syzbot

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WARNING: CPU: 1 PID: 3714 at drivers/gpu/drm/vkms/vkms_crtc.c:97 vkms_get_vblank_timestamp+0x78/0x80 drivers/gpu/drm/vkms/vkms_crtc.c:110
Modules linked in:
CPU: 1 UID: 0 PID: 3714 Comm: syz.3.62 Not tainted syzkaller #0 PREEMPT 
Hardware name: linux,dummy-virt (DT)
pstate: 614020c9 (nZCv daIF +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
pc : vkms_get_vblank_timestamp+0x78/0x80 drivers/gpu/drm/vkms/vkms_crtc.c:97
lr : vkms_get_vblank_timestamp+0x1c/0x80 drivers/gpu/drm/vkms/vkms_crtc.c:88
sp : ffff80008933b900
x29: ffff80008933b900 x28: f0f00000041e3270 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000000 x24: fdf0000004510080
x23: 0000000000000003 x22: 00000000000000c0 x21: 0000000000000000
x20: faf0000005238080 x19: ffff80008933b9c0 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: 0000ffffe18f9a78
x14: 0000000000000000 x13: 0000000000000000 x12: 0101010101010101
x11: 000000000000fde8 x10: 00000000000004a0 x9 : 000000000000001c
x8 : ffff800082c6f000 x7 : 0000000000000002 x6 : 00000000000003e8
x5 : 0000000000000000 x4 : ffff8000809e4acc x3 : 0000000000000000
x2 : 0000000000000138 x1 : 0000004890bdaaa0 x0 : 0000004890bdaaa0
Call trace:
 vkms_get_vblank_timestamp+0x78/0x80 drivers/gpu/drm/vkms/vkms_crtc.c:110 (P)
 drm_crtc_get_last_vbltimestamp+0x98/0xa8 drivers/gpu/drm/drm_vblank.c:879
 drm_get_last_vbltimestamp drivers/gpu/drm/drm_vblank.c:898 [inline]
 drm_update_vblank_count+0x8c/0x3c8 drivers/gpu/drm/drm_vblank.c:311
 drm_vblank_disable_and_save+0x80/0x114 drivers/gpu/drm/drm_vblank.c:480
 drm_crtc_vblank_off+0xc0/0x2a4 drivers/gpu/drm/drm_vblank.c:1364
 vkms_crtc_atomic_disable+0x10/0x1c drivers/gpu/drm/vkms/vkms_crtc.c:225
 crtc_disable+0x114/0x1ec drivers/gpu/drm/drm_atomic_helper.c:1258
 disable_outputs drivers/gpu/drm/drm_atomic_helper.c:1340 [inline]
 drm_atomic_helper_commit_modeset_disables+0x28/0x64 drivers/gpu/drm/drm_atomic_helper.c:1524
 vkms_atomic_commit_tail+0x28/0xcc drivers/gpu/drm/vkms/vkms_drv.c:61
 commit_tail+0xa4/0x18c drivers/gpu/drm/drm_atomic_helper.c:1986
 drm_atomic_helper_commit+0x164/0x178 drivers/gpu/drm/drm_atomic_helper.c:2226
 drm_atomic_commit+0x88/0xc4 drivers/gpu/drm/drm_atomic.c:1577
 drm_client_modeset_commit_atomic+0x20c/0x26c drivers/gpu/drm/drm_client_modeset.c:1103
 drm_client_modeset_commit_locked+0x5c/0x18c drivers/gpu/drm/drm_client_modeset.c:1206
 drm_client_modeset_commit+0x30/0x58 drivers/gpu/drm/drm_client_modeset.c:1232
 __drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:238 [inline]
 __drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:217 [inline]
 drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:268 [inline]
 drm_fb_helper_lastclose+0x64/0xb0 drivers/gpu/drm/drm_fb_helper.c:1986
 drm_fbdev_client_restore+0x14/0x24 drivers/gpu/drm/clients/drm_fbdev_client.c:31
 drm_client_dev_restore+0xb4/0xfc drivers/gpu/drm/drm_client_event.c:117
 drm_lastclose drivers/gpu/drm/drm_file.c:408 [inline]
 drm_release+0xe0/0x128 drivers/gpu/drm/drm_file.c:441
 __fput+0xcc/0x2dc fs/file_table.c:468
 ____fput+0x14/0x20 fs/file_table.c:496
 task_work_run+0x78/0xd4 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 do_notify_resume+0x13c/0x16c arch/arm64/kernel/entry-common.c:155
 exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:173 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:182 [inline]
 el0_svc+0x108/0x10c arch/arm64/kernel/entry-common.c:880
 el0t_64_sync_handler+0xa0/0xe4 arch/arm64/kernel/entry-common.c:898
 el0t_64_sync+0x1a4/0x1a8 arch/arm64/kernel/entry.S:596
---[ end trace 0000000000000000 ]---