============================================
WARNING: possible recursive locking detected
5.3.0-rc7+ #0 Not tainted
--------------------------------------------
v4l_id/3016 is trying to acquire lock:
0000000069c3004e (&usbvision->v4l2_lock){+.+.}, at: vidioc_querycap+0x62/0x3b0 drivers/media/usb/usbvision/usbvision-video.c:456

but task is already holding lock:
0000000069c3004e (&usbvision->v4l2_lock){+.+.}, at: __video_do_ioctl+0x3ba/0xba0 drivers/media/v4l2-core/v4l2-ioctl.c:2846

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

       CPU0
       ----
  lock(&usbvision->v4l2_lock);
  lock(&usbvision->v4l2_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

1 lock held by v4l_id/3016:
 #0: 0000000069c3004e (&usbvision->v4l2_lock){+.+.}, at: __video_do_ioctl+0x3ba/0xba0 drivers/media/v4l2-core/v4l2-ioctl.c:2846

stack backtrace:
CPU: 0 PID: 3016 Comm: v4l_id Not tainted 5.3.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xca/0x13e lib/dump_stack.c:113
 print_deadlock_bug kernel/locking/lockdep.c:2301 [inline]
 check_deadlock kernel/locking/lockdep.c:2342 [inline]
 validate_chain kernel/locking/lockdep.c:2881 [inline]
 __lock_acquire.cold+0x148/0x29b kernel/locking/lockdep.c:3880
 lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4412
 __mutex_lock_common kernel/locking/mutex.c:930 [inline]
 __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077
 vidioc_querycap+0x62/0x3b0 drivers/media/usb/usbvision/usbvision-video.c:456
 v4l_querycap+0x121/0x340 drivers/media/v4l2-core/v4l2-ioctl.c:1058
 __video_do_ioctl+0x969/0xba0 drivers/media/v4l2-core/v4l2-ioctl.c:2878
 video_usercopy+0x446/0xf40 drivers/media/v4l2-core/v4l2-ioctl.c:3060
 v4l2_ioctl+0x1a2/0x220 drivers/media/v4l2-core/v4l2-dev.c:360
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0xd2d/0x1330 fs/ioctl.c:696
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:718
 do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f642b0b9347
Code: 90 90 90 48 8b 05 f1 fa 2a 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 90 90 90 90 90 90 90 90 90 90 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c1 fa 2a 00 31 d2 48 29 c2 64
RSP: 002b:00007ffc2fc62b28 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f642b0b9347
RDX: 00007ffc2fc62b30 RSI: 0000000080685600 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000400884
R13: 00007ffc2fc62c80 R14: 0000000000000000 R15: 0000000000000000