内核崩溃，RIP hash_net4_test

Issue

• 内核崩溃，RIP hash_net4_test
• NULL 指针在 ipset 中 dereference，带有类似如下的回溯信息：

crash> bt
PID: 0      TASK: ffff8afef238a100  CPU: 43  COMMAND: "swapper/43"
 #0 [ffff8b2bff4c3530] machine_kexec at ffffffffb12662c4
 #1 [ffff8b2bff4c3590] __crash_kexec at ffffffffb1322802
 #2 [ffff8b2bff4c3660] crash_kexec at ffffffffb13228f0
 #3 [ffff8b2bff4c3678] oops_end at ffffffffb198b798
 #4 [ffff8b2bff4c36a0] no_context at ffffffffb1275d14
 #5 [ffff8b2bff4c36f0] __bad_area_nosemaphore at ffffffffb1275fe2
 #6 [ffff8b2bff4c3740] bad_area_nosemaphore at ffffffffb1276104
 #7 [ffff8b2bff4c3750] __do_page_fault at ffffffffb198e750
 #8 [ffff8b2bff4c37c0] do_page_fault at ffffffffb198e975
 #9 [ffff8b2bff4c37f0] page_fault at ffffffffb198a778
    [exception RIP: hash_net4_kadt+0x4f]
    RIP: ffffffffc09f414f  RSP: ffff8b2bff4c38a8  RFLAGS: 00010246
    RAX: 0000000000000000  RBX: ffffffffc09f6190  RCX: 0000000000000006
    RDX: ffffffffc09fa4c0  RSI: ffff8b11691e6c00  RDI: ffff8b5b7b8bf2c0
    RBP: ffff8b2bff4c3908   R8: ffff8b2bff4c3950   R9: 0000000000000020
    R10: ffff8b5b7b8bf2c0  R11: ffffffffc02c55f8  R12: 0000000000000002
    R13: ffff8b11691e6c00  R14: ffff8b2bff4c3a80  R15: ffff8b11691e6c00
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
#10 [ffff8b2bff4c3910] ip_set_test at ffffffffc0895cc0 [ip_set]
#11 [ffff8b2bff4c3948] set_match_v4 at ffffffffc0914dc0 [xt_set]
#12 [ffff8b2bff4c39a0] ipt_do_table at ffffffffc02c0640 [ip_tables]
#13 [ffff8b2bff4c3af0] iptable_filter_hook at ffffffffc0720036 [iptable_filter]
#14 [ffff8b2bff4c3b00] nf_iterate at ffffffffb1894a48
#15 [ffff8b2bff4c3b40] nf_hook_slow at ffffffffb1894b38
#16 [ffff8b2bff4c3b78] ip_local_deliver at ffffffffb189f206
#17 [ffff8b2bff4c3bd8] ip_rcv_finish at ffffffffb189eb10
#18 [ffff8b2bff4c3c00] ip_rcv at ffffffffb189f4e0
#19 [ffff8b2bff4c3c70] __netif_receive_skb_core at ffffffffb1854829
#20 [ffff8b2bff4c3ce8] __netif_receive_skb at ffffffffb1854b28
#21 [ffff8b2bff4c3d08] netif_receive_skb_internal at ffffffffb1854bb0
#22 [ffff8b2bff4c3d38] napi_gro_receive at ffffffffb1855838
... (NIC receive here)