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Date:      Fri, 10 Feb 2012 10:43:08 -0600
From:      Martin McCormick <martin@dc.cis.okstate.edu>
To:        freebsd-questions@freebsd.org
Subject:   Removal Attempt of Directory under ZFS causes Kernel Panic
Message-ID:  <201202101643.q1AGh8E0046843@x.it.okstate.edu>

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	We have a ZFS file system under FreeBSD9.0 running on a
virtual machine which had been running flawlessly for a bit over
a month when I discovered that I had copied our home directory
into /usr/home such that we had /usr/home/home. As root, I cd'd
to /usr/home and then typed

rm -r home

at which point the kernel panicked after removing most of this
bogus home directory. It got to one particular user's
subdirectory, worked normally for a bit and then that's when the
kernel panicked.

	What we found were normal symlinks and files that, if
you make any attempt to delete them or touch them, provoke the
kernel panic and crash. If you mount the file system on a
rescue disk, it crashes that. We've tried mounting on a debian
rescue disk that supported zfs and it didn't crash, but hung.

	A coworker ran the debug version of our kernel and it
complained about values being out of bounds for the several
files in question.

	Basically, in the roughly 20 years of working with unix
systems, I have never once seen anything like this. We don't
think it has to do with the virtual machine because you can
trigger the disaster only by trying to remove the specific
files. everything else appears to be working normally including
creating and deleting other files and directories.

	My gut feeling is that it is related to zfs. 

	The bogus home directory was an attempt by me to rsync
from the actual hardware system to the virtual system back in
November and every file came out owned by root. I got the rsync
working properly and forgot about this home/home directory until
yesterday when I realized the mistake and tried to delete it.

	Does this sound familiar to anybody? This is the first
zfs installation I have used and I am not real wild about trying
it again if we can't solve this mystery. We can't seem to
duplicate the problem. Any ideas are appreciated.

Martin McCormick WB5AGZ  Stillwater, OK 
Systems Engineer
OSU Information Technology Department Telecommunications Services Group



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