From: Andrew Morton <akpm@linux-foundation.org>
To: netdev@vger.kernel.org
Cc: bugzilla-daemon@bugzilla.kernel.org,
bugme-daemon@bugzilla.kernel.org, roysjosh@gmail.com
Subject: Re: [Bugme-new] [Bug 15507] New: kernel misses 3rd part of tcp handshake (ACK), stays in SYN_RECV state
Date: Thu, 18 Mar 2010 16:01:03 -0700 [thread overview]
Message-ID: <20100318160103.cc28c367.akpm@linux-foundation.org> (raw)
In-Reply-To: <bug-15507-10286@http.bugzilla.kernel.org/>
(switched to email. Please respond via emailed reply-to-all, not via the
bugzilla web interface).
On Wed, 10 Mar 2010 14:50:51 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:
> http://bugzilla.kernel.org/show_bug.cgi?id=15507
>
> Summary: kernel misses 3rd part of tcp handshake (ACK), stays
> in SYN_RECV state
> Product: Networking
> Version: 2.5
> Kernel Version: 2.6.32.9-67.fc12
> Platform: All
> OS/Version: Linux
> Tree: Fedora
> Status: NEW
> Severity: normal
> Priority: P1
> Component: IPV4
> AssignedTo: shemminger@linux-foundation.org
> ReportedBy: roysjosh@gmail.com
> Regression: Yes
>
>
> Created an attachment (id=25450)
> --> (http://bugzilla.kernel.org/attachment.cgi?id=25450)
> tcpdump from virtual guest over ::1 showing dup synacks
>
> Setup:
> 64-bit dual-core, latest F12. (I've experienced this on .31 and .32 kernels.)
>
> I have also experienced this on 2 other machines, all 64-bit. One was a
> single-core virtual guest.
>
> 1. Install httpd.
> 2. Start it. Don't bother configuring anything unless you need to.
> 3. tcpdump .....
> 4. connect from localhost or (possibly) a nearby host. I'm not sure if this is
> timing related yet.
> 5. note duplicate SYN-ACKs sent out at the exponential backoff. Some setups
> exhibit this more/worse than others, and will actually time out the connection.
> (Others will only send one or two duplicate SYN-ACKs, and then enter the
> ESTABLISHED state.) However, if any data is sent the kernel enters
> ESTABLISHED.
>
> Note that this isn't ipv4 specific. I have seen it under ipv4 and ipv6 (via
> loopback).
>
next parent reply other threads:[~2010-03-18 23:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-15507-10286@http.bugzilla.kernel.org/>
2010-03-18 23:01 ` Andrew Morton [this message]
2010-03-18 23:12 ` [Bugme-new] [Bug 15507] New: kernel misses 3rd part of tcp handshake (ACK), stays in SYN_RECV state Eric Dumazet
2010-03-19 11:53 ` Joshua Roys
2010-03-19 13:42 ` Eric Dumazet
2010-03-19 14:46 ` Eric Dumazet
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