From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Justin P. Mattock" Subject: Re: INFO: suspicious rcu_dereference_check() usage. Date: Tue, 24 May 2011 09:22:37 -0700 Message-ID: <4DDBDB4D.4080606@gmail.com> References: <4DDB491A.2070901@gmail.com> <20110524155608.GA17977@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: Dave Jones , "linux-kernel@vger.kernel.org" , netdev Return-path: In-Reply-To: <20110524155608.GA17977@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 05/24/2011 08:56 AM, Dave Jones wrote: > On Mon, May 23, 2011 at 11:50:46PM -0700, Justin Mattock wrote: > > > [ 2862.310349] WARNING: at net/ipv4/route.c:1668 ip_rt_bug+0x5c/0x62() > > Awesome, adding that WARN_ON paid off. This is the same bug I've been trying > to reproduce the last few weeks. DaveM mentioned that it means we used > an input route for packet output. > > > [ 2862.310414] Pid: 6153, comm: gcm-session Not tainted > > 2.6.39-04906-g5e152b4-dirty #2 > > [ 2862.310417] Call Trace: > > [ 2862.310424] [] warn_slowpath_common+0x83/0x9b > > [ 2862.310430] [] warn_slowpath_null+0x1a/0x1c > > [ 2862.310434] [] ip_rt_bug+0x5c/0x62 > > [ 2862.310439] [] dst_output+0x19/0x1d > > [ 2862.310443] [] ip_local_out+0x20/0x25 > > [ 2862.310448] [] ip_send_skb+0x19/0x58 > > [ 2862.310453] [] udp_send_skb+0x239/0x29b > > [ 2862.310458] [] udp_sendmsg+0x5a1/0x7d4 > > [ 2862.310464] [] ? trace_hardirqs_off+0xd/0xf > > [ 2862.310469] [] ? ip_select_ident+0x3d/0x3d > > [ 2862.310475] [] ? local_bh_enable_ip+0xe/0x10 > > [ 2862.310481] [] ? _raw_spin_unlock_bh+0x31/0x35 > > [ 2862.310486] [] ? release_sock+0x14c/0x155 > > [ 2862.310490] [] inet_sendmsg+0x66/0x6f > > [ 2862.310495] [] sock_sendmsg+0xe6/0x109 > > [ 2862.310501] [] ? lock_acquire+0xe1/0x109 > > [ 2862.310505] [] ? lock_release+0x1aa/0x1d3 > > [ 2862.310512] [] ? might_fault+0xa5/0xac > > [ 2862.310516] [] ? copy_from_user+0x2f/0x31 > > [ 2862.310521] [] sys_sendto+0x132/0x174 > > [ 2862.310526] [] ? sysret_check+0x2e/0x69 > > [ 2862.310531] [] ? trace_hardirqs_on_caller+0x13f/0x172 > > [ 2862.310537] [] ? audit_syscall_entry+0x11c/0x148 > > [ 2862.310542] [] ? trace_hardirqs_on_thunk+0x3a/0x3f > > [ 2862.310546] [] system_call_fastpath+0x16/0x1b > > [ 2862.310549] ---[ end trace 2d2332adaa8bf2b5 ]--- > > [ 2863.373889] ip_rt_bug: 10.0.0.10 -> 255.255.255.255, ? > > The common thing between your bug and the trace I triggered was the > destination ip reported. A clue maybe ? > > Dave > > there was a bug for http://marc.info/?l=linux-kernel&m=129913127722786&w=2 but looking I see something in there with recv.c not route.c but probably something same or in the same vacinity. as for the sluggishness I have been noticing the system doing so, but never saw anything like the above, so if it is your WARN_ON then kudos to you! Justin P. Mattock