[Bug 906358] Re: udev and lvm2 hang at boot

[David]

It seems the problem is due to udevadm called from the initramfs
(/usr/share/initramfs-tools/scripts/init-bottom/udev). On my system
udevadm runs for 61 seconds and times out (see bootchart). It only
occurs with kernel 3.0.0-14, older kernels are working fine. Reducing
the timeout to 20 seconds will result in an unusable system. I get an
error message that the lvm partition is not found.

** Attachment added: "bootchart with kernel 3.0.0-14"
   https://bugs.launchpad.net/ubuntu/+source/udev/+bug/906358/+attachment/2661376/+files/bootchart-3.0.0-14.png

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https://bugs.launchpad.net/bugs/906358

Title:
  udev and lvm2 hang at boot

Status in “udev” package in Ubuntu:
  Confirmed

Bug description:
  I'm experiencing a really long wait when booting freshly installed
  xubuntu 11.10 with only updates and mdadm + lvm2 installed. I have
  managed to narrow it down somewhat but still looking for a fix.

  After disabling splash and quiet from grub I noticed it's waiting at /scripts/init-bottom/udev in initrd and continues after 61 seconds.
  Not surprisingly i found a "udevadm control --timeout 61 --exit" line in there. Well, why does it fail so badly it waits for timeout before exiting?

  After quite a bit of googling I found this:
  http://us.generation-nt.com/answer/problem-lvm-gets-stuck-during-booting-due-recent-uevent-change-help-205241751.html
  Ari Savolainen writes:
  An init script (/scripts/init-bottom/udev in initrd) issues command
  "udevadm control --timeouta --exit".
  At the same time udevd is executing "/sbin/lvm vgchange -a y" (from
  /lib/udev/rules.d/85-lvm2.rules) that calls ioctl to resume a logical
  volume. After that lvm gets stuck forever. Booting continues after the
  61 second timeout.

  Milan Broz writes:
  If you call vgchange or even vgscan from udev rule, it is completely wrong.
  This is not lvm upstream udev rule btw.

  This makes me slightly worried, does this cause any other problems
  than a annoyingly slow boot? Is there any way to fix this? I this a
  known issue?

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