[Bug 1910815] Re: race on boot between multiple invocations of grub-editenv

[Łukasz Zemczak]

Hello Steve, or anyone else affected,

Accepted grub2 into focal-proposed. The package will build now and be
available at https://launchpad.net/ubuntu/+source/grub2/2.04-1ubuntu26.9
in a few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, what testing has been
performed on the package and change the tag from verification-needed-
focal to verification-done-focal. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-focal. In either case, without details of your testing we will
not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: grub2 (Ubuntu Focal)
       Status: In Progress => Fix Committed

** Tags added: verification-needed-focal

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https://bugs.launchpad.net/bugs/1910815

Title:
  race on boot between multiple invocations of grub-editenv

Status in grub2 package in Ubuntu:
  Fix Committed
Status in grub2 source package in Focal:
  Fix Committed
Status in grub2 source package in Groovy:
  Fix Committed
Status in grub2 source package in Hirsute:
  Fix Committed

Bug description:
  [Impact]

   * two grub systemd units run in parallel.

   * ensure they are serialzed.

  [Test Case]

   * boot on initrdless systems (such as modern/recent public cloud
  instances)

   * observe that grub-initrd-fallback.service is always after grub-
  common.service

   * observe that both are successful

  this is easy to view using

  $ sudo journalctl -u grub-initrd-fallback.service grub-common.service

  the output should be in order, not interleaved, with grub-common first
  and then grub-initrd-fallback.

  [Where problems could occur]

   * The boot is slightly slower as the two jobs are serialized, but
  they are not computationally intensive and shouldn't affect bootspeed
  at all, especially on multicore systems where other things are
  happening in parallel to these.

  [Other Info]
   
   * Original bug report

  
  On focal, it appears systemd can run /etc/init.d/grub-common in parallel with /lib/systemd/system/grub-initrd-fallback.service. Both of these invoke grub-editenv for different reasons, apparently resulting in race conditions that generate messages like this:

  Jan 08 18:07:15 asr-host systemd[1]: Starting LSB: Record successful boot for GRUB...
  Jan 08 18:07:15 asr-host systemd[1]: Starting GRUB failed boot detection...
  [..]
  Jan 08 18:07:15 asr-host grub-common[1822]:  * Recording successful boot for GRUB
  [..]
  Jan 08 18:07:16 asr-host grub-editenv[1886]: /usr/bin/grub-editenv: error: cannot rename the file /boot/grub/grubenv.new to /boot/grub/grubenv.
  Jan 08 18:07:16 asr-host systemd[1]: grub-initrd-fallback.service: Main process exited, code=exited, status=1/FAILURE
  Jan 08 18:07:16 asr-host systemd[1]: grub-initrd-fallback.service: Failed with result 'exit-code'.
  Jan 08 18:07:16 asr-host systemd[1]: Failed to start GRUB failed boot detection.
  Jan 08 18:07:16 asr-host grub-common[1822]:    ...done.
  Jan 08 18:07:16 asr-host systemd[1]: Started LSB: Record successful boot for GRUB.

  Google search for "Failed to start GRUB failed boot detection" throws
  up a few hits, which suggests this isn't necessarily something to
  weird about the machine I'm running on:

  https://www.google.co.uk/search?q=%22Failed+to+start+GRUB+failed+boot+detection.%22

  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: grub-common 2.04-1ubuntu26.7
  ProcVersionSignature: Ubuntu 5.4.0-59.65-generic 5.4.78
  Uname: Linux 5.4.0-59-generic x86_64
  ApportVersion: 2.20.11-0ubuntu27.14
  Architecture: amd64
  CasperMD5CheckResult: skip
  Date: Fri Jan  8 20:19:42 2021
  ProcEnviron:
   TERM=screen.xterm-256color
   PATH=(custom, no user)
   LANG=en_GB.UTF-8
   SHELL=/bin/bash
  SourcePackage: grub2
  UpgradeStatus: Upgraded to focal on 2020-12-23 (15 days ago)

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