kgmon -b causes processes to crash

[Olivier Piras]

Hi,

I'm getting a strange behaviour while trying to perform some basic kernel
profiling
with kgmon and gprof on -CURRENT.

context:

. Installed last week's -CURRENT snapshot from an .iso on a spare machine.
. Updated /usr/src, compiled world and the kernel (make -j4 kernel
CONFIGARGS=-p).
. rebooted, then make installworld; mergemaster -Ui
. rebooted again.

problem:

root at current:~ # kgmon -b
kgmon: kernel profiling is running.
Segmentati�^3���
oprs at current% id
<jemalloc>: jemalloc_extent.c:463: Failed assertion:
"!extent_heap_empty(&extents->heaps[i])"
Abort trap (core dumped)

>From that point on, the system is totally unusable (processes crash
repeatedly).
The kernel itself seems to be running though; I can still ping the machine,
in fact
my ssh session is still up at this point.

After rebooting (reset from kdb), dmesg shows a lot of process crashes:

pid 941 (csh), jid 0, uid 0: exited on signal 11 (core dumped)
pid 931 (login), jid 0, uid 0: exited on signal 11
pid 946 (getty), jid 0, uid 0: exited on signal 6 (core dumped)
pid 947 (getty), jid 0, uid 0: exited on signal 6 (core dumped)
pid 948 (getty), jid 0, uid 0: exited on signal 6 (core dumped)
[...]

My first instinct was to rebuild the kernel again, this time with world
already installed,
as I was suspecting some kind of inconsistency between libkvm and the
kernel, but
obviously the problem is still there.

Am I doing something wrong here ? I'd like to get your opinion before I
investigate
further, and possibly create a bug report.

Regards,
  -Olivier.