------------[ cut here ]------------
conntrack cleanup blocked for 60s
WARNING: net/netfilter/nf_conntrack_core.c:2504 at nf_conntrack_cleanup_net_list+0x4f7/0x6e0 net/netfilter/nf_conntrack_core.c:2504, CPU#2: kworker/u32:1/13
Modules linked in:
CPU: 2 UID: 0 PID: 13 Comm: kworker/u32:1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: netns cleanup_net
RIP: 0010:nf_conntrack_cleanup_net_list+0x4f7/0x6e0 net/netfilter/nf_conntrack_core.c:2504
Code: 29 c3 48 89 de e8 e9 35 1d f8 48 85 db 78 0f e8 3f 3b 1d f8 e8 0a 49 e5 01 e9 0e fc ff ff e8 30 3b 1d f8 48 8d 3d 39 67 66 08 <67> 48 0f b9 3a eb de 4c 8b 6c 24 40 e8 18 3b 1d f8 48 b8 00 00 00
RSP: 0018:ffffc900001f7950 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffffffffffffff RCX: 0000000000000000
RDX: ffff88801db48000 RSI: ffffffff89ee78e0 RDI: ffffffff9254e020
RBP: 0000000000000001 R08: 0000000000000007 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000001 R14: ffffc900001f7b08 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88809594a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f724f824 CR3: 000000006aaf7000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 ops_exit_list net/core/net_namespace.c:206 [inline]
 ops_undo_list+0x363/0xab0 net/core/net_namespace.c:253
 cleanup_net+0x499/0x920 net/core/net_namespace.c:706
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
 process_scheduled_works kernel/workqueue.c:3479 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
----------------
Code disassembly (best guess):
   0:	29 c3                	sub    %eax,%ebx
   2:	48 89 de             	mov    %rbx,%rsi
   5:	e8 e9 35 1d f8       	call   0xf81d35f3
   a:	48 85 db             	test   %rbx,%rbx
   d:	78 0f                	js     0x1e
   f:	e8 3f 3b 1d f8       	call   0xf81d3b53
  14:	e8 0a 49 e5 01       	call   0x1e54923
  19:	e9 0e fc ff ff       	jmp    0xfffffc2c
  1e:	e8 30 3b 1d f8       	call   0xf81d3b53
  23:	48 8d 3d 39 67 66 08 	lea    0x8666739(%rip),%rdi        # 0x8666763
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb de                	jmp    0xf
  31:	4c 8b 6c 24 40       	mov    0x40(%rsp),%r13
  36:	e8 18 3b 1d f8       	call   0xf81d3b53
  3b:	48                   	rex.W
  3c:	b8                   	.byte 0xb8
  3d:	00 00                	add    %al,(%rax)