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Date:	Wed, 26 Nov 2008 22:12:19 +0000
From:	Ian Campbell <ijc@...lion.org.uk>
To:	Trond Myklebust <trond.myklebust@....uio.no>
Cc:	linux-nfs@...r.kernel.org, Max Kellermann <mk@...all.com>,
	linux-kernel@...r.kernel.org, gcosta@...hat.com,
	Grant Coady <grant_lkml@...o.com.au>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Tom Tucker <tom@...ngridcomputing.com>
Subject: Re: [PATCH] NFS regression in 2.6.26?, "task blocked for more than
	120 seconds"

On Tue, 2008-11-25 at 14:04 +0000, Ian Campbell wrote:
> On Tue, 2008-11-25 at 08:57 -0500, Trond Myklebust wrote:
> > On Tue, 2008-11-25 at 13:38 +0000, Ian Campbell wrote:
> > > > That would indicate that the server is failing to close the TCP
> > > > connection when the client closes on its end.
> > > > 
> > > > Could you remind me what server you are using?
> > > 
> > > 2.6.25-2-486 which is a Debian package from backports.org, changelog
> > > indicates that it contains 2.6.25.7.
> > 
> > Hmm... It should normally close sockets when the state changes. There
> > might be a race, though...
> > 
> > > > Also, does 'netstat -t'
> > > > show connections that are stuck in the CLOSE_WAIT state when you see the
> > > > hang?
> > > 
> > > I'd have to wait for it to reproduce again to be 100% sure but according
> > > to http://lkml.indiana.edu/hypermail/linux/kernel/0808.3/0120.html
> > > I was seeing connections in FIN_WAIT2 but not CLOSE_WAIT.
> > 
> > That would be on the client side. I'm talking about the server.
> 
> Ah, OK. I'll abort my current test of 2.6.26+revert and wait for a repro
> so I can netstat the server, give me a couple of days...

So on the server I see the following. 192.168.1.4 is the problematic
client and 192.168.1.6 is the server.

Maybe not interesting but 192.168.1.5 also uses NFS for my $HOME and
runs 2.6.26 with no lockups.

# netstat -t -n
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        1      0 192.168.1.6:2049        192.168.1.4:723         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:920         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:890         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:698         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:705         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:943         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:915         CLOSE_WAIT 
tcp        0      0 192.168.1.6:2049        192.168.1.5:783         ESTABLISHED
tcp        1      0 192.168.1.6:2049        192.168.1.4:998         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:758         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:955         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:845         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:827         CLOSE_WAIT 
tcp        0      0 192.168.1.6:58464       128.31.0.36:80          ESTABLISHED
tcp        1      0 192.168.1.6:2049        192.168.1.4:754         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:837         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:918         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:865         CLOSE_WAIT 
tcp        0      0 192.168.1.6:48343       192.168.1.5:832         ESTABLISHED
tcp        1      0 192.168.1.6:2049        192.168.1.4:840         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:883         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:785         CLOSE_WAIT 
tcp        1      0 192.168.1.6:2049        192.168.1.4:720         CLOSE_WAIT 
tcp6       0      0 ::ffff:192.168.1.6:22   ::ffff:192.168.1.:38206 ESTABLISHED
tcp6       0      0 ::ffff:192.168.1.6:143  ::ffff:192.168.1.:41308 ESTABLISHED
tcp6       0      0 ::ffff:192.168.1.6:143  ::ffff:192.168.1.:55784 ESTABLISHED
tcp6       0      0 ::ffff:192.168.1.6:22   ::ffff:192.168.1.:39046 ESTABLISHED

and on the client

# netstat -t -n
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 192.168.1.4:943         192.168.1.6:2049        FIN_WAIT2  
tcp        0      0 192.168.1.4:33959       192.168.1.4:6543        ESTABLISHED
tcp        0      0 192.168.1.4:6543        192.168.1.4:54157       ESTABLISHED
tcp        0      0 127.0.0.1:13666         127.0.0.1:33364         ESTABLISHED
tcp        0      0 192.168.1.4:22          192.168.1.5:54696       ESTABLISHED
tcp        0      0 192.168.1.4:22          192.168.1.5:47599       ESTABLISHED
tcp        0      0 192.168.1.4:54156       192.168.1.4:6543        ESTABLISHED
tcp        0      0 192.168.1.4:6543        192.168.1.4:33957       ESTABLISHED
tcp        0      0 192.168.1.4:33957       192.168.1.4:6543        ESTABLISHED
tcp        0      0 192.168.1.4:54157       192.168.1.4:6543        ESTABLISHED
tcp        0      0 192.168.1.4:6543        192.168.1.4:54156       ESTABLISHED
tcp        0      0 192.168.1.4:6543        192.168.1.4:33959       ESTABLISHED
tcp        0      0 127.0.0.1:47756         127.0.0.1:6545          ESTABLISHED
tcp        0      0 127.0.0.1:33364         127.0.0.1:13666         ESTABLISHED
tcp        0      0 127.0.0.1:6545          127.0.0.1:47756         ESTABLISHED

> 
> Ian.
-- 
Ian Campbell

Just once, I wish we would encounter an alien menace that wasn't
immune to bullets.
		-- The Brigadier, "Dr. Who"

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