BUG: workqueue leaked atomic, lock or RCU: kworker/u9:8[6305]
     preempt=0x00000000 lock=0->1 RCU=0->0 workfn=hci_rx_work
1 lock held by kworker/u9:8/6305:
 #0: ffff0000f0952518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_chan_lock include/net/bluetooth/l2cap.h:827 [inline]
 #0: ffff0000f0952518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_conless_channel net/bluetooth/l2cap_core.c:6764 [inline]
 #0: ffff0000f0952518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_recv_frame+0x610/0xc934 net/bluetooth/l2cap_core.c:6830
CPU: 1 PID: 6305 Comm: kworker/u9:8 Not tainted 6.10.0-rc7-syzkaller-g1a6f53de2eb9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: hci5 hci_rx_work
Call trace:
 dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:317
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:324
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:114
 dump_stack+0x1c/0x28 lib/dump_stack.c:123
 process_one_work+0xdc0/0x15b8 kernel/workqueue.c:3269
 process_scheduled_works kernel/workqueue.c:3329 [inline]
 worker_thread+0x938/0xecc kernel/workqueue.c:3409
 kthread+0x288/0x310 kernel/kthread.c:389
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860

======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc7-syzkaller-g1a6f53de2eb9 #0 Not tainted
------------------------------------------------------
kworker/u9:8/6305 is trying to acquire lock:
ffff0000ea694948 ((wq_completion)hci1#2){+.+.}-{0:0}, at: process_one_work+0x624/0x15b8 kernel/workqueue.c:3222

but task is already holding lock:
ffff0000f0952518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_chan_lock include/net/bluetooth/l2cap.h:827 [inline]
ffff0000f0952518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_conless_channel net/bluetooth/l2cap_core.c:6764 [inline]
ffff0000f0952518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_recv_frame+0x610/0xc934 net/bluetooth/l2cap_core.c:6830

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&chan->lock/1){+.+.}-{3:3}:
       __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
       __mutex_lock kernel/locking/mutex.c:752 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
       l2cap_chan_lock include/net/bluetooth/l2cap.h:827 [inline]
       l2cap_conless_channel net/bluetooth/l2cap_core.c:6764 [inline]
       l2cap_recv_frame+0x610/0xc934 net/bluetooth/l2cap_core.c:6830
       l2cap_recv_acldata+0x4a8/0x15dc net/bluetooth/l2cap_core.c:7513
       hci_acldata_packet net/bluetooth/hci_core.c:3810 [inline]
       hci_rx_work+0x2b8/0xa78 net/bluetooth/hci_core.c:4047
       process_one_work+0x79c/0x15b8 kernel/workqueue.c:3248
       process_scheduled_works kernel/workqueue.c:3329 [inline]
       worker_thread+0x938/0xecc kernel/workqueue.c:3409
       kthread+0x288/0x310 kernel/kthread.c:389
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860

-> #1 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}:
       process_one_work+0x6c8/0x15b8 kernel/workqueue.c:3224
       process_scheduled_works kernel/workqueue.c:3329 [inline]
       worker_thread+0x938/0xecc kernel/workqueue.c:3409
       kthread+0x288/0x310 kernel/kthread.c:389
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860

-> #0 ((wq_completion)hci1#2){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x3384/0x763c kernel/locking/lockdep.c:5137
       lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5754
       process_one_work+0x668/0x15b8 kernel/workqueue.c:3223
       process_scheduled_works kernel/workqueue.c:3329 [inline]
       worker_thread+0x938/0xecc kernel/workqueue.c:3409
       kthread+0x288/0x310 kernel/kthread.c:389
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860

other info that might help us debug this:

Chain exists of:
  (wq_completion)hci1#2 --> (work_completion)(&hdev->rx_work) --> &chan->lock/1

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&chan->lock/1);
                               lock((work_completion)(&hdev->rx_work));
                               lock(&chan->lock/1);
  lock((wq_completion)hci1#2);

 *** DEADLOCK ***

1 lock held by kworker/u9:8/6305:
 #0: ffff0000f0952518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_chan_lock include/net/bluetooth/l2cap.h:827 [inline]
 #0: ffff0000f0952518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_conless_channel net/bluetooth/l2cap_core.c:6764 [inline]
 #0: ffff0000f0952518 (&chan->lock/1){+.+.}-{3:3}, at: l2cap_recv_frame+0x610/0xc934 net/bluetooth/l2cap_core.c:6830

stack backtrace:
CPU: 1 PID: 6305 Comm: kworker/u9:8 Not tainted 6.10.0-rc7-syzkaller-g1a6f53de2eb9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: hci1 hci_cmd_timeout
Call trace:
 dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:317
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:324
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:114
 dump_stack+0x1c/0x28 lib/dump_stack.c:123
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2060
 check_noncircular+0x310/0x404 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x3384/0x763c kernel/locking/lockdep.c:5137
 lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5754
 process_one_work+0x668/0x15b8 kernel/workqueue.c:3223
 process_scheduled_works kernel/workqueue.c:3329 [inline]
 worker_thread+0x938/0xecc kernel/workqueue.c:3409
 kthread+0x288/0x310 kernel/kthread.c:389
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
Bluetooth: hci1: command tx timeout
BUG: workqueue leaked atomic, lock or RCU: kworker/u9:8[6305]
     preempt=0x00000000 lock=1->0 RCU=0->0 workfn=hci_cmd_timeout
INFO: lockdep is turned off.
CPU: 0 PID: 6305 Comm: kworker/u9:8 Not tainted 6.10.0-rc7-syzkaller-g1a6f53de2eb9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: hci1 hci_cmd_timeout
Call trace:
 dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:317
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:324
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:114
 dump_stack+0x1c/0x28 lib/dump_stack.c:123
 process_one_work+0xdc0/0x15b8 kernel/workqueue.c:3269
 process_scheduled_works kernel/workqueue.c:3329 [inline]
 worker_thread+0x938/0xecc kernel/workqueue.c:3409
 kthread+0x288/0x310 kernel/kthread.c:389
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
Bluetooth: hci1: command tx timeout
Bluetooth: hci1: command tx timeout