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        <tr>
          <th>Priority</th>
          <td>medium
          </td>
        </tr>

        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - networkd fails assertion on tap device going away"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=80556">80556</a>
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>systemd-bugs@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>networkd fails assertion on tap device going away
          </td>
        </tr>

        <tr>
          <th>QA Contact</th>
          <td>systemd-bugs@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux (All)
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>d@falconindy.com
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>x86-64 (AMD64)
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>general
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>systemd
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=101800" name="attach_101800" title="bt full">attachment 101800</a> <a href="attachment.cgi?id=101800&action=edit" title="bt full">[details]</a></span>
bt full

I can semi-reliably hit a failed assertion when shutting down a VM:

tap0            : link 41 added
tap0            : udev initializing link...
tap0            : flags change: +MULTICAST +BROADCAST
tap0            : MAC address: fe:8d:25:75:f8:a1
br-qemu         : MAC address: fe:8d:25:75:f8:a1
tap0            : flags change: +UP +LOWER_UP +RUNNING
tap0            : gained carrier
br-qemu         : flags change: +LOWER_UP +RUNNING
br-qemu         : gained carrier
sd-rtnl: discarding 20 bytes of incoming message
tap0            : added address: fe80::fc8d:25ff:fe75:f8a1/64
tap0            : udev initialized link
tap0            : link state is up-to-date
tap0            : unmanaged
tap0            : flags change: -UP -LOWER_UP -RUNNING
tap0            : removed address: fe80::fc8d:25ff:fe75:f8a1/64
tap0            : link removed
tap0            : link 41 added
tap0            : could not find udev device
could not add new link
br-qemu         : MAC address: 00:00:00:00:00:00
br-qemu         : flags change: -LOWER_UP
tap0            : link removed
br-qemu         : flags change: -RUNNING
br-qemu         : lost carrier
sd-rtnl: discarding 20 bytes of incoming message
Assertion 'm' failed at src/network/networkd-link.c:2029, function
link_rtnl_process_address(). Aborting.

The KVM is given a bridge device:

# /etc/systemd/network/br-qemu.netdev
[NetDev]
Name=br-qemu
Kind=bridge

# /etc/systemd/network/br-qemu.network
[Match]
Name=br-qemu

[Network]
Description=Qemu vlan
Address=10.0.2.1/24
Address=2001:470:736c:107::1/64


And is started with args: -netdev bridge,br=br-qemu,id=mynet0 -device
virtio-net,netdev=mynet0,mac=de:ad:be:ef:00:07

I've bisected this breakage to fbbeb65a93e2f90f6576001b. Backtrace attached.
It's likely a race condition somewhere -- the SIGABRT sometimes turns into a
SIGSEGV when I set SYSTEMD_LOG_LEVEL=debug.</pre>
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