[Bug 802626] lvm hangs: watershed and environment

Ian Jackson ijackson at chiark.greenend.org.uk
Tue Nov 8 12:04:17 UTC 2011


Another possible cause of problems is that, due to the use of
watershed, DM_COOKIE is not passed to the actual invocation of
vgchange, or vgchange is run fewer times than expected.

watershed considers two identical command lines with different
environments coalescable.  So if you run
  watershed vgchange -a y &
  DM_COOKIE=A watershed vgchange -a y &
  DM_COOKIE=B watershed vgchange -a y &
vgchange may see any subset (by DM_COOKIE setting) of the calls.

I don't know the innards of the lvm/udev plumbing well enough to know
if this is going to be a problem, but from the descriptions in this
bug it seems it might be.

Of course simply removing the use of watershed, or manually putting
the cookie in the watershed command-id (or on the watershed command
line, for the same effect), will with the current udev rules result in
lots of serialised invocations of vgscan.

Ian.

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https://bugs.launchpad.net/bugs/802626

Title:
  vgchange may deadlock in initramfs when VG present that's not used for
  rootfs

Status in “lvm2” package in Ubuntu:
  Triaged
Status in “udev” package in Ubuntu:
  Confirmed
Status in “lvm2” source package in Oneiric:
  Triaged
Status in “udev” source package in Oneiric:
  Confirmed

Bug description:
  The system is now unable to boot.
  I had to boot on previous kernel 3.0.0.
  Symptoms are boot freezes. When debugging, issuing a vgscan works ok.
  doing the vgchange -a y just hangs. I need to reboot the system afterwards.

  ProblemType: Bug
  DistroRelease: Ubuntu 11.10
  Package: lvm2 2.02.66-4ubuntu2
  ProcVersionSignature: Ubuntu 3.0-0.1-generic 3.0.0-rc2
  Uname: Linux 3.0-0-generic x86_64
  Architecture: amd64
  Date: Mon Jun 27 18:15:46 2011
  ProcEnviron:
   LANGUAGE=fr_FR:en
   PATH=(custom, user)
   LANG=fr_FR.utf8
   LC_MESSAGES=fr_FR.UTF-8
   SHELL=/bin/bash
  SourcePackage: lvm2
  UpgradeStatus: No upgrade log present (probably fresh install)

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