Gpu stop working after reload the driver

I did:

modprobe -r nvidia_drm
modprobe -r nvidia_uvm
modprobe -r nvidia_modeset
modprobe -r nvidia

modprobe nvidia_drm

Then the nvidia-smi cannot find any of my GPUs. The dmesg shows:

[  822.819561] [drm] [nvidia-drm] [GPU ID 0x00000900] Unloading driver
[  823.086731] [drm] [nvidia-drm] [GPU ID 0x00000800] Unloading driver
[  823.372662] nvidia-modeset: Unloading
[  826.127048] nvidia-uvm: Unloaded the UVM driver.
[  826.146945] nvidia-nvlink: Unregistered the Nvlink Core, major device number 240
[  851.543833] nvidia-nvlink: Nvlink Core is being initialized, major device number 240
[  851.546874] nvidia 0000:08:00.0: vgaarb: changed VGA decodes: olddecodes=none,decodes=none:owns=none
[  851.752335] nvidia 0000:09:00.0: vgaarb: changed VGA decodes: olddecodes=none,decodes=none:owns=none
[  851.952559] NVRM: loading NVIDIA UNIX x86_64 Kernel Module  440.100  Fri May 29 08:45:51 UTC 2020
[  851.969016] nvidia-uvm: Loaded the UVM driver, major device number 238.
[  851.974881] nvidia-modeset: Loading NVIDIA Kernel Mode Setting Driver for UNIX platforms  440.100  Fri May 29 08:14:04 UTC 2020
[  851.978580] [drm] [nvidia-drm] [GPU ID 0x00000800] Loading driver
[  860.425495] NVRM: GPU 0000:08:00.0: RmInitAdapter failed! (0x26:0x65:1227)
[  860.426236] NVRM: GPU 0000:08:00.0: rm_init_adapter failed, device minor number 0
[  860.445089] [drm:nv_drm_load [nvidia_drm]] *ERROR* [nvidia-drm] [GPU ID 0x00000800] Failed to allocate NvKmsKapiDevice
[  860.445940] [drm:nv_drm_probe_devices [nvidia_drm]] *ERROR* [nvidia-drm] [GPU ID 0x00000800] Failed to register device
[  860.446285] [drm] [nvidia-drm] [GPU ID 0x00000900] Loading driver
[  868.864061] NVRM: GPU 0000:09:00.0: RmInitAdapter failed! (0x26:0x65:1227)
[  868.865209] NVRM: GPU 0000:09:00.0: rm_init_adapter failed, device minor number 1
[  868.866447] [drm:nv_drm_load [nvidia_drm]] *ERROR* [nvidia-drm] [GPU ID 0x00000900] Failed to allocate NvKmsKapiDevice
[  868.867069] [drm:nv_drm_probe_devices [nvidia_drm]] *ERROR* [nvidia-drm] [GPU ID 0x00000900] Failed to register device
[  919.677771] NVRM: GPU 0000:08:00.0: RmInitAdapter failed! (0x26:0x65:1227)
[  919.678356] NVRM: GPU 0000:08:00.0: rm_init_adapter failed, device minor number 0
[  928.028777] NVRM: GPU 0000:09:00.0: RmInitAdapter failed! (0x26:0x65:1227)
[  928.029707] NVRM: GPU 0000:09:00.0: rm_init_adapter failed, device minor number 1

what is the problem?