====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/4418 is trying to acquire lock: ffff0000d0aa0c28 ((work_completion)(&hdev->bg_scan_update)){+.+.}-{0:0}, at: __flush_work+0xe4/0x1ec kernel/workqueue.c:3087 but task is already holding lock: ffff80001664a428 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_fop_write+0x240/0x5dc net/rfkill/core.c:1266 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (rfkill_global_mutex){+.+.}-{3:3}: __mutex_lock_common+0x194/0x1f14 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743 rfkill_register+0x44/0x77c net/rfkill/core.c:1045 hci_register_dev+0x3d8/0x850 net/bluetooth/hci_core.c:3964 __vhci_create_device drivers/bluetooth/hci_vhci.c:129 [inline] vhci_create_device+0x2bc/0x54c drivers/bluetooth/hci_vhci.c:153 vhci_get_user drivers/bluetooth/hci_vhci.c:210 [inline] vhci_write+0x30c/0x3ac drivers/bluetooth/hci_vhci.c:290 call_write_iter include/linux/fs.h:2173 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x590/0xa60 fs/read_write.c:594 ksys_write+0x12c/0x224 fs/read_write.c:647 __do_sys_write fs/read_write.c:659 [inline] __se_sys_write fs/read_write.c:656 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:656 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #3 (&data->open_mutex){+.+.}-{3:3}: __mutex_lock_common+0x194/0x1f14 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743 vhci_send_frame+0x88/0x118 drivers/bluetooth/hci_vhci.c:71 hci_send_frame+0x194/0x2ec net/bluetooth/hci_core.c:4260 hci_sched_acl_pkt net/bluetooth/hci_core.c:4785 [inline] hci_sched_acl net/bluetooth/hci_core.c:4870 [inline] hci_tx_work+0x7e0/0x1378 net/bluetooth/hci_core.c:4936 process_one_work+0x79c/0x1138 kernel/workqueue.c:2310 worker_thread+0x8f4/0x1034 kernel/workqueue.c:2457 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:856 -> #2 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}: __flush_work+0x10c/0x1ec kernel/workqueue.c:3090 flush_work+0x24/0x38 kernel/workqueue.c:3115 hci_dev_do_close+0x164/0xfe4 net/bluetooth/hci_core.c:1756 hci_unregister_dev+0x234/0x4a8 net/bluetooth/hci_core.c:4044 vhci_release+0x74/0xc4 drivers/bluetooth/hci_vhci.c:345 __fput+0x1c0/0x7e8 fs/file_table.c:311 ____fput+0x20/0x30 fs/file_table.c:339 task_work_run+0x12c/0x1d8 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x688/0x1f50 kernel/exit.c:883 do_group_exit+0x100/0x268 kernel/exit.c:997 get_signal+0x73c/0x1334 kernel/signal.c:2900 do_signal arch/arm64/kernel/signal.c:893 [inline] do_notify_resume+0x354/0x309c arch/arm64/kernel/signal.c:946 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_svc+0xf0/0x1d0 arch/arm64/kernel/entry-common.c:609 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #1 (&hdev->req_lock){+.+.}-{3:3}: __mutex_lock_common+0x194/0x1f14 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743 hci_req_sync net/bluetooth/hci_request.c:278 [inline] bg_scan_update+0x48/0x3d0 net/bluetooth/hci_request.c:2952 process_one_work+0x79c/0x1138 kernel/workqueue.c:2310 worker_thread+0x8f4/0x1034 kernel/workqueue.c:2457 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:856 -> #0 ((work_completion)(&hdev->bg_scan_update)){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2870/0x67ec kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x618 kernel/locking/lockdep.c:5623 __flush_work+0x10c/0x1ec kernel/workqueue.c:3090 __cancel_work_timer+0x300/0x458 kernel/workqueue.c:3181 cancel_work_sync+0x24/0x38 kernel/workqueue.c:3217 hci_request_cancel_all+0xbc/0x2c8 net/bluetooth/hci_request.c:3522 hci_dev_do_close+0x54/0xfe4 net/bluetooth/hci_core.c:1736 hci_rfkill_set_block+0xdc/0x1bc net/bluetooth/hci_core.c:2235 rfkill_set_block+0x18c/0x374 net/rfkill/core.c:345 rfkill_fop_write+0x4ac/0x5dc net/rfkill/core.c:1274 vfs_write+0x284/0xa60 fs/read_write.c:592 ksys_write+0x12c/0x224 fs/read_write.c:647 __do_sys_write fs/read_write.c:659 [inline] __se_sys_write fs/read_write.c:656 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:656 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 other info that might help us debug this: Chain exists of: (work_completion)(&hdev->bg_scan_update) --> &data->open_mutex --> rfkill_global_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(rfkill_global_mutex); lock(&data->open_mutex); lock(rfkill_global_mutex); lock((work_completion)(&hdev->bg_scan_update)); *** DEADLOCK *** 1 lock held by syz-executor.0/4418: #0: ffff80001664a428 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_fop_write+0x240/0x5dc net/rfkill/core.c:1266 stack backtrace: CPU: 0 PID: 4418 Comm: syz-executor.0 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call trace: dump_backtrace+0x0/0x458 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2011 check_noncircular+0x264/0x2f8 kernel/locking/lockdep.c:2133 check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2870/0x67ec kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x618 kernel/locking/lockdep.c:5623 __flush_work+0x10c/0x1ec kernel/workqueue.c:3090 __cancel_work_timer+0x300/0x458 kernel/workqueue.c:3181 cancel_work_sync+0x24/0x38 kernel/workqueue.c:3217 hci_request_cancel_all+0xbc/0x2c8 net/bluetooth/hci_request.c:3522 hci_dev_do_close+0x54/0xfe4 net/bluetooth/hci_core.c:1736 hci_rfkill_set_block+0xdc/0x1bc net/bluetooth/hci_core.c:2235 rfkill_set_block+0x18c/0x374 net/rfkill/core.c:345 rfkill_fop_write+0x4ac/0x5dc net/rfkill/core.c:1274 vfs_write+0x284/0xa60 fs/read_write.c:592 ksys_write+0x12c/0x224 fs/read_write.c:647 __do_sys_write fs/read_write.c:659 [inline] __se_sys_write fs/read_write.c:656 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:656 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584