[Bug 2045586] Re: livecd-rootfs uses losetup -P for theoretically reliable/synchronous partition setup but it's not reliable in noble

[Steve Langasek]

Oh.  To the question of whether there was a systemd change in this
window: yes absolutely, because this is the point at which the riscv64
builders moved from lgw manually-operated qemu with a 20.04 guest image,
to bos03 openstack-operated qemu with a 22.04 guest image.

Which is also why we've moved from 5.13.0-1019-generic to
5.19.0-1021-generic.

But again, it was my understanding that these devices are supposed to be
created synchronously WITHOUT the involvement of udev.  In fact, we had
to make launchpad-buildd changes to make use of these devices at all
because udev would NOT set them up for us.

So if these are now being set up via udev, that's a significant
departure from expectations and it's not clear we even CAN have
synchronous behavior given that they would be set up by the host udev
and not the udev in the lxd container!

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to util-linux in Ubuntu.
https://bugs.launchpad.net/bugs/2045586

Title:
  livecd-rootfs uses losetup -P for theoretically reliable/synchronous
  partition setup but it's not reliable in noble

Status in linux package in Ubuntu:
  New
Status in livecd-rootfs package in Ubuntu:
  New
Status in util-linux package in Ubuntu:
  New

Bug description:
  In mantic, we migrated livecd-rootfs to use losetup -P instead of
  kpartx, with the expectation that this would give us a reliable, race-
  free way of loop-mounting partitions from a disk image during image
  build.

  In noble, we are finding that it is no longer reliable, and in fact
  fails rather often.

  It is most noticeable with riscv64 builds, which is the architecture
  where we most frequently ran into problems before with kpartx.  The
  first riscv64+generic build in noble where the expected loop partition
  device is not available is

    https://launchpad.net/~ubuntu-
  cdimage/+livefs/ubuntu/noble/cpc/+build/531790

  The failure is however not unique to riscv64, and the autopkgtest for
  the latest version of livecd-rootfs (24.04.7) - an update that
  specifically tries to add more debugging code for this scenario - has
  also failed on ppc64el.

    https://autopkgtest.ubuntu.com/packages/l/livecd-
  rootfs/noble/ppc64el

  The first failure happened on November 16.  While there has been an
  update to the util-linux package in noble, this did not land until
  November 23.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2045586/+subscriptions