Hello,

We have the same issue on our k8s cluster.

Description:    Ubuntu 16.04.3 LTS
Release:        16.04

Docker: 17.03.2-ce
Kubernetes: v1.10.11
Kernel: 4.4.0-145-generic, 4.4.0-109-generic


[5493817.706210] ------------[ cut here ]------------
[5493817.707602] kernel BUG at /build/linux-6VmqmP/linux-4.4.0/include/linux/fs.h:2585!
[5493817.708284] invalid opcode: 0000 [#1] SMP
[5493817.708935] Modules linked in: xt_set xt_multiport iptable_raw iptable_mangle ip_set_hash_net veth nf_conntrack_netlink xt_statistic xt_nat xt_recent ipt_REJECT nf_reject_ipv4 xt_tcpudp ip_set nfnetlink ip_vs ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6_tables xt_comment xt_mark ipt_MASQUERADE nf_nat_masquerade_ipv4 xfrm_user xfrm_algo iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 xt_addrtype iptable_filter ip_tables xt_conntrack x_tables nf_nat nf_conntrack br_netfilter bridge stp llc aufs vmw_balloon vmw_vsock_vmci_transport vsock joydev input_leds serio_raw shpchp i2c_piix4 vmw_vmci mac_hid ib_iser rdma_cm iw_cm ib_cm ib_sa ib_mad ib_core ib_addr sunrpc iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq
[5493817.714295]  async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel vmwgfx aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd ttm psmouse drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops vmxnet3 drm vmw_pvscsi ahci libahci pata_acpi fjes
[5493817.716942] CPU: 5 PID: 13487 Comm: iptables-save Not tainted 4.4.0-145-generic #171-Ubuntu
[5493817.717597] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/05/2016
[5493817.718885] task: ffff8800bb16d400 ti: ffff88045f38c000 task.ti: ffff88045f38c000
[5493817.719627] RIP: 0010:[<ffffffff8121df13>]  [<ffffffff8121df13>] __fput+0x223/0x230
[5493817.720314] RSP: 0018:ffff88045f38fe78  EFLAGS: 00010246
[5493817.721030] RAX: 0000000000000000 RBX: ffff88005f20e200 RCX: 00000000b86bfbc9
[5493817.721714] RDX: 0000000000000001 RSI: ffffe8ffffd51350 RDI: 0000000000000000
[5493817.722383] RBP: ffff88045f38feb0 R08: 000060f7c0011350 R09: ffffffff811beded
[5493817.723038] R10: ffffea000a9f3f00 R11: ffff88005f20e210 R12: 0000000000000010
[5493817.723695] R13: ffff880816bd11a8 R14: ffff8808130a1520 R15: ffff880816aaed80
[5493817.724371] FS:  00007f6087f8b700(0000) GS:ffff88083fd40000(0000) knlGS:0000000000000000
[5493817.725147] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[5493817.725835] CR2: 00007f6085f6d1f0 CR3: 00000004621e2000 CR4: 0000000000060670
[5493817.726518] Stack:
[5493817.727156]  ffff880816bd11a8 ffff88005f20e210 ffffffff82113f30 ffff8800bb16daa8
[5493817.727806]  ffff8800bb16d400 0000000000000000 ffff8800bb16d400 ffff88045f38fec0
[5493817.728508]  ffffffff8121df5e ffff88045f38fef0 ffffffff810a4895 0000000000000002
[5493817.729138] Call Trace:
[5493817.729845]  [<ffffffff8121df5e>] ____fput+0xe/0x10
[5493817.730511]  [<ffffffff810a4895>] task_work_run+0x95/0xb0
[5493817.731222]  [<ffffffff81003532>] exit_to_usermode_loop+0xc2/0xd0
[5493817.731875]  [<ffffffff81003c7e>] syscall_return_slowpath+0x4e/0x60
[5493817.732579]  [<ffffffff818629d3>] int_ret_from_sys_call+0x25/0xa3
[5493817.733214] Code: fe ff ff 48 8b 43 28 48 8b 80 80 00 00 00 48 85 c0 0f 84 b8 fe ff ff 31 d2 48 89 de bf ff ff ff ff e8 32 a5 64 00 e9 a4 fe ff ff <0f> 0b 90 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 31 ff 48
[5493817.735013] RIP  [<ffffffff8121df13>] __fput+0x223/0x230
[5493817.735582]  RSP <ffff88045f38fe78>