[Bug 1726930] Re: System fails to start (boot) on battery due to read-only root file-system

Tue Jan 9 16:41:37 UTC 2018

This would still be a flaky device or a kernel bug. Because the
mentioned laptop-mode-tools version (1.71) brought in forced execution
mode, so that it could apply proper power saving values. That's pretty
much it. That does not result in read only rootfs because if it
logically did, it'd be seen on every machine.

BTW, does Ubuntu have the systemd/udevd mount propagation fix included ?

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Title:
  System fails to start (boot) on battery due to read-only root file-
  system

Status in laptop-mode-tools package in Ubuntu:
  Confirmed
Status in systemd package in Ubuntu:
  Confirmed
Status in systemd package in Debian:
  Fix Released

Bug description:
  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

  When the user purged laptop-mode-tools the system starts successfully
  on battery.

  The user installed a fresh instance of 17.10 on a 2nd M2 SSD. When
  laptop-mode-tools was added to that instance it also exhibited the
  failure.

  # apt-cache rdepends laptop-mode-tools
  laptop-mode-tools
  Reverse Depends:
    systemd
    tlp
    powertop-1.13
    powertop

  # apt show systemd | grep Breaks
  Breaks: apparmor (<< 2.9.2-1), ifupdown (<< 0.8.5~), laptop-mode-tools (<< 1.68~), systemd-shim (<< 10-3~), udev (<< 228-5)

  # apt-cache policy laptop-mode-tools
  laptop-mode-tools:
    Installed: (none)
    Candidate: 1.71-2ubuntu1

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