Every `source envkernel.sh` stacks another /mnt/linux bind mount

scope: generic · severity: trap · confidence: proven · subsystem: build

source envkernel.sh bind-mounts the kernel tree onto chroot_native/mnt/linux without removing the previous one — deactivate does not unmount. After a day of build cycles it was stacked 16 deep.

The breakage is not the shape the error suggests. The .output/Makefile overmount sits on whichever /mnt/linux layer was on top when it was created. Later binds stack on top of it, so the path /mnt/linux/.output/Makefile now resolves to the newest layer, where nothing is mounted. It is still listed in /proc/mounts but is unreachable by name, so umount returns 32 “not mounted” and pmb.helpers.mount.umount_all aborts the whole command — during build (skipping the reindex) or during install.

The overmount is a child of the bottom layer, buried under everything else, which is why pmbootstrap shutdown cannot recover on its own. Peel one layer at a time, retrying the Makefile at each level as it becomes visible again: tkclean does this.

awk -v p=<mnt> '$5==p' /proc/self/mountinfo    # what is actually there