[debian-mysql] Bug#1148646: The fix may cause problems

[McIntyre, Vincent (S&A, Marsfield)]

I did a few upgrades from 1:10.11.18+deb12u1 to 1:10.11.19+deb12u1.

Most of these worked fine, but in one case, mariadb failed to stop.
I think this was because mariadb was running under socket activation
but there must have been other factors at play. I have not been
able to determine what the critical factor was; the couple of others
I checked were running under socket activation. 

I did check for /var/run paths to the socket in the config,
this was only found in my.cnf.fallback.
debian.cnf contains (sans comments)

[client]
host     = localhost
user     = root
protocol = socket
[mysql_upgrade]
host     = localhost
user     = root
protocol = socket

The upgrade started normally enough

# apt upgrade
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
  mariadb-backup mariadb-client mariadb-client-core mariadb-server mariadb-server-core
5 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 21.5 MB of archives.
After this operation, 636 kB of additional disk space will be used.
Do you want to continue? [Y/n] 
...
Fetched 21.5 MB in 3s (8,258 kB/s)        
Reading changelogs... Done
Preconfiguring packages ...
(Reading database ... 86799 files and directories currently installed.)
Preparing to unpack .../mariadb-backup_1%3a10.11.19-0+deb12u1_amd64.deb ...
Unpacking mariadb-backup (1:10.11.19-0+deb12u1) over (1:10.11.18-0+deb12u1) ...
Preparing to unpack .../mariadb-server_1%3a10.11.19-0+deb12u1_amd64.deb ...
Warning: Stopping mariadb.service, but it can still be activated by:
  mariadb.socket
/var/lib/mysql: found previous version 10.11
 
at this point dpkg was stuck:

# ps -fade|grep maria
root      536865  536570  0 11:13 pts/4    00:00:00 /usr/bin/dpkg --status-fd 45 --no-triggers --unpack --auto-deconfigure
  /var/cache/apt/archives/mariadb-backup_1%3a10.11.19-0+deb12u1_amd64.deb
  /var/cache/apt/archives/mariadb-server_1%3a10.11.19-0+deb12u1_amd64.deb
  /var/cache/apt/archives/mariadb-server-core_1%3a10.11.19-0+deb12u1_amd64.deb
  /var/cache/apt/archives/mariadb-client-core_1%3a10.11.19-0+deb12u1_amd64.deb
  /var/cache/apt/archives/mariadb-client_1%3a10.11.19-0+deb12u1_amd64.
mysql     537002       1  0 11:13 ?        00:00:01 /usr/sbin/mariadbd
root      537018  537007  0 11:13 pts/4    00:00:00 /bin/sh /usr/sbin/invoke-rc.d mariadb stop
root      537021  537018  0 11:13 pts/4    00:00:00 systemctl stop mariadb.service
 

'systemctl status mariadb' was showing

Active: deactivating (final-sigterm) (Result: timeout)
TriggeredBy: * mariadb.socket

Eventually I killed the shell doing the restart (537018) and then dpkg (536570).

/var/lib/dpkg/tmp.ci/preinst: line 36: 537018 Killed                  invoke-rc.d mariadb stop
E: Sub-process /usr/bin/dpkg exited unexpectedly
W: Operation was interrupted before it could finish

The mariadb process sailed on, I could not access mysql.
# /usr/bin/mysql
<crickets>


After reading this bug, I ran these commands

# systemctl stop mariadb.socket.         #no impact?
# systemctl disable --now mariadb.socket
# systemctl mask mariadb.socket


'systemctl status mariadb' then showed:

Active: activating (auto-restart) (Result: resources)


but was not properly restarting because a mariadb process
was left running (this is why Result: was 'resources').

I waited for several minutes, then 'kill -9 <that process>'


At this point I was able to start the service normally.
# systemctl stop mariadb
Active: inactive (dead) since ...

# systemctl start mariadb

# systemct status mariadb

Active: active (running)
<no TriggeredBy line>

Kind regards