INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
CPU: 1 PID: 8149 Comm: kworker/1:4 Not tainted 5.9.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 assign_lock_key kernel/locking/lockdep.c:894 [inline]
 register_lock_class+0x157d/0x1630 kernel/locking/lockdep.c:1206
 __lock_acquire+0xf9/0x5640 kernel/locking/lockdep.c:4305
 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:5005
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175
 spin_lock_bh include/linux/spinlock.h:359 [inline]
 lock_sock_nested+0x3b/0x110 net/core/sock.c:3048
 l2cap_sock_teardown_cb+0x88/0x400 net/bluetooth/l2cap_sock.c:1520
 l2cap_chan_del+0xad/0x1300 net/bluetooth/l2cap_core.c:618
 l2cap_chan_close+0x118/0xb10 net/bluetooth/l2cap_core.c:823
 l2cap_chan_timeout+0x173/0x450 net/bluetooth/l2cap_core.c:436
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
==================================================================
BUG: KASAN: use-after-free in debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline]
BUG: KASAN: use-after-free in do_raw_spin_lock+0x262/0x2b0 kernel/locking/spinlock_debug.c:112
Read of size 4 at addr ffff88809f07208c by task kworker/1:4/8149

CPU: 1 PID: 8149 Comm: kworker/1:4 Not tainted 5.9.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline]
 do_raw_spin_lock+0x262/0x2b0 kernel/locking/spinlock_debug.c:112
 spin_lock_bh include/linux/spinlock.h:359 [inline]
 lock_sock_nested+0x3b/0x110 net/core/sock.c:3048
 l2cap_sock_teardown_cb+0x88/0x400 net/bluetooth/l2cap_sock.c:1520
 l2cap_chan_del+0xad/0x1300 net/bluetooth/l2cap_core.c:618
 l2cap_chan_close+0x118/0xb10 net/bluetooth/l2cap_core.c:823
 l2cap_chan_timeout+0x173/0x450 net/bluetooth/l2cap_core.c:436
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

The buggy address belongs to the page:
page:000000009ab5b0dd refcount:1 mapcount:-1024 mapping:0000000000000000 index:0x0 pfn:0x9f072
flags: 0xfffe0000000000()
raw: 00fffe0000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000000 ffff8880a1f69600 00000001fffffbff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809f071f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809f072000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88809f072080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                      ^
 ffff88809f072100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88809f072180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================