------------[ 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#1: kworker/u32:0/13581
Modules linked in:
CPU: 1 UID: 0 PID: 13581 Comm: kworker/u32:0 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 49 4a 5c f8 48 85 db 78 0f e8 5f 4f 5c f8 e8 da c7 e2 01 e9 0e fc ff ff e8 50 4f 5c f8 48 8d 3d f9 a4 3c 07 <67> 48 0f b9 3a eb de 4c 8b 6c 24 40 e8 38 4f 5c f8 48 b8 00 00 00
RSP: 0018:ffffc90004eff970 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffffffffffffff RCX: ffffffff89abc8f7
RDX: ffff8880276dc980 RSI: ffffffff89abc910 RDI: ffffffff90e86e10
RBP: 0000000000000001 R08: 0000000000000007 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000001 R14: ffffc90004effb28 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88809724a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f5453edc CR3: 000000006d555000 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+0x499/0x920 net/core/net_namespace.c:704
 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276
 process_scheduled_works kernel/workqueue.c:3359 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 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 49 4a 5c f8       	call   0xf85c4a53
   a:	48 85 db             	test   %rbx,%rbx
   d:	78 0f                	js     0x1e
   f:	e8 5f 4f 5c f8       	call   0xf85c4f73
  14:	e8 da c7 e2 01       	call   0x1e2c7f3
  19:	e9 0e fc ff ff       	jmp    0xfffffc2c
  1e:	e8 50 4f 5c f8       	call   0xf85c4f73
  23:	48 8d 3d f9 a4 3c 07 	lea    0x73ca4f9(%rip),%rdi        # 0x73ca523
* 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 38 4f 5c f8       	call   0xf85c4f73
  3b:	48                   	rex.W
  3c:	b8                   	.byte 0xb8
  3d:	00 00                	add    %al,(%rax)