Dear Maintainer,

The binfmt-support service fails to start, with the following output:

systemd[1]: Starting Enable support for additional executable binary formats...
update-binfmts[536]: update-binfmts: warning: unable to close /proc/sys/fs/binfmt_misc/register: File exists
update-binfmts[536]: update-binfmts: warning: unable to close /proc/sys/fs/binfmt_misc/register: File exists
update-binfmts[536]: update-binfmts: warning: unable to close /proc/sys/fs/binfmt_misc/register: File exists
update-binfmts[536]: update-binfmts: exiting due to previous errors
systemd[1]: binfmt-support.service: Main process exited, code=exited, status=2/INVALIDARGUMENT
systemd[1]: binfmt-support.service: Failed with result 'exit-code'.
systemd[1]: Failed to start Enable support for additional executable binary formats.

Best,
Facundo

Hi Facundo,

what you see here is a race condition between binfmt-support.service and
systemd-binfmt.service.
E.g. qemu installs binfmt config files for both binfmt-support and
systemd-binfmt leading to the issue you see.

I plan to add a
ConditionFileIsExecutable=!/usr/sbin/update-binfmts
to systemd-binfmt.service. This will disable systemd-binfmt.service when
binfmt-support is installed and should mitigate this issue.
(thus reassigning to systemd)

Afaics binfmt-support has remained a Debian-only solution, so long-term
I'd think it would be beneficial if we'd consider systemd-binfmt as a
cross-distro solution.

There aren't that many packages installing config snippets in
/usr/share/binfmts, so a transition seems reasonably doable.

Colin, what's your take on this?

Michael

Thanks for investigating that.

I am not interested in this.

Am 01.06.22 um 13:18 schrieb Colin Watson:

Thinking more about it, it might actually be preferrable, if this
condition is shipped by binfmt-support via a drop-in config for
systemd-binfmt.service.

This way, the condition is only evaluated when binfmt-support is
actually installed.

I've attached a possible patch for that.

Colin, could you please review and if you agree, I'd re-assign this bug
report back to binfmt-support.

Michael

Am 02.06.22 um 11:16 schrieb Michael Biebl:

Thinking about this a bit more, binfmt.d might not strictly be a subset
of the config files shipped for binfmt-support.
So disabling systemd-binfmt.service via a Condition might not be the
best way forward.

Since we only need to ensure, that systemd-binfmt.service and
binfmt-support.service do not run concurrently (and both trying to
access /proc/sys/fs/binfmt_misc/register), we simply need to apply a
proper ordering.
Thankfully, this is rather simple and the attached patch is even more
minimal then the previous one.
I chose to run binfmt-support.service after systemd-binfmt.service, as
the former is pulled in via multi-user.target and the latter via
sysinit.target.

Regards,
Michael

Control: tag -1 fixed-upstream

Thanks, makes sense.  I've pushed this patch upstream
(https://gitlab.com/cjwatson/binfmt-support/-/commit/54f0e1af8a).

We believe that the bug you reported is fixed in the latest version of
binfmt-support, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1012154@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Colin Watson <cjwatson@debian.org> (supplier of updated binfmt-support package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Fri, 03 Jun 2022 00:45:44 +0100
Source: binfmt-support
Architecture: source
Version: 2.2.2-1
Distribution: unstable
Urgency: medium
Maintainer: Colin Watson <cjwatson@debian.org>
Changed-By: Colin Watson <cjwatson@debian.org>
Closes: 1012154
Changes:
 binfmt-support (2.2.2-1) unstable; urgency=medium
 .
   * debian/upstream/metadata: Update for upstream move to GitLab.
   * New upstream release.
     - Run binfmt-support.service after systemd-binfmt.service (thanks,
       Michael Biebl; closes: #1012154).
   * Add Pre-Depends: ${misc:Pre-Depends}, since dh_installinit relies on
     that for "invoke-rc.d --skip-systemd-native".
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Am 02.06.22 um 21:52 schrieb Colin Watson:

Thank you, Colin!