INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
CPU: 0 PID: 6848 Comm: kworker/0:3 Not tainted 5.9.0-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+0xa3/0xc8 lib/dump_stack.c:118
 assign_lock_key kernel/locking/lockdep.c:933 [inline]
 register_lock_class+0x575/0x580 kernel/locking/lockdep.c:1245
 __lock_acquire+0x75/0x1770 kernel/locking/lockdep.c:4716
 lock_acquire+0xf9/0x420 kernel/locking/lockdep.c:5442
 __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+0x2c/0x90 net/core/sock.c:3048
 l2cap_sock_teardown_cb+0x20/0x160 net/bluetooth/l2cap_sock.c:1520
 l2cap_chan_del+0x35/0x320 net/bluetooth/l2cap_core.c:618
 l2cap_chan_close+0xfb/0x270 net/bluetooth/l2cap_core.c:823
 l2cap_chan_timeout+0x70/0xe0 net/bluetooth/l2cap_core.c:436
 process_one_work+0x273/0x600 kernel/workqueue.c:2269
 worker_thread+0x38/0x380 kernel/workqueue.c:2415
 kthread+0x148/0x170 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 0 P4D 0 
Oops: 0010 [#1] PREEMPT SMP
CPU: 0 PID: 6848 Comm: kworker/0:3 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90000e37d88 EFLAGS: 00010246
RAX: 0000000000000005 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000001 RSI: ffffffff840abdb6 RDI: ffff88810f8a9000
RBP: ffff88810f8a9000 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000001aa40 R11: 0000000000000000 R12: 000000000000006f
R13: ffff88810e117800 R14: 0000000000000000 R15: ffff88810e117918
FS:  0000000000000000(0000) GS:ffff88812c000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000123737000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 l2cap_sock_teardown_cb+0x143/0x160 net/bluetooth/l2cap_sock.c:1547
 l2cap_chan_del+0x35/0x320 net/bluetooth/l2cap_core.c:618
 l2cap_chan_close+0xfb/0x270 net/bluetooth/l2cap_core.c:823
 l2cap_chan_timeout+0x70/0xe0 net/bluetooth/l2cap_core.c:436
 process_one_work+0x273/0x600 kernel/workqueue.c:2269
 worker_thread+0x38/0x380 kernel/workqueue.c:2415
 kthread+0x148/0x170 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Modules linked in:
CR2: 0000000000000000
---[ end trace adb7cb1a2a48bfb7 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90000e37d88 EFLAGS: 00010246
RAX: 0000000000000005 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000001 RSI: ffffffff840abdb6 RDI: ffff88810f8a9000
RBP: ffff88810f8a9000 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000001aa40 R11: 0000000000000000 R12: 000000000000006f
R13: ffff88810e117800 R14: 0000000000000000 R15: ffff88810e117918
FS:  0000000000000000(0000) GS:ffff88812c000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000123737000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400