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Date:      Thu, 3 Oct 1996 10:53:50 -0700 (MST)
From:      Terry Lambert <terry@lambert.org>
To:        dfr@render.com (Doug Rabson)
Cc:        julian@freefall.freebsd.org, current@freefall.freebsd.org
Subject:   Re: HELP!! kernel deadlock found..
Message-ID:  <199610031753.KAA06374@phaeton.artisoft.com>
In-Reply-To: <Pine.BSF.3.95.961003105257.10204P-100000@minnow.render.com> from "Doug Rabson" at Oct 3, 96 11:09:13 am

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> > 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.
> 
> It looks as if N+2 is attempting to perform a pathname lookup while it has
> a locked vnode.

I'm glad Doug jumped in here.  8-).

I think the lookup might be the result of the NFS export handling.  Is
this system an NFS server?  Do you remember what the exports list
looked like?

I think the current handling of the NFS stuff is a bit bogus.  I'd like
to eventually see an exportfs mechanism used instea, and take the string
list mechanism out of the kernel entirely.  The idea that I have to
enable an FS for NFS export irks me a bit.  All FS's, by their very
nature as FS's, should be intrinsically consumable by all VFS consumers.
NFS is a VFS consumer, just like the system calls are a VFS consumer.
Just like a decent LKM system or kernel threading system would be a
VFS consumer.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.



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