======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/0:5/6619 is trying to acquire lock:
ffff0000c8644338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_info_timeout+0x70/0xb0 net/bluetooth/l2cap_core.c:1668

but task is already holding lock:
ffff8000a4397be0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: process_one_work+0x6d4/0x155c kernel/workqueue.c:3237

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}:
       touch_work_lockdep_map+0x98/0x118 kernel/workqueue.c:3951
       start_flush_work kernel/workqueue.c:4205 [inline]
       __flush_work+0x4fc/0x8c0 kernel/workqueue.c:4237
       __cancel_work_sync kernel/workqueue.c:4393 [inline]
       cancel_delayed_work_sync+0xc4/0x120 kernel/workqueue.c:4467
       l2cap_conn_del+0x460/0x5f0 net/bluetooth/l2cap_core.c:1796
       l2cap_connect_cfm+0x110/0xd40 net/bluetooth/l2cap_core.c:7259
       hci_connect_cfm include/net/bluetooth/hci_core.h:2107 [inline]
       hci_conn_failed+0x198/0x318 net/bluetooth/hci_conn.c:1319
       hci_abort_conn_sync+0x558/0xbb8 net/bluetooth/hci_sync.c:5703
       abort_conn_sync+0x58/0x88 net/bluetooth/hci_conn.c:2934
       hci_cmd_sync_work+0x1bc/0x33c net/bluetooth/hci_sync.c:332
       process_one_work+0x7e8/0x155c kernel/workqueue.c:3263
       process_scheduled_works kernel/workqueue.c:3346 [inline]
       worker_thread+0x958/0xed8 kernel/workqueue.c:3427
       kthread+0x5fc/0x75c kernel/kthread.c:463
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844

-> #0 (&conn->lock#2){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237
       lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868
       __mutex_lock_common+0x1d0/0x2678 kernel/locking/mutex.c:598
       __mutex_lock kernel/locking/mutex.c:760 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:812
       l2cap_info_timeout+0x70/0xb0 net/bluetooth/l2cap_core.c:1668
       process_one_work+0x7e8/0x155c kernel/workqueue.c:3263
       process_scheduled_works kernel/workqueue.c:3346 [inline]
       worker_thread+0x958/0xed8 kernel/workqueue.c:3427
       kthread+0x5fc/0x75c kernel/kthread.c:463
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock((work_completion)(&(&conn->info_timer)->work));
                               lock(&conn->lock#2);
                               lock((work_completion)(&(&conn->info_timer)->work));
  lock(&conn->lock#2);

 *** DEADLOCK ***

2 locks held by kworker/0:5/6619:
 #0: ffff0000c0029948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x63c/0x155c kernel/workqueue.c:3237
 #1: ffff8000a4397be0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: process_one_work+0x6d4/0x155c kernel/workqueue.c:3237

stack backtrace:
CPU: 0 UID: 0 PID: 6619 Comm: kworker/0:5 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
Workqueue: events l2cap_info_timeout
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack+0x30/0x40 lib/dump_stack.c:94
 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_circular_bug+0x324/0x32c kernel/locking/lockdep.c:2043
 check_noncircular+0x154/0x174 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237
 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868
 __mutex_lock_common+0x1d0/0x2678 kernel/locking/mutex.c:598
 __mutex_lock kernel/locking/mutex.c:760 [inline]
 mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:812
 l2cap_info_timeout+0x70/0xb0 net/bluetooth/l2cap_core.c:1668
 process_one_work+0x7e8/0x155c kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x958/0xed8 kernel/workqueue.c:3427
 kthread+0x5fc/0x75c kernel/kthread.c:463
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844