Re: Kernel BUG_ON in stable 4.8

[Eric Dumazet]

On Tue, Nov 22, 2016 at 9:57 AM, Eric Dumazet <edumazet@xxxxxxxxxx> wrote:
> On Tue, Nov 22, 2016 at 9:44 AM, Mathieu Desnoyers
> <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
>> ----- On Nov 22, 2016, at 12:01 PM, Francis Deslauriers francis.deslauriers@xxxxxxxxxxxx wrote:
>>
>>> Hi Mathieu,
>>>
>>> Here is a description of the kernel BUG_ON I have encountered. This bug was
>>> triggered by our continuous integration system tracking the stable branches. I
>>> was only able to reproduce it on our Lava baremetal x86_64 worker. Running the
>>> same kernel image on our KVM worker did not trigger the bug.
>>>
>>> The bug occurs at boot time and I believe it's during the configuration of one
>>> of the network cards.
>>>
>>> See attached the .config used.
>>> See attached the dmesg output of the crash containing the kernel panic
>>> output(around line 885 of dmesg.txt)
>>
>> Hi guys,
>>
>> Upstream commit 34fad54c2 "net: __skb_flow_dissect() must cap its return value"
>> triggers this BUG_ON at boot up on our testing machines. We have observed the
>> BUG_ON on v4.9-rc6, as well as stable kernels v4.8.10 and v4.4.34.
>>
>> Relevant bits:
>>
>> [   16.841793] kernel BUG at ./include/linux/skbuff.h:1927!
>> [   16.847101] invalid opcode: 0000 [#1] SMP
>> [   16.851101] Modules linked in:
>> [   16.854172] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.8.10 #1
>> [   16.860081] Hardware name: Supermicro SYS-6018R-TDW/X10DDW-i, BIOS 1.0a 01/14/2015
>> [   16.867637] task: ffffffff8220d500 task.stack: ffffffff82200000
>> [   16.873550] RIP: 0010:[<ffffffff819a7239>]  [<ffffffff819a7239>] eth_type_trans+0xc9/0x110
>> [   16.881826] RSP: 0000:ffff88103fc03df0  EFLAGS: 00010297
>> [   16.887130] RAX: 0000000000000148 RBX: ffff881037b2b5c0 RCX: 0000000000001073
>> [   16.894254] RDX: ffff88103221fdc0 RSI: ffff881038358000 RDI: ffff881037c5bb00
>> [   16.901377] RBP: ffff88103fc03df8 R08: 0000000000000001 R09: 0000000000000800
>> [   16.908503] R10: ffff88103221fec0 R11: ffffea0040de7780 R12: ffff881037c5bb00
>> [   16.915625] R13: ffff881037458000 R14: 0000000000000156 R15: ffff881038358000
>> [   16.922751] FS:  0000000000000000(0000) GS:ffff88103fc00000(0000) knlGS:0000000000000000
>> [   16.930829] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [   16.936565] CR2: ffff88207ffff000 CR3: 0000000002206000 CR4: 00000000001406f0
>> [   16.943689] Stack:
>> [   16.945702]  ffffffff815c098f ffff88103fc03e90 ffffffff8181c651 ffff88103fc0dc20
>> [   16.953153]  0000000000000000 0000000000000020 0000000000000002 ffff88103fc03e38
>> [   16.960607]  ffffea0040de7780 ffffea0000000008 ffffffff00000001 ffffea0040de7780
>> [   16.968061] Call Trace:
>> [   16.970507]  <IRQ>
>> [   16.972432]  [<ffffffff815c098f>] ? swiotlb_sync_single_for_device+0xf/0x20
>> [   16.979575]  [<ffffffff8181c651>] igb_poll+0x691/0xe60
>> [   16.984714]  [<ffffffff8198383b>] net_rx_action+0x1bb/0x2f0
>> [   16.990291]  [<ffffffff81afcad6>] __do_softirq+0xf6/0x280
>> [   16.995689]  [<ffffffff810f82dc>] irq_exit+0xdc/0xf0
>> [   17.000648]  [<ffffffff81afc834>] do_IRQ+0x54/0xd0
>> [   17.005433]  [<ffffffff81afa80c>] common_interrupt+0x8c/0x8c
>> [   17.011083]  <EOI>
>> [   17.013014]  [<ffffffff8108c866>] ? mwait_idle+0x76/0x170
>> [   17.018596]  [<ffffffff8108cdef>] arch_cpu_idle+0xf/0x20
>> [   17.023907]  [<ffffffff8113524a>] default_idle_call+0x2a/0x40
>> [   17.029648]  [<ffffffff811354fa>] cpu_startup_entry+0x29a/0x300
>> [   17.035561]  [<ffffffff81aed057>] rest_init+0x77/0x80
>> [   17.040608]  [<ffffffff823ecf46>] start_kernel+0x40b/0x418
>> [   17.046091]  [<ffffffff823ec120>] ? early_idt_handler_array+0x120/0x120
>> [   17.052702]  [<ffffffff823ec2d6>] x86_64_start_reservations+0x2a/0x2c
>> [   17.059132]  [<ffffffff823ec413>] x86_64_start_kernel+0x13b/0x14a
>> [   17.065215] Code: 00 04 00 00 c9 c3 48 33 86 58 03 00 00 48 c1 e0 10 48 85 c0 0f b6 87 80 00 00 00 75 25 83 e0 f8 83 c8 01 88 87 80 00 00 00 eb 9c <0f> 0b 0f b6 87 80 00 00 00 83 e0 f8 83 c8 03 88 87 80 00 00 00
>> [   17.085165] RIP  [<ffffffff819a7239>] eth_type_trans+0xc9/0x110
>> [   17.091094]  RSP <ffff88103fc03df0>
>> [   17.094586] ---[ end trace e233c88f3b369632 ]---
>> [   17.101432] Kernel panic - not syncing: Fatal exception in interrupt
>> [   17.107790] Kernel Offset: disabled
>> [   17.113484] ---[ end Kernel panic - not syncing: Fatal exception in interrupt
>>
>> Do you have clues on what is going on ?
>>
>> Thanks,
>>
>> Mathieu
>>
>>
>
> Under investigation. Look around other threads. Thanks.

Probable fix is : https://patchwork.ozlabs.org/patch/697891/