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

[Chris Murphy]

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.


-- 
Chris Murphy