====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc3-syzkaller-00342-g5bc1018675ec #0 Not tainted ------------------------------------------------------ syz.6.762/8908 is trying to acquire lock: ffff8880566c2040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: touch_work_lockdep_map kernel/workqueue.c:3922 [inline] ffff8880566c2040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4176 [inline] ffff8880566c2040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: __flush_work+0x4d0/0xcc0 kernel/workqueue.c:4208 but task is already holding lock: ffff8880566c2338 (&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+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 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_disconn_cfm net/bluetooth/l2cap_core.c:7300 [inline] l2cap_disconn_cfm+0x96/0xd0 net/bluetooth/l2cap_core.c:7293 hci_disconn_cfm include/net/bluetooth/hci_core.h:2069 [inline] hci_conn_hash_flush+0x10b/0x260 net/bluetooth/hci_conn.c:2701 hci_dev_close_sync+0x602/0x11d0 net/bluetooth/hci_sync.c:5225 hci_dev_do_close+0x2e/0x90 net/bluetooth/hci_core.c:483 hci_rfkill_set_block+0x225/0x360 net/bluetooth/hci_core.c:911 rfkill_set_block+0x1fb/0x550 net/rfkill/core.c:346 rfkill_fop_write+0x2c0/0x580 net/rfkill/core.c:1301 vfs_write+0x25c/0x1180 fs/read_write.c:682 ksys_write+0x205/0x240 fs/read_write.c:736 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 *** 6 locks held by syz.6.762/8908: #0: ffffffff905be068 (rfkill_global_mutex){+.+.}-{4:4}, at: rfkill_fop_write+0x166/0x580 net/rfkill/core.c:1293 #1: ffff888031894d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0x90 net/bluetooth/hci_core.c:481 #2: ffff888031894078 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x3ae/0x11d0 net/bluetooth/hci_sync.c:5213 #3: ffffffff90392808 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2066 [inline] #3: ffffffff90392808 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x260 net/bluetooth/hci_conn.c:2701 #4: ffff8880566c2338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x80/0x730 net/bluetooth/l2cap_core.c:1761 #5: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #5: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #5: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: start_flush_work kernel/workqueue.c:4150 [inline] #5: ffffffff8e3bf5c0 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xfb/0xcc0 kernel/workqueue.c:4208 stack backtrace: CPU: 0 UID: 0 PID: 8908 Comm: syz.6.762 Not tainted 6.15.0-rc3-syzkaller-00342-g5bc1018675ec #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 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_disconn_cfm net/bluetooth/l2cap_core.c:7300 [inline] l2cap_disconn_cfm+0x96/0xd0 net/bluetooth/l2cap_core.c:7293 hci_disconn_cfm include/net/bluetooth/hci_core.h:2069 [inline] hci_conn_hash_flush+0x10b/0x260 net/bluetooth/hci_conn.c:2701 hci_dev_close_sync+0x602/0x11d0 net/bluetooth/hci_sync.c:5225 hci_dev_do_close+0x2e/0x90 net/bluetooth/hci_core.c:483 hci_rfkill_set_block+0x225/0x360 net/bluetooth/hci_core.c:911 rfkill_set_block+0x1fb/0x550 net/rfkill/core.c:346 rfkill_fop_write+0x2c0/0x580 net/rfkill/core.c:1301 vfs_write+0x25c/0x1180 fs/read_write.c:682 ksys_write+0x205/0x240 fs/read_write.c:736 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: 0033:0x7fa4ca78e969 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:00007fa4c85b4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fa4ca9b6160 RCX: 00007fa4ca78e969 RDX: 0000000000000008 RSI: 0000200000000300 RDI: 0000000000000008 RBP: 00007fa4ca810ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fa4ca9b6160 R15: 00007ffde316b2e8