------------[ cut here ]------------
conntrack cleanup blocked for 60s
WARNING: net/netfilter/nf_conntrack_core.c:2503 at nf_conntrack_cleanup_net_list+0x7ed/0xa20 net/netfilter/nf_conntrack_core.c:2503, CPU#2: kworker/u32:4/9376
Modules linked in:
CPU: 2 UID: 0 PID: 9376 Comm: kworker/u32:4 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+0x7ed/0xa20 net/netfilter/nf_conntrack_core.c:2503
Code: 29 c3 48 89 de e8 a3 e0 0d f8 48 85 db 78 0f e8 f9 e5 0d f8 e8 54 3b e8 01 e9 1a f9 ff ff e8 ea e5 0d f8 48 8d 3d d3 21 78 08 <67> 48 0f b9 3a eb de 4c 8b 7c 24 38 e8 d2 e5 0d f8 48 c7 c7 a0 97
RSP: 0018:ffffc9000c3af958 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffffffffffffff RCX: 0000000000000000
RDX: ffff88803699a580 RSI: ffffffff8a003526 RDI: ffffffff92785700
RBP: 0000000000000001 R08: 0000000000000007 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000000 R12: 0000000000000001
R13: ffffc9000c3afb00 R14: dffffc0000000000 R15: fffffbfff24d3c77
FS:  0000000000000000(0000) GS:ffff8880d46ac000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe7021d4ff8 CR3: 000000000fd96000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 ops_exit_list net/core/net_namespace.c:206 [inline]
 ops_undo_list+0x35e/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:3495
 process_scheduled_works kernel/workqueue.c:3578 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3659
 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 a3 e0 0d f8       	call   0xf80de0ad
   a:	48 85 db             	test   %rbx,%rbx
   d:	78 0f                	js     0x1e
   f:	e8 f9 e5 0d f8       	call   0xf80de60d
  14:	e8 54 3b e8 01       	call   0x1e83b6d
  19:	e9 1a f9 ff ff       	jmp    0xfffff938
  1e:	e8 ea e5 0d f8       	call   0xf80de60d
  23:	48 8d 3d d3 21 78 08 	lea    0x87821d3(%rip),%rdi        # 0x87821fd
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb de                	jmp    0xf
  31:	4c 8b 7c 24 38       	mov    0x38(%rsp),%r15
  36:	e8 d2 e5 0d f8       	call   0xf80de60d
  3b:	48                   	rex.W
  3c:	c7                   	.byte 0xc7
  3d:	c7                   	(bad)
  3e:	a0                   	.byte 0xa0
  3f:	97                   	xchg   %eax,%edi