Custom kernel gotcha: Recent kernel versions built per instructions fail to load modules file #41578

(Note: I'm not raising this as an issue because for the moment or unless requested, because it strictly affects those of us building custom kernels from non-Microsoft source. But for my fellow bleeding-edge kernelers who want a 7.x kernel, a cautionary note.)

A kernel fix dropped in November 2025 which caps the size of the orphan inode file for ext4 filesystems, but the parallel fix for mke2fs is still working its way through the distros (Debian forky/sid, for example, is still using an older e2fsprogs package). This means that your modules.vhdx built with the latter will fail to mount, killing the WSL VM on boot, if you're working with a post-fix kernel version. You can work around this by stripping the orphan_file feature from the ext4 filesystem inside your .vhdx.

Full write-up, including more details and step-by-step workaround, over on my Substack here.