====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc5-syzkaller-00158-g3013c33dcbd9 #0 Not tainted ------------------------------------------------------ syz.2.608/8364 is trying to acquire lock: ffff888056462040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: touch_work_lockdep_map kernel/workqueue.c:3922 [inline] ffff888056462040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4176 [inline] ffff888056462040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: __flush_work+0x4d0/0xcc0 kernel/workqueue.c:4208 but task is already holding lock: ffff888056462338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x80/0x730 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}: __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:746 l2cap_info_timeout+0x79/0xa0 net/bluetooth/l2cap_core.c:1667 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c5/0x780 kernel/kthread.c:464 ret_from_fork+0x48/0x80 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 kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 touch_work_lockdep_map kernel/workqueue.c:3922 [inline] start_flush_work kernel/workqueue.c:4176 [inline] __flush_work+0x4e4/0xcc0 kernel/workqueue.c:4208 __cancel_work_sync+0x10c/0x130 kernel/workqueue.c:4364 l2cap_conn_del+0x5af/0x730 net/bluetooth/l2cap_core.c:1795 l2cap_connect_cfm+0x9e1/0xf80 net/bluetooth/l2cap_core.c:7234 hci_connect_cfm include/net/bluetooth/hci_core.h:2052 [inline] hci_conn_failed+0x1bd/0x330 net/bluetooth/hci_conn.c:1269 hci_abort_conn_sync+0x740/0xb40 net/bluetooth/hci_sync.c:5616 hci_disconnect_all_sync.constprop.0+0x104/0x3c0 net/bluetooth/hci_sync.c:5639 hci_suspend_sync+0x770/0xab0 net/bluetooth/hci_sync.c:6116 hci_suspend_dev+0x308/0x500 net/bluetooth/hci_core.c:2812 hci_suspend_notifier+0x28d/0x2f0 net/bluetooth/hci_core.c:2392 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85 notifier_call_chain_robust kernel/notifier.c:120 [inline] blocking_notifier_call_chain_robust kernel/notifier.c:345 [inline] blocking_notifier_call_chain_robust+0xc8/0x160 kernel/notifier.c:333 pm_notifier_call_chain_robust+0x27/0x60 kernel/power/main.c:102 snapshot_open+0x189/0x2b0 kernel/power/user.c:77 misc_open+0x35d/0x420 drivers/char/misc.c:179 chrdev_open+0x234/0x6a0 fs/char_dev.c:414 do_dentry_open+0x744/0x1c10 fs/open.c:956 vfs_open+0x82/0x3f0 fs/open.c:1086 do_open fs/namei.c:3880 [inline] path_openat+0x1e5e/0x2d40 fs/namei.c:4039 do_filp_open+0x20b/0x470 fs/namei.c:4066 do_sys_openat2+0x11b/0x1d0 fs/open.c:1429 do_sys_open fs/open.c:1444 [inline] __do_sys_openat fs/open.c:1460 [inline] __se_sys_openat fs/open.c:1455 [inline] __x64_sys_openat+0x174/0x210 fs/open.c:1455 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 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 *** 8 locks held by syz.2.608/8364: #0: ffffffff8f0e2e88 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:143 #1: ffffffff8e283788 (system_transition_mutex){+.+.}-{4:4}, at: lock_system_sleep+0x87/0xa0 kernel/power/main.c:56 #2: ffffffff8e2c32d0 ((pm_chain_head).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain_robust kernel/notifier.c:344 [inline] #2: ffffffff8e2c32d0 ((pm_chain_head).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain_robust+0xa8/0x160 kernel/notifier.c:333 #3: ffff888033ad8d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_suspend_dev+0x300/0x500 net/bluetooth/hci_core.c:2811 #4: ffff888033ad8078 (&hdev->lock){+.+.}-{4:4}, at: hci_abort_conn_sync+0x146/0xb40 net/bluetooth/hci_sync.c:5597 #5: ffffffff90394448 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2049 [inline] #5: ffffffff90394448 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_failed+0x14f/0x330 net/bluetooth/hci_conn.c:1269 #6: ffff888056462338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x80/0x730 net/bluetooth/l2cap_core.c:1761 #7: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #7: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #7: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: start_flush_work kernel/workqueue.c:4150 [inline] #7: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xfb/0xcc0 kernel/workqueue.c:4208 stack backtrace: CPU: 1 UID: 0 PID: 8364 Comm: syz.2.608 Not tainted 6.15.0-rc5-syzkaller-00158-g3013c33dcbd9 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2079 check_noncircular+0x14c/0x170 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 kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 touch_work_lockdep_map kernel/workqueue.c:3922 [inline] start_flush_work kernel/workqueue.c:4176 [inline] __flush_work+0x4e4/0xcc0 kernel/workqueue.c:4208 __cancel_work_sync+0x10c/0x130 kernel/workqueue.c:4364 l2cap_conn_del+0x5af/0x730 net/bluetooth/l2cap_core.c:1795 l2cap_connect_cfm+0x9e1/0xf80 net/bluetooth/l2cap_core.c:7234 hci_connect_cfm include/net/bluetooth/hci_core.h:2052 [inline] hci_conn_failed+0x1bd/0x330 net/bluetooth/hci_conn.c:1269 hci_abort_conn_sync+0x740/0xb40 net/bluetooth/hci_sync.c:5616 hci_disconnect_all_sync.constprop.0+0x104/0x3c0 net/bluetooth/hci_sync.c:5639 hci_suspend_sync+0x770/0xab0 net/bluetooth/hci_sync.c:6116 hci_suspend_dev+0x308/0x500 net/bluetooth/hci_core.c:2812 hci_suspend_notifier+0x28d/0x2f0 net/bluetooth/hci_core.c:2392 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85 notifier_call_chain_robust kernel/notifier.c:120 [inline] blocking_notifier_call_chain_robust kernel/notifier.c:345 [inline] blocking_notifier_call_chain_robust+0xc8/0x160 kernel/notifier.c:333 pm_notifier_call_chain_robust+0x27/0x60 kernel/power/main.c:102 snapshot_open+0x189/0x2b0 kernel/power/user.c:77 misc_open+0x35d/0x420 drivers/char/misc.c:179 chrdev_open+0x234/0x6a0 fs/char_dev.c:414 do_dentry_open+0x744/0x1c10 fs/open.c:956 vfs_open+0x82/0x3f0 fs/open.c:1086 do_open fs/namei.c:3880 [inline] path_openat+0x1e5e/0x2d40 fs/namei.c:4039 do_filp_open+0x20b/0x470 fs/namei.c:4066 do_sys_openat2+0x11b/0x1d0 fs/open.c:1429 do_sys_open fs/open.c:1444 [inline] __do_sys_openat fs/open.c:1460 [inline] __se_sys_openat fs/open.c:1455 [inline] __x64_sys_openat+0x174/0x210 fs/open.c:1455 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f273df8e969 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:00007f273ee44038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f273e1b6080 RCX: 00007f273df8e969 RDX: 0000000000000400 RSI: 0000200000000800 RDI: ffffffffffffff9c RBP: 00007f273e010ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f273e1b6080 R15: 00007ffe1818eed8