====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc1-syzkaller-g0af2f6be1b42 #0 Not tainted ------------------------------------------------------ syz-executor/7788 is trying to acquire lock: ffff0000c9ea3040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: touch_work_lockdep_map+0x74/0x11c kernel/workqueue.c:3922 but task is already holding lock: ffff0000c9ea3338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x78/0x518 net/bluetooth/l2cap_core.c:1761 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+0x1f0/0x2604 kernel/locking/mutex.c:601 __mutex_lock kernel/locking/mutex.c:746 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:798 l2cap_info_timeout+0x74/0xb4 net/bluetooth/l2cap_core.c:1667 process_one_work+0x810/0x1638 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x97c/0xf08 kernel/workqueue.c:3400 kthread+0x674/0x7dc kernel/kthread.c:464 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862 -> #0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x17b8/0x32c4 kernel/locking/lockdep.c:5235 lock_acquire+0x150/0x2e8 kernel/locking/lockdep.c:5866 touch_work_lockdep_map+0x9c/0x11c kernel/workqueue.c:3922 start_flush_work kernel/workqueue.c:4176 [inline] __flush_work+0x57c/0x958 kernel/workqueue.c:4208 __cancel_work_sync kernel/workqueue.c:4364 [inline] cancel_delayed_work_sync+0xc4/0x120 kernel/workqueue.c:4438 l2cap_conn_del+0x384/0x518 net/bluetooth/l2cap_core.c:1795 l2cap_disconn_cfm+0x90/0xe0 net/bluetooth/l2cap_core.c:7299 hci_disconn_cfm include/net/bluetooth/hci_core.h:2069 [inline] hci_conn_hash_flush+0x100/0x220 net/bluetooth/hci_conn.c:2701 hci_dev_close_sync+0x8a4/0x1158 net/bluetooth/hci_sync.c:5225 hci_dev_do_close net/bluetooth/hci_core.c:483 [inline] hci_unregister_dev+0x1f8/0x4b8 net/bluetooth/hci_core.c:2678 vhci_release+0x7c/0xd0 drivers/bluetooth/hci_vhci.c:665 __fput+0x340/0x760 fs/file_table.c:465 ____fput+0x20/0x58 fs/file_table.c:493 task_work_run+0x230/0x2e0 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x4e8/0x1a20 kernel/exit.c:953 do_group_exit+0x194/0x22c kernel/exit.c:1102 __do_sys_exit_group kernel/exit.c:1113 [inline] __se_sys_exit_group kernel/exit.c:1111 [inline] pid_child_should_wake+0x0/0x1dc kernel/exit.c:1111 __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+0x54/0x168 arch/arm64/kernel/entry-common.c:744 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 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/7788: #0: ffff0000d0328d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:481 [inline] #0: ffff0000d0328d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x1f0/0x4b8 net/bluetooth/hci_core.c:2678 #1: ffff0000d0328078 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x4c8/0x1158 net/bluetooth/hci_sync.c:5213 #2: ffff8000931e7b68 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2066 [inline] #2: ffff8000931e7b68 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xac/0x220 net/bluetooth/hci_conn.c:2701 #3: ffff0000c9ea3338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x78/0x518 net/bluetooth/l2cap_core.c:1761 #4: ffff800090127de0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:330 stack backtrace: CPU: 1 UID: 0 PID: 7788 Comm: syz-executor Not tainted 6.15.0-rc1-syzkaller-g0af2f6be1b42 #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C) __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x32c/0x334 kernel/locking/lockdep.c:2079 check_noncircular+0x15c/0x178 kernel/locking/lockdep.c:2211 check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x17b8/0x32c4 kernel/locking/lockdep.c:5235 lock_acquire+0x150/0x2e8 kernel/locking/lockdep.c:5866 touch_work_lockdep_map+0x9c/0x11c kernel/workqueue.c:3922 start_flush_work kernel/workqueue.c:4176 [inline] __flush_work+0x57c/0x958 kernel/workqueue.c:4208 __cancel_work_sync kernel/workqueue.c:4364 [inline] cancel_delayed_work_sync+0xc4/0x120 kernel/workqueue.c:4438 l2cap_conn_del+0x384/0x518 net/bluetooth/l2cap_core.c:1795 l2cap_disconn_cfm+0x90/0xe0 net/bluetooth/l2cap_core.c:7299 hci_disconn_cfm include/net/bluetooth/hci_core.h:2069 [inline] hci_conn_hash_flush+0x100/0x220 net/bluetooth/hci_conn.c:2701 hci_dev_close_sync+0x8a4/0x1158 net/bluetooth/hci_sync.c:5225 hci_dev_do_close net/bluetooth/hci_core.c:483 [inline] hci_unregister_dev+0x1f8/0x4b8 net/bluetooth/hci_core.c:2678 vhci_release+0x7c/0xd0 drivers/bluetooth/hci_vhci.c:665 __fput+0x340/0x760 fs/file_table.c:465 ____fput+0x20/0x58 fs/file_table.c:493 task_work_run+0x230/0x2e0 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x4e8/0x1a20 kernel/exit.c:953 do_group_exit+0x194/0x22c kernel/exit.c:1102 __do_sys_exit_group kernel/exit.c:1113 [inline] __se_sys_exit_group kernel/exit.c:1111 [inline] pid_child_should_wake+0x0/0x1dc kernel/exit.c:1111 __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+0x54/0x168 arch/arm64/kernel/entry-common.c:744 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600