[Bug 802626] Re: vgchange may deadlock in initramfs when VG present that's not used for rootfs

[Eduard Hasenleithner]

The "udevadm control --exit" fix was not supposed to fix this bug. I
still have the (occasional) 60 seconds hang at boot. It is just that
'/dev' is now moved to rootfs, enabling the filesystems to be mounted
rw.

The very same lvm process which waits for the semaphore is the process
which set it to 1. It waits for udevd to call the 55-dm.rules rule

ENV{DM_COOKIE}=="?*", RUN+="/sbin/dmsetup udevcomplete $env{DM_COOKIE}"

to be processed. But since udevd is not accepting events after "udevadm
control --exit", and any event, which arrived before closing the netlink
socket, is discarded, 'vgchange -a y' waits forever.

Reading the documentation of dmsetup, I found the udevcomplete_all
option. This might be a means to finish hanging 'vgchange -a y'
processes, and could be called from within a init-bottom script of
initramfs

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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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