====================================================== WARNING: possible circular locking dependency detected 6.16.0-syzkaller-10499-g89748acdf226 #0 Not tainted ------------------------------------------------------ kworker/0:3/5314 is trying to acquire lock: ffff888040225b38 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_info_timeout+0x60/0xa0 net/bluetooth/l2cap_core.c:1668 but task is already holding lock: ffffc9000fc67bc0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline] ffffc9000fc67bc0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 touch_work_lockdep_map kernel/workqueue.c:3922 [inline] start_flush_work kernel/workqueue.c:4176 [inline] __flush_work+0x6b8/0xbc0 kernel/workqueue.c:4208 __cancel_work_sync+0xbe/0x110 kernel/workqueue.c:4364 l2cap_conn_del+0x4f0/0x680 net/bluetooth/l2cap_core.c:1796 l2cap_connect_cfm+0x11d/0x1040 net/bluetooth/l2cap_core.c:7259 hci_connect_cfm include/net/bluetooth/hci_core.h:2050 [inline] hci_conn_failed+0x1ce/0x310 net/bluetooth/hci_conn.c:1278 hci_abort_conn_sync+0x658/0xe30 net/bluetooth/hci_sync.c:5689 hci_disconnect_all_sync+0x1b5/0x350 net/bluetooth/hci_sync.c:5712 hci_suspend_sync+0x3b8/0xbf0 net/bluetooth/hci_sync.c:6188 hci_suspend_dev+0x28d/0x4d0 net/bluetooth/hci_core.c:2849 hci_suspend_notifier+0xf2/0x290 net/bluetooth/hci_core.c:2420 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85 notifier_call_chain_robust kernel/notifier.c:120 [inline] blocking_notifier_call_chain_robust+0x85/0x100 kernel/notifier.c:345 pm_notifier_call_chain_robust+0x2c/0x60 kernel/power/main.c:103 snapshot_open+0x19c/0x280 kernel/power/user.c:77 misc_open+0x2b9/0x330 drivers/char/misc.c:161 chrdev_open+0x4c9/0x5e0 fs/char_dev.c:414 do_dentry_open+0x950/0x13f0 fs/open.c:965 vfs_open+0x3b/0x340 fs/open.c:1095 do_open fs/namei.c:3887 [inline] path_openat+0x2ee5/0x3830 fs/namei.c:4046 do_filp_open+0x1fa/0x410 fs/namei.c:4073 do_sys_openat2+0x121/0x1c0 fs/open.c:1435 do_sys_open fs/open.c:1450 [inline] __do_sys_openat fs/open.c:1466 [inline] __se_sys_openat fs/open.c:1461 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1461 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&conn->lock#2){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1340 kernel/locking/mutex.c:760 l2cap_info_timeout+0x60/0xa0 net/bluetooth/l2cap_core.c:1668 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((work_completion)(&(&conn->info_timer)->work)); lock(&conn->lock#2); lock((work_completion)(&(&conn->info_timer)->work)); lock(&conn->lock#2); *** DEADLOCK *** 2 locks held by kworker/0:3/5314: #0: ffff88801a474d48 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline] #0: ffff88801a474d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319 #1: ffffc9000fc67bc0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline] #1: ffffc9000fc67bc0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319 stack backtrace: CPU: 0 UID: 0 PID: 5314 Comm: kworker/0:3 Not tainted 6.16.0-syzkaller-10499-g89748acdf226 #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: events l2cap_info_timeout Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043 check_noncircular+0x134/0x160 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1340 kernel/locking/mutex.c:760 l2cap_info_timeout+0x60/0xa0 net/bluetooth/l2cap_core.c:1668 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245