/proc/sys/net/ipv4/tcp_tw_reuse etc. items are missing in container on android 9 arm32 SBC

[chairwa]

Run docker on an android 9 arm32 rooted SBC, but /proc/sys/net/ipv4/tcp_tw_reuse etc. items are missing in container.
What's the possible reason? How runc is controlling what items come into container /proc/sys/net/ipv4/ when prepareRootfs?

docker run --privileged nginx sh -c 'ls /proc/sys/net/ipv4/tcp_*' <
/proc/sys/net/ipv4/tcp_base_mss
/proc/sys/net/ipv4/tcp_ecn
/proc/sys/net/ipv4/tcp_ecn_fallback
/proc/sys/net/ipv4/tcp_fin_timeout
/proc/sys/net/ipv4/tcp_fwmark_accept
/proc/sys/net/ipv4/tcp_keepalive_intvl
/proc/sys/net/ipv4/tcp_keepalive_probes
/proc/sys/net/ipv4/tcp_keepalive_time
/proc/sys/net/ipv4/tcp_mtu_probing
/proc/sys/net/ipv4/tcp_notsent_lowat
/proc/sys/net/ipv4/tcp_orphan_retries
/proc/sys/net/ipv4/tcp_probe_interval
/proc/sys/net/ipv4/tcp_probe_threshold
/proc/sys/net/ipv4/tcp_reordering
/proc/sys/net/ipv4/tcp_retries1
/proc/sys/net/ipv4/tcp_retries2
/proc/sys/net/ipv4/tcp_syn_retries
/proc/sys/net/ipv4/tcp_synack_retries
/proc/sys/net/ipv4/tcp_syncookies

On host, tcp_tw_reuse is there:
ls /proc/sys/net/ipv4/tcp_
tcp_abort_on_overflow tcp_keepalive_intvl tcp_reordering
tcp_adv_win_scale tcp_keepalive_probes tcp_retrans_collapse
tcp_allowed_congestion_control tcp_keepalive_time tcp_retries1
tcp_app_win tcp_limit_output_bytes tcp_retries2
tcp_autocorking tcp_low_latency tcp_rfc1337
tcp_available_congestion_control tcp_max_orphans tcp_rmem
tcp_base_mss tcp_max_reordering tcp_sack
tcp_challenge_ack_limit tcp_max_syn_backlog tcp_slow_start_after_idle
tcp_congestion_control tcp_max_tw_buckets tcp_stdurg
tcp_default_init_rwnd tcp_mem tcp_syn_retries
tcp_delack_seg tcp_min_rtt_wlen tcp_synack_retries
tcp_dsack tcp_min_tso_segs tcp_syncookies
tcp_early_retrans tcp_moderate_rcvbuf tcp_thin_dupack
tcp_ecn tcp_mtu_probing tcp_thin_linear_timeouts
tcp_ecn_fallback tcp_no_metrics_save tcp_timestamps
tcp_fack tcp_notsent_lowat tcp_tso_win_divisor
tcp_fastopen tcp_orphan_retries tcp_tw_recycle
tcp_fastopen_key tcp_pacing_ca_ratio tcp_tw_reuse
tcp_fin_timeout tcp_pacing_ss_ratio tcp_use_userconfig
tcp_frto tcp_probe_interval tcp_window_scaling
tcp_fwmark_accept tcp_probe_threshold tcp_wmem
tcp_invalid_ratelimit tcp_recovery tcp_workaround_signed_windows

docker info
Client:
Context: default
Debug Mode: false
Server:
Containers: 22
Running: 15
Paused: 0
Stopped: 7
Images: 18
Server Version: 23.0.1
Storage Driver: overlay2
Backing Filesystem: extfs
Supports d_type: true
Using metacopy: false
Native Overlay Diff: true
userxattr: false
Logging Driver: json-file
Cgroup Driver: cgroupfs
Cgroup Version: 1
Plugins:
Volume: local
Network: bridge host ipvlan macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
Swarm: inactive
Runtimes: io.containerd.runc.v2 runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 31aa4358a36870b21a992d3ad2bef29e1d693bec
runc version: v1.1.4-0-g5fd4c4d
init version: de40ad0
Security Options:
seccomp
Profile: builtin
Kernel Version: 4.9.113
OSType: linux
Architecture: armv7l
CPUs: 4
Total Memory: 1.958GiB
Name: localhost
ID: 7cccad0a-1a5f-46fd-9f3d-ba9ff8e070ab
Docker Root Dir: /var/lib/docker
Debug Mode: false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
127.0.0.0/8
Registry Mirrors:
https://docker.mirrors.ustc.edu.cn/
Live Restore Enabled: false
Product License: Community Engine