[Bug 789930] Re: [natty] boot hangs / udev vgchange deadlock in nested vgs?

[Jens Wilke]

The special thing on this system is, that it is used as virtual server
host system and logical volumes contain volume groups for the guest
systems. After debugging with udev debug output, I got this relevant
message:

. . .
udevd-work[173]: creating link '/dev/SAS/vb-flat-fast' to '/dev/dm-5'

udevd-work[173]: creating symlink '/dev/SAS/vb-flat-fast' to '../dm-5'

udevd-work[173]: created db file '/dev/.udev/data/b251:5' for
'/devices/virtual/block/dm-5'

udevd-work[173]: 'watershed sh -c '/sbin/lvm vgscan; /sbin/lvm vgchange
-a y'' started

After this the system stalls.

1. The LVs containing on the system VG are not fully processed yet. The LV containing the root is not yet available.
2. The above LV is the first containing another VG, which triggers another vgchange.

So the problem seams to be a deadlock situation when recursively
activating volume groups.

I did fix the problem by overriding the 85-lvm2.rules udev rule in
/etc/udev/rules.d/85-lvm2.rules:

---snip---
# override default 85-lvm2.rules and don't run vgchange recursively on LV devices (ENV{DM_LV_NAME}=="")
# 2011-05-29;jw
SUBSYSTEM=="block", ACTION=="add|change", ENV{ID_FS_TYPE}=="lvm*|LVM*", ENV{DM_LV_NAME}=="" \
        RUN+="watershed sh -c '/sbin/lvm vgscan; /sbin/lvm vgchange -a y'"
---snip---

And "update-initramfs -u".

It must be noted that the same system boots fine with Lucid without this
modification.

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https://bugs.launchpad.net/bugs/789930

Title:
  [natty] boot hangs / udev vgchange deadlock in nested vgs?

Status in “udev” package in Ubuntu:
  New

Bug description:
  Binary package hint: udev

  After upgrading a server system from lucid to natty the system is not booting any more.
  The boot stalls before mounting the root filesystem.

  After a while the following messages appear:

  udevd[138]: worker [168] exit

  udevd[138]: worker [168] unexpectedly returned with status 0x0100

  udevd[138]: worker [168] failed while handling
  '/devices/pci0000:00/0000:00:03.0/0000:03:00.0/host0/target0:2:0/0:2:0:0/block/sda/sda1'

  udevd[138]: seq 1664 done with -32

  udevd[138]: worker [168] cleaned up

  udevd[138]: worker [167] exit

  udevd[138]: worker [167] unexpectedly returned with status 0x0100

  udevd[138]: worker [167] failed while handling
  '/devices/pci0000:00/0000:00:03.0/0000:03:00.0/host0/target0:2:1/0:2:1:0/block/sdb/sdb1'

  udevd[138]: seq 1661 done with -32

  udevd[138]: worker [167] cleaned up

  udevd[138]: worker [173] exit

  udevd[138]: worker [173] unexpectedly returned with status 0x0100

  udevd[138]: worker [173] failed while handling
  '/devices/virtual/block/dm-5'

  udevd[138]: seq 1770 done with -32

  udevd[138]: worker [173] cleaned up