[Bug 1864041] Re: xen_netfront devices unresponsive after hibernation/resume

[Balint Reczey]

I'm ready to put the workaround to ec2-hibinit-agent, but it would be
much better if the kernel could be fixed.

** Also affects: ec2-hibinit-agent (Ubuntu)
   Importance: Undecided
       Status: New

** Also affects: linux-aws (Ubuntu Bionic)
   Importance: Undecided
       Status: New

** Also affects: ec2-hibinit-agent (Ubuntu Bionic)
   Importance: Undecided
       Status: New

** Also affects: linux-aws (Ubuntu Focal)
   Importance: Undecided
       Status: New

** Also affects: ec2-hibinit-agent (Ubuntu Focal)
   Importance: Undecided
       Status: New

** Also affects: linux-aws (Ubuntu Eoan)
   Importance: Undecided
       Status: New

** Also affects: ec2-hibinit-agent (Ubuntu Eoan)
   Importance: Undecided
       Status: New

** Changed in: ec2-hibinit-agent (Ubuntu Focal)
       Status: New => In Progress

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https://bugs.launchpad.net/bugs/1864041

Title:
  xen_netfront devices unresponsive after hibernation/resume

Status in ec2-hibinit-agent package in Ubuntu:
  In Progress
Status in linux-aws package in Ubuntu:
  New
Status in ec2-hibinit-agent source package in Bionic:
  New
Status in linux-aws source package in Bionic:
  New
Status in ec2-hibinit-agent source package in Eoan:
  New
Status in linux-aws source package in Eoan:
  New
Status in ec2-hibinit-agent source package in Focal:
  In Progress
Status in linux-aws source package in Focal:
  New

Bug description:
  The xen_netfront device is sometimes unresponsive after a hibernate
  and resume event. This is limited to the c4, c5, m4, m5, r4, r5
  instance families, all of which are xen based, and support
  hibernation.

  When the issue occurrs, the instance is inaccessible without a full
  restart. Debugging by running a process which outputs regularly to the
  serial console shows that the instance is still running.

  A workaround is to build the xen_netfront module separately and
  restart the module and networking during the resume handler. For
  example:

  modprobe -r xen_netfront
  modprobe xen_netfront
  systemctl restart systemd-networkd

  With this workaround in place, the unresponsive issue is no longer
  observed.

  To reproduce this problem:

  1) Launch an c4, c5, m4, m5, r4, r5 instance type with a 5.0 or 5.3 kernel with on-demand hibernation support enabled.
  2) Start a long-running process which generates messages to the serial console
  3) Begin observing these messages on the console (using the AWS UI or CLI  to grab a screenshot).
  4) Suspend and resume the instance, continuing to refresh the console screenshot.
  5) The screenshot should continue to show updates even if ssh access is no longer working.
  --- 
  ProblemType: Bug
  ApportVersion: 2.20.9-0ubuntu7.9
  Architecture: amd64
  DistroRelease: Ubuntu 18.04
  Ec2AMI: ami-0edf3b95e26a682df
  Ec2AMIManifest: (unknown)
  Ec2AvailabilityZone: us-west-2a
  Ec2InstanceType: m4.large
  Ec2Kernel: unavailable
  Ec2Ramdisk: unavailable
  Package: linux-aws 4.15.0.1058.59
  PackageArchitecture: amd64
  ProcEnviron:
   TERM=screen
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=C.UTF-8
   SHELL=/bin/bash
  ProcVersionSignature: User Name 5.0.0-1025.28-aws 5.0.21
  Tags:  bionic ec2-images
  Uname: Linux 5.0.0-1025-aws x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm audio cdrom dialout dip floppy lxd netdev plugdev sudo video
  _MarkForUpload: True

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