From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fan Du Subject: Re: suspicious RCU usage in xfrm_net_init() Date: Thu, 16 Aug 2012 17:36:35 +0800 Message-ID: <502CBF23.4070805@windriver.com> References: <20120816073724.GA10660@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Priyanka Jain , , LKML To: Fengguang Wu Return-path: Received: from mail1.windriver.com ([147.11.146.13]:41634 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751822Ab2HPJgH (ORCPT ); Thu, 16 Aug 2012 05:36:07 -0400 In-Reply-To: <20120816073724.GA10660@localhost> Sender: netdev-owner@vger.kernel.org List-ID: Hi, Fengguang Could you please try the below patch, see if spewing still there? thanks From a3f86ecc3ee16ff81d49416bbf791780422988b3 Mon Sep 17 00:00:00 2001 =46rom: Fan Du Date: Thu, 16 Aug 2012 17:31:25 +0800 Subject: [PATCH] Use rcu_dereference_bh to deference pointer protected=20 by rcu_read_lock_bh Signed-off-by: Fan Du --- net/xfrm/xfrm_policy.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 5ad4d2c..75a9d6a 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -2501,7 +2501,7 @@ static void __net_init xfrm_dst_ops_init(struct=20 net *net) struct xfrm_policy_afinfo *afinfo; rcu_read_lock_bh(); - afinfo =3D rcu_dereference(xfrm_policy_afinfo[AF_INET]); + afinfo =3D rcu_dereference_bh(xfrm_policy_afinfo[AF_INET]); if (afinfo) net->xfrm.xfrm4_dst_ops =3D *afinfo->dst_ops; #if IS_ENABLED(CONFIG_IPV6) --=20 1.7.1 On 2012=E5=B9=B408=E6=9C=8816=E6=97=A5 15:37, Fengguang Wu wrote: > Hi Priyanka, > > The below warning shows up, probably related to this commit: > > 418a99ac6ad487dc9c42e6b0e85f941af56330f2 Replace rwlock on xfrm_polic= y_afinfo with rcu > > [ 0.921216] > [ 0.921645] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > [ 0.922766] [ INFO: suspicious RCU usage. ] > [ 0.923887] 3.5.0-01540-g1669891 #64 Not tainted > [ 0.925123] ------------------------------- > [ 0.932860] /c/kernel-tests/src/tip/net/xfrm/xfrm_policy.c:2504 su= spicious rcu_dereference_check() usage! > [ 0.935361] > [ 0.935361] other info that might help us debug this: > [ 0.935361] > [ 0.937472] > [ 0.937472] rcu_scheduler_active =3D 1, debug_locks =3D 0 > [ 0.939182] 2 locks held by swapper/1: > [ 0.940171] #0: (net_mutex){+.+.+.}, at: [] re= gister_pernet_subsys+0x21/0x57 > [ 0.942705] #1: (rcu_read_lock_bh){......}, at: [] xfrm_net_init+0x1e4/0x437 > [ 0.951507] > [ 0.951507] stack backtrace: > [ 0.952660] Pid: 1, comm: swapper Not tainted 3.5.0-01540-g1669891= #64 > [ 0.954364] Call Trace: > [ 0.955074] [] lockdep_rcu_suspicious+0x174/0x1= 87 > [ 0.956736] [] xfrm_net_init+0x30e/0x437 > [ 0.958205] [] ? xfrm_net_init+0x1e4/0x437 > [ 0.959712] [] ops_init+0x1bb/0x1ff > [ 0.961067] [] ? trace_hardirqs_on+0x1b/0x24 > [ 0.962644] [] register_pernet_operations.isra.= 5+0x9d/0xfe > [ 0.971376] [] register_pernet_subsys+0x30/0x57 > [ 0.972992] [] xfrm_init+0x17/0x2c > [ 0.974316] [] ip_rt_init+0x82/0xe7 > [ 0.975668] [] ip_init+0x10/0x25 > [ 0.976952] [] inet_init+0x235/0x360 > [ 0.978352] [] ? devinet_init+0xf2/0xf2 > [ 0.979808] [] do_one_initcall+0xb4/0x203 > [ 0.981313] [] kernel_init+0x1a9/0x29a > [ 0.982732] [] ? loglevel+0x46/0x46 > [ 0.990889] [] kernel_thread_helper+0x4/0x10 > [ 0.992472] [] ? retint_restore_args+0x13/0x13 > [ 0.994076] [] ? do_one_initcall+0x203/0x203 > [ 0.995636] [] ? gs_change+0x13/0x13 > [ 0.997197] TCP established hash table entries: 8192 (order: 5, 13= 1072 bytes) > [ 1.000074] TCP bind hash table entries: 8192 (order: 7, 655360 by= tes) > > Thanks, > Fengguang --=20 Love each day! --fan