From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: mmotm 2010-04-28 - RCU whinges Date: Mon, 3 May 2010 08:43:57 -0700 Message-ID: <20100503154357.GF2597@linux.vnet.ibm.com> References: <201004290021.o3T0L04Y028017@imap1.linux-foundation.org> <5702.1272822394@localhost> <1272865137.2173.179.camel@edumazet-laptop> <5933.1272897014@localhost> <1272898726.2226.47.camel@edumazet-laptop> <5112.1272900590@localhost> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Eric Dumazet , Andrew Morton , Peter Zijlstra , Patrick McHardy , "David S. Miller" , linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, netdev@vger.kernel.org To: Valdis.Kletnieks@vt.edu Return-path: Received: from e7.ny.us.ibm.com ([32.97.182.137]:38018 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932822Ab0ECPoA (ORCPT ); Mon, 3 May 2010 11:44:00 -0400 Content-Disposition: inline In-Reply-To: <5112.1272900590@localhost> Sender: netfilter-devel-owner@vger.kernel.org List-ID: On Mon, May 03, 2010 at 11:29:50AM -0400, Valdis.Kletnieks@vt.edu wrote= : > On Mon, 03 May 2010 16:58:46 +0200, Eric Dumazet said: > > Le lundi 03 mai 2010 =E0 10:30 -0400, Valdis.Kletnieks@vt.edu a =E9= crit : >=20 > > > [ 9.129872] net/netfilter/nf_log.c:55 invoked rcu_dereference_= check() without protection! >=20 > > Thanks for the report ! > >=20 > > [PATCH] net: nf_log RCU fixes > >=20 > > nf_log_register() and nf_log_unregister() use a mutex to have exclu= sive > > access to nf_logers[]. Use appropriate rcu_dereference_protected() > > lockdep annotation. >=20 > Confirming that one fixed. Now it lives a whole 36 seconds before wh= inging: >=20 > [ 35.328729] =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=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D > [ 35.328803] [ INFO: suspicious rcu_dereference_check() usage. ] > [ 35.328837] --------------------------------------------------- > [ 35.328872] net/ipv6/addrconf.c:2977 invoked rcu_dereference_check= () without protection! > [ 35.328926]=20 > [ 35.328927] other info that might help us debug this: > [ 35.328928]=20 > [ 35.329016]=20 > [ 35.329016] rcu_scheduler_active =3D 1, debug_locks =3D 0 > [ 35.329089] 2 locks held by ifconfig/2680: > [ 35.329120] #0: (&p->lock){+.+.+.}, at: [] seq= _read+0x3a/0x42d > [ 35.329217] #1: (rcu_read_lock_bh){.+....}, at: [] rcu_read_lock_bh+0x0/0x35 > [ 35.329322]=20 > [ 35.329323] stack backtrace: > [ 35.329380] Pid: 2680, comm: ifconfig Tainted: G W 2.6.34= -rc5-mmotm0428 #3 > [ 35.329439] Call Trace: > [ 35.329471] [] lockdep_rcu_dereference+0xaa/0xb= 2 > [ 35.329514] [] if6_get_next+0x34/0x6d > [ 35.329554] [] if6_seq_next+0x11/0x18 > [ 35.329595] [] seq_read+0x305/0x42d > [ 35.329635] [] ? seq_read+0x0/0x42d > [ 35.329676] [] proc_reg_read+0x8d/0xac > [ 35.329717] [] vfs_read+0xe0/0x140 > [ 35.329758] [] sys_read+0x45/0x69 > [ 35.329799] [] system_call_fastpath+0x16/0x1b >=20 > Maybe I need to go and stick the "RCU whinge multiple times" patch on= this > kernel and get it over with. :) Highly recommended. ;-) And thanks to you for your testing efforts and to Eric for the fixes!!! Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe netfilter-dev= el" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html