------------[ cut here ]------------
refcnt < 0
WARNING: net/bluetooth/hci_conn.c:631 at hci_conn_timeout+0xff/0x2c0, CPU#1: kworker/u11:1/4988
Modules linked in:
CPU: 1 UID: 0 PID: 4988 Comm: kworker/u11:1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: hci0 hci_conn_timeout
RIP: 0010:hci_conn_timeout+0xff/0x2c0
Code: 48 89 df e8 b3 c3 09 00 eb 07 e8 2c a7 03 f7 b0 13 0f b6 f0 48 89 df 5b 41 5c 41 5e 41 5f 5d e9 57 a1 fe ff e8 12 a7 03 f7 90 <0f> 0b 90 eb 8c 44 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 31 ff ff ff
RSP: 0018:ffffc900075efad0 EFLAGS: 00010293
RAX: ffffffff8ac3442e RBX: ffff88819d9b0000 RCX: ffff88816d6c3c00
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 0000000000000000
RBP: 00000000ffffffff R08: ffff88819d9b0013 R09: 1ffff11033b36002
R10: dffffc0000000000 R11: ffffed1033b36003 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff88819d9b0a40 R15: ffff88819d9b0010
FS:  0000000000000000(0000) GS:ffff8882a8f5c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f972ae70000 CR3: 000000000e946000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 process_scheduled_works+0xa8e/0x14e0
 worker_thread+0xa47/0xfb0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
