1. Select both "Build.." and "Publish.." for backtraces at https://launchpad.net/~mysql-ubuntu/+archive/ubuntu/mariadb-10.5/+edit
2. Upload to trigger new build
3. Enable PPA

$ nano /etc/apt/sources.list.d/mysql-ubuntu-ubuntu-mariadb-10_5-bionic.list
deb http://ppa.launchpad.net/mysql-ubuntu/mariadb-10.5/ubuntu bionic main
deb-src http://ppa.launchpad.net/mysql-ubuntu/mariadb-10.5/ubuntu bionic main
deb http://ppa.launchpad.net/mysql-ubuntu/mariadb-10.5/ubuntu bionic main/debug

$ sudo apt update

Ignore from "apt update":

W: Skipping acquire of configured file 'main/debug/i18n/Translation-en_US' as repository 'http://ppa.launchpad.net/mysql-ubuntu/mariadb-10.5/ubuntu bionic InRelease' doesn't have the component 'main/debug' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'main/debug/i18n/Translation-en' as repository 'http://ppa.launchpad.net/mysql-ubuntu/mariadb-10.5/ubuntu bionic InRelease' doesn't have the component 'main/debug' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'main/debug/cnf/Commands-amd64' as repository 'http://ppa.launchpad.net/mysql-ubuntu/mariadb-10.5/ubuntu bionic InRelease' doesn't have the component 'main/debug' (component misspelt in sources.list?)

$ find-dbgsym-packages /usr/sbin/mariadbd 
mariadb-server-core-10.5-dbgsym

4. Install server + debug packages

$ sudo apt install libmariadb3 mariadb-backup mariadb-backup-dbgsym mariadb-client mariadb-client-10.5 mariadb-client-10.5-dbgsym mariadb-client-core-10.5 mariadb-client-core-10.5-dbgsym mariadb-common mariadb-server mariadb-server-10.5 mariadb-server-10.5-dbgsym mariadb-server-core-10.5 mariadb-server-core-10.5-dbgsym

$ file /usr/sbin/mariadbd 
/usr/sbin/mariadbd: ELF 64-bit LSB shared object, x86-64, version 1 (GNU/Linux), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=3d8638db4dbc4250209fc0e6b1ba31c0a25afd0c, stripped

5. Enable core dumps for MariaDB

sudo tee /etc/mysql/conf.d/core-dump.cnf <<EOF
[mariadb]
core_file
EOF

$ sudo my_print_defaults --mysqld | grep core
--core_file

sudo tee /etc/systemd/system/mariadb.service.d/limitcore.conf <<EOF
[Service]

LimitCORE=infinity
EOF
sudo systemctl daemon-reload


6. Configure core dumps location and naming scheme

sudo mkdir /tmp/corefiles
sudo chmod 777 /tmp/corefiles
echo /tmp/corefiles/core | sudo tee /proc/sys/kernel/core_pattern
echo echo 1 | sudo tee /proc/sys/kernel/core_uses_pid


7. Run server and trigger the crash

Verify that there are core dumps

$ ls -la /tmp/corefiles/
total 462560
drwxrwxrwx   2 root  root       4096 tammi 12 19:42 .
drwxrwxrwt 115 root  root      20480 tammi 12 20:02 ..
-rw-------   1 mysql mysql 394960896 tammi 12 19:39 core.21073
-rw-------   1 mysql mysql 188612608 tammi 12 19:40 core.22988
-rw-------   1 mysql mysql 188616704 tammi 12 19:40 core.23372
-rw-------   1 mysql mysql  60432384 tammi 12 19:40 core.23794


8. Run gdb to produce a full trace

$ sudo gdb /usr/sbin/mysqld /tmp/corefiles/core.63031
set logging file /tmp/gdb-6520.log
set logging on
set pagination off
set print frame-arguments all
thread apply all bt full
set logging off


9. Attach trace to bug report

https://mariadb.com/kb/en/how-to-produce-a-full-stack-trace-for-mysqld/
https://mariadb.com/kb/en/enabling-core-dumps/
https://wiki.ubuntu.com/Debug%20Symbol%20Packages