[Bug 2144745] Re: linux-image-7.0.0-7-generic: dracut fails to include zfs module on ZFS-on-root system (Ubuntu 26.04 Resolute)

Perhaps related, linux-modules-7.0.0-1004-raspi doesn't include the zfs
modules at all.

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Title:
linux-image-7.0.0-7-generic: dracut fails to include zfs module on
ZFS-on-root system (Ubuntu 26.04 Resolute)

Status in linux package in Ubuntu:
Confirmed

Bug description:
Bug Report: Kernel 7.0.0-7-generic unbootable on ZFS-on-root

Package: linux-image-7.0.0-7-generic (Version 7.0.0-7.7) / dracut
Severity: Critical (System unbootable)

Description:
During a routine upgrade on Ubuntu 26.04 Resolute Raccoon, the installation of kernel 7.0.0-7-generic fails to generate a valid initramfs using dracut. The process terminates because the zfs module cannot be found in the new kernel's directory, despite the system running on a ZFS root pool.

The resulting /boot/initrd.img-7.0.0-7-generic lacks the necessary
drivers to mount the encrypted ZFS root filesystem, leading to a
Kernel Panic or an emergency initramfs prompt upon boot.

Steps to Reproduce:

Use Ubuntu 26.04 (Resolute) installed on a ZFS root partition
(rpool).

Run sudo apt update && sudo apt upgrade.

Observe the dracut post-installation triggers for linux-
image-7.0.0-7-generic.

Actual Results:
dracut fails with the following error:

/etc/kernel/postinst.d/dracut:
dracut: Generating /boot/initrd.img-7.0.0-7-generic
dracut-install: Failed to find module 'zfs'
dracut[E]: FAILED: /usr/lib/dracut/dracut-install -D /var/tmp/dracut.XXXXXX/initramfs --kerneldir /usr/lib/modules/7.0.0-7-generic -m zfs

System Information:

Distro: Ubuntu 26.04 (Resolute Raccoon)

Working Kernel: 6.19.0-9-generic (x86_64)

Motherboard: ASUS ROG MAXIMUS Z790 HERO

BIOS: American Megatrends Inc. v3001 (04/25/2025)

ZFS Version: Userspace 2.4.1-1ubuntu1 / Module 2.4.0-1ubuntu3

Storage: Samsung SSD 990 PRO (NVMe)

Root FS: ZFS rpool/ROOT/ubuntu_o2oj4n with aes-256-gcm encryption

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