INFO: task hung in hci_conn_del_sysfs

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a8ad60f2af58 Linux 4.14.305
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=133e4a10c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=2f23dc9802022031
dashboard link: https://syzkaller.appspot.com/bug?extid=8872a104b6d01f552923
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c38348fd389d/disk-a8ad60f2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3a775d221689/vmlinux-a8ad60f2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/32e71e04d2b4/bzImage-a8ad60f2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8872a1...@syzkaller.appspotmail.com

INFO: task syz-executor.3:8033 blocked for more than 140 seconds.
Not tainted 4.14.305-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3 D25072 8033 1 0x80000006
Call Trace:
context_switch kernel/sched/core.c:2811 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3386
schedule+0x8d/0x1b0 kernel/sched/core.c:3430
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3488
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x669/0x1310 kernel/locking/mutex.c:893
kobject_uevent_env+0x755/0xf30 lib/kobject_uevent.c:460
device_del+0x642/0xa80 drivers/base/core.c:2097
hci_conn_del_sysfs+0xca/0x160 net/bluetooth/hci_sysfs.c:81
hci_conn_cleanup+0x216/0x500 net/bluetooth/hci_conn.c:128
hci_conn_del+0x253/0x6f0 net/bluetooth/hci_conn.c:611
hci_conn_hash_flush+0x19c/0x260 net/bluetooth/hci_conn.c:1394
hci_dev_do_close+0x57d/0xd80 net/bluetooth/hci_core.c:1642
hci_unregister_dev+0x143/0x420 net/bluetooth/hci_core.c:3210
vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:354
__fput+0x25f/0x7a0 fs/file_table.c:210
task_work_run+0x11f/0x190 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0xa44/0x2850 kernel/exit.c:915


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