Message-ID: <1305638195.2850.97.camel@edumazet-laptop>
Date:	Tue, 17 May 2011 15:16:35 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Denys Fedoryshchenko <denys@...p.net.lb>
Cc:	netdev@...r.kernel.org
Subject: Re: WARNING, net/core/dev.c, skb_gso_segment, 2.6.39-rc7-git11
 inclusive

Le mardi 17 mai 2011 à 15:52 +0300, Denys Fedoryshchenko a écrit :
> Hi
> 
>  Just tried some non-standard pedit rules to modify tcp data, and got 
>  WARNING almost instantly.
>  Maybe it is just invalid pedit, but probably will be interesting. My 
>  idea was to modify outgoing tcp window size,
>  rules was not complete by mistake, but got that warning.
> 
>  Rules
>  tc qdisc del dev eth1 root
>  tc qdisc add dev eth1 root handle 1: htb default 1
>  tc class add dev eth1 parent 1: classid 1:1 htb rate 900Mbit ceil 
>  900Mbit burst 10000 cburst 10000 quantum 60000
>  tc qdisc add dev eth1 parent 1:1 handle 11 pfifo limit 10000
> 
>  tc filter add dev eth1 prio 1 protocol ip parent 1: \
>    u32 match ip protocol 0x06 0xff match ip dport 80 0x2000 flowid 1:1 \
>    match u16 0x0000 0xffff at 34 action gact ok
> 
>  tc filter add dev eth1 prio 1 protocol ip parent 1: \
>    u32 match ip protocol 0x06 0xff match ip dport 80 0x2000 flowid 1:1 \
>      action pedit munge offset 34 u16 set 0x2000 \
>        pipe csum ip and tcp
> 
>  Warning:
> 
> 
>   2298.298075] GACT probability on
>  [ 2298.369166] ------------[ cut here ]------------
>  [ 2298.369175] WARNING: at net/core/dev.c:1876 
>  skb_gso_segment+0x156/0x2b8()
>  [ 2298.369178] Hardware name: RS700-E6/ERS4
>  [ 2298.369181] igb: caps=(0x21143b3, 0x0) len=11636 data_len=0 
>  ip_summed=0
>  [ 2298.369184] Modules linked in: act_gact act_csum act_pedit cls_u32 
>  sch_htb ipv6 i2c_i801 i7core_edac i2c_core edac_core rtc_cmos igb e1000e 
>  rtc_core rtc_lib iTCO_wdt ghes hed button
>  [ 2298.369200] Pid: 0, comm: swapper Not tainted 2.6.39-rc7-insat #1
>  [ 2298.369203] Call Trace:
>  [ 2298.369205]  <IRQ>  [<ffffffff810338cf>] 
>  warn_slowpath_common+0x80/0x98
>  [ 2298.369218]  [<ffffffff8103397b>] warn_slowpath_fmt+0x41/0x43
>  [ 2298.369222]  [<ffffffff8132a10d>] skb_gso_segment+0x156/0x2b8
>  [ 2298.369227]  [<ffffffff8132a700>] dev_hard_start_xmit+0x37c/0x522
>  [ 2298.369233]  [<ffffffff81341135>] sch_direct_xmit+0x67/0x18d
>  [ 2298.369237]  [<ffffffff81341365>] __qdisc_run+0x10a/0x126
>  [ 2298.369241]  [<ffffffff8132ac39>] dev_queue_xmit+0x393/0x4c3
>  [ 2298.369247]  [<ffffffff81332a8a>] neigh_resolve_output+0x28f/0x2ed
>  [ 2298.369250]  [<ffffffff8134b8da>] ? nf_hook_slow+0x6d/0x108
>  [ 2298.369253]  [<ffffffff81357ec4>] ? ip_options_build+0x143/0x143
>  [ 2298.369255]  [<ffffffff8135a964>] ip_finish_output+0x260/0x2a3
>  [ 2298.369257]  [<ffffffff8135aa4d>] ip_output+0xa6/0xad
>  [ 2298.369258]  [<ffffffff81359d79>] ? __ip_local_out+0x9c/0x9e
>  [ 2298.369260]  [<ffffffff81359d9f>] ip_local_out+0x24/0x28
>  [ 2298.369262]  [<ffffffff8135a31c>] ip_queue_xmit+0x2dd/0x328
>  [ 2298.369265]  [<ffffffff8131fcd5>] ? __skb_clone+0x29/0xf2
>  [ 2298.369268]  [<ffffffff8136bbd4>] tcp_transmit_skb+0x74d/0x78b
>  [ 2298.369270]  [<ffffffff8136e389>] tcp_write_xmit+0x806/0x8f5
>  [ 2298.369272]  [<ffffffff8136b04f>] ? 
>  tcp_established_options+0x2e/0xa9
>  [ 2298.369274]  [<ffffffff8136e4c9>] 
>  __tcp_push_pending_frames+0x20/0x7c
>  [ 2298.369276]  [<ffffffff8136a685>] tcp_rcv_established+0x104/0x60f
>  [ 2298.369278]  [<ffffffff81371696>] tcp_v4_do_rcv+0x1ba/0x377
>  [ 2298.369283]  [<ffffffff81173e9f>] ? security_sock_rcv_skb+0x11/0x13
>  [ 2298.369284]  [<ffffffff81371d6f>] tcp_v4_rcv+0x51c/0x869
>  [ 2298.369287]  [<ffffffff81355b34>] ? ip_rcv+0x28a/0x28a
>  [ 2298.369289]  [<ffffffff81355b34>] ? ip_rcv+0x28a/0x28a
>  [ 2298.369291]  [<ffffffff81355cac>] 
>  ip_local_deliver_finish+0x178/0x235
>  [ 2298.369293]  [<ffffffff81355ddb>] ip_local_deliver+0x72/0x79
>  [ 2298.369295]  [<ffffffff81355880>] ip_rcv_finish+0x2dc/0x306
>  [ 2298.369297]  [<ffffffff81355b06>] ip_rcv+0x25c/0x28a
>  [ 2298.369299]  [<ffffffff81329536>] __netif_receive_skb+0x4b8/0x4ea
>  [ 2298.369301]  [<ffffffff81329778>] netif_receive_skb+0x67/0x6e
>  [ 2298.369303]  [<ffffffff81329861>] napi_skb_finish+0x24/0x3b
>  [ 2298.369305]  [<ffffffff81329d44>] napi_gro_receive+0xa8/0xad
>  [ 2298.369309]  [<ffffffffa003668f>] igb_poll+0x783/0xaaa [igb]
>  [ 2298.369314]  [<ffffffff81213d16>] ? put_device+0x12/0x14
>  [ 2298.369317]  [<ffffffff81226e3d>] ? scsi_next_command+0x3e/0x46
>  [ 2298.369319]  [<ffffffff81329e79>] net_rx_action+0xa3/0x1bb
>  [ 2298.369322]  [<ffffffff81038537>] __do_softirq+0x83/0x114
>  [ 2298.369324]  [<ffffffff813babcc>] call_softirq+0x1c/0x30
>  [ 2298.369328]  [<ffffffff81003e0f>] do_softirq+0x33/0x68
>  [ 2298.369329]  [<ffffffff810383d4>] irq_exit+0x3f/0x88
>  [ 2298.369331]  [<ffffffff810036f6>] do_IRQ+0x98/0xaf
>  [ 2298.369334]  [<ffffffff813b9453>] common_interrupt+0x13/0x13
>  [ 2298.369335]  <EOI>  [<ffffffff8104d2d7>] ? 
>  __hrtimer_start_range_ns+0x2a3/0x2b5
>  [ 2298.369343]  [<ffffffff811c05a9>] ? intel_idle+0xc3/0xe9
>  [ 2298.369345]  [<ffffffff811c058c>] ? intel_idle+0xa6/0xe9
>  [ 2298.369348]  [<ffffffff813097cb>] cpuidle_idle_call+0x94/0xcd
>  [ 2298.369350]  [<ffffffff81001c47>] cpu_idle+0x5a/0x91
>  [ 2298.369353]  [<ffffffff813a5564>] rest_init+0x68/0x6a
>  [ 2298.369356]  [<ffffffff8160d930>] start_kernel+0x2f3/0x2fe
>  [ 2298.369358]  [<ffffffff8160d085>] 
>  x86_64_start_reservations+0x82/0x86
>  [ 2298.369360]  [<ffffffff8160d172>] x86_64_start_kernel+0xe9/0xf0
>  [ 2298.369361] ---[ end trace 408f79c72c45f490 ]---
>  [ 2298.369807] ------------[ cut here ]------------
>  [ 2298.369809] WARNING: at net/core/dev.c:1876 
>  skb_gso_segment+0x156/0x2b8()
>  [ 2298.369810] Hardware name: RS700-E6/ERS4
>  [ 2298.369811] igb: caps=(0x21143b3, 0x0) len=2948 data_len=0 
>  ip_summed=0
>  [ 2298.369812] Modules linked in: act_gact act_csum act_pedit cls_u32 
>  sch_htb ipv6 i2c_i801 i7core_edac i2c_core edac_core rtc_cmos igb e1000e 
>  rtc_core rtc_lib iTCO_wdt ghes hed button
>  [ 2298.369818] Pid: 5867, comm: syslog-ng Tainted: G        W   
>  2.6.39-rc7-insat #1
>  [ 2298.369819] Call Trace:
>  [ 2298.369820]  <IRQ>  [<ffffffff810338cf>] 
>  warn_slowpath_common+0x80/0x98
>  [ 2298.369824]  [<ffffffff8103397b>] warn_slowpath_fmt+0x41/0x43
>  [ 2298.369826]  [<ffffffff8132a10d>] skb_gso_segment+0x156/0x2b8
>  [ 2298.369828]  [<ffffffff8132a700>] dev_hard_start_xmit+0x37c/0x522
>  [ 2298.369830]  [<ffffffff81341135>] sch_direct_xmit+0x67/0x18d
>  [ 2298.369831]  [<ffffffff81341365>] __qdisc_run+0x10a/0x126
>  [ 2298.369833]  [<ffffffff8132ac39>] dev_queue_xmit+0x393/0x4c3
>  [ 2298.369835]  [<ffffffff81332a8a>] neigh_resolve_output+0x28f/0x2ed
>  [ 2298.369837]  [<ffffffff8134b8da>] ? nf_hook_slow+0x6d/0x108
>  [ 2298.369838]  [<ffffffff81357ec4>] ? ip_options_build+0x143/0x143
>  [ 2298.369840]  [<ffffffff8135a964>] ip_finish_output+0x260/0x2a3
>  [ 2298.369841]  [<ffffffff8135aa4d>] ip_output+0xa6/0xad
>  [ 2298.369843]  [<ffffffff81359d79>] ? __ip_local_out+0x9c/0x9e
>  [ 2298.369844]  [<ffffffff81359d9f>] ip_local_out+0x24/0x28
>  [ 2298.369846]  [<ffffffff8135a31c>] ip_queue_xmit+0x2dd/0x328
>  [ 2298.369848]  [<ffffffff8131fcd5>] ? __skb_clone+0x29/0xf2
>  [ 2298.369850]  [<ffffffff8136bbd4>] tcp_transmit_skb+0x74d/0x78b
>  [ 2298.369852]  [<ffffffff8136e389>] tcp_write_xmit+0x806/0x8f5
>  [ 2298.369854]  [<ffffffff8136b04f>] ? 
>  tcp_established_options+0x2e/0xa9
>  [ 2298.369856]  [<ffffffff8136e4c9>] 
>  __tcp_push_pending_frames+0x20/0x7c
>  [ 2298.369857]  [<ffffffff8136a685>] tcp_rcv_established+0x104/0x60f
>  [ 2298.369859]  [<ffffffff81371696>] tcp_v4_do_rcv+0x1ba/0x377
>  [ 2298.369861]  [<ffffffff81173e9f>] ? security_sock_rcv_skb+0x11/0x13
>  [ 2298.369863]  [<ffffffff81371d6f>] tcp_v4_rcv+0x51c/0x869
>  [ 2298.369865]  [<ffffffff81355b34>] ? ip_rcv+0x28a/0x28a
>  [ 2298.369867]  [<ffffffff81355b34>] ? ip_rcv+0x28a/0x28a
>  [ 2298.369869]  [<ffffffff81355cac>] 
>  ip_local_deliver_finish+0x178/0x235
>  [ 2298.369870]  [<ffffffff81355ddb>] ip_local_deliver+0x72/0x79
>  [ 2298.369872]  [<ffffffff81355880>] ip_rcv_finish+0x2dc/0x306
>  [ 2298.369874]  [<ffffffff81355b06>] ip_rcv+0x25c/0x28a
>  [ 2298.369876]  [<ffffffff81329536>] __netif_receive_skb+0x4b8/0x4ea
>  [ 2298.369878]  [<ffffffff81329778>] netif_receive_skb+0x67/0x6e
>  [ 2298.369879]  [<ffffffff81329861>] napi_skb_finish+0x24/0x3b
>  [ 2298.369881]  [<ffffffff81329d44>] napi_gro_receive+0xa8/0xad
>  [ 2298.369884]  [<ffffffffa003668f>] igb_poll+0x783/0xaaa [igb]
>  [ 2298.369886]  [<ffffffff8100e0d3>] ? x86_pmu_enable+0x1fc/0x263
>  [ 2298.369889]  [<ffffffff810794cb>] ? perf_ctx_adjust_freq+0x29/0x10a
>  [ 2298.369890]  [<ffffffff81329e79>] net_rx_action+0xa3/0x1bb
>  [ 2298.369893]  [<ffffffff8106f3d4>] ? 
>  __rcu_process_callbacks+0x75/0x265
>  [ 2298.369895]  [<ffffffff81038537>] __do_softirq+0x83/0x114
>  [ 2298.369897]  [<ffffffff813babcc>] call_softirq+0x1c/0x30
>  [ 2298.369899]  [<ffffffff81003e0f>] do_softirq+0x33/0x68
>  [ 2298.369900]  [<ffffffff810383d4>] irq_exit+0x3f/0x88
>  [ 2298.369902]  [<ffffffff810036f6>] do_IRQ+0x98/0xaf
>  [ 2298.369904]  [<ffffffff813b9453>] common_interrupt+0x13/0x13
>  [ 2298.369905]  <EOI>  [<ffffffff8104dc74>] ? 
>  atomic_notifier_call_chain+0x13/0x15
>  [ 2298.369910]  [<ffffffff81202714>] ? do_con_write+0x57b/0x1db7
>  [ 2298.369912]  [<ffffffff812025eb>] ? do_con_write+0x452/0x1db7
>  [ 2298.369913]  [<ffffffff810340da>] ? console_unlock+0x170/0x19a
>  [ 2298.369915]  [<ffffffff811ff9b0>] ? con_flush_chars+0x3e/0x43
>  [ 2298.369917]  [<ffffffff8104daa8>] ? up+0x34/0x39
>  [ 2298.369918]  [<ffffffff81203f97>] con_write+0x11/0x26
>  [ 2298.369920]  [<ffffffff8104a0c5>] ? add_wait_queue+0x3f/0x46
>  [ 2298.369923]  [<ffffffff811f3896>] n_tty_write+0x239/0x35a
>  [ 2298.369925]  [<ffffffff8102f2a9>] ? try_to_wake_up+0x240/0x240
>  [ 2298.369926]  [<ffffffff811f0b13>] tty_write+0x19d/0x22f
>  [ 2298.369928]  [<ffffffff811f365d>] ? n_tty_ioctl+0xab/0xab
>  [ 2298.369931]  [<ffffffff810b3e82>] vfs_write+0xae/0x133
>  [ 2298.369933]  [<ffffffff810b3fc0>] sys_write+0x45/0x6c
>  [ 2298.369935]  [<ffffffff813b9a7b>] system_call_fastpath+0x16/0x1b
>  [ 2298.369936] ---[ end trace 408f79c72c45f491 ]---
> 
> --

Hi Denys

net/sched/act_csum.c sets skb->ip_summed = CHECKSUM_NONE;  after csum
changes.

and skb_gso_segment() barfs if skb->ip_summed != CHECKSUM_PARTIAL

You could disable GRO for the time being.



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