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Container start failure when ipv6 is disabled [message #38584] Tue, 05 January 2010 16:16 Go to next message
tdaniel is currently offline  tdaniel
Messages: 2
Registered: January 2010
Location: Romania
Junior Member
Hello,

I am a long time user of OpenVZ. I've setup a new machine for which I disabled ipv6 support in order to troubleshoot some OpenVZ unrelated networking issues and I stumbled on a problem.

If ipv6 support is completely disabled using the modprobe.d approach, containers fail to start.

If the following option is entered in a file under /etc/modprobe.d

options ipv6 disable=1


Containers fail to start with the following dmesg output:

CT: 170: failed to start with err=-12
CT: 110: stopped
kmem_cache_create: duplicate cache ndisc_cache

Call Trace:
 [<ffffffff8003aa8d>] kmem_cache_create+0x5e8/0x624
 [<ffffffff80229ce9>] neigh_table_init_no_netlink+0x8d/0x37a
 [<ffffffff80226a89>] neigh_sysctl_register+0x241/0x275
 [<ffffffff80229fe4>] neigh_table_init+0xe/0x90
 [<ffffffff8836689f>] :ipv6:ve_ndisc_init+0x6f/0xeb
 [<ffffffff883c4446>] :vzmon:do_env_create+0x951/0xded
 [<ffffffff883c4e74>] :vzmon:vzcalls_ioctl+0x2b8/0x5ee
 [<ffffffff8828516f>] :vzdev:vzctl_ioctl+0x34/0x50
 [<ffffffff800437fa>] do_ioctl+0x21/0x6b
 [<ffffffff80031181>] vfs_ioctl+0x457/0x4b9
 [<ffffffff800c00a0>] audit_syscall_entry+0x180/0x1b3
 [<ffffffff8004eaee>] sys_ioctl+0x3c/0x5c
 [<ffffffff800602dd>] tracesys+0xd5/0xe0


My setup is as follows:

OS:

CentOS 5.4 64-bit


Kernel:

 2.6.18-164.2.1.el5.028stab066.10 #1 SMP Sat Dec 12 18:52:53 MSK 2009 x86_64 x86_64 x86_64 GNU/Linux


Tools:

vzquota-3.0.12-1
vzctl-lib-3.0.23-1
vzctl-3.0.23-1


There is no problem if NETWORKING_IPV6=no is set in /etc/sysconfig/network so i think this is a bug or something.

If i remove the /etc/modprobe.d file containing the ipv6 disable=1 option and reboot the system containers start to function as usual.
Re: Container start failure when ipv6 is disabled [message #38585 is a reply to message #38584] Tue, 05 January 2010 18:19 Go to previous messageGo to next message
Paparaciz
Messages: 302
Registered: August 2009
Senior Member
I think it's more or less related
http://bugzilla.openvz.org/show_bug.cgi?id=651
main idea- why do you want disable ipv6 support?
Re: Container start failure when ipv6 is disabled [message #38587 is a reply to message #38584] Tue, 05 January 2010 22:14 Go to previous messageGo to next message
tdaniel is currently offline  tdaniel
Messages: 2
Registered: January 2010
Location: Romania
Junior Member
Well,

Since ipv6 is not widely available and still not mainstream there are a few reasons why ipv6 would need to be disabled due to compatibility reasons.

I didn't encountered a scenario that would require ipv6 to be explicitly disabled but a warning would be a more correct approach to signal a sysadmin that ipv6 is required for a vps to start than a stack dump don't you agree ?

The bug mentioned by you seems unrelated to the situation I encountered since it clearly stated that ipv6 is disabled when an ipv6 address was used for a vps.

I didn't attempted to assign an ipv6 address to my containers, they all use ipv4 addresses.

The cryptic nature of the error message determined me to create this thread more with a fyi purpose than to require a fix for it.

Otherwise i would have opened a bug report in the bugzilla.
Re: Container start failure when ipv6 is disabled [message #38610 is a reply to message #38585] Thu, 07 January 2010 05:10 Go to previous messageGo to next message
nuno is currently offline  nuno
Messages: 43
Registered: January 2010
Member
Paparaciz wrote on Tue, 05 January 2010 18:19
I think it's more or less related
http://bugzilla.openvz.org/show_bug.cgi?id=651
main idea- why do you want disable ipv6 support?


Most people disable ipv6 for security reasons. In a tight environment many times you don't have a choice.

It would be nice to run a batch of openvz tests after a "rm -f ipv6.ko". And the opposite: with ipv6 enabled and ipv4 disabled Rolling Eyes

Openvz's target audience may be in those situations.
Re: Container start failure when ipv6 is disabled [message #39347 is a reply to message #38584] Wed, 07 April 2010 20:40 Go to previous message
mangust is currently offline  mangust
Messages: 39
Registered: April 2008
Location: USA
Member
Hi,
Bug. If you create container then you can run it one time Smile then not possible to start again.

Enabling ipv6, will disable it by iptables6
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