RHEL7.5: ログに nfsd: last server has exited, flushing export cache が表示された直後に svc_sock にアクセスする rx 割り込みハンドラーで Linux NFS サーバーカーネルがクラッシュする

Issue

ファイルの制限に達したというメッセージ VFS: file-max limit 19513468 reached が定期的に表示されます。 次に、このメッセージのしばらく後、そして "nfsd: last server has exited, flushing export cache" メッセージのほぼ直後に、ixgbe ドライバーの Rx 側の割り込みハンドラーでマシンがクラッシュします。 TCP 受信の処理中で、svc_tcp_listen_data_ready を呼び出していました。

crash> bt
PID: 0      TASK: ffff9ce73a284f10  CPU: 2   COMMAND: "swapper/2"
 #0 [ffff9ce9cfc83730] machine_kexec at ffffffffb2e6178a
 #1 [ffff9ce9cfc83790] __crash_kexec at ffffffffb2f13bf2
 #2 [ffff9ce9cfc83860] crash_kexec at ffffffffb2f13ce0
 #3 [ffff9ce9cfc83878] oops_end at ffffffffb3518728
 #4 [ffff9ce9cfc838a0] die at ffffffffb2e2e96b
 #5 [ffff9ce9cfc838d0] do_general_protection at ffffffffb35180de
 #6 [ffff9ce9cfc83900] general_protection at ffffffffb35176f8
    [exception RIP: __x86_indirect_thunk_rax+0xa]
    RIP: ffffffffb315b00a  RSP: ffff9ce9cfc839b0  RFLAGS: 00010286
    RAX: 310000009edd0402  RBX: ffff9ce9cc287000  RCX: 00000001b6b4cb71
    RDX: 00000001b6b4cb70  RSI: 0000000000000000  RDI: ffff9ce5c7878f80
    RBP: ffff9ce9cfc839d0   R8: 000000000001bb00   R9: ffffffffb33d5457
    R10: ffff9ce9cfc9bb00  R11: fffff41b40772080  R12: ffff9ce5c7878f80
    R13: 0000000000000000  R14: ffff9ce5ddc82b00  R15: ffff9ce5c7879648
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #7 [ffff9ce9cfc839b0] svc_tcp_listen_data_ready at ffffffffc04137ab [sunrpc]
 #8 [ffff9ce9cfc839d8] tcp_data_queue at ffffffffb3449ead
 #9 [ffff9ce9cfc83a30] tcp_rcv_established at ffffffffb344d1e7
#10 [ffff9ce9cfc83a80] tcp_v4_do_rcv at ffffffffb3457e6a
#11 [ffff9ce9cfc83ac8] tcp_v4_rcv at ffffffffb34595f8
#12 [ffff9ce9cfc83b60] ip_local_deliver_finish at ffffffffb3432729
#13 [ffff9ce9cfc83b88] ip_local_deliver at ffffffffb3432a19
#14 [ffff9ce9cfc83be0] ip_rcv_finish at ffffffffb3432390
#15 [ffff9ce9cfc83c08] ip_rcv at ffffffffb3432d49
#16 [ffff9ce9cfc83c70] __netif_receive_skb_core at ffffffffb33ecab9
#17 [ffff9ce9cfc83ce0] __netif_receive_skb at ffffffffb33ecdc8
#18 [ffff9ce9cfc83d00] netif_receive_skb_internal at ffffffffb33ece50
#19 [ffff9ce9cfc83d30] napi_gro_receive at ffffffffb33eda78
#20 [ffff9ce9cfc83d58] ixgbe_clean_rx_irq at ffffffffc03a5360 [ixgbe]
#21 [ffff9ce9cfc83de0] ixgbe_poll at ffffffffc03a660e [ixgbe]
#22 [ffff9ce9cfc83e78] net_rx_action at ffffffffb33ed46f
#23 [ffff9ce9cfc83ef8] __do_softirq at ffffffffb2e9b085
#24 [ffff9ce9cfc83f68] call_softirq at ffffffffb3523cec
#25 [ffff9ce9cfc83f80] do_softirq at ffffffffb2e2d625
#26 [ffff9ce9cfc83fa0] irq_exit at ffffffffb2e9b405
#27 [ffff9ce9cfc83fb8] do_IRQ at ffffffffb3524f86
--- <IRQ stack> ---
#28 [ffff9ce73a29bdb8] ret_from_intr at ffffffffb3517362
    [exception RIP: cpuidle_enter_state+0x54]
    RIP: ffffffffb3369e84  RSP: ffff9ce73a29be60  RFLAGS: 00000202
    RAX: 000ad9879bbe3afe  RBX: ffff9ce73a29be40  RCX: 0000000000000018
    RDX: 0000000225c17d03  RSI: 0000000000000002  RDI: 000ad9879bbe3afe
    RBP: ffff9ce73a29be88   R8: 000000000000037a   R9: 0000000000000018
    R10: 00000000000003d3  R11: 7fffffffffffffff  R12: 0000000000000002
    R13: ffff9ce9cfc93a20  R14: ffffffffb2ebee35  R15: ffff9ce73a29bde0
    ORIG_RAX: ffffffffffffff97  CS: 0010  SS: 0018
#29 [ffff9ce73a29be90] cpuidle_idle_call at ffffffffb3369fde
#30 [ffff9ce73a29bed0] arch_cpu_idle at ffffffffb2e356de
#31 [ffff9ce73a29bee0] cpu_startup_entry at ffffffffb2ef335a
#32 [ffff9ce73a29bf28] start_secondary at ffffffffb2e55f97
#33 [ffff9ce73a29bf50] start_cpu at ffffffffb2e000d5