Lock error

========================================================
WARNING: possible irq lock inversion dependency detected
4.15.0+ #2 Tainted: G           O
--------------------------------------------------------
tracer_test/274 just changed the state of lock:
 (trc_lock){+...}, at: [<4df3db5f>] trc_ioctl+0xa2/0x1c0 [tracer]
but this lock was taken by another, HARDIRQ-safe lock in the past:
 (&(&vblk->vqs[i].lock)->rlock){-.-.}


and interrupts could create inverse lock ordering between them.


other info that might help us debug this:
Chain exists of:
  &(&vblk->vqs[i].lock)->rlock --> &(kretprobe_table_locks[i].lock) --> trc_lock

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(trc_lock);
                               local_irq_disable();
                               lock(&(&vblk->vqs[i].lock)->rlock);
                               lock(&(kretprobe_table_locks[i].lock));
  <Interrupt>
    lock(&(&vblk->vqs[i].lock)->rlock);

 *** DEADLOCK ***

no locks held by tracer_test/274.

the shortest dependencies between 2nd lock and 1st lock:
  -> (&(&vblk->vqs[i].lock)->rlock){-.-.} ops: 460 {
     IN-HARDIRQ-W at:
                        lock_acquire+0x69/0x80
                        _raw_spin_lock_irqsave+0x46/0x60
                        virtblk_done+0x34/0xc0
                        vring_interrupt+0x20/0x50
                        vp_interrupt+0x5a/0xb0
                        __handle_irq_event_percpu+0x57/0xe0
                        handle_irq_event_percpu+0x1d/0x50
                        handle_irq_event+0x32/0x60
                        handle_fasteoi_irq+0x7a/0x160
                        handle_irq+0x7a/0xb0
                        do_IRQ+0x55/0x120
                        common_interrupt+0x39/0x40
                        blk_mq_dispatch_rq_list+0x76/0x470
                        blk_mq_do_dispatch_sched+0x50/0xb0
                        blk_mq_sched_dispatch_requests+0xfd/0x180
                        __blk_mq_run_hw_queue+0xa3/0x1d0
                        blk_mq_run_work_fn+0x25/0x30
                        process_one_work+0x16f/0x410
                        worker_thread+0x37/0x420
                        kthread+0xcf/0x100
                        ret_from_fork+0x2e/0x38
     IN-SOFTIRQ-W at:
                        lock_acquire+0x69/0x80
                        _raw_spin_lock_irqsave+0x46/0x60
                        virtblk_done+0x34/0xc0
                        vring_interrupt+0x20/0x50
                        vp_interrupt+0x5a/0xb0
                        __handle_irq_event_percpu+0x57/0xe0
                        handle_irq_event_percpu+0x1d/0x50
                        handle_irq_event+0x32/0x60
                        handle_fasteoi_irq+0x7a/0x160
                        handle_irq+0x7a/0xb0
                        do_IRQ+0x55/0x120
                        common_interrupt+0x39/0x40
                        __do_softirq+0x80/0x1f2
                        do_softirq_own_stack+0x57/0x70
                        irq_exit+0x7d/0x90
                        smp_apic_timer_interrupt+0x4f/0x90
                        apic_timer_interrupt+0x3a/0x40
                        vp_notify+0xf/0x20
                        virtqueue_notify+0xf/0x30
                        virtio_queue_rq+0x27f/0x2f0
                        blk_mq_dispatch_rq_list+0x66/0x470
                        blk_mq_do_dispatch_sched+0x50/0xb0
                        blk_mq_sched_dispatch_requests+0xfd/0x180
                        __blk_mq_run_hw_queue+0xa3/0x1d0
                        __blk_mq_delay_run_hw_queue+0xb7/0xc0
                        blk_mq_run_hw_queue+0x24/0x80
                        blk_mq_sched_insert_requests+0x54/0x80
                        blk_mq_flush_plug_list+0xfd/0x110
                        blk_flush_plug_list+0x9d/0x1e0
                        blk_finish_plug+0x29/0x40
                        __do_page_cache_readahead+0x2de/0x370
                        filemap_fault+0x526/0x5a0
                        ext4_filemap_fault+0x27/0x40
                        __do_fault+0x18/0x70
                        handle_mm_fault+0x357/0x8f0
                        __do_page_fault+0x1dd/0x520
                        do_page_fault+0xb/0x10
                        common_exception+0x7c/0x82
     INITIAL USE at:
                       lock_acquire+0x69/0x80
                       _raw_spin_lock_irqsave+0x46/0x60
                       virtio_queue_rq+0xc7/0x2f0
                       blk_mq_dispatch_rq_list+0x66/0x470
                       blk_mq_do_dispatch_sched+0x50/0xb0
                       blk_mq_sched_dispatch_requests+0xfd/0x180
                       __blk_mq_run_hw_queue+0xa3/0x1d0
                       blk_mq_run_work_fn+0x25/0x30
                       process_one_work+0x16f/0x410
                       worker_thread+0x37/0x420
                       kthread+0xcf/0x100
                       ret_from_fork+0x2e/0x38
   }
   ... key      at: [<43d50c97>] __key.38703+0x0/0x8
   ... acquired at:
   _raw_spin_lock_irqsave+0x46/0x60
   pre_handler_kretprobe+0xb7/0x140
   aggr_pre_handler+0x3b/0x70
   kprobe_int3_handler+0xc4/0x150
   do_int3+0x57/0x120
   int3+0x39/0x40
   __kmalloc+0x1/0x210
   virtqueue_add_sgs+0xf4/0x420
   virtio_queue_rq+0x177/0x2f0
   blk_mq_dispatch_rq_list+0x66/0x470
   blk_mq_do_dispatch_sched+0x50/0xb0
   blk_mq_sched_dispatch_requests+0xfd/0x180
   __blk_mq_run_hw_queue+0xa3/0x1d0
   __blk_mq_delay_run_hw_queue+0xb7/0xc0
   blk_mq_run_hw_queue+0x24/0x80
   blk_mq_sched_insert_requests+0x54/0x80
   blk_mq_flush_plug_list+0xfd/0x110
   blk_flush_plug_list+0x9d/0x1e0
   blk_finish_plug+0x29/0x40
   __do_page_cache_readahead+0x2de/0x370
   filemap_fault+0x526/0x5a0
   ext4_filemap_fault+0x27/0x40
   __do_fault+0x18/0x70
   handle_mm_fault+0x357/0x8f0
   __do_page_fault+0x1dd/0x520
   do_page_fault+0xb/0x10
   common_exception+0x7c/0x82

 -> (&(kretprobe_table_locks[i].lock)){....} ops: 783 {
    INITIAL USE at:
                     lock_acquire+0x69/0x80
                     _raw_spin_lock_irqsave+0x46/0x60
                     kprobe_flush_task+0x3b/0xc0
                     finish_task_switch+0xf5/0x210
                     __schedule+0x209/0x5e0
                     schedule+0x30/0x80
                     schedule_timeout+0x12e/0x220
                     rcu_gp_kthread+0x4ba/0x7c0
                     kthread+0xcf/0x100
                     ret_from_fork+0x2e/0x38
  }
  ... key      at: [<bee617ff>] __key.33539+0x0/0x8
  ... acquired at:
   _raw_spin_lock+0x39/0x50
   kmalloc_ret+0x14/0xc0 [tracer]
   trampoline_handler+0xfa/0x1a0
   kretprobe_trampoline+0x18/0x30

-> (trc_lock){+...} ops: 23 {
   HARDIRQ-ON-W at:
                    lock_acquire+0x69/0x80
                    _raw_spin_lock+0x39/0x50
                    trc_ioctl+0xa2/0x1c0 [tracer]
                    do_vfs_ioctl+0x84/0x7b0
                    SyS_ioctl+0x34/0x60
                    do_fast_syscall_32+0x97/0x2b0
                    entry_SYSENTER_32+0x4c/0x7b
   INITIAL USE at:
                   lock_acquire+0x69/0x80
                   _raw_spin_lock+0x39/0x50
                   kmalloc_ret+0x14/0xc0 [tracer]
                   trampoline_handler+0xfa/0x1a0
                   kretprobe_trampoline+0x18/0x30
 }
 ... key      at: [<6e906a15>] trc_lock+0x10/0xffffef40 [tracer]
 ... acquired at:
   mark_lock+0x307/0x610
   __lock_acquire+0x50e/0x1710
   lock_acquire+0x69/0x80
   _raw_spin_lock+0x39/0x50
   trc_ioctl+0xa2/0x1c0 [tracer]
   do_vfs_ioctl+0x84/0x7b0
   SyS_ioctl+0x34/0x60
   do_fast_syscall_32+0x97/0x2b0
   entry_SYSENTER_32+0x4c/0x7b


stack backtrace:
CPU: 0 PID: 274 Comm: tracer_test Tainted: G           O     4.15.0+ #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Call Trace:
 dump_stack+0x5f/0x89
 print_irq_inversion_bug.part.21+0x16c/0x175
 check_usage_backwards+0x108/0x110
 ? print_shortest_lock_dependencies+0x1a0/0x1a0
 mark_lock+0x307/0x610
 ? __switch_to_asm+0x1a/0x40
 ? print_shortest_lock_dependencies+0x1a0/0x1a0
 __lock_acquire+0x50e/0x1710
 ? trace_hardirqs_on_caller+0x11c/0x1a0
 ? finish_task_switch+0xb0/0x210
 ? trace_hardirqs_on+0xb/0x10
 ? _raw_spin_unlock_irq+0x22/0x30
 ? finish_task_switch+0x6e/0x210
 ? __schedule+0x209/0x5e0
 lock_acquire+0x69/0x80
 ? trc_ioctl+0xa2/0x1c0 [tracer]
 _raw_spin_lock+0x39/0x50
 ? trc_ioctl+0xa2/0x1c0 [tracer]
 ? kmalloc_ret+0xc0/0xc0 [tracer]
 trc_ioctl+0xa2/0x1c0 [tracer]
 ? kmalloc_ret+0xc0/0xc0 [tracer]
 do_vfs_ioctl+0x84/0x7b0
 ? hrtimer_nanosleep+0xbf/0x1a0
 ? __might_fault+0x41/0xa0
 SyS_ioctl+0x34/0x60
 do_fast_syscall_32+0x97/0x2b0
 entry_SYSENTER_32+0x4c/0x7b
EIP: 0xb7fc9b35
EFLAGS: 00000296 CPU: 0
EAX: ffffffda EBX: 00000003 ECX: 4004012a EDX: 00000117
ESI: 080ee00c EDI: 00000006 EBP: bf88f7c8 ESP: bf88f788
 DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b