System hangs and vsapiapp process blocked in call_usermodehelper_exec() via nfs_idmap_get_key() due to splxmod

Issue

• System hangs and the following messages are shown:

  INFO: task vsapiapp:660298 blocked for more than 120 seconds.
        Tainted: G           OE    --------- -  - 4.18.0-305.17.1.el8_4.x86_64 #1
  "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  vsapiapp        D    0 660298      1 0x00004080
  Call Trace:
   __schedule+0x2c4/0x700
   schedule+0x38/0xa0
   schedule_timeout+0x246/0x2f0
   ? try_to_wake_up+0x1cd/0x540
   wait_for_completion+0x97/0x100
   call_usermodehelper_exec+0x12e/0x160
   call_sbin_request_key+0x264/0x340
   ? request_key_auth_new+0x1b0/0x1e0
   request_key_and_link+0x310/0x660
   ? keyring_alloc+0x60/0x60
   ? key_default_cmp+0x20/0x20
   request_key+0x3c/0x80
   nfs_idmap_get_key+0x130/0x1e0 [nfsv4]
   nfs_idmap_lookup_id+0x30/0x80 [nfsv4]
   ? nfs4_run_open_task+0x149/0x180 [nfsv4]
   nfs_map_group_to_gid+0x11f/0x140 [nfsv4]
   nfs_fattr_map_and_free_names+0xad/0xf0 [nfsv4]
   nfs4_do_open+0x767/0xa40 [nfsv4]
   nfs4_atomic_open+0xeb/0x100 [nfsv4]
   nfs4_file_open+0xfb/0x220 [nfsv4]
   ? nfs42_fallocate+0x80/0x80 [nfsv4]
   do_dentry_open+0x132/0x340
   path_openat+0x53e/0x14f0
   ? __wake_up_common_lock+0x89/0xc0
   ? __rpc_sleep_on_priority_timeout+0xe0/0xe0 [sunrpc]
   ? __ia32_sys_open+0x20/0x20
   do_filp_open+0x93/0x100
   ? getname_flags+0x4a/0x1e0
   ? __check_object_size+0xa8/0x16b
   do_sys_open+0x184/0x220
   ? __ia32_sys_open+0x20/0x20
   open_hook_comm+0x1ed/0x940 [splxmod]
   ? nfs_access_add_cache+0x2f/0x290 [nfs]
   ? kmem_cache_alloc_trace+0x131/0x270
   ? nfs_access_add_cache+0xec/0x290 [nfs]
   ? nfs_do_access+0xf9/0x260 [nfs]
   ? syscall_trace_enter+0x1d3/0x2c0
   ? __audit_syscall_exit+0x249/0x2a0
   do_syscall_64+0x5b/0x1a0
   entry_SYSCALL_64_after_hwframe+0x65/0xca
  RIP: 0033:0x7f6a2b0f2761
  Code: Unable to access opcode bytes at RIP 0x7f6a2b0f2737.
  RSP: 002b:00007f6a29b02660 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
  RAX: ffffffffffffffda RBX: 00007f6a0c01ca70 RCX: 00007f6a2b0f2761
  RDX: 0000000000000000 RSI: 00007f6a0c019240 RDI: 00000000ffffff9c
  RBP: 00007f6a29b03530 R08: 0000000000000000 R09: 00007f6a0c000a24
  R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
  R13: 00007f6a29b02710 R14: 00007f6a29b03530 R15: 000000000000003c