heartbeat panic: swapping?

Hi!

I woke up to

savecore: reboot after panic: [ 312649.0082489] panic: cpu0: softints stuck for 16 seconds

(gdb) target kvm netbsd.27.core
0xffffffff80239eca in cpu_reboot (howto=howto@entry=260, bootstr=bootstr@entry=0x0) at /usr/src/sys/arch/amd64/amd64/machdep.c:709
709			dumpsys();
(gdb) bt
#0  0xffffffff80239eca in cpu_reboot (howto=howto@entry=260, bootstr=bootstr@entry=0x0) at /usr/src/sys/arch/amd64/amd64/machdep.c:709
#1  0xffffffff80e2bfbf in kern_reboot (howto=howto@entry=260, bootstr=bootstr@entry=0x0) at /usr/src/sys/kern/kern_reboot.c:91
#2  0xffffffff80e77295 in vpanic (fmt=fmt@entry=0xffffffff816f1d30 "%s: softints stuck for %u seconds", ap=ap@entry=0xffffa72469e83bd0) at /usr/src/sys/kern/subr_prf.c:288
#3  0xffffffff80e7736a in panic (fmt=fmt@entry=0xffffffff816f1d30 "%s: softints stuck for %u seconds") at /usr/src/sys/kern/subr_prf.c:209
#4  0xffffffff80e0e03c in heartbeat () at /usr/src/sys/kern/kern_heartbeat.c:702
#5  0xffffffff80df34ad in hardclock (frame=0xffffa72469e83ce8) at /usr/src/sys/kern/kern_clock.c:342
#6  0xffffffff8021075e in Xresume_lapic_ltimer ()

and since I had been putting pressure on the system to use much swap,
and this was the result, I was wondering if there might be a relation.

I'm bulk building in tmpfs, and at times when there are a lot of
pkg_add/pkg_delete and the system kind of hangs already (which would
be nice to avoid). Can this be related?

Anyway, core dump available if someone has ideas what to check.
 Thomas