Kernel hang on 6.x

[John Baldwin]

On Wednesday 10 January 2007 16:52, Brad L. Chisholm wrote:
> On Thu, 4 Jan 2007 12:53:47 -0500, John Baldwin wrote:
> > On Thursday 04 January 2007 10:27, Brian Dean wrote:
> > >
> > > I believe that I can generate a kernel dump.  We tried this yesterday
> > > but didn't have a dump device configured. 
> >
> > If this is 6.x, turn on minidumps via the sysctl.  The dump size normally is 
> > the size of RAM.  With minidumps it can be a lot smaller.  If you get a dump, 
> > let me know and I'll point you at some gdb scripts to generate 'ps' type 
> > output, etc.
> > 
> 
> I work with Brian, and have been helping him analyze this problem.  We have
> been able to generate kernel dumps, and have also done some additional
> analysis under ddb.  Here is a summary of our analysis so far.  Suggestions
> as to how to proceed from here are most welcome.

How much swap do you have?  You might have run out of buckets in the
swap_zone before you ran out of swap space, in which case the kernel
deadlocks rather than killing the hog like it does when it runs out of
swap space.  I added a printf to catch this on HEAD recently that will
be MFC'd soonish.  You can try bumping up kern.maxswzone (loader tunable).

-- 
John Baldwin