[Bus error] huge_pages default value (try) not fall back

Hi,

We have seen a bus error when running postgresql in container (where on K8s). According current finding, there is bug on K8s, they are working on it.
But we also want to know why huge_pages default value(try) didn't fall back.

K8s BUG https://github.com/kubernetes/kubernetes/issues/71233

Problem quick summary:
When hugepage not working, initdb produce bus error.

Logs:
2020-02-17 06:33:21,606 INFO: trying to bootstrap a new cluster
2020-02-17 06:33:21,610 INFO: pg_ctl args: ('-o', '--auth-host=md5 --auth-local=trust --encoding=UTF8 --locale=en_US.UTF-8 --data-checksums --username=postgres --pwfile=/tmp/tmpcdHEH3'), {}
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.

The database cluster will be initialized with locale "en_US.UTF-8".
The default text search configuration will be set to "english".

Data page checksums are enabled.

fixing permissions on existing directory /var/lib/postgresql/data/pgdata ... ok
creating subdirectories ... ok
sh: line 1: 100 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=100 -c shared_buffers=1000 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 102 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=50 -c shared_buffers=500 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 104 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=40 -c shared_buffers=400 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 106 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=30 -c shared_buffers=300 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 108 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=200 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
selecting default max_connections ... 20
sh: line 1: 110 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=16384 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 112 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=8192 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 114 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=4096 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 116 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=3584 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 118 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=3072 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 120 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=2560 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 122 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=2048 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 124 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=1536 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 126 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=1000 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 128 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=900 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 130 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=800 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 132 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=700 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 134 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=600 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 136 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=500 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 138 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=400 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 140 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=300 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 142 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=200 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 144 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=100 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
sh: line 1: 146 Bus error (core dumped) "/usr/lib/postgresql10/bin/postgres" --boot -x0 -F -c max_connections=20 -c shared_buffers=50 -c dynamic_shared_memory_type=none < "/dev/null" > "/dev/null" 2>&1
selecting default shared_buffers ... 400kB
selecting default timezone ... UTC
selecting dynamic shared memory implementation ... posix
creating configuration files ... ok
child process was terminated by signal 7: Bus error
initdb: removing contents of data directory "/var/lib/postgresql/data/pgdata"
pg_ctl: database system initialization failed
running bootstrap script ... 2020-02-17 06:33:22,254 INFO: removing initialize key after failed attempt to bootstrap the cluster
------------ end of log -------------

Hugepage:

Output from "kubectl describe node"
========================
Capacity:
cpu: 56
ephemeral-storage: 365912640Ki
hugepages-1Gi: 16Gi
hugepages-2Mi: 0
memory: 131922340Ki
pods: 110
Allocatable:
cpu: 55900m
ephemeral-storage: 337225088466
hugepages-1Gi: 16Gi
hugepages-2Mi: 0
memory: 114792724Ki
pods: 110

========================
Grub command line:
GRUB_CMDLINE_LINUX_DEFAULT="console=tty0 console=ttyS0,115200 no_timer_check nofb nomodeset vga=normal default_hugepagesz=1G hugepagesz=1G hugepages=16 hugepagesz=2M hugepages=0"

========================

BRs,
Fan Liu
ADP Document Database PG