[    8.919483] grep (1056) used greatest stack depth: 12536 bytes left
[   10.314657] ip (1075) used greatest stack depth: 12504 bytes left
[   10.342822] mptcp_connect (952) used greatest stack depth: 12496 bytes left
[   11.097042] mptcp_connect (1240) used greatest stack depth: 12456 bytes left
[   12.606232] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   12.606317] #PF: supervisor write access in kernel mode
[   12.606363] #PF: error_code(0x0002) - not-present page
[   12.606396] PGD 0 P4D 0 
[   12.606418] Oops: Oops: 0002 [#1] SMP
[   12.606450] CPU: 0 UID: 0 PID: 12 Comm: kworker/u16:0 Not tainted 6.18.0-rc5-virtme #1 PREEMPT(voluntary) 
[   12.606522] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   12.606573] Workqueue: netns cleanup_net
[   12.606611] RIP: 0010:work_grab_pending+0x2f/0x1b0
[   12.606656] Code: 83 e6 01 41 57 41 56 4c 8d 77 20 41 55 41 54 41 89 f4 55 48 89 d5 53 48 89 fb 9c 58 fa 48 89 45 00 45 85 e4 0f 85 8a 00 00 00 <f0> 48 0f ba 2b 00 41 0f 92 c5 72 0e 5b 44 89 e8 5d 41 5c 41 5d 41
[   12.606785] RSP: 0018:ffffad8500067bb8 EFLAGS: 00010046
[   12.606823] RAX: 0000000000000246 RBX: 0000000000000000 RCX: 00000000ffffffff
[   12.606883] RDX: ffffad8500067bf0 RSI: 0000000000000000 RDI: 0000000000000000
[   12.606935] RBP: ffffad8500067bf0 R08: ffffffff8ae779b0 R09: 0000000000000101
[   12.607002] R10: ffffffff8b6080d8 R11: ffffad8500003ff8 R12: 0000000000000000
[   12.607062] R13: ffffad8500067ce8 R14: 0000000000000020 R15: ffffad8500067df0
[   12.607118] FS:  0000000000000000(0000) GS:ffff919af2dc1000(0000) knlGS:0000000000000000
[   12.607172] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   12.607218] CR2: 0000000000000000 CR3: 000000002a447006 CR4: 0000000000772ef0
[   12.607275] PKRU: 55555554
[   12.607304] Call Trace:
[   12.607324]  <TASK>
[   12.607348]  __cancel_work+0x29/0xe0
[   12.607381]  ? dev_deactivate_many+0x2c9/0x300
[   12.607424]  __cancel_work_sync+0x16/0x80
[   12.607455]  __dev_close_many+0x11b/0x280
[   12.607491]  netif_close_many+0x98/0x160
[   12.607520]  unregister_netdevice_many_notify+0x1d8/0xa50
[   12.607565]  default_device_exit_batch+0x29b/0x300
[   12.607601]  ops_undo_list+0xec/0x1f0
[   12.607633]  cleanup_net+0x1b7/0x2b0
[   12.607662]  process_one_work+0x162/0x380
[   12.607707]  worker_thread+0x299/0x3c0
[   12.607740]  ? rescuer_thread+0x4c0/0x4c0
[   12.607771]  kthread+0x101/0x1f0
[   12.607801]  ? kthreads_online_cpu+0x110/0x110
[   12.607839]  ? kthreads_online_cpu+0x110/0x110
[   12.607881]  ret_from_fork+0x11c/0x140
[   12.607912]  ? kthreads_online_cpu+0x110/0x110
[   12.607955]  ret_from_fork_asm+0x11/0x20
[   12.607992]  </TASK>
[   12.608012] Modules linked in: tcp_diag mptcp_diag inet_diag
[   12.608071] CR2: 0000000000000000
[   12.608102] ---[ end trace 0000000000000000 ]---
[   12.608139] RIP: 0010:work_grab_pending+0x2f/0x1b0
[   12.608176] Code: 83 e6 01 41 57 41 56 4c 8d 77 20 41 55 41 54 41 89 f4 55 48 89 d5 53 48 89 fb 9c 58 fa 48 89 45 00 45 85 e4 0f 85 8a 00 00 00 <f0> 48 0f ba 2b 00 41 0f 92 c5 72 0e 5b 44 89 e8 5d 41 5c 41 5d 41
[   12.608300] RSP: 0018:ffffad8500067bb8 EFLAGS: 00010046
[   12.608350] RAX: 0000000000000246 RBX: 0000000000000000 RCX: 00000000ffffffff
[   12.608404] RDX: ffffad8500067bf0 RSI: 0000000000000000 RDI: 0000000000000000
[   12.608458] RBP: ffffad8500067bf0 R08: ffffffff8ae779b0 R09: 0000000000000101
[   12.608516] R10: ffffffff8b6080d8 R11: ffffad8500003ff8 R12: 0000000000000000
[   12.608574] R13: ffffad8500067ce8 R14: 0000000000000020 R15: ffffad8500067df0
[   12.608625] FS:  0000000000000000(0000) GS:ffff919af2dc1000(0000) knlGS:0000000000000000
[   12.608687] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   12.608738] CR2: 0000000000000000 CR3: 000000002a447006 CR4: 0000000000772ef0
[   12.608789] PKRU: 55555554
[   12.608806] note: kworker/u16:0[12] exited with irqs disabled