------------[ cut here ]------------
Have pending ack frames!
WARNING: net/mac80211/main.c:1712 at ieee80211_free_ack_frame+0x14/0x30 net/mac80211/main.c:1712, CPU#2: kworker/u32:18/17917
Modules linked in:

CPU: 2 UID: 0 PID: 17917 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~bpo12+1 04/01/2014
Workqueue: netns cleanup_net
RIP: 0010:ieee80211_free_ack_frame+0x14/0x30 net/mac80211/main.c:1712
Code: ff ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 53 48 89 f3 e8 e3 36 dc f6 48 8d 3d 7c 8d b5 05 <67> 48 0f b9 3a ba 02 00 00 00 48 89 de 31 ff e8 38 02 5e fe 31 c0
RSP: 0018:ffffc90006db7820 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888058b84c80 RCX: ffffffff8b6d8cd3
RDX: ffff8880249924c0 RSI: ffffffff8ae2afad RDI: ffffffff90983d30
RBP: ffff8880277dc030 R08: 0000000000000007 R09: 000000007fffffff
R10: 0000000000000001 R11: 0000000000002ba1 R12: dffffc0000000000
R13: ffffffff8ae2afa0 R14: 0000000080000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880d6af5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c343d6a CR3: 0000000026363000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 idr_for_each+0x143/0x270 lib/idr.c:208
 ieee80211_free_hw+0x59/0x1d0 net/mac80211/main.c:1724
 mac80211_hwsim_del_radio drivers/net/wireless/virtual/mac80211_hwsim.c:5919 [inline]
 hwsim_exit_net+0x7d9/0x1590 drivers/net/wireless/virtual/mac80211_hwsim.c:6807
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x2ee/0xab0 net/core/net_namespace.c:252
 cleanup_net+0x41b/0x830 net/core/net_namespace.c:696
 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	0f 1f 40 00          	nopl   0x0(%rax)
   4:	90                   	nop
   5:	90                   	nop
   6:	90                   	nop
   7:	90                   	nop
   8:	90                   	nop
   9:	90                   	nop
   a:	90                   	nop
   b:	90                   	nop
   c:	90                   	nop
   d:	90                   	nop
   e:	90                   	nop
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	f3 0f 1e fa          	endbr64
  18:	53                   	push   %rbx
  19:	48 89 f3             	mov    %rsi,%rbx
  1c:	e8 e3 36 dc f6       	call   0xf6dc3704
  21:	48 8d 3d 7c 8d b5 05 	lea    0x5b58d7c(%rip),%rdi        # 0x5b58da4
* 28:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2d:	ba 02 00 00 00       	mov    $0x2,%edx
  32:	48 89 de             	mov    %rbx,%rsi
  35:	31 ff                	xor    %edi,%edi
  37:	e8 38 02 5e fe       	call   0xfe5e0274
  3c:	31 c0                	xor    %eax,%eax