Messages in this thread | | | Subject | Re: Problems with /proc/net/tcp6 - possible bug - ipv6 | From | Eric Dumazet <> | Date | Sat, 22 Jan 2011 09:59:41 +0100 |
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Le vendredi 21 janvier 2011 à 22:30 -0800, PK a écrit : > Creating many ipv6 connections hits a ceiling on connections/fds ; okay, fine. > > But in my case I'm seeing millions of entries spring up within a few seconds and > then vanish within a few minutes, in /proc/net/tcp6 (vanish due to garbage > collection?) > > Furthermore I can trigger this easily on vanilla kernels from 2.6.36 to > 2.6.38-rc1-next-20110121 inside a ubuntu 10.10 amd64 vm, causing the kernel to > spew warnings. There is also some corruption in the logs (see kernel-sample.log > line 296), but that may be unrelated. > > More explanation, kernel config of the primary machine I saw this on, sample > ruby script to reproduce (inside the ubuntu VMs I apt-get and use ruby-1.9.1), > are located at > https://github.com/runningdogx/net6-bug > > Seems to only affect 64-bit. So far I have not been able to reproduce on 32-bit > ubuntu VMs of any kernel version. > Seems to only affect IPv6. So far I have not been able to reproduce using IPv4 > connections (and watching /proc/net/tcp of course). > Does not trigger the bug if the connections are made to ::1. Only externally > routable local and global IPv6 addresses seem to cause problems. > Seems to have been introduced between 2.6.35 and 2.6.36 (see README on github > for more kernels I've tried) > > All the tested Ubuntu VMs are stock 10.10 userland, with vanilla kernels (the > latest ubuntu kernel is 2.6.35-something, and my initial test didn't show it > suffering from this problem) > > Originally noticed on separate Gentoo 64-bit non-vm system when doing web > benchmarking. > > not subscribed, so please keep me in cc although I'll try to follow the thread > >
Hi PK (Sorry, your real name is hidden)
I could not reproduce this on current linux-2.6 kernel.
How many vcpus running in your VM, and memory ?
Note : a recent commit did fix /proc/net/tcp[6] behavior
commit 1bde5ac49398a064c753bb490535cfad89e99a5f Author: Eric Dumazet <eric.dumazet@gmail.com> Date: Thu Dec 23 09:32:46 2010 -0800
tcp: fix listening_get_next()
Alexey Vlasov found /proc/net/tcp could sometime loop and display millions of sockets in LISTEN state.
In 2.6.29, when we converted TCP hash tables to RCU, we left two sk_next() calls in listening_get_next().
We must instead use sk_nulls_next() to properly detect an end of chain.
Reported-by: Alexey Vlasov <renton@renton.name> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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