kern/54181: postgresql/pg_dump causes memory exhaustion

[dogan%tesmer.org.tr@localhost]

>Number:         54181
>Category:       kern
>Synopsis:       postgresql/pg_dump causes memory exhaustion
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu May 09 08:10:00 +0000 2019
>Originator:     Mustafa Dogan
>Release:        NetBSD 8_STABLE
>Organization:
TESMER
>Environment:
NetBSD localhost 8.0_STABLE NetBSD 8.0_STABLE (GENERIC) #0: Fri Mar  8 03:35:49 +03 2019  root@localhost:/root/OBJ/sys/arch/amd64/compile/GENERIC amd64
>Description:
This PR seems to pkgsrc problem, but I think this problem is related to vm.
Some of packages causes memory exhaustion and DoS. For example PostgreSQL and samba3, which I tried, uses all of available memory, swap, and causes server unusable.
sysctl vm.{anon,file,exec}{min,max} doesn't help.
My scenario is follows:
I installed and used postgresql for approximately 15 years on NetBSD. When I upgrade NetBSD 8 (in fact, I started using NetBSD 8.0_BETA, and it has the same problem too), problems arises. There weren't any problem with NetBSD 7. My database size is bigger than RAM size. Server RAM is 128 GB. While I trying to dump database, (pg_dumpall) RAM usage is increasing very fast. After dump size exceeds RAM size, server starts using swap. After dump size exceeds RAM+swap size, server crashes. Without reboot, can't reduce RAM size.
A similar scenario is applicable for samba3. Transfering file(s) causes DoS.
top shows memory usage as follows:
load averages:  0.12,  0.20,  0.20;               up 7+07:20:28                                                                              10:59:48
227 processes: 225 sleeping, 2 on CPU
CPU states:  0.0% user,  0.0% nice,  0.4% system,  0.0% interrupt, 99.4% idle
Memory: 100G Act, 212K Inact, 1104K Wired, 50M Exec, 120G File, 7120M Free
S
>How-To-Repeat:
On NetBSD 8, Install postgresql and have big database(s). Run pg_dump, pg_dumpall, or pg_basebackup. Then, monitor memory usage.
>Fix: