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Date:      Fri, 11 Oct 1996 09:38:03 -0500 (CDT)
From:      Wm Brian McCane <root@bmccane.uit.net>
To:        Julian Elischer <julian@freefall.freebsd.org>
Cc:        current@freefall.freebsd.org
Subject:   Re: HELP!! kernel deadlock found..
Message-ID:  <Pine.BSF.3.91.961011093358.840A-100000@bmccane.uit.net>
In-Reply-To: <199610030539.WAA02269@freefall.freebsd.org>

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On Wed, 2 Oct 1996, Julian Elischer wrote:

> 
> Take the following 3 processes:
> 
> proc N, with a lock on file / (inode 2)
> 		wchan of that inode, waitstring of "ufslk2"
> is waiting for inode for /mnt in the root filesystem (inode M)
> 
> proc N+1 with a lock on the inode M (/mnt in root filesystem)
> is waiting for inode for / (inode 2) in  the mounted filesystem /mnt
> it is showing "uihget" as a waitstring.
> 
> proc N+2 with a lock on inode 2 of the mnt filesystem (/ of that filesystem)
> is waiting for the inode for / and is showing "ufslk2" as a waitstring.
> 
> It is my suspicion that process N+2 may be trying to unmount /mnt.
> 
> Unfortunatly though I have the system stopped in gdb
> I don't know how to examine the stacktrace of arbitrary
> processes so I can't say how those 3 processes got where
> they are. All other processes on the system
> that need to access the filesystem are locked in "ufslk2"
> 
> e.g. any new logins go there immediatly. :(
> 
> if anyone knows how to examine an arbitrary process stacktrace
> I'd like to hear about it.......
> 
> I'll leave the system frozen in this state,
> and I can arange to get other people with internet access
> to be able to run gdb and examine whatever they want..
> 
> David?
> Terry?
> John?
> any takers?
> 
> I'd love to be able to see what those 3 stack traces show.....
> 
> 
> julian
> 
I am seeing a strange "lockup" on my system as well.  After running for an
unspecified length of time, I will see that 'innd' is in ufslk2.  After it
does this, the 'df' command gets stuck in vfsbsy, down in vfs_subr.c.  The
only way to fix this problem is to reboot the system, which I can do from
the root account no problem.  Another "interesting" side effect, is that
any files which are written after this time end up 0 bytes long after the
'fsck' on system reboot.  I discovered this when I rebuilt and installed a
new kernel one time 8(.

	brian




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