port-xen/51668: The xentop commands leaks memory

[tg%gmplib.org@localhost]

>Number:         51668
>Category:       port-xen
>Synopsis:       The xentop commands leaks memory
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-xen-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Nov 28 14:40:00 +0000 2016
>Originator:     Torbjörn Granlund
>Release:        7.0
>Organization:
>Environment:
NetBSD martin.gmplib.org 7.0_STABLE NetBSD 7.0_STABLE (GMPLIB) #0: Sun Oct  9 00:40:15 CEST 2016  root%martin.gmplib.org@localhost:/usr/src/sys/arch/amd64/compile/GMPLIB amd64

>Description:
The xentop command leaks memory.  This is a long-term issue which affected NetBSD 6.1.x and affects NetBSD 7.0.x. This has messed up my systems a few times as Dom0 runs out of memory and starts killing processes.

With my 38 guests, xentop leaks about 80 KiB per update. I don't know if the leak rate is a function of the number of guests, but it is unsurprisingly a function of the update frequency.
>How-To-Repeat:
1. Start some Xen guests (in my case both HVM and PV guests)
2. Run xentop, optionally use the D command and give 1 as delay to speed up the leak
3. Run
     while true; do
       x=$(ps -o vsz,comm,pid | grep xentop)
       mem=$(echo $x | awk '{print $1}')
       echo $mem
       sleep 1
     done
   to enjoy the gradually increasing, apparently unbounded memory use.

>Fix:
No fix known.  I run a cronjob as root on my NetBSD Dom0 systems which kills xentop processes which have become greater than 1 GiB.