Comment 0 for bug 1726930

This report is to capture the extended diagnostic efforts done on IRC #ubuntu for user maszlo, who has a Lenovo T450 with SSD that was upgraded from 17.04 to 17.10 and since fails to complete start-up of services when powered on battery.

We'd previously applied the "acpi=os=! 'acpi_osi=Windows 2015'" workaround in case this was an ACPI DSDT issue.

This appears to be due to a read-only root file-system. What is not clear is how the rootfs goes read-only.

The file-system (sda6, ext4) is fsck-ed successfully in the initrd according to the /run/initramfs/fsck.log.

From the start-up logs (with "systemd.log_level=debug") we see the ext4 driver report a remount operation not once but five times.

$ grep 'EXT4-fs.*sda6' systemd-debug.log
Oct 23 18:10:44 T450s kernel: EXT4-fs (sda6): mounted filesystem with ordered data mode. Opts: (null)
Oct 23 18:10:44 T450s kernel: EXT4-fs (sda6): re-mounted. Opts: errors=remount-ro
Oct 23 18:10:46 T450s kernel: EXT4-fs (sda6): re-mounted. Opts: errors=remount-ro,data=ordered,commit=600
Oct 23 18:10:47 T450s kernel: EXT4-fs (sda6): re-mounted. Opts: errors=remount-ro,data=ordered,commit=600
Oct 23 18:10:48 T450s kernel: EXT4-fs (sda6): re-mounted. Opts: errors=remount-ro,data=ordered,commit=600
Oct 23 18:10:48 T450s kernel: EXT4-fs (sda6): re-mounted. Opts: errors=remount-ro,data=ordered,commit=600
Oct 23 18:10:49 T450s kernel: EXT4-fs (sda6): re-mounted. Opts: errors=remount-ro,data=ordered,commit=600

Those last five appear to be carrying options generated by laptop-mode-tools.

User has disabled laptop-mode.service and laptop-mode.timer, and lmt-poll.service, but the issue remains.

We see several reports of "read-only file-system":

$ grep 'Read-only' systemd-debug.log
Oct 23 18:10:46 T450s grub-common[1792]: grub-editenv: error: cannot open `/boot/grub/grubenv': Read-only file system.
Oct 23 18:10:46 T450s systemd[1]: colord.service: Failed to run 'start' task: Read-only file system
Oct 23 18:10:46 T450s gpu-manager[1797]: Warning: writing to /var/log/gpu-manager.log failed (Read-only file system)
Oct 23 18:10:46 T450s systemd[1]: systemd-resolved.service: Failed to run 'start' task: Read-only file system
Oct 23 18:10:46 T450s systemd[1]: systemd-resolved.service: Failed to run 'start' task: Read-only file system
Oct 23 18:10:46 T450s gdm3[1932]: Failed to create LogDir /var/log/gdm3: Read-only file system
...
Oct 23 18:11:26 T450s cupsd[1461]: Unable to change ownership of "/var/log/cups" - Read-only file system
Oct 23 18:11:26 T450s cupsd[1461]: Unable to open log file "/var/log/cups/access_log" - Read-only file system
Oct 23 18:12:52 T450s login[9248]: pam_lastlog(login:session): unable to open /var/log/lastlog: Read-only file system

We also see several problems with systemd's connection to Dbus:

$ grep 'Transport endpoint' systemd-debug.log
Oct 23 18:10:46 T450s systemd[1]: Failed to send job change signal for 773: Transport endpoint is not connected
Oct 23 18:10:46 T450s systemd[1]: systemd-logind.service: Failed to send unit change signal for systemd-logind.service: Transport endpoint is not connected
Oct 23 18:10:46 T450s systemd[1]: Failed to send job remove signal for 156: Transport endpoint is not connected
Oct 23 18:10:46 T450s systemd[1]: lmt-poll.service: Failed to send unit change signal for lmt-poll.service: Transport endpoint is not connected
Oct 23 18:10:46 T450s systemd[1]: Failed to send job remove signal for 182: Transport endpoint is not connected
Oct 23 18:10:46 T450s systemd[1]: Failed to send job remove signal for 95: Transport endpoint is not connected
Oct 23 18:10:46 T450s systemd[1]: polkit.service: Failed to send unit change signal for polkit.service: Transport endpoint is not connected
Oct 23 18:10:46 T450s systemd[1]: cups-browsed.service: Failed to send unit change signal for cups-browsed.service: Transport endpoint is not connected
Oct 23 18:10:46 T450s systemd[1]: Failed to send job change signal for 773: Transport endpoint is not connected
Oct 23 18:10:46 T450s systemd[1]: Failed to send job remove signal for 161: Transport endpoint is not connected
Oct 23 18:10:46 T450s systemd[1]: gdomap.service: Failed to send unit change signal for gdomap.service: Transport endpoint is not connected