Re: kern/46600: Kernel panic when interrupting process reading from pad(4)

[Aleksej Saushev <asau%inbox.ru@localhost>]

Aleksej Saushev <asau%inbox.ru@localhost> writes:

>>Description:
>         Interrupting process that reads from pad(4) device brings system down.
>         Kernel crash dump isn't saved by "sync", "reboot" doesn't work either,
>         manually recorded backtrace is as follows:

>>How-To-Repeat:
> With freshly built kernel (and modules) from netbsd-6:
>
>       mpg123 some-file.mp3 &
>         cat < /dev/pad0 > test.wav # intterrupt this process, e.g. by 
> pressing ctrl-C in tty.

In another experiment, when starting processes in another order:

cat < /dev/pad0 > test.wav # 1
mpg123 some-file.mp3 # 2

process #1 doesn't stop after #2 finishes.
Output file is empty (problem potentially described by Matthew Mondor earlier).
Attempt to kill #1 with "pkill -KILL cat" brings kernel down.
Last kernel messages (panic included) are these (copied manually):

pad0: outputs: 44100Hz, 16-bit, stereo
audio1 at pad0: half duplex, playback, capture
audio1: detached
pad0: detached
panic: kernel diagnostic assertion "cv_is_valid(cv)" failed: file 
"/usr/src/sys/kern/kern_condvar.c", line 197
...
stopped in pid ... (pkill)

Backtrace:

vpanic
kern_assert
cv_unsleep
setrunnable
sigpost
kpsignal2
kill1.clone.0
sig_kill
syscall

It was possible to save crash dump, but the latter wasn't picked up by 
savecore(8)
for unknown reasons.