syzbot

------------[ cut here ]------------
WARNING: CPU: 0 PID: 7091 at drivers/gpu/drm/vkms/vkms_crtc.c:103 vkms_get_vblank_timestamp+0x188/0x1d0 drivers/gpu/drm/vkms/vkms_crtc.c:103
Modules linked in:
CPU: 0 PID: 7091 Comm: syz.2.326 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:vkms_get_vblank_timestamp+0x188/0x1d0 drivers/gpu/drm/vkms/vkms_crtc.c:103
Code: 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 5d c0 9f fc 4c 89 33 b0 01 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 58 98 47 fc <0f> 0b eb ea 44 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c ba fe ff ff 4c
RSP: 0018:ffffc900045cf688 EFLAGS: 00010293
RAX: ffffffff853f7c58 RBX: ffffc900045cf800 RCX: ffff88801936bc00
RDX: 0000000000000000 RSI: 00000034b989f657 RDI: 00000034b989f657
RBP: 1ffff920008b9f00 R08: ffffffff911bf557 R09: 1ffffffff2237eaa
R10: dffffc0000000000 R11: fffffbfff2237eab R12: 00000034b989f657
R13: dffffc0000000000 R14: ffff888021154000 R15: 00000034b989f657
FS:  00005555824eb500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c29d825 CR3: 0000000027eb4000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 drm_crtc_get_last_vbltimestamp drivers/gpu/drm/drm_vblank.c:877 [inline]
 drm_crtc_next_vblank_start+0x22b/0x480 drivers/gpu/drm/drm_vblank.c:1012
 set_fence_deadline drivers/gpu/drm/drm_atomic_helper.c:1583 [inline]
 drm_atomic_helper_wait_for_fences+0x21b/0x8e0 drivers/gpu/drm/drm_atomic_helper.c:1630
 commit_tail+0x79/0x390 drivers/gpu/drm/drm_atomic_helper.c:1844
 drm_atomic_helper_commit+0xa42/0xae0 drivers/gpu/drm/drm_atomic_helper.c:2098
 drm_atomic_commit+0x226/0x280 drivers/gpu/drm/drm_atomic.c:1513
 drm_client_modeset_commit_atomic+0x651/0x7b0 drivers/gpu/drm/drm_client_modeset.c:1057
 drm_client_modeset_commit_locked+0xcb/0x4c0 drivers/gpu/drm/drm_client_modeset.c:1160
 drm_client_modeset_commit+0x4a/0x70 drivers/gpu/drm/drm_client_modeset.c:1186
 __drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:251 [inline]
 drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:278 [inline]
 drm_fb_helper_lastclose+0x9f/0x150 drivers/gpu/drm/drm_fb_helper.c:2018
 drm_fbdev_generic_client_restore+0x34/0x40 drivers/gpu/drm/drm_fbdev_generic.c:257
 drm_client_dev_restore+0x138/0x270 drivers/gpu/drm/drm_client.c:257
 drm_lastclose drivers/gpu/drm/drm_file.c:466 [inline]
 drm_release+0x4bd/0x670 drivers/gpu/drm/drm_file.c:497
 __fput+0x234/0x970 fs/file_table.c:384
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f1c7b79aeb9
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:00007ffc77d3ac78 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f1c7ba17da0 RCX: 00007f1c7b79aeb9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f1c7ba17da0 R08: 0000000000000006 R09: 0000000000000000
R10: 00007f1c7ba17cb0 R11: 0000000000000246 R12: 000000000003747b
R13: 00007f1c7ba1627c R14: 0000000000037444 R15: 00007f1c7ba16270
 </TASK>