kern/104406: [ufs] Processes get stuck in "ufs" state under persistent CPU load

[Eugene Grosbein]

On Fri, Oct 19, 2007 at 03:05:01PM -0700, Alfred Perlstein wrote:

> > Can anyone take a look on PR kern/104406 ? I got repeatable hang situation, 
> > but I can't obtain a kernel dump to get result of all show commands from 
> > here:
> > 
> > http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/kerneldebug-deadlocks.html
> > 
> > After my break to debugger using Ctrl+Alt+Esc sequence and entering a 
> > "panic" command kernel does not wrote a kernel dump but seems to hang. Can 
> > anyone describe how to obtain a kernel dump in this situation, or at least 
> > say - which output of show commands need in first place to debug this ? 
> > Output of all suggested commands is huge and I afraid of making mistake 
> > when carrying this output from screen to list of paper and back :-)

This very easy to reproduce [ufs] uninterruptable deadlock
for both of RELENG_6 and RELENG_7. Look at this PR:
http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/107439

The PR is closed but the problem is still here with 7.0-PRERELEASE
and, perhaps, CURRENT.

Eugene