syzbot

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WARNING: CPU: 0 PID: 4689 at drivers/gpu/drm/vkms/vkms_crtc.c:103 vkms_get_vblank_timestamp+0x184/0x1d0 drivers/gpu/drm/vkms/vkms_crtc.c:103
Modules linked in:
CPU: 0 PID: 4689 Comm: syz.1.327 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:vkms_get_vblank_timestamp+0x184/0x1d0 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 e1 f0 ee fc 4c 89 33 b0 01 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 ec d6 a9 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:ffffc9000c4bf728 EFLAGS: 00010093
RAX: ffffffff84cf7204 RBX: ffffc9000c4bf7d0 RCX: ffff888028cd0000
RDX: 0000000000000000 RSI: 000000142171f56f RDI: 000000142171f56f
RBP: 1ffff92001897efa R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52001897ee8 R12: 000000142171f56f
R13: dffffc0000000000 R14: ffff888020180000 R15: 000000142171f56f
FS:  000055558d855500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb6fc180c00 CR3: 000000005c2c6000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 drm_get_last_vbltimestamp drivers/gpu/drm/drm_vblank.c:881 [inline]
 drm_update_vblank_count+0x29f/0x930 drivers/gpu/drm/drm_vblank.c:303
 drm_vblank_disable_and_save+0xd6/0x3a0 drivers/gpu/drm/drm_vblank.c:477
 drm_crtc_vblank_off+0x210/0x7f0 drivers/gpu/drm/drm_vblank.c:1325
 disable_outputs drivers/gpu/drm/drm_atomic_helper.c:1145 [inline]
 drm_atomic_helper_commit_modeset_disables+0xbca/0x17a0 drivers/gpu/drm/drm_atomic_helper.c:1349
 vkms_atomic_commit_tail+0x4d/0x200 drivers/gpu/drm/vkms/vkms_drv.c:71
 commit_tail+0x27a/0x390 drivers/gpu/drm/drm_atomic_helper.c:1721
 drm_atomic_helper_commit+0x6d3/0x730 drivers/gpu/drm/drm_atomic_helper.c:1940
 drm_client_modeset_commit_atomic+0x638/0x790 drivers/gpu/drm/drm_client_modeset.c:1055
 drm_client_modeset_commit_locked+0xc7/0x4c0 drivers/gpu/drm/drm_client_modeset.c:1158
 drm_client_modeset_commit+0x46/0x70 drivers/gpu/drm/drm_client_modeset.c:1184
 __drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:252 [inline]
 drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:279 [inline]
 drm_fb_helper_lastclose drivers/gpu/drm/drm_fb_helper.c:2007 [inline]
 drm_fbdev_client_restore+0xb5/0x150 drivers/gpu/drm/drm_fb_helper.c:2410
 drm_client_dev_restore+0x134/0x260 drivers/gpu/drm/drm_client.c:226
 drm_lastclose drivers/gpu/drm/drm_file.c:467 [inline]
 drm_release+0x41d/0x5e0 drivers/gpu/drm/drm_file.c:498
 __fput+0x234/0x930 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fb6fc2aee59
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:00007ffee3a94b18 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffee3a94c00 RCX: 00007fb6fc2aee59
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00000000000151c9 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b31520000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb6fc527fac R14: 00007fb6fc527fa8 R15: 00007fb6fc527fa0
 </TASK>