[systemd-devel] transient hang when starting cryptography setup for swap

[Chris Murphy]

On Mon, Mar 25, 2019 at 3:18 AM Lennart Poettering
<lennart at poettering.net> wrote:
>
> On Do, 21.03.19 19:36, Chris Murphy (lists at colorremedies.com) wrote:
>
> > Hi,
> >
> > Problem Summary (which I forgot to put in the bug):
> > /etc/crypttab configured to use /dev/urandom to generate a new key
> > each boot for encrypted device to be used as swap. The dmcrypt device
> > is successfully created, and mkswap succeeds, but somewhere just
> > before (?) swapon the job gets stuck and boot hangs indefinitely.
> > There is no stuck swapon process listed by ps.
> >
> > This happens maybe 1 in 10 boots with Fedora 29. And maybe 1 in 2
> > boots with Fedora 30. I guess it could be a race of some kind? I'm not
> > really sure.
> >
> > I filed a bug with attachments and details here:
> > https://bugzilla.redhat.com/show_bug.cgi?id=1691589
> >
> > But it's not a great bug report yet because I don't have enough
> > information why it's hanging. Ordinarily I'd use
> > `systemd.log_level=debug` but the problem never happens so far if I
> > use it. So I'm looking for advice on getting more information why it's
> > stuck.
>
> See:
>
> https://freedesktop.org/wiki/Software/systemd/Debugging/#index1h1
>
> In particular, you might want to do the "systemctl enable
> debug-shell.service" thing, so that you can do "systemctl list-jobs"
> and similar when it hangs to figure out what's going on.


Drat. I didn't see this until just now, so I didn't do list-jobs.
However, I finally got a boot with systemd.log_level=debug to hang so
maybe that's useful?

I attached to the bug report
https://bugzilla.redhat.com/show_bug.cgi?id=1691589

Next time it happens I'll do list-jobs.

-- 
Chris Murphy