====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc1-next-20250408-syzkaller #0 Not tainted ------------------------------------------------------ syz.2.157/6694 is trying to acquire lock: ffff88802951f040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] ffff88802951f040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] ffff88802951f040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4150 [inline] ffff88802951f040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: __flush_work+0xee/0xc60 kernel/workqueue.c:4208 but task is already holding lock: ffff88802951f338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x71/0x690 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}: lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x1a5/0x10c0 kernel/locking/mutex.c:746 l2cap_info_timeout+0x60/0xa0 net/bluetooth/l2cap_core.c:1667 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319 worker_thread+0x870/0xd50 kernel/workqueue.c:3400 kthread+0x7b7/0x940 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #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+0xa69/0x24e0 kernel/locking/lockdep.c:3909 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 touch_work_lockdep_map kernel/workqueue.c:3922 [inline] start_flush_work kernel/workqueue.c:4176 [inline] __flush_work+0x75b/0xc60 kernel/workqueue.c:4208 __cancel_work_sync+0xbc/0x110 kernel/workqueue.c:4364 l2cap_conn_del+0x507/0x690 net/bluetooth/l2cap_core.c:1795 hci_disconn_cfm include/net/bluetooth/hci_core.h:2069 [inline] hci_conn_hash_flush+0xff/0x240 net/bluetooth/hci_conn.c:2701 hci_dev_close_sync+0xa8d/0x1260 net/bluetooth/hci_sync.c:5225 hci_dev_do_close net/bluetooth/hci_core.c:483 [inline] hci_dev_close+0x112/0x210 net/bluetooth/hci_core.c:508 sock_do_ioctl+0x15a/0x490 net/socket.c:1190 sock_ioctl+0x644/0x900 net/socket.c:1311 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 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.2.157/6694: #0: ffff88803299cd80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:481 [inline] #0: ffff88803299cd80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_close+0x10a/0x210 net/bluetooth/hci_core.c:508 #1: ffff88803299c078 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x60f/0x1260 net/bluetooth/hci_sync.c:5213 #2: ffffffff902662e8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2066 [inline] #2: ffffffff902662e8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xa6/0x240 net/bluetooth/hci_conn.c:2701 #3: ffff88802951f338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x71/0x690 net/bluetooth/l2cap_core.c:1761 #4: ffffffff8ed3d200 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #4: ffffffff8ed3d200 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #4: ffffffff8ed3d200 (rcu_read_lock){....}-{1:3}, at: start_flush_work kernel/workqueue.c:4150 [inline] #4: ffffffff8ed3d200 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xee/0xc60 kernel/workqueue.c:4208 stack backtrace: CPU: 0 UID: 0 PID: 6694 Comm: syz.2.157 Not tainted 6.15.0-rc1-next-20250408-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2079 check_noncircular+0x142/0x160 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+0xa69/0x24e0 kernel/locking/lockdep.c:3909 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 touch_work_lockdep_map kernel/workqueue.c:3922 [inline] start_flush_work kernel/workqueue.c:4176 [inline] __flush_work+0x75b/0xc60 kernel/workqueue.c:4208 __cancel_work_sync+0xbc/0x110 kernel/workqueue.c:4364 l2cap_conn_del+0x507/0x690 net/bluetooth/l2cap_core.c:1795 hci_disconn_cfm include/net/bluetooth/hci_core.h:2069 [inline] hci_conn_hash_flush+0xff/0x240 net/bluetooth/hci_conn.c:2701 hci_dev_close_sync+0xa8d/0x1260 net/bluetooth/hci_sync.c:5225 hci_dev_do_close net/bluetooth/hci_core.c:483 [inline] hci_dev_close+0x112/0x210 net/bluetooth/hci_core.c:508 sock_do_ioctl+0x15a/0x490 net/socket.c:1190 sock_ioctl+0x644/0x900 net/socket.c:1311 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8a28b8d169 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8a2999c038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f8a28da6080 RCX: 00007f8a28b8d169 RDX: 0000000000000000 RSI: 00000000400448ca RDI: 0000000000000004 RBP: 00007f8a28c0e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f8a28da6080 R15: 00007ffd20ad73b8