syzbot

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f7763815fac R14: 00007f7763815fa0 R15: 00007f7763815fa0
 </TASK>
------------[ cut here ]------------
[CRTC:37:crtc-0] vblank wait timed out
WARNING: drivers/gpu/drm/drm_atomic_helper.c:1920 at drm_atomic_helper_wait_for_vblanks.part.0+0x738/0x8a0 drivers/gpu/drm/drm_atomic_helper.c:1920, CPU#0: syz.1.333/6503
Modules linked in:
CPU: 0 UID: 0 PID: 6503 Comm: syz.1.333 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:drm_atomic_helper_wait_for_vblanks.part.0+0x73e/0x8a0 drivers/gpu/drm/drm_atomic_helper.c:1920
Code: 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 0f b6 04 01 84 c0 74 08 3c 03 0f 8e 44 01 00 00 48 8d 3d 58 95 2c 0b 8b b3 d8 00 00 00 <67> 48 0f b9 3a e9 e1 fc ff ff e8 d3 95 70 fc e9 7c fe ff ff e8 d9
RSP: 0018:ffffc900038b77b0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8881043c0040 RCX: 1ffff11020878023
RDX: ffff888027294bc0 RSI: 0000000000000025 RDI: ffffffff90c30110
RBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880320fd900
FS:  0000555577ff9500(0000) GS:ffff8880d65bd000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fec2e584640 CR3: 0000000056db5000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 drm_atomic_helper_wait_for_vblanks drivers/gpu/drm/drm_atomic_helper.c:1894 [inline]
 drm_atomic_helper_commit_tail+0xff/0x130 drivers/gpu/drm/drm_atomic_helper.c:1996
 commit_tail+0x338/0x430 drivers/gpu/drm/drm_atomic_helper.c:2073
 drm_atomic_helper_commit+0x303/0x380 drivers/gpu/drm/drm_atomic_helper.c:2311
 drm_atomic_commit+0x230/0x300 drivers/gpu/drm/drm_atomic.c:1743
 drm_client_modeset_commit_atomic+0x6a6/0x7e0 drivers/gpu/drm/drm_client_modeset.c:1103
 drm_client_modeset_commit_locked+0x14d/0x580 drivers/gpu/drm/drm_client_modeset.c:1206
 drm_client_modeset_commit+0x4f/0x80 drivers/gpu/drm/drm_client_modeset.c:1232
 __drm_fb_helper_restore_fbdev_mode_unlocked.part.0+0x137/0x160 drivers/gpu/drm/drm_fb_helper.c:235
 __drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:223 [inline]
 drm_fb_helper_restore_fbdev_mode_unlocked+0x93/0xc0 drivers/gpu/drm/drm_fb_helper.c:266
 drm_fbdev_client_restore+0x1b/0x30 drivers/gpu/drm/clients/drm_fbdev_client.c:45
 drm_client_dev_restore+0x205/0x2a0 drivers/gpu/drm/drm_client_event.c:118
 drm_lastclose drivers/gpu/drm/drm_file.c:408 [inline]
 drm_release+0x2c6/0x360 drivers/gpu/drm/drm_file.c:441
 __fput+0x3ff/0xb40 fs/file_table.c:469
 task_work_run+0x150/0x240 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
 exit_to_user_mode_loop+0x100/0x4b0 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x4fe/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f776359af79
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:00007ffe53761a88 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffe53761b70 RCX: 00007f776359af79
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00000000000255cc R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2ed20000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7763815fac R14: 00007f7763815fa8 R15: 00007f7763815fa0
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	00 fc                	add    %bh,%ah
   4:	ff                   	lcall  (bad)
   5:	df 48 89             	fisttps -0x77(%rax)
   8:	f9                   	stc
   9:	48 c1 e9 03          	shr    $0x3,%rcx
   d:	0f b6 04 01          	movzbl (%rcx,%rax,1),%eax
  11:	84 c0                	test   %al,%al
  13:	74 08                	je     0x1d
  15:	3c 03                	cmp    $0x3,%al
  17:	0f 8e 44 01 00 00    	jle    0x161
  1d:	48 8d 3d 58 95 2c 0b 	lea    0xb2c9558(%rip),%rdi        # 0xb2c957c
  24:	8b b3 d8 00 00 00    	mov    0xd8(%rbx),%esi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 e1 fc ff ff       	jmp    0xfffffd15
  34:	e8 d3 95 70 fc       	call   0xfc70960c
  39:	e9 7c fe ff ff       	jmp    0xfffffeba
  3e:	e8                   	.byte 0xe8
  3f:	d9                   	.byte 0xd9