Subject: Re: BUG: unable to handle kernel NULL pointer dereference at 000000000000002c

From: Stefan Priebe - Profihost AG <[email-masked]>
Date: Mon, 06 Feb 2012 10:04:04 +0100

Hi Eric, Hi David

today i've seen this:
[1048676.660457] ------------[ cut here ]------------
[1048676.688131] WARNING: at net/ipv4/tcp_input.c:2964
tcp_ack+0xfe1/0x2420()
[1048676.716291] Hardware name: X8SIL
[1048676.744292] Modules linked in: xt_tcpudp ipt_REJECT iptable_filter
ip_tables x_tables coretemp k8temp ipv6 dm_snapshot dm_mod
[1048676.802468] Pid: 0, comm: kworker/0:1 Not tainted 2.6.40.17.1intel #1
[1048676.831737] Call Trace:
[1048676.860455]  <IRQ>  [<ffffffff81565921>] ? tcp_ack+0xfe1/0x2420
[1048676.860765]  [<ffffffff81045e10>] warn_slowpath_common+0x80/0xc0
[1048676.860771]  [<ffffffff81045e65>] warn_slowpath_null+0x15/0x20
[1048676.860777]  [<ffffffff81565921>] tcp_ack+0xfe1/0x2420
[1048676.860784]  [<ffffffff81567060>] tcp_rcv_established+0x300/0x630
[1048676.860791]  [<ffffffff815708a4>] tcp_v4_do_rcv+0x154/0x2d0
[1048676.860796]  [<ffffffff8157111b>] tcp_v4_rcv+0x6fb/0x880
[1048676.860804]  [<ffffffff8154e4e7>] ip_local_deliver_finish+0x127/0x250
[1048676.860810]  [<ffffffff8154e69d>] ip_local_deliver+0x8d/0xa0
[1048676.860815]  [<ffffffff8154dda2>] ip_rcv_finish+0x172/0x340
[1048676.860820]  [<ffffffff8154e1e5>] ip_rcv+0x275/0x2f0
[1048676.860827]  [<ffffffff81523387>] __netif_receive_skb+0x427/0x4a0
[1048676.860832]  [<ffffffff81529148>] netif_receive_skb+0x78/0x80
[1048676.860837]  [<ffffffff81529280>] napi_skb_finish+0x50/0x70
[1048676.860842]  [<ffffffff81529735>] napi_gro_receive+0xc5/0xd0
[1048676.860851]  [<ffffffff81462786>] e1000_receive_skb+0x56/0x70
[1048676.860856]  [<ffffffff814646eb>] e1000_clean_rx_irq+0x22b/0x3d0
[1048676.860862]  [<ffffffff814630f2>] e1000_clean+0xb2/0x2f0
[1048676.860868]  [<ffffffff81054efc>] ? run_timer_softirq+0x3c/0x320
[1048676.860873]  [<ffffffff815298fa>] net_rx_action+0x10a/0x2b0
[1048676.860879]  [<ffffffff8104c300>] __do_softirq+0xd0/0x1c0
[1048676.860887]  [<ffffffff815eb20c>] call_softirq+0x1c/0x30
[1048676.860895]  [<ffffffff810047b5>] do_softirq+0x55/0x90
[1048676.860900]  [<ffffffff8104c0dd>] irq_exit+0xad/0xe0
[1048676.860905]  [<ffffffff81003f94>] do_IRQ+0x64/0xe0
[1048676.860910]  [<ffffffff815e9a93>] common_interrupt+0x13/0x13
[1048676.860913]  <EOI>  [<ffffffff8106bdff>] ?
notifier_call_chain+0x3f/0x80
[1048676.860926]  [<ffffffff813117b3>] ? intel_idle+0xb3/0x120
[1048676.860931]  [<ffffffff81311795>] ? intel_idle+0x95/0x120
[1048676.860937]  [<ffffffff814fc27c>] cpuidle_idle_call+0xdc/0x1a0
[1048676.860942]  [<ffffffff81002091>] cpu_idle+0xb1/0x110
[1048676.860948]  [<ffffffff81b0d7aa>] start_secondary+0x201/0x297
[1048676.860953] ---[ end trace 4d27234ace919a1b ]---

Any idea about that? Is it due to my custom patch being buggy or is it
anything you know which is missing in 3.0.X too?

Thanks!

Stefan