====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz-executor/18100 is trying to acquire lock: ffff88802a692840 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: touch_work_lockdep_map kernel/workqueue.c:3955 [inline] ffff88802a692840 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4209 [inline] ffff88802a692840 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: __flush_work+0x4ca/0xcb0 kernel/workqueue.c:4241 but task is already holding lock: ffff88802a692b38 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x80/0x760 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+0x1a2/0x1b90 kernel/locking/mutex.c:776 l2cap_info_timeout+0x79/0xa0 net/bluetooth/l2cap_core.c:1669 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257 process_scheduled_works kernel/workqueue.c:3340 [inline] worker_thread+0x5da/0xe40 kernel/workqueue.c:3421 kthread+0x3b3/0x730 kernel/kthread.c:463 ret_from_fork+0x754/0xaf0 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x17c/0x330 kernel/locking/lockdep.c:5825 touch_work_lockdep_map kernel/workqueue.c:3955 [inline] start_flush_work kernel/workqueue.c:4209 [inline] __flush_work+0x4de/0xcb0 kernel/workqueue.c:4241 __cancel_work_sync kernel/workqueue.c:4397 [inline] cancel_delayed_work_sync+0xd1/0xf0 kernel/workqueue.c:4471 l2cap_conn_del+0x5c5/0x760 net/bluetooth/l2cap_core.c:1797 l2cap_disconn_cfm net/bluetooth/l2cap_core.c:7326 [inline] l2cap_disconn_cfm+0x9f/0x100 net/bluetooth/l2cap_core.c:7319 hci_disconn_cfm include/net/bluetooth/hci_core.h:2146 [inline] hci_conn_hash_flush+0x10e/0x280 net/bluetooth/hci_conn.c:2637 hci_dev_close_sync+0x5a7/0x1240 net/bluetooth/hci_sync.c:5327 hci_dev_do_close+0x2e/0xb0 net/bluetooth/hci_core.c:501 hci_unregister_dev+0x227/0x670 net/bluetooth/hci_core.c:2715 vhci_release+0x17d/0x230 drivers/bluetooth/hci_vhci.c:690 __fput+0x3ff/0xb40 fs/file_table.c:468 task_work_run+0x150/0x240 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x829/0x2a30 kernel/exit.c:971 do_group_exit+0xd5/0x2a0 kernel/exit.c:1112 __do_sys_exit_group kernel/exit.c:1123 [inline] __se_sys_exit_group kernel/exit.c:1121 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1121 x64_sys_call+0x14fd/0x1510 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94 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/18100: #0: ffff88805dd60ec0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:499 #1: ffff88805dd600c0 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x35c/0x1240 net/bluetooth/hci_sync.c:5315 #2: ffffffff9068c768 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2143 [inline] #2: ffffffff9068c768 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x280 net/bluetooth/hci_conn.c:2637 #3: ffff88802a692b38 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x80/0x760 net/bluetooth/l2cap_core.c:1763 #4: ffffffff8e5e32e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #4: ffffffff8e5e32e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #4: ffffffff8e5e32e0 (rcu_read_lock){....}-{1:3}, at: start_flush_work kernel/workqueue.c:4183 [inline] #4: ffffffff8e5e32e0 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xfd/0xcb0 kernel/workqueue.c:4241 stack backtrace: CPU: 0 UID: 0 PID: 18100 Comm: syz-executor Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x17c/0x330 kernel/locking/lockdep.c:5825 touch_work_lockdep_map kernel/workqueue.c:3955 [inline] start_flush_work kernel/workqueue.c:4209 [inline] __flush_work+0x4de/0xcb0 kernel/workqueue.c:4241 __cancel_work_sync kernel/workqueue.c:4397 [inline] cancel_delayed_work_sync+0xd1/0xf0 kernel/workqueue.c:4471 l2cap_conn_del+0x5c5/0x760 net/bluetooth/l2cap_core.c:1797 l2cap_disconn_cfm net/bluetooth/l2cap_core.c:7326 [inline] l2cap_disconn_cfm+0x9f/0x100 net/bluetooth/l2cap_core.c:7319 hci_disconn_cfm include/net/bluetooth/hci_core.h:2146 [inline] hci_conn_hash_flush+0x10e/0x280 net/bluetooth/hci_conn.c:2637 hci_dev_close_sync+0x5a7/0x1240 net/bluetooth/hci_sync.c:5327 hci_dev_do_close+0x2e/0xb0 net/bluetooth/hci_core.c:501 hci_unregister_dev+0x227/0x670 net/bluetooth/hci_core.c:2715 vhci_release+0x17d/0x230 drivers/bluetooth/hci_vhci.c:690 __fput+0x3ff/0xb40 fs/file_table.c:468 task_work_run+0x150/0x240 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x829/0x2a30 kernel/exit.c:971 do_group_exit+0xd5/0x2a0 kernel/exit.c:1112 __do_sys_exit_group kernel/exit.c:1123 [inline] __se_sys_exit_group kernel/exit.c:1121 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1121 x64_sys_call+0x14fd/0x1510 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f074859aeb9 Code: Unable to access opcode bytes at 0x7f074859ae8f. RSP: 002b:00007ffca4baab88 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f0748608125 RCX: 00007f074859aeb9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000043 RBP: 00007f0748608168 R08: 0000000000000000 R09: 000000000000002e R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 000000000000002e R14: 0000000000000025 R15: 00007ffca4baacc2