Re: [PATCH] NFS regression in 2.6.26?, "task blocked for more than 120 seconds"

Ian Campbell
2008-11-26T22:12:34Z

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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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