From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: net/ipv4/route.c:645 suspicious rcu_dereference_check() usage! Date: Mon, 10 Sep 2012 11:46:51 +0200 Message-ID: <1347270411.1234.1360.camel@edumazet-glaptop> References: <84c8a8$5m6f27@orsmga001.jf.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: chris@chris-wilson.co.uk Return-path: Received: from mail-ey0-f174.google.com ([209.85.215.174]:57712 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751034Ab2IJJq4 (ORCPT ); Mon, 10 Sep 2012 05:46:56 -0400 In-Reply-To: <84c8a8$5m6f27@orsmga001.jf.intel.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2012-09-10 at 09:44 +0100, chris@chris-wilson.co.uk wrote: > I've not seen this reported yet, so here's a warning that happens > occasionally: > > [192979.475833] > [192979.475840] =============================== > [192979.475841] [ INFO: suspicious RCU usage. ] > [192979.475844] 3.6.0-rc2+ #33 Not tainted > [192979.475846] ------------------------------- > [192979.475848] net/ipv4/route.c:645 suspicious rcu_dereference_check() usage! > [192979.475850] > [192979.475850] other info that might help us debug this: > [192979.475850] > [192979.475853] > [192979.475853] rcu_scheduler_active = 1, debug_locks = 0 > [192979.475856] 2 locks held by firefox-bin/4634: > [192979.475858] #0: (slock-AF_INET){+.-...}, at: [] release_sock+0x34/0x1e0 > [192979.475870] #1: (fnhe_lock){+.-...}, at: [] update_or_create_fnhe.isra.30+0x44/0x480 > [192979.475878] > [192979.475878] stack backtrace: > [192979.475881] Pid: 4634, comm: firefox-bin Not tainted 3.6.0-rc2+ #33 > [192979.475883] Call Trace: > [192979.475891] [] lockdep_rcu_suspicious+0xfd/0x130 > [192979.475895] [] update_or_create_fnhe.isra.30+0x23e/0x480 > [192979.475899] [] __ip_rt_update_pmtu.isra.31+0x6a/0xb0 > [192979.475903] [] ip_rt_update_pmtu+0x48/0xd0 > [192979.475907] [] inet_csk_update_pmtu+0x31/0x80 > [192979.475912] [] tcp_v4_mtu_reduced+0x33/0xd0 > [192979.475915] [] tcp_release_cb+0x5e/0xb0 > [192979.475919] [] release_sock+0x109/0x1e0 > [192979.475922] [] tcp_sendmsg+0x527/0x1030 > [192979.475927] [] inet_sendmsg+0xed/0x240 > [192979.475931] [] ? inet_autobind+0x70/0x70 > [192979.475934] [] ? sock_update_classid+0xaa/0x370 > [192979.475937] [] ? sock_update_classid+0xd8/0x370 > [192979.475941] [] sock_sendmsg+0xab/0xe0 > [192979.475946] [] sys_sendto+0x11e/0x160 > [192979.475951] [] ? sysret_check+0x1b/0x56 > [192979.475956] [] ? trace_hardirqs_on_thunk+0x3a/0x3f > [192979.475960] [] system_call_fastpath+0x16/0x1b > Probably already fixed in commit c5ae7d41927d (ipv4: must use rcu protection while calling fib_lookup) 3.6.0-rc2 is quite old for a dev kernel ;) Thanks