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Date: Mon, 27 Jun 2016 12:47:51 +0530
From: Arjun V <arjun@...lsio.com>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: Eric Dumazet <edumazet@...gle.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Hariprasad S <hariprasad@...lsio.com>,
Casey Leedom <leedom@...lsio.com>,
Kumar A S <kumaras@...lsio.com>,
Santosh Rastapur <santosh@...lsio.com>,
Nirranjan Kirubaharan <nirranjan@...lsio.com>,
"davem@...emloft.net" <davem@...emloft.net>,
"ycheng@...gle.com" <ycheng@...gle.com>
Subject: Re: [REGRESSION, bisect]cxgb4 port failure with TSO traffic after
commit 10d3be569243def8("tcp-tso: do not split TSO packets at retransmit
time")
On Friday, June 06/24/16, 2016 at 21:55:07 +0530, Eric Dumazet wrote:
> On Fri, 2016-06-24 at 07:25 -0700, Eric Dumazet wrote:
> > Please do not top post on netdev mailing list
> >
> > On Fri, Jun 24, 2016 at 4:38 AM, Arjun V. <arjun@...lsio.com> wrote:
> > > Eric,
> > > We are seeing skb's with length(skb->len) greater than 65536 coming into our ndo_start_xmit() callback routine.
> > > We can add a check in our eth_xmit() routine to skip those packets, but it will be better if you fix this in kernel.
> > >
> > >
> > > I have attached pcap file obtained from tcpdump. In the pcap file there are 2 such packets(I used tcpdump filter to extract out those packets).
> > >
> > > Let us know if you need anything else.
> > >
> >
> > Beats me really.
> >
> > At retransmit time, we only can eventually reduce packet sizes
> > (assuming GSO is used, because we might coalesce sub-mss packets in
> > tcp_retrans_try_collapse())
> >
> > So why are you seeing too big packets at retransmit, I really have no idea.
> >
> > MIght be some bug related to MSS computation, overflowing somehow ?
>
> Could you try this ?
>
> Thanks !
>
> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> index d39e9e47a26e55ad2b8f775bf9ea9dfb5b12aee5..27013056bcfb9aa49601806bb3aa55a1ac664873 100644
> --- a/net/ipv4/af_inet.c
> +++ b/net/ipv4/af_inet.c
> @@ -1177,6 +1177,7 @@ int inet_sk_rebuild_header(struct sock *sk)
>
> /* Routing failed... */
> sk->sk_route_caps = 0;
> + sk->sk_gso_max_segs = 1;
> /*
> * Other protocols have to map its equivalent state to TCP_SYN_SENT.
> * DCCP maps its DCCP_REQUESTING state to TCP_SYN_SENT. -acme
> diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
> index 2076c21107d07e4e78a0a29f1d374c3414b8e1bd..ecc0281acfb702b138c68ac51e3a0518052785b0 100644
> --- a/net/ipv6/af_inet6.c
> +++ b/net/ipv6/af_inet6.c
> @@ -685,6 +685,7 @@ int inet6_sk_rebuild_header(struct sock *sk)
> dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
> if (IS_ERR(dst)) {
> sk->sk_route_caps = 0;
> + sk->sk_gso_max_segs = 1;
> sk->sk_err_soft = -PTR_ERR(dst);
> return PTR_ERR(dst);
> }
>
>
>
>
Eric,
Thanks for the quick patch. It didn't help much. We still see packets larger than 65536 with the patch.
Below is the dump_stack() trace I am seeing for packets larger than 65536 in our xmit routine:
[ 619.094366] CPU: 5 PID: 19322 Comm: netperf Not tainted 4.7.0-rc2+ #85
[ 619.094373] Hardware name: Supermicro Super Server/X10SRi-F, BIOS 1.0b 04/21/2015
[ 619.094379] 0000000000000001 ffff88067fd42c58 ffffffff81534635 ffff88065b59c2e0
[ 619.094393] ffff88065b520000 ffff8806570e1ae0 ffff88065b520000 ffff88067fd42d68
[ 619.094404] ffffffffa001cbee 000005f27fd42ca8 ffff880600000005 ffff880600000300
[ 619.094417] Call Trace:
[ 619.094421] <IRQ> [<ffffffff81534635>] dump_stack+0xa5/0xe0
[ 619.094445] [<ffffffffa001cbee>] t4_eth_xmit+0x43e/0xd90 [cxgb4]
[ 619.094455] [<ffffffff81187fa9>] ? trace_clock_local+0x9/0x10
[ 619.094461] [<ffffffff81198672>] ? rb_reserve_next_event+0x642/0x750
[ 619.094469] [<ffffffff81aee5ed>] dev_hard_start_xmit+0x15d/0x460
[ 619.094475] [<ffffffff81aedb80>] ? __netdev_pick_tx+0x170/0x1f0
[ 619.094482] [<ffffffff81af58ff>] ? validate_xmit_skb_list+0x4f/0xc0
[ 619.094489] [<ffffffff81b2b861>] sch_direct_xmit+0x221/0x2b0
[ 619.094497] [<ffffffff81af602c>] __dev_queue_xmit+0x6bc/0x9a0
[ 619.094504] [<ffffffff81bf79bf>] ? ipt_do_table+0x30f/0x620
[ 619.094512] [<ffffffff81af6330>] dev_queue_xmit+0x10/0x20
[ 619.094518] [<ffffffff81b774f9>] ip_finish_output2+0x459/0x570
[ 619.094525] [<ffffffff81b426c4>] ? nf_iterate+0xa4/0x110
[ 619.094531] [<ffffffff81b426c4>] ? nf_iterate+0xa4/0x110
[ 619.094538] [<ffffffff81b7973b>] ip_finish_output+0x1eb/0x330
[ 619.094545] [<ffffffff81b798f4>] ip_output+0x74/0x110
[ 619.094552] [<ffffffff81b78802>] ? __ip_local_out+0xb2/0x100
[ 619.094557] [<ffffffff81b79550>] ? ip_queue_xmit+0x4f0/0x4f0
[ 619.094564] [<ffffffff81b788d1>] ip_local_out+0x81/0xa0
[ 619.094571] [<ffffffff81b792b1>] ip_queue_xmit+0x251/0x4f0
[ 619.094579] [<ffffffff81b9bf19>] ? tcp_options_write+0x279/0x350
[ 619.094585] [<ffffffff81b9c7bb>] tcp_transmit_skb+0x7cb/0xe70
[ 619.094592] [<ffffffff81b9ef03>] ? tcp_current_mss+0x53/0xc0
[ 619.094599] [<ffffffff81b9f815>] __tcp_retransmit_skb+0x2e5/0x9c0
[ 619.094607] [<ffffffff810cb4a6>] ? get_nohz_timer_target+0x26/0x140
[ 619.094613] [<ffffffff81b9ff07>] tcp_retransmit_skb+0x17/0x100
[ 619.094620] [<ffffffff81ba046e>] tcp_xmit_retransmit_queue+0x47e/0x670
[ 619.094626] [<ffffffff81b8e753>] tcp_xmit_recovery+0xa3/0xb0
[ 619.094631] [<ffffffff81b98897>] tcp_ack+0xd67/0x1e70
[ 619.094639] [<ffffffff81b9634f>] ? tcp_validate_incoming+0x7f/0x560
[ 619.094646] [<ffffffff81b99af2>] tcp_rcv_established+0x152/0x780
[ 619.094654] [<ffffffff81baa13e>] tcp_v4_do_rcv+0x10e/0x3a0
[ 619.094661] [<ffffffff81bab24d>] tcp_v4_rcv+0xe7d/0xf20
[ 619.094667] [<ffffffff81bf4f93>] ? ipv4_confirm+0x133/0x1d0
[ 619.094673] [<ffffffff81b426c4>] ? nf_iterate+0xa4/0x110
[ 619.094680] [<ffffffff81b70138>] ip_local_deliver_finish+0xc8/0x2c0
[ 619.094686] [<ffffffff81b703f8>] ip_local_deliver+0xc8/0x140
[ 619.094692] [<ffffffff81ba9f02>] ? tcp_v4_early_demux+0x162/0x290
[ 619.094697] [<ffffffff81b70070>] ? ip_call_ra_chain+0x220/0x220
[ 619.094703] [<ffffffff81b6fc5f>] ip_rcv_finish+0x3ef/0x5e0
[ 619.094709] [<ffffffff81b4294a>] ? nf_hook_slow+0x4a/0x1b0
[ 619.094714] [<ffffffff81b70abb>] ip_rcv+0x64b/0x750
[ 619.094721] [<ffffffff81b6f870>] ? inet_add_protocol+0x60/0x60
[ 619.094727] [<ffffffff81af1e93>] __netif_receive_skb_core+0xd53/0x13e0
[ 619.094735] [<ffffffff81bb325f>] ? tcp4_gro_receive+0xef/0x2d0
[ 619.094743] [<ffffffff81bcd256>] ? inet_gro_receive+0x3b6/0x4e0
[ 619.094749] [<ffffffff81ae794a>] ? gro_pull_from_frag0+0x16a/0x190
[ 619.094755] [<ffffffff81af25a5>] __netif_receive_skb+0x85/0xe0
[ 619.094762] [<ffffffff81af2928>] netif_receive_skb_internal+0xf8/0x160
[ 619.094768] [<ffffffff81ae789d>] ? gro_pull_from_frag0+0xbd/0x190
[ 619.094774] [<ffffffff81b29f6c>] ? eth_type_trans+0x14c/0x280
[ 619.094780] [<ffffffff81af44d5>] napi_gro_frags+0x3e5/0x400
[ 619.094792] [<ffffffffa001bd85>] t4_ethrx_handler+0x8e5/0x9f0 [cxgb4]
[ 619.094799] [<ffffffff81b796c9>] ? ip_finish_output+0x179/0x330
[ 619.094809] [<ffffffffa001af55>] process_responses+0x735/0x8b0 [cxgb4]
[ 619.094815] [<ffffffff81b798f4>] ? ip_output+0x74/0x110
[ 619.094822] [<ffffffff81b788d1>] ? ip_local_out+0x81/0xa0
[ 619.094828] [<ffffffff8103e532>] ? native_sched_clock+0x82/0x1a0
[ 619.094834] [<ffffffff81187fa9>] ? trace_clock_local+0x9/0x10
[ 619.094840] [<ffffffff81198672>] ? rb_reserve_next_event+0x642/0x750
[ 619.094849] [<ffffffff81193e82>] ? rb_set_commit_to_write+0x212/0x350
[ 619.094861] [<ffffffffa001b186>] napi_rx_handler+0xb6/0x260 [cxgb4]
[ 619.094868] [<ffffffff81af3b4c>] napi_poll+0x1fc/0x3d0
[ 619.094873] [<ffffffff81198985>] ? ring_buffer_lock_reserve+0x205/0x260
[ 619.094881] [<ffffffff811933b3>] ? rb_event_data+0x53/0xa0
[ 619.094886] [<ffffffff81af3e1e>] net_rx_action+0xfe/0x2f0
[ 619.094893] [<ffffffff811b88e9>] ? trace_event_buffer_commit+0x179/0x2b0
[ 619.094901] [<ffffffff8109b225>] ? trace_event_raw_event_softirq+0x115/0x150
[ 619.094909] [<ffffffff81deed4d>] __do_softirq+0x1cd/0x4e1
[ 619.094916] [<ffffffff8109a868>] ? irq_exit+0x58/0x110
[ 619.094925] [<ffffffff81dedf1c>] do_softirq_own_stack+0x1c/0x30
[ 619.094929] <EOI> [<ffffffff8109a458>] do_softirq+0x68/0x70
[ 619.094940] [<ffffffff8109a629>] __local_bh_enable_ip+0xf9/0x160
[ 619.094946] [<ffffffff81bf79bf>] ipt_do_table+0x30f/0x620
[ 619.094954] [<ffffffff81bfae3f>] iptable_mangle_hook+0xef/0x1d0
[ 619.094960] [<ffffffff81b426c4>] nf_iterate+0xa4/0x110
[ 619.094966] [<ffffffff81b4294a>] nf_hook_slow+0x4a/0x1b0
[ 619.094972] [<ffffffff81b7884b>] __ip_local_out+0xfb/0x100
[ 619.094978] [<ffffffff81b74f00>] ? neigh_key_eq32+0x20/0x20
[ 619.094984] [<ffffffff81b78882>] ip_local_out+0x32/0xa0
[ 619.094990] [<ffffffff81b792b1>] ip_queue_xmit+0x251/0x4f0
[ 619.094997] [<ffffffff81b9bf19>] ? tcp_options_write+0x279/0x350
[ 619.095003] [<ffffffff81b9c7bb>] tcp_transmit_skb+0x7cb/0xe70
[ 619.095010] [<ffffffff81b9e942>] tcp_send_ack+0x182/0x1c0
[ 619.095016] [<ffffffff81b96093>] __tcp_ack_snd_check+0x63/0x100
[ 619.095023] [<ffffffff81b99d9f>] tcp_rcv_established+0x3ff/0x780
[ 619.095029] [<ffffffff81baa13e>] tcp_v4_do_rcv+0x10e/0x3a0
[ 619.095035] [<ffffffff81b86969>] tcp_prequeue_process+0x169/0x190
[ 619.095042] [<ffffffff81b84e32>] ? tcp_cleanup_rbuf+0x72/0x280
[ 619.095049] [<ffffffff81b8b6ed>] tcp_recvmsg+0xfed/0x12d0
[ 619.095057] [<ffffffff812bb776>] ? __fget_light+0x96/0x100
[ 619.095064] [<ffffffff81bcc4b9>] inet_recvmsg+0xa9/0xe0
[ 619.095071] [<ffffffff81ac13da>] sock_recvmsg+0x4a/0x60
[ 619.095078] [<ffffffff81ac343d>] SYSC_recvfrom+0x13d/0x1d0
[ 619.095085] [<ffffffff8100276e>] ? do_audit_syscall_entry+0xae/0xe0
[ 619.095093] [<ffffffff81002a1e>] ? syscall_trace_enter_phase2+0x27e/0x2f0
[ 619.095100] [<ffffffff81ac34de>] SyS_recvfrom+0xe/0x10
[ 619.095105] [<ffffffff81003426>] do_syscall_64+0xa6/0x170
[ 619.095111] [<ffffffff81002479>] ? prepare_exit_to_usermode+0x49/0x80
[ 619.095118] [<ffffffff81dec4fc>] entry_SYSCALL64_slow_path+0x25/0x25
Thanks,
Arjun.
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