// journalctl -xe output

Jan 28 20:43:23 myhost kernel: apt-check invoked oom-killer: gfp_mask=0x100cca(GFP_HIGHUSER_MOVABLE), order=0, oom_score_adj=0
Jan 28 20:43:23 myhost kernel: CPU: 0 PID: 10849 Comm: apt-check Not tainted 5.4.0-65-generic #73-Ubuntu
Jan 28 20:43:23 myhost kernel: Hardware name: Selectel OpenStack Nova, BIOS 1.10.2-1ubuntu1 04/01/2014
Jan 28 20:43:23 myhost kernel: Call Trace:
Jan 28 20:43:23 myhost kernel:  dump_stack+0x6d/0x9a
Jan 28 20:43:23 myhost kernel:  dump_header+0x4f/0x1eb
Jan 28 20:43:23 myhost kernel:  oom_kill_process.cold+0xb/0x10


// journalctl -xe output 2

root@myhost:~# systemctl restart mysql
Job for mysql.service failed because a fatal signal was delivered to the control process.
See "systemctl status mysql.service" and "journalctl -xe" for details.
root@myhost:~# journalctl -xe
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- Automatic restarting of the unit mysql.service has been scheduled, as the result for
-- the configured Restart= setting for the unit.
Jan 28 20:56:52 myhost systemd[1]: Stopped MySQL Community Server.
-- Subject: A stop job for unit mysql.service has finished
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- A stop job for unit mysql.service has finished.
--
-- The job identifier is 15858 and the job result is done.
Jan 28 20:56:52 myhost systemd[1]: Starting MySQL Community Server...
-- Subject: A start job for unit mysql.service has begun execution
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- A start job for unit mysql.service has begun execution.
--
-- The job identifier is 15858.


// ldd /usr/sbin/mysqld output
root@myhost:~# ldd /usr/sbin/mysqld
        linux-vdso.so.1 (0x00007fff3508a000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f8bf0faa000)
        libevent_core-2.1.so.7 => /lib/x86_64-linux-gnu/libevent_core-2.1.so.7 (0x00007f8bf0f72000)
        libevent_pthreads-2.1.so.7 => /lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7 (0x00007f8bf0f6d000)
        libprotobuf-lite.so.3.11.4 => /usr/lib/mysql/private/libprotobuf-lite.so.3.11.4 (0x00007f8bf0ee1000)
        librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f8bf0ed6000)
        libssl.so.1.1 => /lib/x86_64-linux-gnu/libssl.so.1.1 (0x00007f8bf0e43000)
        libcrypto.so.1.1 => /lib/x86_64-linux-gnu/libcrypto.so.1.1 (0x00007f8bf0b6b000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f8bf0b65000)
        libaio.so.1 => /lib/x86_64-linux-gnu/libaio.so.1 (0x00007f8bf0b60000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f8bf0b44000)
        liblz4.so.1 => /lib/x86_64-linux-gnu/liblz4.so.1 (0x00007f8bf0b23000)
        libnuma.so.1 => /lib/x86_64-linux-gnu/libnuma.so.1 (0x00007f8bf0b16000)
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f8bf0933000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f8bf07e4000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f8bf07c9000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f8bf05d7000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f8bf54b2000)