Hi, Not sure on your case, but on mine I've a kernel crash on zfs module.
So it might not be so simple as changing those scripts. A real fix is probably on newer zfs module or on newer Linux itself. Perhaps even in both. Best Regards, Helio Loureiro https://helio.loureiro.eng.br https://github.com/helioloureiro https://mastodon.social/@helioloureiro On Thu, Jul 10, 2025, 22:25 Seth Arnold <[email protected]> wrote: > The two mechanisms I have thought of so far, completely untested, are: > > - do 'something' with the /var/lib/dpkg/info/zfsutils-linux.prerm script > supplied by plucky, questing, and whatever the next 'r' release is > called, to deal with this situation > > - modify do-release-upgrade to deal with this situation (hopefully we > have a mechanism to fix do-release-upgrade in oracular after eol?) > > And the approaches I've thought of to "deal with this situation" are: > > - use dpkg-divert in do-release-upgrade to move aside the new binaries > and libraries during installation (so the old utilities will talk with > the old kernel interfaces during the big pile of maintainer scripts and > triggers) and then undo dpkg-divert and "finish" the zfsutils-linux > upgrade immediately before rebooting. > > - use dpkg-divert in do-release-upgrade to move aside the new binaries > and libraries .. and then use a systemd service to undo the dpkg-divert > and "finish" the zfsutils-linux upgrade after reboot. > > - modify the zfsutils-linux.prerm script from the newer releases to > monkeypatch / cowboy / mangle the 10_linux_zfs file and hope that that's > the only thing that triggers this problem -- and depending upon the > mangling that was done, maybe it needs to be undone, maybe not. This is > a big question mark. This script is pretty complex and I can't figure > out what it does and why. > > -- > You received this bug notification because you are subscribed to the bug > report. > https://bugs.launchpad.net/bugs/2110891 > > Title: > System freeze on release upgrade 24.10 oracular to 25.04 plucky with > root fs on ZFS > > Status in linux package in Ubuntu: > Confirmed > Status in ubuntu-release-upgrader package in Ubuntu: > Deferred > Status in zfs-linux package in Ubuntu: > Confirmed > Status in linux source package in Plucky: > Confirmed > Status in ubuntu-release-upgrader source package in Plucky: > Fix Released > Status in zfs-linux source package in Plucky: > Confirmed > > Bug description: > [Impact] > Upgrades to 25.10 (and newer) fail as the ZFS userspace modules are > newer than the kernel modules and there is some incompatibility that can > cause the kernel to hang, particularly the bug observes a problem with > iterating over the snapshots of the root file system freezing it. > > [Test plan: ubuntu-release-upgrader] > 1. Create a vm > 2. Check that the upgrade doesn't trigger the screen > (no zpool exists) > 3. Install zfsutils-linux > 4. Check that the upgrade doesn't trigger the screen > (zpool list -H will be empty) > 5. Create a zpool, for example in a file > # fallocate /swap -l 2G > # zpool create foo /swap > # zpool list > NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT > foo 1.88G 134K 1.87G - - 0% 0% 1.00x ONLINE - > # zpool list -H > foo 1.88G 110K 1.87G - - 0% 0% 1.00x ONLINE - > 6. Check that the upgrade aborts > > [Where problems could occur: ubuntu-release-upgrader] > The change disables upgrades for all systems with a zpool, regardless of > snapshots existing or zpool being on root, this also may include systems > that could upgrade successfully. > > If the code is wrong it could inadvertently block systems without ZFS > from upgrading, however this seems reasonably mitigated by the test > plan. > > [Original bug report] > > SUMMARY: > I'm running Ubuntu 24.10 on a ZFS root fs on LUKS which also has > snapshots. As part of the release upgrade process ubuntu-release-upgrader > is triggering a bug in ZFS triggered by the update-grub steps which > executes ls /.zfs/snapshot/… via 10_linux_zfs and eventually causes a > kernel deadlock on mount.zfs. > > As the `ls` statement in question works flawlessly before the upgrade > process, I assume the hang is caused due to ZoL been replaced by apt > previously? That's why I feel this is a ubuntu-release-upgrader > package bug. > > I've reported this bug also upstream at ZoL: > https://github.com/openzfs/zfs/issues/17337 > > DETAILED DESCRIPTION: > I've failed now 7 time to upgrade my Ubuntu 24.10 to 25.04 (Beta, RC, > First Release, Today). In all cases the upgrade runs into a complete system > freeze deadlock. `zfs rollback` for the rescue. Today, only using text > console with screen & running `dmesg -Hxw`, `htop -d 5` and > `do-release-upgrade` in parallel I finally was able to pinpoint the problem: > > 1. `do-release-upgrade` downloads & install all updated .deb > packages > > 2. Eventually, the upgrade tries to run `upgrade-grub` > > 3. The grub script executes the hook `10_linux_zfs` to identify the > available kernel versions for the grub boot menu > > 4. As part of this discovery an `ls /.zfs/snapshot/[snapshot]/etc` > is executed which causes a system freeze > > 5. Eventually, after a long pause the kernel reports `task ls:… > blocked for more than 122 seconds.` > > 6. Only option left for me is to shutdown server and revert to ZFS > snapshot I did before the upgrade > > REMARKS: > * Executing "ls /.zfs/snapshot/[snapshot]/etc" and "update-grub" works > successfully BEFORE upgrade > * Rebooting into the partial upgraded system, running "strace > update-grub" reproduces the problem. > > To manage notifications about this bug go to: > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2110891/+subscriptions > > -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2110891 Title: System freeze on release upgrade 24.10 oracular to 25.04 plucky with root fs on ZFS To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2110891/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
