System crash during IO errors on nbd devices

Issue

• During the issues in connectivity to nbd devices, the IOs started failing with following errors. Shortly after these errors, the system got crashed:

  block nbd1: Connection timed out, retrying (3/3 alive)
  block nbd1: Connection timed out, retrying (2/3 alive)
  block nbd1: Receive control failed (result -32)
  block nbd1: Connection timed out, retrying (2/3 alive)
  block nbd1: Connection timed out, retrying (1/3 alive)
  block nbd1: Receive control failed (result -32)
  block nbd1: NBD_DISCONNECT
  block nbd1: Send disconnect failed -32
  block nbd1: Send disconnect failed -32
  block nbd1: Disconnected due to user request.
  block nbd1: shutting down sockets
  block nbd1: Connection timed out, retrying (0/3 alive)
  block nbd1: Connection timed out, retrying (0/3 alive)
  BUG: unable to handle kernel NULL pointer dereference at 0000000000000118
  PGD 8000000107920067 
  blk_update_request: I/O error, dev nbd1, sector 7632 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
  [...]
  block nbd1: NBD_DISCONNECT
  Oops: 0000 [#1] SMP PTI
  CPU: 0 PID: 108135 Comm: kworker/0:0H Kdump: loaded Tainted: G        W         -------- -  - 4.18.0-553.8.1.el8_10.x86_64 #1
  Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020
  Workqueue: kblockd blk_mq_requeue_work
  block nbd1: Send disconnect failed -32        
  RIP: 0010:dd_insert_requests+0x30/0x330
  block nbd1: Send disconnect failed -32
  Code: 57 41 56 41 55 41 54 55 53 48 83 ec 40 48 89 7c 24 10 48 89 34 24 88 54 24 1f 65 48 8b 04 25 28 00 00 00 48 89 44 24 38 31 c0 <48> 8b 87 18 01 00 00 48 8b 40 18 48 8b 40 08 48 05 20 01 00 00 48
  RSP: 0018:ffffad702d3f7d80 EFLAGS: 00010246
  RAX: 0000000000000000 RBX: ffffa02f65844990 RCX: ffffa02f658449d8
  block nbd1: Send disconnect failed -32
  RDX: 0000000000000001 RSI: ffffad702d3f7e00 RDI: 0000000000000000
  XFS (dm-15): log I/O error -5
  RBP: 0000000000000001 R08: ffffad702d3f7e00 R09: 00646b636f6c626b
  R10: 8080808080808080 R11: ffffffffa685c048 R12: ffffa02e9679d400
  R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
  FS:  0000000000000000(0000) GS:ffffa0355fc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000118 CR3: 0000000107924000 CR4: 00000000000006f0
  Call Trace:
   ? __die_body+0x1a/0x60
   ? no_context+0x1ba/0x3f0
   ? __bad_area_nosemaphore+0x157/0x180
   ? insert_work+0x65/0xc0
   ? do_page_fault+0x37/0x12d
   ? page_fault+0x1e/0x30
   ? dd_insert_requests+0x30/0x330
   blk_mq_sched_insert_request+0xc2/0x140
   blk_mq_requeue_work+0x10d/0x180
   process_one_work+0x1d3/0x390
   ? process_one_work+0x390/0x390
   worker_thread+0x30/0x390
   ? process_one_work+0x390/0x390
   kthread+0x134/0x150
   ? set_kthread_struct+0x50/0x50
   ret_from_fork+0x35/0x40