misc/131290: How to completely freeze FreeBSD 7.1 under a non-privileged user

[Mikolaj Golub]

On Tue, 3 Feb 2009 04:19:33 -0800 Sergey S wrote:

 >> I have tried your scripts and have not managed to reproduce the hang, even
 >> running the loop script without sleep.

 SS> It's very strange, because the bug is 100% reprodusable to me (on two
 SS> separate computers) :(

Sorry, I missed previously that your system was amd64. I tried on i386 FreeBSD
7.1-STABLE. Currently, I don't have amd64 where I can install erlang and do
such tests.

 >> http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/kerneldebug-deadlocks.html

 SS> Thanks for your suggestion. I hope it will help.

 >> But I would recommend you to start from simpler techniques, e.g. running in
 >> parallel top and other system utilities and writing the output to the file for
 >> further investigation. Something like this:
 >>
 >> top -b -s1 -S -d1000 1000 > top.output &
 >> ./gistfile1.sh

 SS> I've done it. gzipped top.output is attached to this letter.

So, according to top output (I don't see the script process here) it hanged
the system in less then one second? I have observed freezes when top with -S
option froze while without -S option worked. You can try removing -S
option. But I am afraid this won't help and you will have to make the system
core dump (as described at URL above) and do post-mortem analysis of the dump.

-- 
Mikolaj Golub