Date: Wed, 1 May 2019 11:05:56 +0300 From: Slava Shwartsman <slavash@FreeBSD.org> To: John Baldwin <jhb@FreeBSD.org>, Hans Petter Selasky <hps@selasky.org>, "Andrey V. Elsukov" <bu7cher@yandex.ru>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r341586 - head/sys/dev/mlx5/mlx5_en Message-ID: <76a05c08-b851-c50a-16fa-ac42c872413c@FreeBSD.org> In-Reply-To: <737bfa62-eb3e-7c48-6356-0e0b76bb0593@FreeBSD.org> References: <201812051425.wB5EP38T004562@repo.freebsd.org> <a1ff0879-abae-25c5-9350-809186d2cf85@yandex.ru> <bc601976-7d6b-f849-0305-66feb11a7130@selasky.org> <7cea5305-4136-a0b6-487b-51307b1c6db9@FreeBSD.org> <123654bf-59f7-1db8-55ce-36306bdac43d@FreeBSD.org> <67b638e0-8e6f-f960-b263-62eed8ce28b7@FreeBSD.org> <0e80cb1d-20b9-5b8c-330e-5f64a603ff10@FreeBSD.org> <737bfa62-eb3e-7c48-6356-0e0b76bb0593@FreeBSD.org>
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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. Slava
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