From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753138Ab2JHPuB (ORCPT ); Mon, 8 Oct 2012 11:50:01 -0400 Received: from mail-ie0-f174.google.com ([209.85.223.174]:61192 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751645Ab2JHPt7 (ORCPT ); Mon, 8 Oct 2012 11:49:59 -0400 Date: Mon, 8 Oct 2012 08:49:52 -0700 From: Greg KH To: Peter Zijlstra , Christoph Lameter , "Paul E. McKenney" , Michael Wang , Pekka Enberg Cc: stable@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Patch Upstream: slab: fix the DEADLOCK issue on l3 alien lock Message-ID: <20121008154952.GA27015@kroah.com> References: <20121007143944.B00BA2759@git.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121007143944.B00BA2759@git.kroah.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 07, 2012 at 10:39:44AM -0400, Gregs git-bot wrote: > commit: 947ca1856a7e60aa6d20536785e6a42dff25aa6e > From: Michael Wang > Date: Wed, 5 Sep 2012 10:33:18 +0800 > Subject: slab: fix the DEADLOCK issue on l3 alien lock > > DEADLOCK will be report while running a kernel with NUMA and LOCKDEP enabled, > the process of this fake report is: > > kmem_cache_free() //free obj in cachep > -> cache_free_alien() //acquire cachep's l3 alien lock > -> __drain_alien_cache() > -> free_block() > -> slab_destroy() > -> kmem_cache_free() //free slab in cachep->slabp_cache > -> cache_free_alien() //acquire cachep->slabp_cache's l3 alien lock > > Since the cachep and cachep->slabp_cache's l3 alien are in the same lock class, > fake report generated. > > This should not happen since we already have init_lock_keys() which will > reassign the lock class for both l3 list and l3 alien. > > However, init_lock_keys() was invoked at a wrong position which is before we > invoke enable_cpucache() on each cache. > > Since until set slab_state to be FULL, we won't invoke enable_cpucache() > on caches to build their l3 alien while creating them, so although we invoked > init_lock_keys(), the l3 alien lock class won't change since we don't have > them until invoked enable_cpucache() later. > > This patch will invoke init_lock_keys() after we done enable_cpucache() > instead of before to avoid the fake DEADLOCK report. > > Michael traced the problem back to a commit in release 3.0.0: > > 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 > > The commit moved init_lock_keys() before we build up the alien, so we > failed to reclass it. > > Cc: # 3.0+ > Acked-by: Christoph Lameter > Tested-by: Paul E. McKenney > Signed-off-by: Michael Wang > Signed-off-by: Pekka Enberg The commit above shows up in 3.1, not 3.0, so this patch does not apply to the 3.0.y kernel from what I can tell. If this is incorrect, please let me know. thanks, greg k-h