Executing nvidia-smi on production Linux GPU servers suddenly halts with an immediate exit code: Failed to initialize NVML: Driver/library version mismatch. All downstream AI applications, including vLLM inference engines, Ollama daemons, and PyTorch training jobs, fail instantly because user-space NVIDIA Management Library (libnvidia-ml.so) cannot establish a handshake with the host kernel driver.

This failure occurs when Ubuntu automatic background updates (unattended-upgrades) or manual apt upgrade installs an updated NVIDIA package version in user-space while the host kernel keeps running the older driver module in memory. You do not need to reboot your host machine.

The Direct Solution: Reloading Kernel Modules Without a System Reboot

Terminate all processes holding GPU file descriptors, cleanly unload the four linked NVIDIA kernel modules in reverse dependency order, and reload the newly installed kernel driver:

# Step 1: Identify and terminate all processes consuming /dev/nvidia*
sudo fuser -v /dev/nvidia* -k -9

# Step 2: Stop display managers and system monitoring agents if running
sudo systemctl stop nvidia-persistenced
sudo systemctl stop dcgm 2>/dev/null || true

# Step 3: Unload the NVIDIA kernel modules in strict dependency sequence
sudo rmmod nvidia_uvm
sudo rmmod nvidia_drm
sudo rmmod nvidia_modeset
sudo rmmod nvidia

# Step 4: Reload the new driver module into the running kernel
sudo modprobe nvidia
sudo systemctl start nvidia-persistenced

# Step 5: Verify immediate restoration
nvidia-smi

Executing this sequence unloads the stale in-memory module, binds the updated user-space library directly to the newly compiled kernel objects, and restores nvidia-smi functionality within 4 seconds.

Root Cause and Diagnostic Verification

The NVIDIA driver operates in two distinct execution domains:

1. Kernel-Space Driver Modules: nvidia.ko, nvidia_modeset.ko, nvidia_uvm.ko, and nvidia_drm.ko. These are compiled against your active Linux kernel and loaded into RAM at boot time.
2. User-Space Libraries: libnvidia-ml.so.1 (NVML) and libcudart.so. These live in /usr/lib/x86_64-linux-gnu/ and execute inside user processes.

When apt upgrade executes, package managers unpack updated shared libraries (e.g., driver version 550.120) and compile new kernel modules into /lib/modules/$(uname -r)/updates/dkms/. However, Linux does not automatically swap loaded kernel drivers in memory.

Confirm the version discrepancy between your running kernel and user-space libraries:

# 1. Inspect the driver version loaded in active kernel memory
cat /proc/driver/nvidia/version | head -n 1
# Output: NVRM version: NVIDIA UNIX x86_64 Kernel Module  550.54.14  Wed Feb 21 16:51:24 UTC 2024

# 2. Inspect the installed user-space package version
dpkg -l | grep -i nvidia-driver | awk '{print $2, $3}'
# Output: nvidia-driver-550 550.120-0ubuntu0.24.04.1

If the kernel module reports 550.54.14 while dpkg reports 550.120, NVML aborts initialization because minor ABI changes between driver builds break memory layout compatibility.

Step-by-Step Module Disentanglement Protocol

In complex multi-tenant servers running Docker, Kubernetes, or graphical sessions, rmmod nvidia will return rmmod: ERROR: Module nvidia is in use. Follow this systematic procedure to release stuck locks.

1. Kill Container and CUDA Runtime Locks

Check which active PIDs hold open file handles to the character devices:

sudo lsof -n /dev/nvidia*

If container runtimes like containerd or Docker keep GPU handles open, stop them temporarily or kill worker subprocesses directly:

# Target all PIDs accessing character devices
sudo fuser -k -9 /dev/nvidia*
sudo fuser -k -9 /dev/nvidiactl
sudo fuser -k -9 /dev/nvidia-uvm

2. Disable Conflicting Systemd Services

NVIDIA installs persistent background helpers that restart automatically when killed:

# Stop persistence daemon and fabric manager
sudo systemctl stop nvidia-persistenced
sudo systemctl stop nvidia-fabricmanager 2>/dev/null || true

3. Handle Graphical Session Locks (Workstations and Desktops)

If you are operating an Ubuntu workstation running GDM, LightDM, or X11, the display server locks nvidia_drm:

# Temporarily switch to multi-user target (headless terminal mode)
sudo systemctl isolate multi-user.target

After executing module reload, return to your graphical interface with sudo systemctl isolate graphical.target.

4. Unload Modules with Modprobe Recursion

If rmmod complains about dependencies, use modprobe -r to automatically trace the dependency tree:

sudo modprobe -r nvidia_uvm nvidia_drm nvidia_modeset nvidia

Verify that no NVIDIA modules remain in memory:

lsmod | grep nvidia
# Expected output: (empty)

5. Reinitialize the Kernel Driver Stack

Load the updated driver:

sudo modprobe nvidia
sudo modprobe nvidia_uvm
sudo systemctl start nvidia-persistenced

Execute nvidia-smi. The command now renders the standard ASCII hardware telemetry dashboard displaying your updated driver version.

Diagnostic and Resolution Matrix

The following table summarizes common failure symptoms and specific resolution paths:

System Symptom	Underlying Block	Required Action
NVML: Driver/library version mismatch	Outdated in-memory kernel module	Run fuser -k -9 /dev/nvidia* then rmmod and modprobe nvidia
rmmod: ERROR: Module nvidia is in use	Background containers or persistenced	Stop nvidia-persistenced and kill PIDs from lsof /dev/nvidia*
rmmod: ERROR: Module nvidia_drm is in use	Active Xorg, Wayland, or GDM session	Run systemctl isolate multi-user.target before unloading
Reoccurrence after overnight update	Ubuntu unattended-upgrades package	Mark packages with apt-mark hold nvidia* libnvidia*
modprobe: FATAL: Module nvidia not found	DKMS compilation failed during update	Run sudo dkms autoinstall -k $(uname -r) to rebuild module

Preventing Future Mismatches in Production

To prevent automatic Ubuntu security updates from unexpectedly breaking running inference pipelines in production, freeze the NVIDIA driver packages:

# Pin all installed NVIDIA driver and NVML libraries
sudo apt-mark hold $(dpkg -l | grep -iE 'nvidia-driver|libnvidia' | awk '{print $2}')

# Verify hold status
apt-mark showhold | grep nvidia

Additionally, exclude NVIDIA packages from automatic background updates by adding a blacklist rule to /etc/apt/apt.conf.d/50unattended-upgrades:

Unattended-Upgrade::Package-Blacklist {
    "nvidia-.*";
    "libnvidia-.*";
    "cuda-.*";
};

This configuration ensures production inference nodes remain 100% stable, deferring driver upgrades to controlled, scheduled maintenance windows.