Date: Mon, 26 Nov 2012 13:49:57 -0800 (PST)
From: Andrei Warkentin <awarkentin@vmware.com>
To: linux-nfs@vger.kernel.org
Message-ID: <864189844.31754280.1353966597599.JavaMail.root@vmware.com>
In-Reply-To: <477254919.31693823.1353963259597.JavaMail.root@vmware.com>
Subject: Race between NFS server thread increase / decrease
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Sender: linux-nfs-owner@vger.kernel.org

Hi NFSD developers,

I've found what I think is an interesting problem that occurs on single-CPU machines as far as I can tell.

Basically the following snippet will occasionally loop forever printing that one thread is still running. Further
attempts to run "/usr/sbin/rpc.nfsd 0" don't help.

/usr/sbin/rpc.nfsd 1
/usr/sbin/rpc.nfsd 0
while [ ! $[`cat /proc/fs/nfsd/threads`] -eq 0 ]; do
        echo $[`cat /proc/fs/nfsd/threads`] still running
        sleep .1
done

I've not looked a whole lot at it. It appears that although the paths calling svc_set_num_threads synchronize on nfsd_mutex, the code doesn't seem to try waiting on the number of threads to reach the desired count.

What do you guys think?

Thanks.

A