Kernel hang on 6.x

[John Baldwin]

On Thursday 04 January 2007 10:27, Brian Dean wrote:
> On Wed, Dec 27, 2006 at 11:50:43PM -0500, John Baldwin wrote:
> 
> > The 'traceall' seemed to miss several threads actually (like pid
> > 18).  Can you get a 'ps'?  Also, are you able to get a kernel dump
> > when this happens?
> 
> I can't ps that particular session since it is no longer available,
> however I can reproduce another one and generate a new set of debug
> output.  One note, the "swap_pager: indefinite wait buffer: ..."
> timeout message may have been a result of a misconfigured secondary
> swap file, so that might be a red herring.  However, we can still
> reliably reproduce the hang with 32 Gig swap, but we don't get any
> console messages associated with it.
> 
> The system is set up as a test system so I'm not under any pressure to
> get it rebooted and back up when it hangs, so I have the ability to
> take some time to debug it.
> 
> I believe that I can generate a kernel dump.  We tried this yesterday
> but didn't have a dump device configured.  I think we've got that set
> up now and plan to generate a kernel dump.  I'm assuming that since
> the process size and swap size is so large, that the dump size is
> going to be very large also, on the order of 32 Gig.  I beleive I can
> host this on a server and make it accessible to you if you are willing
> to download it.

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.

-- 
John Baldwin