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

Dimitri John Ledkov 1910815 at bugs.launchpad.net
Fri Feb 12 22:15:04 UTC 2021 

** Changed in: grub2 (Ubuntu Groovy)
       Status: New => In Progress

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

** Description changed:

- 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:
+ [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
+  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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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:
  In Progress
Status in grub2 source package in Groovy:
  In Progress
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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