------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use))
WARNING: kernel/locking/lockdep.c:5207 at 0x0, CPU#0: syz.0.10245/10538
Modules linked in:
CPU: 0 UID: 0 PID: 10538 Comm: syz.0.10245 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:__lock_acquire+0x171a/0x22f0 kernel/locking/lockdep.c:5207
Code: d4 07 03 85 c0 74 0d 83 3d 82 b1 ed 0e 00 0f 84 65 08 00 00 90 31 c0 e9 5e fa ff ff 48 8d 3d fd c5 f0 0e 48 c7 c6 d0 4b bb 8d <67> 48 0f b9 3a e9 e0 ed ff ff 44 8b 05 55 b1 ed 0e 45 85 c0 0f 85
RSP: 0018:ffffc900069d75c0 EFLAGS: 00010046
RAX: 0000000000000001 RBX: ffff88802494d500 RCX: ffffc9000d06d000
RDX: 0000000000000000 RSI: ffffffff8dbb4bd0 RDI: ffffffff90898bc0
RBP: ffff88802494c980 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88809778a000(0063) knlGS:00000000f5456b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f7350e54 CR3: 0000000059c1f000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825
 down_write+0x92/0x200 kernel/locking/rwsem.c:1590
 kernfs_remove_by_name_ns+0x3d/0x100 fs/kernfs/dir.c:1712
 sysfs_remove_file include/linux/sysfs.h:770 [inline]
 driver_remove_file drivers/base/driver.c:201 [inline]
 driver_remove_file+0x4a/0x60 drivers/base/driver.c:197
 remove_bind_files drivers/base/bus.c:605 [inline]
 bus_remove_driver+0x224/0x2c0 drivers/base/bus.c:743
 driver_unregister+0x76/0xb0 drivers/base/driver.c:277
 comedi_device_detach_locked+0x12f/0xa50 drivers/comedi/drivers.c:207
 do_devconfig_ioctl+0x555/0x710 drivers/comedi/comedi_fops.c:848
 comedi_unlocked_ioctl+0x165d/0x2ee0 drivers/comedi/comedi_fops.c:2178
 comedi_compat_ioctl+0x1d0/0x960 drivers/comedi/comedi_fops.c:3249
 __do_compat_sys_ioctl fs/ioctl.c:695 [inline]
 __se_compat_sys_ioctl fs/ioctl.c:638 [inline]
 __ia32_compat_sys_ioctl+0x242/0x370 fs/ioctl.c:638
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xe8/0x680 arch/x86/entry/syscall_32.c:307
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:332
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7f67579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f545655c EFLAGS: 00000296 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000040946400
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	03 85 c0 74 0d 83    	add    -0x7cf28b40(%rbp),%eax
   6:	3d 82 b1 ed 0e       	cmp    $0xeedb182,%eax
   b:	00 0f                	add    %cl,(%rdi)
   d:	84 65 08             	test   %ah,0x8(%rbp)
  10:	00 00                	add    %al,(%rax)
  12:	90                   	nop
  13:	31 c0                	xor    %eax,%eax
  15:	e9 5e fa ff ff       	jmp    0xfffffa78
  1a:	48 8d 3d fd c5 f0 0e 	lea    0xef0c5fd(%rip),%rdi        # 0xef0c61e
  21:	48 c7 c6 d0 4b bb 8d 	mov    $0xffffffff8dbb4bd0,%rsi
* 28:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2d:	e9 e0 ed ff ff       	jmp    0xffffee12
  32:	44 8b 05 55 b1 ed 0e 	mov    0xeedb155(%rip),%r8d        # 0xeedb18e
  39:	45 85 c0             	test   %r8d,%r8d
  3c:	0f                   	.byte 0xf
  3d:	85                   	.byte 0x85