Comment 19 for bug 1897561

Can confirm, this bug is still a reality in Ubuntu 20.04 (focal) and is triggered by two reloads in a row.

root@nginx:~# ps aux|grep nginx
root 3356067 0.0 0.1 71600 9788 ? Ss 15:46 0:00 nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
www-data 3356068 0.0 0.1 73012 15348 ? S 15:46 0:00 nginx: worker process
www-data 3356069 0.0 0.1 73012 15348 ? S 15:46 0:00 nginx: worker process
www-data 3356070 0.0 0.1 73012 15348 ? S 15:46 0:00 nginx: worker process
www-data 3356071 0.0 0.1 73012 15348 ? S 15:46 0:00 nginx: worker process
www-data 3356072 0.0 0.1 73012 15348 ? S 15:46 0:00 nginx: worker process
www-data 3356073 0.0 0.1 73012 15348 ? S 15:46 0:00 nginx: worker process
www-data 3356074 0.0 0.1 73012 15348 ? S 15:46 0:00 nginx: worker process
www-data 3356075 0.0 0.1 73012 15348 ? S 15:46 0:00 nginx: worker process
root 3356102 0.0 0.0 8900 676 pts/0 S+ 15:46 0:00 grep --color=auto nginx

root@nginx:~# service nginx reload

root@nginx:~# ps aux|grep nginx
root 3356067 0.2 0.3 81404 28848 ? Ss 15:46 0:00 nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
www-data 3356266 0.0 0.2 81644 22608 ? S 15:46 0:00 nginx: worker process
www-data 3356267 0.0 0.2 81644 22608 ? S 15:46 0:00 nginx: worker process
www-data 3356268 0.0 0.2 81644 22608 ? S 15:46 0:00 nginx: worker process
www-data 3356269 0.0 0.2 81644 22608 ? S 15:46 0:00 nginx: worker process
www-data 3356270 0.0 0.2 81644 22608 ? S 15:46 0:00 nginx: worker process
www-data 3356271 0.0 0.2 81644 22608 ? S 15:46 0:00 nginx: worker process
www-data 3356272 0.0 0.2 81644 22608 ? S 15:46 0:00 nginx: worker process
www-data 3356273 0.0 0.2 81644 22608 ? S 15:46 0:00 nginx: worker process
root 3356296 0.0 0.0 17196 7168 ? R 15:46 0:00 /usr/bin/pgrep nginx
root 3356309 0.0 0.0 8900 736 pts/0 S+ 15:46 0:00 grep --color=auto nginx

root@nginx:~# service nginx reload

root@nginx:~# ps aux|grep nginx
root 3356355 0.0 0.0 8900 736 pts/0 S+ 15:46 0:00 grep --color=auto nginx

At the time of the second reload, the following segfault is logged in /var/log/kern.log:

May 4 15:46:50 onl-paylb02-p kernel: [4141537.262674] nginx[3356067]: segfault at 51 ip 00007f6b7d1535c9 sp 00007ffe634334d0 error 4 in libperl.so.5.30.0[7f6b7d0eb000+166000]
May 4 15:46:50 onl-paylb02-p kernel: [4141537.262681] Code: 00 0f b6 40 30 49 c1 ed 03 49 29 c5 0f 84 17 01 00 00 48 8b 76 10 48 8b 52 10 4c 8d 3c fe 4c 8d 0c c2 84 c9 0f 84 c7 02 00 00 <49> 83 39 00 0f 85 ad 03 00 00 49 83 c1 08 49 83 ed 01 49 8d 74 1d