OK, it appears that a simple way to trigger this bug is to run sudo losetup -f /var/lib/snapd/snaps/bare_5.snap
Every time this command is run, the error is reported. If you add the "-P" option, which should be used to force a partition scan, then you get an additional warning line: Sep 20 10:07:48 boxxo2-VirtualBox kernel: loop_reread_partitions: partition scan of loop19 (/var/lib/snapd/snaps/bare_5.snap) failed (rc=-5) I'm going to mark this as invalid for snapd, because the squashfs images we use are perfectly valid, and the bug seems to be in the kernel, and at a first sight it appears that there are two things going wrong: 1) a partition scan occurs even though it was not explicitly requested 2) the RDB driver should be less verbose, and just assume that if the device is smaller than 8k, then it's not a RDB partition -- no need to report anything in the kernel logs. ** Changed in: snapd (Ubuntu) Status: Confirmed => Invalid ** Also affects: linux (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1979633 Title: The "bare" snap is the cause of error messages "unable to read partition table" and "partition table beyond EOD, truncated" Status in linux package in Ubuntu: New Status in snapd package in Ubuntu: Invalid Bug description: Hi, here is the problem: # journalctl | grep loop4 Jun 23 09:49:45 vougeot kernel: loop4: detected capacity change from 0 to 8 Jun 23 09:49:45 vougeot kernel: Dev loop4: unable to read RDB block 8 Jun 23 09:49:45 vougeot kernel: loop4: unable to read partition table Jun 23 09:49:45 vougeot kernel: loop4: partition table beyond EOD, truncated The loop4 device is used to mount the "bare" snap: $ df -a | grep /snap/bare/ [...] /dev/loop4 128 128 0 100% /snap/bare/5 Note that on another system, the loop device will probably have another number. The error messages can be found with the following commands: # journalctl | grep "unable to read RDB block" Jun 23 09:49:45 vougeot kernel: Dev loop4: unable to read RDB block 8 # journalctl | grep "unable to read partition table" Jun 23 09:49:45 vougeot kernel: loop4: unable to read partition table # journalctl | grep "partition table beyond EOD" Jun 23 09:49:45 vougeot kernel: loop4: partition table beyond EOD, truncated ProblemType: Bug DistroRelease: Ubuntu 22.04 Package: snapd 2.55.5+22.04 Uname: Linux 5.18.6-051806-generic x86_64 ApportVersion: 2.20.11-0ubuntu82.1 Architecture: amd64 CasperMD5CheckResult: unknown CurrentDesktop: KDE Date: Thu Jun 23 11:39:16 2022 Snap.Changes: no changes found SourcePackage: snapd UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1979633/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp