On Tue, Jun 27, 2017 at 4:31 AM, Greg KH <greg@xxxxxxxxx> wrote: > 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 Hi. I do not have a reproducible test case to trigger this warning. However, I have not seen this on Ubuntu 4.8 kernels yet. I am hoping one of the maintainers might better definitively say if this patch could address this warning. In addition, this netdev thread suggests that the original author is okay with this patch being backported to 4.4. https://www.mail-archive.com/netdev@xxxxxxxxxxxxxxx/msg121600.html Cheers, Vinson