Re: LOR: ufs vs bufwait

On Mon, 10.05.2010 at 22:53:32 +0200, Attilio Rao wrote:
> 2010/5/10 Peter Jeremy <peterjeremy_at_acm.org>:
> > On 2010-May-08 12:20:05 +0200, Ulrich Spörlein <uqs_at_spoerlein.net> wrote:
> >>This LOR also is not yet listed on the LOR page, so I guess it's rather
> >>new. I do use SUJ.
> >>
> >>lock order reversal:
> >> 1st 0xc48388d8 ufs (ufs) _at_ /usr/src/sys/kern/vfs_lookup.c:502
> >> 2nd 0xec0fe304 bufwait (bufwait) _at_ /usr/src/sys/ufs/ffs/ffs_softdep.c:11363
> >> 3rd 0xc49e56b8 ufs (ufs) _at_ /usr/src/sys/kern/vfs_subr.c:2091
> >
> > I'm seeing exactly the same LOR (and subsequent deadlock) on a recent
> > -current without SUJ.
> 
> I think this LOR was reported since a long time.
> The deadlock may be new and someway related to the vm_page_lock work
> (if not SUJ).

I was not able to reproduce this with a kernel prior to SUJ, a kernel
just after SUJ went it shows this "deadlock" or infinite loop ...

Now it might be that the SUJ kernel only increases the pressure so it
happens during a systems uptime. It does not seem directly related to
actually using SUJ on a volume, as I could reproduce it with SU only,
too.

I will try to get a hang not involving GELI and also re-do my tests when
the volumes have neither SUJ nor SU enabled, which led to 10-20s "hangs"
of the system IIRC. It seems SU/SUJ then only prolongs these hangs ad
infinitum.

I'll be back next week with new results here

Uli