On Mon, Jun 19, 2017 at 02:51:20PM -0700, Vinson Lee wrote: > Hi. > > I am seeing this warning on this 4.4.62 based kernel from Ubuntu 16.04. > > ------------[ cut here ]------------ > WARNING: CPU: 13 PID: 0 at > /build/linux-0XAgc4/linux-4.4.0/net/ipv4/tcp_output.c:1145 > tcp_fragment+0x34d/0x370() > Modules linked in: ip6table_filter ipip tunnel4 ip_tunnel cpuid 8021q > garp mrp stp llc ip6_tables binfmt_misc xt_comment nf_log_ipv4 > nf_log_common xt_LOG xt_limit xt_tcpudp xt_addrtype iptable_filter > iptable_mangle iptable_raw ip_tables x_tables intel_rapl > x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass > crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel > ipmi_ssif aes_x86_64 lrw gf128mul glue_helper ablk_helper hpilo cryptd > serio_raw sb_edac edac_core ioatdma lpc_ich shpchp 8250_fintek mac_hid > acpi_power_meter ipmi_si ipmi_devintf ipmi_msghandler autofs4 raid10 > raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor > raid6_pq libcrc32c raid1 raid0 multipath linear ixgbe dca vxlan > ip6_udp_tunnel udp_tunnel ptp ahci pps_core psmouse libahci > mdio wmi fjes [last unloaded: nf_conntrack] > CPU: 13 PID: 0 Comm: swapper/13 Not tainted 4.4.0-78-generic #99-Ubuntu > 0000000000000286 24b314fc942cf971 ffff88105f3439a8 ffffffff813f8dd3 > 0000000000000000 ffffffff81d71d78 ffff88105f3439e0 ffffffff81081302 > ffff88088a1c5000 ffff880cc988f800 000000000000004b 0000000000000000 > Call Trace: > <IRQ> [<ffffffff813f8dd3>] dump_stack+0x63/0x90 > [<ffffffff81081302>] warn_slowpath_common+0x82/0xc0 > [<ffffffff8108144a>] warn_slowpath_null+0x1a/0x20 > [<ffffffff817903ad>] tcp_fragment+0x34d/0x370 > [<ffffffff81785b7f>] tcp_mark_head_lost+0x14f/0x240 > [<ffffffff8178692c>] tcp_update_scoreboard+0x4c/0x70 > [<ffffffff8178c3d2>] tcp_fastretrans_alert+0x6f2/0xaa0 > [<ffffffff8178cbeb>] tcp_ack+0x46b/0x800 > [<ffffffff8178da39>] tcp_rcv_established+0x1d9/0x780 > [<ffffffff8174c232>] ? sk_filter_trim_cap+0x42/0x160 > [<ffffffff81798a05>] tcp_v4_do_rcv+0x145/0x200 > [<ffffffff81799bf2>] tcp_v4_rcv+0x872/0xa20 > [<ffffffffc02290c7>] ? iptable_filter_hook+0x27/0x56 [iptable_filter] > [<ffffffff8176c172>] ? nf_iterate+0x62/0x80 > [<ffffffff81773504>] ip_local_deliver_finish+0x94/0x1e0 > [<ffffffff8177380f>] ip_local_deliver+0x6f/0xe0 > [<ffffffff81773470>] ? ip_rcv_finish+0x320/0x320 > [<ffffffff817731e2>] ip_rcv_finish+0x92/0x320 > [<ffffffff81773b11>] ip_rcv+0x291/0x3a0 > [<ffffffff81773150>] ? inet_del_offload+0x40/0x40 > [<ffffffff817357a4>] __netif_receive_skb_core+0x704/0xa60 > [<ffffffff8179ec00>] ? tcp4_gro_receive+0x130/0x1d0 > [<ffffffff81735b18>] __netif_receive_skb+0x18/0x60 > [<ffffffff81735b92>] netif_receive_skb_internal+0x32/0xa0 > [<ffffffff81736813>] napi_gro_receive+0xc3/0x120 > [<ffffffffc02b8dfa>] gro_cell_poll+0x5a/0x90 [ip_tunnel] > [<ffffffff8173605e>] net_rx_action+0x21e/0x360 > [<ffffffff81085de1>] __do_softirq+0x101/0x290 > [<ffffffff810860e3>] irq_exit+0xa3/0xb0 > [<ffffffff81050e13>] smp_call_function_single_interrupt+0x33/0x40 > [<ffffffff81841e62>] call_function_single_interrupt+0x82/0x90 > <EOI> [<ffffffff816d4131>] ? cpuidle_enter_state+0x111/0x2b0 > [<ffffffff816d4307>] cpuidle_enter+0x17/0x20 > [<ffffffff810c4592>] call_cpuidle+0x32/0x60 > [<ffffffff816d42e3>] ? cpuidle_select+0x13/0x20 > [<ffffffff810c4850>] cpu_startup_entry+0x290/0x350 > [<ffffffff810517c4>] start_secondary+0x154/0x190 > ---[ end trace f0d076c2d7e8bb40 ]--- > > > This might be fixed by upstream Linux 4.5 commit "tcp: fix > tcp_mark_head_lost to check skb len before fragmenting". If so, would > you please consider backporting this patch to stable series Linux 4.4? Have you tested this to see if it does resolve the issue or not? That would be helpful :) thanks, greg k-h