Re: [NLM] 2.6.27.14 breakage when grace period expires

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Feb 11, 2009 at 12:23:18PM +0100, Frank van Maarseveen wrote:
> I'm sorry to inform you but... it seems that there is a similar problem
> in the NLM subsystem as reported previously but this time it is triggered
> when the grace time expires after a reboot.
> 
> Client and server run 2.6.27.14 + previous fix, NFSv3.
> 
> On the client there are three shells running:
> 
> 	while :; do lck -w /mnt/foo 2; done
> 
> The "lck" program is the same as posted before and it obtains an exclusive
> write lock then waits 2 seconds in above invocation (there's probably an
> "fcntl" command equivalent). After an orderly server reboot + grace time

How are you rebooting the server?

--b.

> expiration one of above command loops reports:
> 
> 	lck: fcntl: No locks available
> 
> and all three get stuck. After ^C-ing all "lck" loops the server still
> shows an entry in /proc/locks which causes the file to be locked
> indefinately. Maybe two loops are sufficient to reproduce the issue or
> maybe you need more, I don't know.
> 
> Interestingly, during the grace time at least one of the "lck" processes
> should have re-obtained the lock but it didn't show up in /proc/locks
> on the server.
> 
> Interestingly (#2), after removing the file on the server (i.e. no
> sillyrename) the now free inode is still locked according to /proc/locks.
> Even stopping/starting /etc/init.d/nfs-kernel-server plus "echo
> 3 >/proc/sys/vm/drop_caches" did not remove the lock (it did re-enter
> grace).
> 
> -- 
> Frank
> --
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