syzbot

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faux_driver vkms: [drm] vblank wait timed out on crtc 0
WARNING: drivers/gpu/drm/drm_vblank.c:1320 at drm_crtc_wait_one_vblank+0x357/0x500 drivers/gpu/drm/drm_vblank.c:1320, CPU#1: kworker/1:6/6088
Modules linked in:
CPU: 1 UID: 0 PID: 6088 Comm: kworker/1:6 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: events drm_fb_helper_damage_work
RIP: 0010:drm_crtc_wait_one_vblank+0x4b6/0x500 drivers/gpu/drm/drm_vblank.c:1320
Code: e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 ef e8 8a 47 d4 fc 4d 8b 7d 00 48 89 df 4c 89 e6 4c 89 fa 44 89 f1 <67> 48 0f b9 3a 48 8b 3c 24 44 89 f6 e8 e9 f4 ff ff b8 92 ff ff ff
RSP: 0018:ffffc9000419f8c0 EFLAGS: 00010246
RAX: 1ffff11004abe200 RBX: ffffffff8f752160 RCX: 0000000000000000
RDX: ffffffff8bbf5340 RSI: ffffffff8bc111a0 RDI: ffffffff8f752160
RBP: ffffc9000419f9a8 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1ed47b7 R12: ffffffff8bc111a0
R13: ffff8880255f1000 R14: 0000000000000000 R15: ffffffff8bbf5340
FS:  0000000000000000(0000) GS:ffff88812643c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fec7fbf4ff8 CR3: 0000000025248000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 drm_client_modeset_wait_for_vblank+0xc5/0xf0 drivers/gpu/drm/drm_client_modeset.c:1331
 drm_fb_helper_fb_dirty drivers/gpu/drm/drm_fb_helper.c:236 [inline]
 drm_fb_helper_damage_work+0x131/0x6f0 drivers/gpu/drm/drm_fb_helper.c:274
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 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:	e8 03 48 b9 00       	call   0xb94808
   5:	00 00                	add    %al,(%rax)
   7:	00 00                	add    %al,(%rax)
   9:	fc                   	cld
   a:	ff                   	lcall  (bad)
   b:	df 80 3c 08 00 74    	filds  0x7400083c(%rax)
  11:	08 4c 89 ef          	or     %cl,-0x11(%rcx,%rcx,4)
  15:	e8 8a 47 d4 fc       	call   0xfcd447a4
  1a:	4d 8b 7d 00          	mov    0x0(%r13),%r15
  1e:	48 89 df             	mov    %rbx,%rdi
  21:	4c 89 e6             	mov    %r12,%rsi
  24:	4c 89 fa             	mov    %r15,%rdx
  27:	44 89 f1             	mov    %r14d,%ecx
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	48 8b 3c 24          	mov    (%rsp),%rdi
  33:	44 89 f6             	mov    %r14d,%esi
  36:	e8 e9 f4 ff ff       	call   0xfffff524
  3b:	b8 92 ff ff ff       	mov    $0xffffff92,%eax