Comment 5 for bug 1852518

This is the end of the strace interleaved with journalct output:

...
ioctl(4, DM_DEV_STATUS, {version=4.0.0, data_size=16384, name="loop0p1", flags=DM_EXISTS_FLAG|DM_SKIP_BDGET_FLAG} => {version=4.34.0, data_size=16384, name="loop0p1", flags=DM_EXISTS_FLAG|DM_SKIP_BDGET_FLAG}) = -1 ENXIO (No such device or address)
ioctl(4, DM_DEV_STATUS, {version=4.0.0, data_size=16384, uuid="part1-devnode_7:0_Wh5pYvM", flags=DM_EXISTS_FLAG} => {version=4.34.0, data_size=16384, uuid="part1-devnode_7:0_Wh5pYvM", flags=DM_EXISTS_FLAG}) = -1 ENXIO (No such device or address)
openat(AT_FDCWD, "/dev/urandom", O_RDONLY) = 5
read(5, "r\5", 2) = 2
semget(0xd4d0572, 1, IPC_CREAT|IPC_EXCL|0600) = 0
semctl(0, 0, SETVAL, 0x7ffd00000001) = 0
semctl(0, 0, GETVAL, NULL) = 1
close(5) = 0
semop(0, [{0, 1, 0}], 1) = 0
semctl(0, 0, GETVAL, NULL) = 2
ioctl(4, DM_DEV_CREATE, {version=4.0.0, data_size=16384, name="loop0p1", uuid="part1-devnode_7:0_Wh5pYvM", flags=DM_EXISTS_FLAG} => {version=4.34.0, data_size=305, dev=makedev(0xfc, 0), name="loop0p1", uuid="part1-devnode_7:0_Wh5pYvM", target_count=0, open_count=0, event_nr=0, flags=DM_EXISTS_FLAG}) = 0
ioctl(4, DM_TABLE_LOAD, {version=4.0.0, data_size=16384, data_start=312, name="loop0p1", target_count=1, flags=DM_EXISTS_FLAG, ...} => {version=4.34.0, data_size=305, data_start=312, dev=makedev(0xfc, 0), name="loop0p1", uuid="part1-devnode_7:0_Wh5pYvM", target_count=0, open_count=0, event_nr=0, flags=DM_EXISTS_FLAG|DM_INACTIVE_PRESENT_FLAG}) = 0
ioctl(4, DM_DEV_SUSPEND, {version=4.0.0, data_size=16384, name="loop0p1", event_nr=4195698, flags=DM_EXISTS_FLAG|DM_SKIP_BDGET_FLAG} => {version=4.34.0, data_size=305, dev=makedev(0xfc, 0), name="loop0p1", uuid="part1-devnode_7:0_Wh5pYvM", target_count=1, open_count=0, event_nr=0, flags=DM_EXISTS_FLAG|DM_ACTIVE_PRESENT_FLAG|DM_SKIP_BDGET_FLAG|DM_UEVENT_GENERATED_FLAG}) = 0
semget(0xd4d0572, 1, 000) = 0
semctl(0, 0, GETVAL, NULL) = 2
semop(0, [{0, -1, IPC_NOWAIT}], 1) = 0
semop(0, [{0, 0, 0}], 1Nov 14 19:31:53 workable-sunfish-ubuntu-bartender systemd-udevd[19340]: dm-0: Failed to process device, ignoring: No such file or directory
Nov 14 19:31:53 workable-sunfish-ubuntu-bartender systemd-udevd[19339]: dm-0: Failed to process device, ignoring: No such file or directory

@rcj, @mwhudson: I suggest applying the workaround in livecd-rootfs ('kpartx -anv binary/boot/disk.ext4; dmsetup --noudevsync mknodes') to get the builds going quickly (@rcj as I saw there is only one other script in use to fix) and I bisect the issue in systemd in parallel and we will see where this should be fixed.