Hi,

I got this on 4.4.0-116-generic :

[266447.178906] ------------[ cut here ]------------
[266447.178919] WARNING: CPU: 0 PID: 3343 at /build/linux-fQ94TU/linux-4.4.0/net/core/dev.c:2448 skb_warn_bad_offload+0xd1/0x120()
[266447.178924] qr-8a4bd2f3-04: caps=(0x00000184075b59e9, 0x00000184075b59e9) len=2058 data_len=582 gso_size=1406 gso_type=1 ip_summed=3
[266447.178926] Modules linked in: kpatch_livepatch_Ubuntu_4_4_0_116_140_generic_36(OE) xt_REDIRECT nf_nat_redirect ip6table_mangle xt_nat xt_mark xt_connmark ip6table_raw iptable_raw ip_gre ip_tunnel gre xt_recent ip6t_REJECT nf_reject_ipv6 nf_log_ipv6 xt_hl ip6t_rt nf_conntrack_ipv6 ipt_REJECT nf_reject_ipv4 nf_log_ipv4 nf_log_common xt_LOG xt_limit xt_addrtype xt_conntrack dccp_diag dccp tcp_diag udp_diag inet_diag unix_diag veth netlink_diag nbd ip6table_filter ip6_tables xt_CHECKSUM iptable_mangle xt_tcpudp ipt_MASQUERADE nf_nat_masquerade_ipv4 xt_comment iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat iptable_filter ip_tables x_tables openvswitch nf_defrag_ipv6 nf_conntrack binfmt_misc ipmi_ssif intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel bridge stp kvm llc
[266447.178988]  irqbypass sb_edac edac_core ipmi_si hpilo ipmi_msghandler serio_raw 8250_fintek lpc_ich shpchp acpi_power_meter ioatdma mac_hid dca ib_iser rdma_cm iw_cm ib_cm ib_sa ib_mad ib_core ib_addr iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd psmouse tg3 ptp pps_core hpsa scsi_transport_sas wmi fjes
[266447.179045] CPU: 0 PID: 3343 Comm: haproxy Tainted: G        W  OE K 4.4.0-116-generic #140-Ubuntu
[266447.179048] Hardware name: HP ProLiant DL360 Gen9/ProLiant DL360 Gen9, BIOS P89 01/22/2018
[266447.179050]  0000000000000286 6f5737dc927d16dd ffff880a3646b818 ffffffff813ffc13
[266447.179055]  ffff880a3646b860 ffffffff81d715e8 ffff880a3646b850 ffffffff810830f2
[266447.179059]  ffff880064507ce8 ffff880b4ff12000 0000000000000001 ffff8808723268fc
[266447.179064] Call Trace:
[266447.179072]  [<ffffffff813ffc13>] dump_stack+0x63/0x90
[266447.179079]  [<ffffffff810830f2>] warn_slowpath_common+0x82/0xc0
[266447.179084]  [<ffffffff8108318c>] warn_slowpath_fmt+0x5c/0x80
[266447.179090]  [<ffffffff81405d92>] ? ___ratelimit+0xa2/0xe0
[266447.179094]  [<ffffffff8173ff81>] skb_warn_bad_offload+0xd1/0x120
[266447.179100]  [<ffffffff81740155>] skb_checksum_help+0x185/0x1a0
[266447.179106]  [<ffffffffc0524072>] checksum_tg+0x22/0x29 [xt_CHECKSUM]
[266447.179112]  [<ffffffffc03a4e21>] ipt_do_table+0x301/0x720 [ip_tables]
[266447.179117]  [<ffffffffc03a4e69>] ? ipt_do_table+0x349/0x720 [ip_tables]
[266447.179122]  [<ffffffff810bae37>] ? enqueue_entity+0x3a7/0xd20
[266447.179129]  [<ffffffffc04980c9>] iptable_mangle_hook+0x39/0x107 [iptable_mangle]
[266447.179134]  [<ffffffff81778e48>] nf_iterate+0x68/0x80
[266447.179137]  [<ffffffff81778ed3>] nf_hook_slow+0x73/0xd0
[266447.179143]  [<ffffffff8178642f>] ip_output+0xcf/0xe0
[266447.179148]  [<ffffffff81785880>] ? __ip_flush_pending_frames.isra.42+0x90/0x90
[266447.179153]  [<ffffffff81785b8b>] ip_local_out+0x3b/0x50
[266447.179158]  [<ffffffff81785eb4>] ip_queue_xmit+0x154/0x380
[266447.179164]  [<ffffffff8179e2bb>] tcp_transmit_skb+0x51b/0x980
[266447.179169]  [<ffffffff8179e8f6>] tcp_write_xmit+0x1d6/0xf40
[266447.179174]  [<ffffffff8179f8f1>] __tcp_push_pending_frames+0x31/0xd0
[266447.179178]  [<ffffffff8178d7ec>] tcp_push+0xec/0x110
[266447.179181]  [<ffffffff81791969>] tcp_sendmsg+0x739/0xb80
[266447.179186]  [<ffffffff817bd91b>] inet_sendmsg+0x6b/0xa0
[266447.179192]  [<ffffffff81724b5e>] sock_sendmsg+0x3e/0x50
[266447.179196]  [<ffffffff81725151>] SYSC_sendto+0x101/0x190
[266447.179203]  [<ffffffff81003938>] ? syscall_trace_enter_phase1+0xc8/0x140
[266447.179208]  [<ffffffff81725c7e>] SyS_sendto+0xe/0x10
[266447.179215]  [<ffffffff8184efc8>] entry_SYSCALL_64_fastpath+0x1c/0xbb
[266447.179218] ---[ end trace 4c054fa8d617289c ]---


Joseph, can we maybe get a new kernel to test ? The one in your last comment is gone.

Note that this isn't appearing a lot (~10 occurrences on a server with 3 days of uptime)