UVM kills Xorg, supposedly "out of swap"

[Havard Eidnes <he%NetBSD.org@localhost>]

Hi,

one of my laptops is a trusty old Lenovo T60, upgraded with
memory so dmesg says

NetBSD 8.0_STABLE (GENERIC) #3: Mon Apr  1 17:58:51 CEST 2019
        he%nnn.uninett.no@localhost:/usr/obj/sys/arch/i386/compile/GENERIC
total memory = 3070 MB
avail memory = 3000 MB

On this host I've configured 2GB swap space on wd0b, from the
time when it only had 2GB physical memory.

Quite a few times recently I've had the Xorg server be killed by
UVM, with this message dropped in /var/log/messages:

May 31 11:09:52 nnn /netbsd: UVM: pid 168.1 (Xorg), uid 0 killed: out of swap

Of course, switching between consoles no longer works since this
requires the X server's cooperation(?), so I have to initiate a
shutdown with the power button in this case to re-gain usability.

However, I have no indication that any swap has in fact been
used; there's no slowdown and intense disk activity prior to the
X server being killed.

Anyone have any idea what's going on here?

Regards,

- Håvard