INFO: trying to register non-static key.
The code is fine but needs lockdep annotation, or maybe
you didn't initialize this object before use?
turning off the locking correctness validator.
CPU: 1 UID: 0 PID: 31936 Comm: khidpd_4c4a5505 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
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 assign_lock_key kernel/locking/lockdep.c:984 [inline]
 register_lock_class+0x497/0x4b0 kernel/locking/lockdep.c:1299
 __lock_acquire+0xa4/0x2890 kernel/locking/lockdep.c:5112
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
 class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:557 [inline]
 set_task_blocked_on include/linux/sched.h:2165 [inline]
 __mutex_lock_common kernel/locking/mutex.c:701 [inline]
 __mutex_lock+0xca5/0x1ca0 kernel/locking/mutex.c:776
 l2cap_unregister_user+0x71/0x240 net/bluetooth/l2cap_core.c:1729
 hidp_session_thread+0x45e/0x680 net/bluetooth/hidp/core.c:1304
 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>
 non-slab/vmalloc memory
list_del corruption. prev->next should be ffffc90007cb7bf0, but was 0000000000000000. (prev=ffff88806d4dc0a8)
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:62!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 1 UID: 0 PID: 31936 Comm: khidpd_4c4a5505 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
RIP: 0010:__list_del_entry_valid_or_report+0x17a/0x200 lib/list_debug.c:62
Code: 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 8d 00 00 00 48 8b 55 00 48 89 e9 48 89 de 48 c7 c7 20 bb f2 8b e8 17 5a e9 fc 90 <0f> 0b 4c 89 e7 e8 6c d5 4f fd 48 89 ea 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffffc90007cb7ac0 EFLAGS: 00010086
RAX: 000000000000006d RBX: ffffc90007cb7bf0 RCX: ffffffff819c19b5
RDX: 0000000000000000 RSI: ffffffff819c9599 RDI: 0000000000000005
RBP: ffff88806d4dc0a8 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000002 R11: 6c65645f7473696c R12: ffff88806d4dc0a8
R13: dffffc0000000000 R14: ffff88806d4dc058 R15: ffff88806d4dc058
FS:  0000000000000000(0000) GS:ffff8880977f9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f73e8098 CR3: 000000007175e000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __list_del_entry_valid include/linux/list.h:132 [inline]
 __list_del_entry include/linux/list.h:223 [inline]
 list_del include/linux/list.h:237 [inline]
 __mutex_remove_waiter+0x1a/0x1a0 kernel/locking/mutex.c:221
 __mutex_lock_common kernel/locking/mutex.c:742 [inline]
 __mutex_lock+0x12f6/0x1ca0 kernel/locking/mutex.c:776
 l2cap_unregister_user+0x71/0x240 net/bluetooth/l2cap_core.c:1729
 hidp_session_thread+0x45e/0x680 net/bluetooth/hidp/core.c:1304
 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>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__list_del_entry_valid_or_report+0x17a/0x200 lib/list_debug.c:62
Code: 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 8d 00 00 00 48 8b 55 00 48 89 e9 48 89 de 48 c7 c7 20 bb f2 8b e8 17 5a e9 fc 90 <0f> 0b 4c 89 e7 e8 6c d5 4f fd 48 89 ea 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffffc90007cb7ac0 EFLAGS: 00010086
RAX: 000000000000006d RBX: ffffc90007cb7bf0 RCX: ffffffff819c19b5
RDX: 0000000000000000 RSI: ffffffff819c9599 RDI: 0000000000000005
RBP: ffff88806d4dc0a8 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000002 R11: 6c65645f7473696c R12: ffff88806d4dc0a8
R13: dffffc0000000000 R14: ffff88806d4dc058 R15: ffff88806d4dc058
FS:  0000000000000000(0000) GS:ffff8880977f9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f73e8098 CR3: 000000007175e000 CR4: 0000000000352ef0