====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz-executor/18339 is trying to acquire lock: ffff8880672fb840 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] ffff8880672fb840 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] ffff8880672fb840 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4183 [inline] ffff8880672fb840 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: __flush_work+0xd2/0xbc0 kernel/workqueue.c:4241 but task is already holding lock: ffff8880672fbb38 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x70/0x680 net/bluetooth/l2cap_core.c:1763 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:614 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:776 l2cap_info_timeout+0x60/0xa0 net/bluetooth/l2cap_core.c:1669 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 -> #0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}: 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+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868 touch_work_lockdep_map kernel/workqueue.c:3955 [inline] start_flush_work kernel/workqueue.c:4209 [inline] __flush_work+0x6b8/0xbc0 kernel/workqueue.c:4241 __cancel_work_sync+0xbe/0x110 kernel/workqueue.c:4397 l2cap_conn_del+0x4f3/0x680 net/bluetooth/l2cap_core.c:1797 hci_disconn_cfm include/net/bluetooth/hci_core.h:2146 [inline] hci_conn_hash_flush+0x10d/0x230 net/bluetooth/hci_conn.c:2637 hci_dev_close_sync+0x821/0xff0 net/bluetooth/hci_sync.c:5326 hci_dev_do_close net/bluetooth/hci_core.c:501 [inline] hci_unregister_dev+0x21a/0x510 net/bluetooth/hci_core.c:2715 vhci_release+0x152/0x1a0 drivers/bluetooth/hci_vhci.c:690 __fput+0x44c/0xa70 fs/file_table.c:468 task_work_run+0x1d4/0x260 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x6c5/0x2310 kernel/exit.c:973 do_group_exit+0x21c/0x2d0 kernel/exit.c:1114 get_signal+0x1285/0x1340 kernel/signal.c:3034 arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline] exit_to_user_mode_loop+0x87/0x4f0 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2e3/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f 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/18339: #0: ffff888059bb8ec0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:499 [inline] #0: ffff888059bb8ec0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x212/0x510 net/bluetooth/hci_core.c:2715 #1: ffff888059bb80c0 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x640/0xff0 net/bluetooth/hci_sync.c:5314 #2: ffffffff8f467308 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2143 [inline] #2: ffffffff8f467308 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xa1/0x230 net/bluetooth/hci_conn.c:2637 #3: ffff8880672fbb38 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x70/0x680 net/bluetooth/l2cap_core.c:1763 #4: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #4: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #4: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: start_flush_work kernel/workqueue.c:4183 [inline] #4: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xd2/0xbc0 kernel/workqueue.c:4241 stack backtrace: CPU: 1 UID: 0 PID: 18339 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 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+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868 touch_work_lockdep_map kernel/workqueue.c:3955 [inline] start_flush_work kernel/workqueue.c:4209 [inline] __flush_work+0x6b8/0xbc0 kernel/workqueue.c:4241 __cancel_work_sync+0xbe/0x110 kernel/workqueue.c:4397 l2cap_conn_del+0x4f3/0x680 net/bluetooth/l2cap_core.c:1797 hci_disconn_cfm include/net/bluetooth/hci_core.h:2146 [inline] hci_conn_hash_flush+0x10d/0x230 net/bluetooth/hci_conn.c:2637 hci_dev_close_sync+0x821/0xff0 net/bluetooth/hci_sync.c:5326 hci_dev_do_close net/bluetooth/hci_core.c:501 [inline] hci_unregister_dev+0x21a/0x510 net/bluetooth/hci_core.c:2715 vhci_release+0x152/0x1a0 drivers/bluetooth/hci_vhci.c:690 __fput+0x44c/0xa70 fs/file_table.c:468 task_work_run+0x1d4/0x260 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x6c5/0x2310 kernel/exit.c:973 do_group_exit+0x21c/0x2d0 kernel/exit.c:1114 get_signal+0x1285/0x1340 kernel/signal.c:3034 arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline] exit_to_user_mode_loop+0x87/0x4f0 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2e3/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f527ed915dc Code: Unable to access opcode bytes at 0x7f527ed915b2. RSP: 002b:00007fff44a59100 EFLAGS: 00000293 ORIG_RAX: 000000000000002c RAX: 0000000000000038 RBX: 00007f527fb14620 RCX: 00007f527ed915dc RDX: 0000000000000038 RSI: 00007f527fb14670 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007fff44a59154 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003 R13: 0000000000000000 R14: 00007f527fb14670 R15: 0000000000000000