[linux-lvm] [PATCH 1/1] pvscan: wait for udevd

[Martin Wilck]

On Thu, 2021-02-18 at 16:30 +0100, Oleksandr Natalenko wrote:
> > 
> > So what's timing out here is the attempt to _stop_ pvscan. That's
> > curious. It looks like a problem in pvscan to me, not having
> > reacted to
> > a TERM signal for 30s.
> > 
> > It's also worth noting that the parallel pvscan process for device
> > 9:0
> > terminated correctly (didn't hang).
> 
> Yes, pvscan seems to not react to SIGTERM. I have
> DefaultTimeoutStopSec=30s, if I set this to 90s, pvscan hangs for 90s
> respectively.
> 

Good point. That allows us to conclude that pvscan may hang on exit
when udevd isn't available at the time (has been already stopped). That
positively looks like an lvm problem. The After= is a viable
workaround, nothing more and nothing less. We'd need to run pvscan with
increased debug/log level to figure out why it doesn't stop. Given that
you have a workaround, I'm not sure if it's worth the effort for you.

What strikes me more in your logs is the fact that systemd proceeds
with switching root even though the pvscan at 253:2 service hasn't
terminated yet. That looks a bit fishy, really. systemd should have
KILLed pvscan before proceeding.

Martin