From owner-freebsd-current@freebsd.org  Tue Aug 11 04:43:33 2015
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Date: Tue, 11 Aug 2015 07:43:23 +0300
From: Konstantin Belousov <kostikbel@gmail.com>
To: Tim Kientzle <tim@kientzle.com>
Cc: FreeBSD Current <freebsd-current@freebsd.org>
Subject: Re: Consistent crash of BeagleBone kernel
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On Mon, Aug 10, 2015 at 09:33:11PM -0700, Tim Kientzle wrote:
> I have a guess, though:  I noticed that the old bufwait/dirhash LOR is being triggered before this.  Could the backtrace from that be teaching Witness a bogus ufs -> kld ordering?

I do not see how it could.

The (directory) buffer lock is after the directory vnode lock, and both
of them should be after the kld_sx.  If some buffer lock appears before
kld_sx, this is the same problem as with the vnode lock.