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

[Lennart Poettering]

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.

Lennart

--
Lennart Poettering, Berlin