Bug#867368: systemd-udevd: delays boot for 2+ minutes when LVM PV is inside a LV

[Rob Leslie]

Package: udev
Version: 232-25
Severity: important
File: /lib/systemd/systemd-udevd

Dear Maintainer,

After upgrading to stretch I've discovered that some machines are taking a
long time to boot -- more than two minutes -- with no immediately obvious
cause. For example:

> % systemd-analyze
> Startup finished in 2min 55.491s (kernel) + 13.076s (userspace) = 3min 8.568s

During most of this time, nothing appears on the console except a cursor.
Kernel and system logs show nothing to pinpoint the issue other than long
time gaps, e.g.:

> [    3.194336] clocksource: Switched to clocksource tsc
> [  121.499692] md: linear personality registered for level -1

Adding 'debug' to the kernel command line however I got this clue:

> [   64.386629] systemd-udevd[88]: seq 905 '/devices/virtual/block/dm-5' is taking a long time

After some further investigation it appears the problem stems from having an
LVM PV inside another LV. Here is how I am able to recreate the problem on a
fresh stretch install:

> # lvcreate -n pvtest -L 1g $vg
> # pvcreate /dev/$vg/pvtest

(where $vg is some existing volume group name)

Now rebooting the system will result in the long boot delay.

This sort of setup did not cause any problems in jessie. An obvious workaround
is not to put PVs inside other LVs, but this is sometimes a convenient
arrangement and I would hope it could be made to work without an excessive
boot delay.

Thanks.


-- Package-specific info:

-- System Information:
Debian Release: 9.0
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-3-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages udev depends on:
ii  adduser      3.115
ii  dpkg         1.18.24
ii  libacl1      2.2.52-3+b1
ii  libblkid1    2.29.2-1
ii  libc6        2.24-11+deb9u1
ii  libkmod2     23-2
ii  libselinux1  2.6-3+b1
ii  libudev1     232-25
ii  lsb-base     9.20161125
ii  procps       2:3.3.12-3
ii  util-linux   2.29.2-1

udev recommends no packages.

udev suggests no packages.

Versions of packages udev is related to:
ii  systemd  232-25

-- no debconf information