------------[ cut here ]------------
WARNING: CPU: 0 PID: 21366 at drivers/gpu/drm/vkms/vkms_crtc.c:97 vkms_get_vblank_timestamp+0x167/0x1b0 drivers/gpu/drm/vkms/vkms_crtc.c:97
Modules linked in:
CPU: 0 UID: 0 PID: 21366 Comm: syz.3.3795 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:vkms_get_vblank_timestamp+0x167/0x1b0 drivers/gpu/drm/vkms/vkms_crtc.c:97
Code: e8 fb e8 7c bf d5 fb 4c 89 e1 48 ba 00 00 00 00 00 fc ff df 48 c1 e9 03 80 3c 11 00 75 43 49 89 04 24 eb c0 e8 7a 93 e8 fb 90 <0f> 0b 90 eb b5 e8 9f 1f 51 fc e9 dc fe ff ff e8 25 20 51 fc e9 14
RSP: 0018:ffffc9000ccbf2d8 EFLAGS: 00010287
RAX: 0000000000009265 RBX: ffff888141f18028 RCX: ffffc9000eb5d000
RDX: 0000000000080000 RSI: ffffffff85d47a26 RDI: 0000000000000006
RBP: 0000015d74cb7c93 R08: 0000000000000006 R09: 0000015d74cb7c93
R10: 0000015d74cb7c93 R11: 0000000000000001 R12: ffffc9000ccbf440
R13: 0000015d74cb7c93 R14: 0000000000004e20 R15: ffffffff85d478c0
FS:  00007f33a29cd6c0(0000) GS:ffff888124a08000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2db16ff8 CR3: 000000005fce2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 drm_crtc_get_last_vbltimestamp+0x105/0x1b0 drivers/gpu/drm/drm_vblank.c:879
 drm_crtc_next_vblank_start+0x182/0x300 drivers/gpu/drm/drm_vblank.c:1013
 set_fence_deadline drivers/gpu/drm/drm_atomic_helper.c:1718 [inline]
 drm_atomic_helper_wait_for_fences+0x203/0x830 drivers/gpu/drm/drm_atomic_helper.c:1765
 commit_tail+0x83/0x400 drivers/gpu/drm/drm_atomic_helper.c:1979
 drm_atomic_helper_commit+0x2fd/0x380 drivers/gpu/drm/drm_atomic_helper.c:2233
 drm_atomic_commit+0x234/0x300 drivers/gpu/drm/drm_atomic.c:1577
 drm_client_modeset_commit_atomic+0x69d/0x7e0 drivers/gpu/drm/drm_client_modeset.c:1103
 drm_client_modeset_commit_locked+0x14d/0x580 drivers/gpu/drm/drm_client_modeset.c:1206
 pan_display_atomic drivers/gpu/drm/drm_fb_helper.c:1388 [inline]
 drm_fb_helper_pan_display+0x32d/0xa40 drivers/gpu/drm/drm_fb_helper.c:1448
 fb_pan_display+0x47c/0x7d0 drivers/video/fbdev/core/fbmem.c:193
 bit_update_start+0x49/0x1f0 drivers/video/fbdev/core/bitblit.c:405
 fbcon_switch+0xbf8/0x1420 drivers/video/fbdev/core/fbcon.c:2199
 redraw_screen+0x2c1/0x760 drivers/tty/vt/vt.c:966
 fbcon_modechanged+0x456/0x6b0 drivers/video/fbdev/core/fbcon.c:2710
 fbcon_update_vcs+0x42/0x50 drivers/video/fbdev/core/fbcon.c:2755
 do_fb_ioctl+0x787/0x7e0 drivers/video/fbdev/core/fb_chrdev.c:92
 fb_ioctl+0xe5/0x150 drivers/video/fbdev/core/fb_chrdev.c:169
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f33a1b8f6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f33a29cd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f33a1de6090 RCX: 00007f33a1b8f6c9
RDX: 0000200000000800 RSI: 0000000000004601 RDI: 0000000000000007
RBP: 00007f33a1c11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f33a1de6128 R14: 00007f33a1de6090 R15: 00007ffedb7c1bd8
 </TASK>