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

[Felipe Sateler]

On Wed, Jul 5, 2017 at 11:38 PM, Rob Leslie <rob at mars.org> wrote:

> 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
>

This suggests the kernel is the one slowing things down.


>
> 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
>

This is just udev complaining. Udev does not generate the devices, it waits
for the kernel to notify it.


>
> 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.
>


Can you try booting with the old jessie kernel? This looks like a kernel
regression.


-- 

Saludos,
Felipe Sateler
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