------------[ cut here ]------------
conntrack cleanup blocked for 60s
WARNING: net/netfilter/nf_conntrack_core.c:2511 at nf_conntrack_cleanup_net_list+0x4f7/0x690 net/netfilter/nf_conntrack_core.c:2511, CPU#2: kworker/u32:18/13938
Modules linked in:
CPU: 2 UID: 0 PID: 13938 Comm: kworker/u32:18 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+0x4f7/0x690 net/netfilter/nf_conntrack_core.c:2511
Code: 29 c3 48 89 de e8 69 b8 6e f8 48 85 db 78 0f e8 7f bd 6e f8 e8 da 92 df 01 e9 0e fc ff ff e8 70 bd 6e f8 48 8d 3d 39 51 2d 07 <67> 48 0f b9 3a eb de 4c 8b 6c 24 40 e8 58 bd 6e f8 48 b8 00 00 00
RSP: 0018:ffffc90007e8f930 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffffffffffffff RCX: ffffffff89984277
RDX: ffff888033398000 RSI: ffffffff89984290 RDI: ffffffff90c593d0
RBP: 0000000000000001 R08: 0000000000000007 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000001 R14: ffffc90007e8fac0 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880d67dc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3f292c CR3: 0000000056269000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 ops_exit_list net/core/net_namespace.c:205 [inline]
 ops_undo_list+0x363/0xab0 net/core/net_namespace.c:252
 cleanup_net+0x419/0x830 net/core/net_namespace.c:696
 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
----------------
Code disassembly (best guess):
   0:	29 c3                	sub    %eax,%ebx
   2:	48 89 de             	mov    %rbx,%rsi
   5:	e8 69 b8 6e f8       	call   0xf86eb873
   a:	48 85 db             	test   %rbx,%rbx
   d:	78 0f                	js     0x1e
   f:	e8 7f bd 6e f8       	call   0xf86ebd93
  14:	e8 da 92 df 01       	call   0x1df92f3
  19:	e9 0e fc ff ff       	jmp    0xfffffc2c
  1e:	e8 70 bd 6e f8       	call   0xf86ebd93
  23:	48 8d 3d 39 51 2d 07 	lea    0x72d5139(%rip),%rdi        # 0x72d5163
* 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 58 bd 6e f8       	call   0xf86ebd93
  3b:	48                   	rex.W
  3c:	b8                   	.byte 0xb8
  3d:	00 00                	add    %al,(%rax)