Kernel Oops: Fix Driver Faults on Linux 6.x

1. Buggy Driver Module — Update or Roll Back

The most common trigger for a kernel Oops with a driver fault is a mismatched or buggy kernel module. I see this a lot on Ubuntu 22.04 with Nvidia drivers after a kernel update — the module compiles against the wrong kernel headers, or the version just has a known bug.

What's actually happening here is that the module tries to access memory it doesn't own, or calls a function that doesn't exist in the current kernel. The Oops message in dmesg usually names the culprit — look for something like BUG: unable to handle kernel NULL pointer dereference at ... followed by a module name like nvidia, i915, or usb-storage.

The Fix

1. Check dmesg | grep -i oops to see which module crashed.
2. Update that driver. For Nvidia: sudo ubuntu-drivers autoinstall or grab the latest from Nvidia's site. For Intel i915: update your kernel to 6.2+ (they fixed many bugs there).
3. If the update gave you the problem, roll back the driver. On Ubuntu: sudo apt install nvidia-driver-525 (or the version you had before).
4. Reboot and test.

Skip reinstalling the whole system — that's overkill. The reason step 3 works is that the older module was compiled against a kernel ABI that's still compatible, while the new one isn't.

2. Kernel Module Conflict — Blacklist the Bad One

Sometimes two drivers fight over the same hardware. Classic case: the open-source nouveau driver and the proprietary Nvidia driver both try to control your GPU. The kernel panics because they step on each other's memory.

Another real scenario: on a Dell XPS 13 with Fedora 38, the iwlwifi module for Intel wireless sometimes clashes with ath10k if you dual-boot and the wrong module loads. The Oops message here will show both modules in the call trace.

The Fix

1. Identify the conflicting module. If you run Nvidia, lsmod | grep nouveau — if it's loaded, that's the problem.
2. Blacklist the module you don't want. Create a file like /etc/modprobe.d/blacklist-nouveau.conf with:

   blacklist nouveau
   options nouveau modeset=0

3. Update the initramfs: sudo update-initramfs -u (Ubuntu) or sudo dracut -f (Fedora).
4. Reboot. The blacklisted module won't load, and the conflict goes away.

Don't forget step 3 — skipping it means the old initramfs still loads the module. I've seen people reboot three times and wonder why nothing changed.

3. Kernel ABI Mismatch — Recompile the Module from Source

If you're running a custom kernel (like XanMod or liquorix) or an older kernel that a driver vendor doesn't support, you'll get an Oops because the module was built for a different kernel version. The error string typically says disagrees about version of symbol or module layout'X' differs from kernel.

This happens a lot with ZFS (zfs.ko) on kernel 6.5 — the OpenZFS project takes a few weeks to catch up. Also affects VirtualBox guest additions if you update the kernel without recompiling them.

The Fix

1. Get the source for the driver. For ZFS: git clone https://github.com/openzfs/zfs.git. For VirtualBox: run /sbin/rcvboxadd setup as root.
2. Compile against your running kernel:

   cd zfs
   ./configure
   make -j$(nproc)
   sudo make install
   sudo modprobe zfs

3. If compilation fails, your kernel headers are missing. Install them first:

   sudo apt install linux-headers-$(uname -r)

4. Reboot and check dmesg — the Oops should be gone.

The reason you compile from source is that pre-built binary modules (like from a PPA) are built against the generic kernel. Your custom kernel has different CONFIG options, so the module crashes. Building from source matches the config exactly.

Quick Reference Table

If none of these work, check cat /proc/version and compare with your module source. Sometimes the kernel itself has a bug — then you file a bug report, not try to fix it with a workaround.