syzbot

============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.78/6202 is trying to acquire lock:
ffffffff8da32e58 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0x118/0xf10 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095

but task is already holding lock:
ffffffff8da32e58 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0x118/0xf10 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(qp_broker_list.mutex);
  lock(qp_broker_list.mutex);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

1 lock held by syz.0.78/6202:
 #0: ffffffff8da32e58 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0x118/0xf10 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095

stack backtrace:
CPU: 1 PID: 6202 Comm: syz.0.78 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain kernel/locking/lockdep.c:3856 [inline]
 __lock_acquire+0x5dbc/0x7d40 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x136/0xcc0 kernel/locking/mutex.c:747
 vmci_qp_broker_detach+0x118/0xf10 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095
 ctx_free_ctx drivers/misc/vmw_vmci/vmci_context.c:444 [inline]
 kref_put include/linux/kref.h:65 [inline]
 vmci_ctx_put+0x62d/0xc10 drivers/misc/vmw_vmci/vmci_context.c:497
 vmci_ctx_enqueue_datagram+0x3ab/0x420 drivers/misc/vmw_vmci/vmci_context.c:360
 dg_dispatch_as_host drivers/misc/vmw_vmci/vmci_datagram.c:276 [inline]
 vmci_datagram_dispatch+0x44d/0xc60 drivers/misc/vmw_vmci/vmci_datagram.c:340
 qp_notify_peer drivers/misc/vmw_vmci/vmci_queue_pair.c:1481 [inline]
 vmci_qp_broker_detach+0x8d7/0xf10 drivers/misc/vmw_vmci/vmci_queue_pair.c:2188
 ctx_free_ctx drivers/misc/vmw_vmci/vmci_context.c:444 [inline]
 kref_put include/linux/kref.h:65 [inline]
 vmci_ctx_put+0x62d/0xc10 drivers/misc/vmw_vmci/vmci_context.c:497
 vmci_host_close+0x9b/0x160 drivers/misc/vmw_vmci/vmci_host.c:143
 __fput+0x234/0x970 fs/file_table.c:384
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7e8cd9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7e8dccd028 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f7e8d016090 RCX: 00007f7e8cd9c819
RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000000000005
RBP: 00007f7e8ce32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7e8d016128 R14: 00007f7e8d016090 R15: 00007fffa9ea6138
 </TASK>