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Date: Thu, 18 Mar 2010 16:01:03 -0700 From: Andrew Morton <akpm@...ux-foundation.org> To: netdev@...r.kernel.org Cc: bugzilla-daemon@...zilla.kernel.org, bugme-daemon@...zilla.kernel.org, roysjosh@...il.com Subject: Re: [Bugme-new] [Bug 15507] New: kernel misses 3rd part of tcp handshake (ACK), stays in SYN_RECV state (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@...zilla.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@...ux-foundation.org > ReportedBy: roysjosh@...il.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). > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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