------------[ cut here ]------------
bochs-drm 0000:00:01.0: [drm] vblank wait timed out on crtc 0
WARNING: drivers/gpu/drm/drm_vblank.c:1320 at drm_crtc_wait_one_vblank+0x2fd/0x500 drivers/gpu/drm/drm_vblank.c:1320, CPU#0: kworker/0:3/5845
Modules linked in:
CPU: 0 UID: 0 PID: 5845 Comm: kworker/0:3 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: events drm_fb_helper_damage_work
RIP: 0010:drm_crtc_wait_one_vblank+0x303/0x500 drivers/gpu/drm/drm_vblank.c:1320
Code: 48 8b 6b 50 48 85 ed 0f 84 96 01 00 00 e8 85 a0 65 fc 48 89 df e8 9d 93 90 00 48 89 c6 48 8d 3d 33 b9 40 0b 44 89 e9 48 89 ea <67> 48 0f b9 3a 44 89 ee 4c 89 e7 41 be 92 ff ff ff e8 17 f8 ff ff
RSP: 0000:ffffc900062afa68 EFLAGS: 00010293
RAX: ffffffff8c4d4540 RBX: ffff8880211d40d0 RCX: 0000000000000000
RDX: ffff88802078b460 RSI: ffffffff8c4d4540 RDI: ffffffff90e307e0
RBP: ffff88802078b460 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888040efc000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000007ca6
FS:  0000000000000000(0000) GS:ffff88809717d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000004c343000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 drm_client_modeset_wait_for_vblank+0xef/0x120 drivers/gpu/drm/drm_client_modeset.c:1331
 drm_fb_helper_fb_dirty drivers/gpu/drm/drm_fb_helper.c:237 [inline]
 drm_fb_helper_damage_work+0x164/0x640 drivers/gpu/drm/drm_fb_helper.c:275
 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3302
 process_scheduled_works kernel/workqueue.c:3385 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
----------------
Code disassembly (best guess):
   0:	48 8b 6b 50          	mov    0x50(%rbx),%rbp
   4:	48 85 ed             	test   %rbp,%rbp
   7:	0f 84 96 01 00 00    	je     0x1a3
   d:	e8 85 a0 65 fc       	call   0xfc65a097
  12:	48 89 df             	mov    %rbx,%rdi
  15:	e8 9d 93 90 00       	call   0x9093b7
  1a:	48 89 c6             	mov    %rax,%rsi
  1d:	48 8d 3d 33 b9 40 0b 	lea    0xb40b933(%rip),%rdi        # 0xb40b957
  24:	44 89 e9             	mov    %r13d,%ecx
  27:	48 89 ea             	mov    %rbp,%rdx
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	44 89 ee             	mov    %r13d,%esi
  32:	4c 89 e7             	mov    %r12,%rdi
  35:	41 be 92 ff ff ff    	mov    $0xffffff92,%r14d
  3b:	e8 17 f8 ff ff       	call   0xfffff857