svn commit: r341586 - head/sys/dev/mlx5/mlx5_en
Slava Shwartsman
slavash at FreeBSD.org
Wed May 1 19:02:04 UTC 2019
On 01-May-19 19:45, John Baldwin wrote:
> On 5/1/19 1:05 AM, Slava Shwartsman wrote:
>>
>>
>> On 01-May-19 10:28, Slava Shwartsman wrote:
>>>
>>>
>>> On 01-May-19 10:09, Slava Shwartsman wrote:
>>>>
>>>>
>>>> On 30-Apr-19 00:14, John Baldwin wrote:
>>>>> On 4/25/19 12:10 AM, Slava Shwartsman wrote:
>>>>>>
>>>>>>
>>>>>> On 17-Apr-19 00:28, John Baldwin wrote:
>>>>>>> On 4/16/19 8:32 AM, Hans Petter Selasky wrote:
>>>>>>>> On 4/16/19 4:39 PM, Andrey V. Elsukov wrote:
>>>>>>>>> On 05.12.2018 17:25, Slava Shwartsman wrote:
>>>>>>>>>> Author: slavash
>>>>>>>>>> Date: Wed Dec 5 14:25:03 2018
>>>>>>>>>> New Revision: 341586
>>>>>>>>>> URL: https://svnweb.freebsd.org/changeset/base/341586
>>>>>>>>>>
>>>>>>>>>> Log:
>>>>>>>>>> mlx5en: Implement backpressure indication.
>>>>>>>>>> The backpressure indication is implemented using an
>>>>>>>>>> unlimited rate type of
>>>>>>>>>> mbuf send tag. When the upper layers typically the socket
>>>>>>>>>> layer has obtained such
>>>>>>>>>> a tag, it can then query the destination driver queue for
>>>>>>>>>> the current
>>>>>>>>>> amount of space available in the send queue.
>>>>>>>>>> A single mbuf send tag may be referenced multiple times and
>>>>>>>>>> a refcount has been added
>>>>>>>>>> to the mlx5e_priv structure to track its usage. Because the
>>>>>>>>>> send tag resides
>>>>>>>>>> in the mlx5e_channel structure, there is no need to wait
>>>>>>>>>> for refcounts to reach
>>>>>>>>>> zero until the mlx4en(4) driver is detached. The channels
>>>>>>>>>> structure is persistant
>>>>>>>>>> during the lifetime of the mlx5en(4) driver it belongs to
>>>>>>>>>> and can so be accessed
>>>>>>>>>> without any need of synchronization.
>>>>>>>>>> The mlx5e_snd_tag structure was extended to contain a type
>>>>>>>>>> field, because there are now
>>>>>>>>>> two different tag types which end up in the driver which
>>>>>>>>>> need to be distinguished.
>>>>>>>>>> Submitted by: hselasky@
>>>>>>>>>> Approved by: hselasky (mentor)
>>>>>>>>>> MFC after: 1 week
>>>>>>>>>> Sponsored by: Mellanox Technologies
>>>>>>>>>> @@ -587,27 +609,33 @@ mlx5e_xmit(struct ifnet *ifp, struct mbuf
>>>>>>>>>> *mb)
>>>>>>>>>> struct mlx5e_sq *sq;
>>>>>>>>>> int ret;
>>>>>>>>>> - sq = mlx5e_select_queue(ifp, mb);
>>>>>>>>>> - if (unlikely(sq == NULL)) {
>>>>>>>>>> -#ifdef RATELIMIT
>>>>>>>>>> - /* Check for route change */
>>>>>>>>>> - if (mb->m_pkthdr.snd_tag != NULL &&
>>>>>>>>>> - mb->m_pkthdr.snd_tag->ifp != ifp) {
>>>>>>>>>> + if (mb->m_pkthdr.snd_tag != NULL) {
>>>>>>>>>> + sq = mlx5e_select_queue_by_send_tag(ifp, mb);
>>>>>>>>>> + if (unlikely(sq == NULL)) {
>>>>>>>>>> + /* Check for route change */
>>>>>>>>>> + if (mb->m_pkthdr.snd_tag->ifp != ifp) {
>>>>>>>>>> + /* Free mbuf */
>>>>>>>>>> + m_freem(mb);
>>>>>>>>>> +
>>>>>>>>>> + /*
>>>>>>>>>> + * Tell upper layers about route
>>>>>>>>>> + * change and to re-transmit this
>>>>>>>>>> + * packet:
>>>>>>>>>> + */
>>>>>>>>>> + return (EAGAIN);
>>>>>>>>>> + }
>>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> I just discovered something strange and found that this commit is
>>>>>>>>> the
>>>>>>>>> cause.
>>>>>>>>> The test system has mlx5en 100G interface. It has two vlans:
>>>>>>>>> vlan500 and
>>>>>>>>> vlan100.
>>>>>>>>> Via vlan500 it receives some packets flows. Then it routes these
>>>>>>>>> packets
>>>>>>>>> into vlan100.
>>>>>>>>> But packets are dropped in mlx5e_xmit() with EAGAIN error code.
>>>>>>>>>
>>>>>>>>> # dtrace -n 'fbt::ip6_output:return {printf("%d", arg1);}'
>>>>>>>>> dtrace: description 'fbt::ip6_output:return ' matched 1 probe
>>>>>>>>> CPU ID FUNCTION:NAME
>>>>>>>>> 23 54338 ip6_output:return 35
>>>>>>>>> 16 54338 ip6_output:return 35
>>>>>>>>> 21 54338 ip6_output:return 35
>>>>>>>>> 22 54338 ip6_output:return 35
>>>>>>>>> 24 54338 ip6_output:return 35
>>>>>>>>> 23 54338 ip6_output:return 35
>>>>>>>>> 14 54338 ip6_output:return 35
>>>>>>>>> ^C
>>>>>>>>>
>>>>>>>>> # dtrace -n 'fbt::mlx5e_xmit:return {printf("%d", arg1);}'
>>>>>>>>> dtrace: description 'fbt::mlx5e_xmit:return ' matched 1 probe
>>>>>>>>> CPU ID FUNCTION:NAME
>>>>>>>>> 16 69030 mlx5e_xmit:return 35
>>>>>>>>> 23 69030 mlx5e_xmit:return 35
>>>>>>>>> 26 69030 mlx5e_xmit:return 35
>>>>>>>>> 25 69030 mlx5e_xmit:return 35
>>>>>>>>> 24 69030 mlx5e_xmit:return 35
>>>>>>>>> 21 69030 mlx5e_xmit:return 35
>>>>>>>>> 26 69030 mlx5e_xmit:return 35
>>>>>>>>> ^C
>>>>>>>>>
>>>>>>>>> The kernel config is GENERIC.
>>>>>>>>> 13.0-CURRENT #9 r345758+82f3d57(svn_head)-dirty
>>>>>>>>>
>>>>>>>>
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> This might be a case where rcvif in the mbuf's pktheader is not
>>>>>>>> cleared
>>>>>>>> before the packet is fed back on the wire.
>>>>>>>>
>>>>>>>> John Baldwin is working on the send tags implementation, to eliminate
>>>>>>>> the EAGAIN handling in the network drivers.
>>>>>>>
>>>>>>> I will try to push this branch sooner then since it affects more
>>>>>>> than just
>>>>>>> TLS. Part of the change includes a new flag we can use to assert
>>>>>>> that we
>>>>>> Thanks John!
>>>>>>> aren't just getting a stale rcvif (though there are also now
>>>>>>> assertions in
>>>>>>> ip_output that should catch this case I think).
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hi Andrey,
>>>>>>
>>>>>> Yes, we were able to reproduce this issue in house. If you don't
>>>>>> mind, I
>>>>>> prefer to wait for John's update - where he eliminates the EAGAIN
>>>>>> handling in the network drivers.
>>>>>
>>>>> I have rebased the branch for this, but for now it will just panic
>>>>> sooner
>>>>> I believe by tripping an assertion. Can you grab the diff (or just
>>>>> the branch)
>>>>> from the 'send_tags' branch at github/bsdjhb/freebsd and reproduce
>>>>> under a
>>>>> kernel with INVARIANTS? I think we will have to explicitly clear the
>>>>> 'rcvif'
>>>>> pointer somewhere, but I want to see what the stack trace looks like
>>>>> so I can
>>>>> think about the "right" place to clear it.
>>>>>
>>>>
>>>> Hi John,
>>>>
>>>> I grabbed your branch (which doesn't build BTW due to libbe(3): Fix
>>>> mis-application of patch (SHLIBDIR) so I just reverted it).
>>>>
>>>> The kernel doesn't panic in this scenario - it just that the packets
>>>> are being dropped. So I added a kdb_backtrace right before the return
>>>> (EAGAIN) in mlx5e_xmit:
>>>>
>>>> KDB: stack backtrace:
>>>> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
>>>> 0xfffffe0000547d90
>>>> mlx5e_xmit() at mlx5e_xmit+0x3d/frame 0xfffffe0000548160
>>>> vlan_transmit() at vlan_transmit+0xdc/frame 0xfffffe00005481d0
>>>> ether_output_frame() at ether_output_frame+0xa2/frame 0xfffffe0000548200
>>>> ether_output() at ether_output+0x689/frame 0xfffffe00005482a0
>>>> ip_output() at ip_output+0x13a4/frame 0xfffffe00005483f0
>>>> ip_forward() at ip_forward+0x344/frame 0xfffffe00005484b0
>>>> ip_input() at ip_input+0x7f5/frame 0xfffffe0000548560
>>>> netisr_dispatch_src() at netisr_dispatch_src+0xa2/frame
>>>> 0xfffffe00005485d0
>>>> ether_demux() at ether_demux+0x147/frame 0xfffffe0000548600
>>>> ether_nh_input() at ether_nh_input+0x403/frame 0xfffffe0000548660
>>>> netisr_dispatch_src() at netisr_dispatch_src+0xa2/frame
>>>> 0xfffffe00005486d0
>>>> ether_input() at ether_input+0x73/frame 0xfffffe0000548700
>>>> vlan_input() at vlan_input+0x1e7/frame 0xfffffe0000548750
>>>> ether_demux() at ether_demux+0x12d/frame 0xfffffe0000548780
>>>> ether_nh_input() at ether_nh_input+0x403/frame 0xfffffe00005487e0
>>>> netisr_dispatch_src() at netisr_dispatch_src+0xa2/frame
>>>> 0xfffffe0000548850
>>>> ether_input() at ether_input+0x73/frame 0xfffffe0000548880
>>>> mlx5e_rx_cq_comp() at mlx5e_rx_cq_comp+0x8b4/frame 0xfffffe00005489a0
>>>> mlx5_cq_completion() at mlx5_cq_completion+0x5e/frame 0xfffffe00005489d0
>>>> mlx5_msix_handler() at mlx5_msix_handler+0x1ba/frame 0xfffffe0000548a10
>>>> ithread_loop() at ithread_loop+0x187/frame 0xfffffe0000548a70
>>>> fork_exit() at fork_exit+0x84/frame 0xfffffe0000548ab0
>>>> fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe0000548ab0
>>>> --- trap 0, rip = 0, rsp = 0, rbp = 0 ---
>>>>
>>>>
>>>> Please ping me if you want me to try anything else.
>>>>
>>>>
>>>> Slava
>>>
>>> My bad - tested with master. Re-testing now.
>>>
>>>
>>> Slava
>>
>> Got it now:
>>
>> panic: Assertion m->m_pkthdr.snd_tag == NULL failed at
>> /usr/src/sys/netinet/ip_output.c:213
>> cpuid = 0
>> time = 1556697834
>> KDB: stack backtrace:
>> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
>> 0xfffffe00005ac1f0
>> vpanic() at vpanic+0x19d/frame 0xfffffe00005ac240
>> panic() at panic+0x43/frame 0xfffffe00005ac2a0
>> ip_output() at ip_output+0x159f/frame 0xfffffe00005ac3f0
>> ip_forward() at ip_forward+0x38c/frame 0xfffffe00005ac4b0
>> ip_input() at ip_input+0x7f5/frame 0xfffffe00005ac560
>> netisr_dispatch_src() at netisr_dispatch_src+0xa2/frame 0xfffffe00005ac5d0
>> ether_demux() at ether_demux+0x147/frame 0xfffffe00005ac600
>> ether_nh_input() at ether_nh_input+0x403/frame 0xfffffe00005ac660
>> netisr_dispatch_src() at netisr_dispatch_src+0xa2/frame 0xfffffe00005ac6d0
>> ether_input() at ether_input+0x7d/frame 0xfffffe00005ac700
>> vlan_input() at vlan_input+0x1e7/frame 0xfffffe00005ac750
>> ether_demux() at ether_demux+0x12d/frame 0xfffffe00005ac780
>> ether_nh_input() at ether_nh_input+0x403/frame 0xfffffe00005ac7e0
>> netisr_dispatch_src() at netisr_dispatch_src+0xa2/frame 0xfffffe00005ac850
>> ether_input() at ether_input+0x7d/frame 0xfffffe00005ac880
>> mlx5e_rx_cq_comp() at mlx5e_rx_cq_comp+0x8b4/frame 0xfffffe00005ac9a0
>> mlx5_cq_completion() at mlx5_cq_completion+0x5e/frame 0xfffffe00005ac9d0
>> mlx5_msix_handler() at mlx5_msix_handler+0x1ba/frame 0xfffffe00005aca10
>> ithread_loop() at ithread_loop+0x187/frame 0xfffffe00005aca70
>> fork_exit() at fork_exit+0x84/frame 0xfffffe00005acab0
>> fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe00005acab0
>> --- trap 0, rip = 0, rsp = 0, rbp = 0 ---
>> KDB: enter: panic
>> [ thread pid 12 tid 100113 ]
>> Stopped at kdb_enter+0x3b: movq $0,kdb_why
>>
>>
>> I can keep the machine in this state for a while now if you want to take
>> a look at anything specific.
>
> I pushed further changes to this branch (that are now in the review that
> Hans noted) that I think should fix the panic. You can either pull the
> branch (I'll try to rebase it today) or from the review. Please let me
> know if this resolves the panic. Thanks!
>
I puled the branch and it solves the panic (and the issue):
# dtrace -n 'fbt::mlx5e_xmit:return {printf("%d", arg1);}'
dtrace: description 'fbt::mlx5e_xmit:return ' matched 1 probe
CPU ID FUNCTION:NAME
1 61827 mlx5e_xmit:return 0
0 61827 mlx5e_xmit:return 0
0 61827 mlx5e_xmit:return 0
0 61827 mlx5e_xmit:return 0
0 61827 mlx5e_xmit:return 0
0 61827 mlx5e_xmit:return 0
Andrey, do you want to test it on your end too?
Slava
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