[Bug 818177] Re: boot failures because 'udevadm exit' does not kill udevd worker threads

[Steve Langasek]

I'm able to reproduce the same behavior that Serge sees when running in
a VM, and now have a clear understanding of what's happening here at the
top level.

The init-bottom script, as noted earlier, is set -e; and udevadm control
exits non-zero if it hits its timeout.  These two factors combined mean
that if udev gets stuck this way, the mount -o move *is never called*,
because the script terminates immediately after the udevadm call.

This also entirely explains the behavior seen in bug #833783 (in fact, I
just reproduced this problem here) - the difference between systems not
finding the local disks, and systems panicing due to missing
/dev/console, is down to what device nodes happen to be prepopulated on
the root filesystem.  So marking bug #833783 as a duplicate of this one.

I am currently investigating both the most appropriate way to ensure
that udevadm control --exit doesn't have to hit its timeout (raising the
timeout slightly, so that udevd times out first and exits, *should* be
sufficient but doesn't seem to be), and why udev is getting stuck in
seemingly ordinary boot scenarios (pristine vm).

The original problem reported, which involves a missing firmware, seems
to have its own cause in the kernel since the firmware should not fail
to load.  I understand the kernel team is already looking into this.

** Summary changed:

- boot failures because 'udevadm exit' does not kill udevd worker threads
+ boot failures because 'udevadm exit' times out while udevd waits for an already-dead thread

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https://bugs.launchpad.net/bugs/818177

Title:
  boot failures because 'udevadm exit' times out while udevd waits for
  an already-dead thread

Status in Release Notes for Ubuntu:
  Triaged
Status in “linux” package in Ubuntu:
  Invalid
Status in “udev” package in Ubuntu:
  Triaged
Status in “linux” source package in Oneiric:
  Invalid
Status in “udev” source package in Oneiric:
  Triaged
Status in “linux” source package in Precise:
  Invalid
Status in “udev” source package in Precise:
  Triaged

Bug description:
  After running a do-release-upgrade -d on a natty server, I'm unable to
  boot the machine properly.

  It looks like it doesn't see the local disks anymore.

  I think this looks quite a lot like the debbug linked from here:
  https://bugs.launchpad.net/ubuntu/oneiric/+source/linux/+bug/746751

  ProblemType: Bug
  DistroRelease: Ubuntu 11.10
  Package: linux-image-3.0.0-7-server 3.0.0-7.8
  ProcVersionSignature: Ubuntu 3.0.0-7.8-server 3.0.0
  Uname: Linux 3.0.0-7-server x86_64
  AlsaDevices:
   total 0
   crw-rw---- 1 root audio 116,  1 2011-07-29 13:34 seq
   crw-rw---- 1 root audio 116, 33 2011-07-29 13:34 timer
  AplayDevices: Error: [Errno 2] No such file or directory
  Architecture: amd64
  ArecordDevices: Error: [Errno 2] No such file or directory
  AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
  CRDA: Error: [Errno 2] No such file or directory
  Date: Fri Jul 29 13:40:10 2011
  HibernationDevice: RESUME=UUID=844d17fa-ff69-4250-844b-33b930236c56
  IwConfig:
   lo        no wireless extensions.
   
   eth0      no wireless extensions.
   
   eth1      no wireless extensions.
  MachineType: HP ProLiant DL380 G5
  PciMultimedia:
   
  ProcEnviron:
   LANGUAGE=en_US:
   PATH=(custom, user)
   LANG=en_US
   SHELL=/bin/bash
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.0.0-7-server root=/dev/mapper/User Name-root ro INIT_VERBOSE=yes
  RelatedPackageVersions:
   linux-restricted-modules-3.0.0-7-server N/A
   linux-backports-modules-3.0.0-7-server  N/A
   linux-firmware                          1.56
  RfKill: Error: [Errno 2] No such file or directory
  SourcePackage: linux
  UpgradeStatus: Upgraded to oneiric on 2011-07-29 (0 days ago)
  dmi.bios.date: 06/28/2007
  dmi.bios.vendor: HP
  dmi.bios.version: P56
  dmi.chassis.type: 23
  dmi.chassis.vendor: HP
  dmi.modalias: dmi:bvnHP:bvrP56:bd06/28/2007:svnHP:pnProLiantDL380G5:pvr:cvnHP:ct23:cvr:
  dmi.product.name: ProLiant DL380 G5
  dmi.sys.vendor: HP

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