameter , LKML , linux-mm@kvack.org, Matt Mackall , Andrew Morton , Peter Zijlstra On 09/08/2012 04:39 PM, Pekka Enberg wrote: > On Fri, Sep 7, 2012 at 1:29 AM, Paul E. McKenney > wrote: >> On Thu, Sep 06, 2012 at 11:05:11AM +0800, Michael Wang wrote: >>> On 09/05/2012 09:55 PM, Christoph Lameter wrote: >>>> On Wed, 5 Sep 2012, Michael Wang wrote: >>>> >>>>> Since the cachep and cachep->slabp_cache's l3 alien are in the same lock class, >>>>> fake report generated. >>>> >>>> Ahh... That is a key insight into why this occurs. >>>> >>>>> This should not happen since we already have init_lock_keys() which will >>>>> reassign the lock class for both l3 list and l3 alien. >>>> >>>> Right. I was wondering why we still get intermitted reports on this. >>>> >>>>> This patch will invoke init_lock_keys() after we done enable_cpucache() >>>>> instead of before to avoid the fake DEADLOCK report. >>>> >>>> Acked-by: Christoph Lameter >>> >>> Thanks for your review. >>> >>> And add Paul to the cc list(my skills on mailing is really poor...). >> >> Tested-by: Paul E. McKenney > > I'd also like to tag this for the stable tree to avoid bogus lockdep > reports. How far back in release history should we queue this? Hi, Pekka Sorry for the delayed reply, I try to find out the reason for commit 30765b92 but not get it yet, so I add Peter to the cc list. The below patch for release 3.0.0 is the one to cause the bogus report. commit 30765b92ada267c5395fc788623cb15233276f5c Author: Peter Zijlstra Date: Thu Jul 28 23:22:56 2011 +0200 slab, lockdep: Annotate the locks before using them Fernando found we hit the regular OFF_SLAB 'recursion' before we annotate the locks, cure this. The relevant portion of the stack-trace: > [ 0.000000] [] rt_spin_lock+0x50/0x56 > [ 0.000000] [] __cache_free+0x43/0xc3 > [ 0.000000] [] kmem_cache_free+0x6c/0xdc > [ 0.000000] [] slab_destroy+0x4f/0x53 > [ 0.000000] [] free_block+0x94/0xc1 > [ 0.000000] [] do_tune_cpucache+0x10b/0x2bb > [ 0.000000] [] enable_cpucache+0x7b/0xa7 > [ 0.000000] [] kmem_cache_init_late+0x1f/0x61 > [ 0.000000] [] start_kernel+0x24c/0x363 > [ 0.000000] [] i386_start_kernel+0xa9/0xaf Reported-by: Fernando Lopez-Lezcano Acked-by: Pekka Enberg Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1311888176.2617.379.camel@laptop Signed-off-by: Ingo Molnar It moved init_lock_keys() before we build up the alien, so we failed to reclass it. Regards, Michael Wang > -- 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/ . Don't email: email@kvack.org