====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc7-syzkaller-g82af5ea7c611 #0 Not tainted ------------------------------------------------------ syz-executor/8906 is trying to acquire lock: ffff0000f2ab7040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: touch_work_lockdep_map+0x70/0x118 kernel/workqueue.c:3922 but task is already holding lock: ffff0000f2ab7338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x74/0x5f0 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+0x1d0/0x2190 kernel/locking/mutex.c:602 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:799 l2cap_info_timeout+0x70/0xb0 net/bluetooth/l2cap_core.c:1668 process_one_work+0x7e8/0x155c kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3321 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3402 kthread+0x5fc/0x75c kernel/kthread.c:464 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 -> #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+0x1774/0x30a4 kernel/locking/lockdep.c:5240 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5871 touch_work_lockdep_map+0x98/0x118 kernel/workqueue.c:3924 start_flush_work kernel/workqueue.c:4178 [inline] __flush_work+0x4fc/0x8c0 kernel/workqueue.c:4210 __cancel_work_sync kernel/workqueue.c:4366 [inline] cancel_delayed_work_sync+0xc4/0x120 kernel/workqueue.c:4440 l2cap_conn_del+0x460/0x5f0 net/bluetooth/l2cap_core.c:1796 l2cap_disconn_cfm+0x90/0xe0 net/bluetooth/l2cap_core.c:7325 hci_disconn_cfm include/net/bluetooth/hci_core.h:2074 [inline] hci_conn_hash_flush+0x104/0x214 net/bluetooth/hci_conn.c:2560 hci_dev_close_sync+0x89c/0x1154 net/bluetooth/hci_sync.c:5294 hci_dev_do_close net/bluetooth/hci_core.c:501 [inline] hci_unregister_dev+0x200/0x4bc net/bluetooth/hci_core.c:2717 vhci_release+0x7c/0xd0 drivers/bluetooth/hci_vhci.c:665 __fput+0x340/0x75c fs/file_table.c:465 ____fput+0x20/0x58 fs/file_table.c:493 task_work_run+0x1dc/0x260 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x524/0x19fc kernel/exit.c:964 do_group_exit+0x194/0x22c kernel/exit.c:1105 __do_sys_exit_group kernel/exit.c:1116 [inline] __se_sys_exit_group kernel/exit.c:1114 [inline] pid_child_should_wake+0x0/0x1dc kernel/exit.c:1114 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 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 *** 5 locks held by syz-executor/8906: #0: ffff0000c9d68dc0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:499 [inline] #0: ffff0000c9d68dc0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x1f8/0x4bc net/bluetooth/hci_core.c:2717 #1: ffff0000c9d680b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x4c4/0x1154 net/bluetooth/hci_sync.c:5282 #2: ffff800092a307a8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2071 [inline] #2: ffff800092a307a8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xac/0x214 net/bluetooth/hci_conn.c:2560 #3: ffff0000f2ab7338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x74/0x5f0 net/bluetooth/l2cap_core.c:1762 #4: ffff80008f869980 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:330 stack backtrace: CPU: 0 UID: 0 PID: 8906 Comm: syz-executor Not tainted 6.16.0-rc7-syzkaller-g82af5ea7c611 #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 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:2046 check_noncircular+0x154/0x174 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+0x1774/0x30a4 kernel/locking/lockdep.c:5240 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5871 touch_work_lockdep_map+0x98/0x118 kernel/workqueue.c:3924 start_flush_work kernel/workqueue.c:4178 [inline] __flush_work+0x4fc/0x8c0 kernel/workqueue.c:4210 __cancel_work_sync kernel/workqueue.c:4366 [inline] cancel_delayed_work_sync+0xc4/0x120 kernel/workqueue.c:4440 l2cap_conn_del+0x460/0x5f0 net/bluetooth/l2cap_core.c:1796 l2cap_disconn_cfm+0x90/0xe0 net/bluetooth/l2cap_core.c:7325 hci_disconn_cfm include/net/bluetooth/hci_core.h:2074 [inline] hci_conn_hash_flush+0x104/0x214 net/bluetooth/hci_conn.c:2560 hci_dev_close_sync+0x89c/0x1154 net/bluetooth/hci_sync.c:5294 hci_dev_do_close net/bluetooth/hci_core.c:501 [inline] hci_unregister_dev+0x200/0x4bc net/bluetooth/hci_core.c:2717 vhci_release+0x7c/0xd0 drivers/bluetooth/hci_vhci.c:665 __fput+0x340/0x75c fs/file_table.c:465 ____fput+0x20/0x58 fs/file_table.c:493 task_work_run+0x1dc/0x260 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x524/0x19fc kernel/exit.c:964 do_group_exit+0x194/0x22c kernel/exit.c:1105 __do_sys_exit_group kernel/exit.c:1116 [inline] __se_sys_exit_group kernel/exit.c:1114 [inline] pid_child_should_wake+0x0/0x1dc kernel/exit.c:1114 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596