Package: systemd
Version: 257.4-3
Severity: critical
Justification: breaks apt completely

I was upgrading my system from bookworm to trixie when it broke in the
middle with apt complaining about not finding a set of .debs in /tmp.
It turned out that systemd had activated the tmp.mount unit in the
middle of the upgrade.

As this was a large dist-upgrade, I'm not sure exactly what happened,
but some excerpts from the journal:

Mar 24 06:54:36 x systemd[1]: tmp.mount: Directory /tmp to mount over is not empty, mounting anyway.
Mar 24 06:54:36 x systemd[1]: Mounting tmp.mount - Temporary Directory /tmp... Mar 24 06:54:36 x systemd[1]: Mounted tmp.mount - Temporary Directory /tmp.
Mar 24 06:54:36 x systemd[1]: Starting man-db.service - Daily man-db regeneration...
Mar 24 06:54:40 x systemd[1]: man-db.service: Deactivated successfully.
Mar 24 06:54:40 x systemd[1]: Finished man-db.service - Daily man-db regeneration.

man-db.service is a service with PrivateTmp=true, and according to
advice on #debian-devel, such a service will have Wants/After=tmp.mount.
The masking of the tmp.mount unit happens in postinst, so there's a race
where the new package might be unpacked, something calls systemctl daemon-reload and then a service with PrivateTmp gets activated before systemd's postinst is called.

I'm filing this as critical since it left the system completely broken
and required extensive use of dpkg -i to recover.

A better solution is probably to do the masking in preinst instead of
postinst, assuming my analysis is correct.

--
Tollef Fog Heen
UNIX is user friendly, it's just picky about who its friends are

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Processing control commands:

tag -1 pending

Bug #1101175 [systemd] systemd: mounts a tmpfs on /tmp in the middle of upgrade Added tag(s) pending.

--
1101175: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1101175
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems

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Control: tag -1 pending

Hello,

Bug #1101175 in systemd reported by you has been fixed in the
Git repository and is awaiting an upload. You can see the commit
message below and you can check the diff of the fix at:

https://salsa.debian.org/systemd-team/systemd/-/commit/581a5994f54e430300cc9557fb2e2b270f3f1335

------------------------------------------------------------------------
Handle new tmp mount on upgrade in preinst rather than postinst

Avoid race with new units being activated and pulling it in
at the same time

Closes: #1101175 ------------------------------------------------------------------------

(this message was generated automatically)
--
Greetings

https://bugs.debian.org/1101175

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This is a multi-part message in MIME format...

Your message dated Fri, 28 Mar 2025 04:19:28 +0000
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and subject line Bug#1101175: fixed in systemd 257.4-4
has caused the Debian Bug report #1101175,
regarding systemd: mounts a tmpfs on /tmp in the middle of upgrade
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
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--
1101175: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1101175
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems

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