bug#39712: Partitions produced by the installer not properly unmounted?

[Ludovic Courtès]

Hi Mathieu,

I noticed that partitions created by the installer appear to not be
properly unmounted, at least when running in the context of (gnu tests
install):

--8<---------------cut here---------------start------------->8---
ludo@ribbon ~$ qemu-img convert -O raw 
/gnu/store/2d3s2nbb3j2c1hmkz52xds9rfbk4q3x3-installation /tmp/broken.raw
ludo@ribbon ~$ sudo losetup -P /dev/loop0 /tmp/broken.raw 
ludo@ribbon ~$ sudo dmesg |tail -3
[10703.869334] kvm [8936]: vcpu0, guest rIP: 0xffffffffac073dad disabled 
perfctr wrmsr: 0xc2 data 0xffff
[10742.475623] kvm [8957]: vcpu0, guest rIP: 0xffffffffaf073dad disabled 
perfctr wrmsr: 0xc2 data 0xffff
[11774.318468]  loop0: p1 p2 p3
ludo@ribbon ~$ sudo fdisk -l /dev/loop0
Disk /dev/loop0: 2.15 GiB, 2306867200 bytes, 4505600 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 213AE251-0E91-499E-9184-0CCEC6DA64C7

Dispositiu    Start   Final Sectors  Size Tipus
/dev/loop0p1   2048    6143    4096    2M BIOS boot
/dev/loop0p2   6144  231423  225280  110M Intercanvi Linux
/dev/loop0p3 231424 4503551 4272128    2G Linux filesystem
ludo@ribbon ~$ sudo mount /dev/loop0p3 /mnt/usb
ludo@ribbon ~$ sudo dmesg |tail -3
[11774.318468]  loop0: p1 p2 p3
[11803.975300] EXT4-fs (loop0p3): recovery complete
[11803.977277] EXT4-fs (loop0p3): mounted filesystem with ordered data mode. 
Opts: (null)
--8<---------------cut here---------------end--------------->8---

However, I’ve added logging in ‘umount-user-partitions’ in (gnu
installer parted), and the installer does seem to unmount partitions
correctly.

Could it be a side effect of the MS_MOVE dance in
1d02052067e04d7dd8fd1ec17557ca02a30b9bcf?

(I’m observing this on ‘wip-installer-tests’, roughly based on
117d8467be232bcc1b0136d04f362d95d975ca95.)

Thanks,
Ludo’.