Thank you, having a reliable reproducer is very helpful! I can confirm this reproduces locally for me on QEMU.
I prepared a new systemd package [0], containing backports from the above mentioned PR that indeed sounds very related (I wonder why the issue didn't happen before, tho, as this is unrelated to any recent SRU). Using this package, I prepared a new '20211115' core18 base snap [1] and a corresponding UC18 image [2] for further testing. With this systemd version the reproducer passes for me with no problem. So I guess it's worth giving this another try with the full spread test. [0] https://launchpad.net/~slyon/+archive/ubuntu/lp1949089 [1] https://people.ubuntu.com/~slyon/uc18/core18_20211115_amd64.snap [2] https://people.ubuntu.com/~slyon/uc18/uc18-20211115+systemd+3G.img.xz -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1949089 Title: systemd randomly fails to activate mount units in Ubuntu Core 18 Status in systemd package in Ubuntu: New Status in systemd source package in Bionic: New Bug description: Since a month or so, we've been seeing random failures in our snapd spread tests where systemd could not start the mount unit associated with a snap because of a failed dependency. The issue is described in the comments to PR https://github.com/snapcore/snapd/pull/10935, but I'll summarize it here. When starting a snap, snapd creates a mount unit to mount the snap's squashfs (the template is https://github.com/snapcore/snapd/blob/release/2.53/systemd/systemd.go#L1186-L1205). The snapd asks systemd to reload the configuration, and starts the mount unit. The failure we've observed is that sometimes systemd decides to stop our mount unit (search for "Unmounting Mount unit for test-snapd-svc- flip-flop" in the attached log), and then tries to reactivate it again, and at that point it fails. When I asked for help, Lukas pointed out that the latest update contains a patch that is related to reload handling and mount units: http://launchpadlibrarian.net/555420796/systemd_237-3ubuntu10.51_237-3ubuntu10.52.diff.gz (the patch itself is better visible at https://github.com/systemd/systemd/commit/f0831ed2a03fcef582660be1c3b1a9f3e267e656). When looking at the systemd git log, though, I noticed another patch that was applied shortly after this one, which also seems related but was not backported: https://github.com/systemd/systemd/commit/04eb582acc203eab0bc5c2cc5e13986f16e09df0 Since the stopping of our mount unit happens immediately after a systemd reload, it actually seems very likely that the inclusion of f0831ed2a03fcef582660be1c3b1a9f3e267e656 in the systemd update is what causes our woes (though, indeed, the issue is not reliably reproducible, so we cannot be sure). To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1949089/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
