====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc6-syzkaller-00253-g4871b7cb27f4 #0 Not tainted ------------------------------------------------------ kworker/u9:1/19660 is trying to acquire lock: ffff88807d22f840 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: touch_work_lockdep_map kernel/workqueue.c:3924 [inline] ffff88807d22f840 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4178 [inline] ffff88807d22f840 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: __flush_work+0x4d0/0xcc0 kernel/workqueue.c:4210 but task is already holding lock: ffff88807d22fb38 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x80/0x730 net/bluetooth/l2cap_core.c:1762 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&conn->lock#2){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:747 l2cap_info_timeout+0x79/0xa0 net/bluetooth/l2cap_core.c:1668 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3321 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402 kthread+0x3c5/0x780 kernel/kthread.c:464 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5240 lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828 touch_work_lockdep_map kernel/workqueue.c:3924 [inline] start_flush_work kernel/workqueue.c:4178 [inline] __flush_work+0x4e4/0xcc0 kernel/workqueue.c:4210 __cancel_work_sync+0x10c/0x130 kernel/workqueue.c:4366 l2cap_conn_del+0x5af/0x730 net/bluetooth/l2cap_core.c:1796 l2cap_connect_cfm+0x9e1/0xf80 net/bluetooth/l2cap_core.c:7259 hci_connect_cfm include/net/bluetooth/hci_core.h:2059 [inline] hci_conn_failed+0x1bd/0x330 net/bluetooth/hci_conn.c:1275 hci_abort_conn_sync+0x762/0xb10 net/bluetooth/hci_sync.c:5689 abort_conn_sync+0x197/0x360 net/bluetooth/hci_conn.c:2885 hci_cmd_sync_work+0x1ab/0x430 net/bluetooth/hci_sync.c:332 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3321 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402 kthread+0x3c5/0x780 kernel/kthread.c:464 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&conn->lock#2); lock((work_completion)(&(&conn->info_timer)->work)); lock(&conn->lock#2); lock((work_completion)(&(&conn->info_timer)->work)); *** DEADLOCK *** 7 locks held by kworker/u9:1/19660: #0: ffff888052df9948 ((wq_completion)hci6){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213 #1: ffffc9000ef57d10 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214 #2: ffff88807a770dc0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_cmd_sync_work+0x175/0x430 net/bluetooth/hci_sync.c:331 #3: ffff88807a7700b8 (&hdev->lock){+.+.}-{4:4}, at: hci_abort_conn_sync+0x13f/0xb10 net/bluetooth/hci_sync.c:5670 #4: ffffffff905d15a8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2056 [inline] #4: ffffffff905d15a8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_failed+0x14f/0x330 net/bluetooth/hci_conn.c:1275 #5: ffff88807d22fb38 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x80/0x730 net/bluetooth/l2cap_core.c:1762 #6: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #6: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #6: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: start_flush_work kernel/workqueue.c:4152 [inline] #6: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xfb/0xcc0 kernel/workqueue.c:4210 stack backtrace: CPU: 0 UID: 0 PID: 19660 Comm: kworker/u9:1 Not tainted 6.16.0-rc6-syzkaller-00253-g4871b7cb27f4 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: hci6 hci_cmd_sync_work Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2046 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5240 lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828 touch_work_lockdep_map kernel/workqueue.c:3924 [inline] start_flush_work kernel/workqueue.c:4178 [inline] __flush_work+0x4e4/0xcc0 kernel/workqueue.c:4210 __cancel_work_sync+0x10c/0x130 kernel/workqueue.c:4366 l2cap_conn_del+0x5af/0x730 net/bluetooth/l2cap_core.c:1796 l2cap_connect_cfm+0x9e1/0xf80 net/bluetooth/l2cap_core.c:7259 hci_connect_cfm include/net/bluetooth/hci_core.h:2059 [inline] hci_conn_failed+0x1bd/0x330 net/bluetooth/hci_conn.c:1275 hci_abort_conn_sync+0x762/0xb10 net/bluetooth/hci_sync.c:5689 abort_conn_sync+0x197/0x360 net/bluetooth/hci_conn.c:2885 hci_cmd_sync_work+0x1ab/0x430 net/bluetooth/hci_sync.c:332 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3321 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402 kthread+0x3c5/0x780 kernel/kthread.c:464 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Bluetooth: hci6: command 0x041b tx timeout Bluetooth: hci6: command 0x041b tx timeout