netdev - Re: [Bug 194749] New: kernel bonding does not work in a network nameservice in versions above 3.10.0-229.20.1

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Date:   Fri, 3 Mar 2017 17:03:48 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Nicolas Dichtel <nicolas.dichtel@...nd.com>
Cc:     Dan Geist <dan@...ter.net>, Cong Wang <xiyou.wangcong@...il.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        chenweilong@...wei.com, Jiri Pirko <jiri@...lanox.com>
Subject: Re: [Bug 194749] New: kernel bonding does not work in a network
 nameservice in versions above 3.10.0-229.20.1

Fri, Mar 03, 2017 at 04:19:13PM CET, nicolas.dichtel@...nd.com wrote:
>Le 02/03/2017 à 21:39, Dan Geist a écrit :
>> ----- On Mar 2, 2017, at 3:11 PM, Cong Wang xiyou.wangcong@...il.com wrote
>> 
>>> On Thu, Mar 2, 2017 at 10:32 AM, Stephen Hemminger
>>> <stephen@...workplumber.org> wrote:
>>>>
>>>>
>>>> Begin forwarded message:
>>>>
>>>> Date: Wed, 01 Mar 2017 21:08:01 +0000
>>>> From: bugzilla-daemon@...zilla.kernel.org
>>>> To: stephen@...workplumber.org
>>>> Subject: [Bug 194749] New: kernel bonding does not work in a network nameservice
>>>> in versions above 3.10.0-229.20.1
>>>>
>>>>
>>>> https://bugzilla.kernel.org/show_bug.cgi?id=194749
>>>>
>>>>             Bug ID: 194749
>>>>            Summary: kernel bonding does not work in a network nameservice
>>>>                     in versions above 3.10.0-229.20.1
>>>>            Product: Networking
>>>>            Version: 2.5
>>>>     Kernel Version: > 3.10.0-229.20.1
>>>>           Hardware: x86-64
>>>>                 OS: Linux
>>>>               Tree: Mainline
>>>>             Status: NEW
>>>>           Severity: blocking
>>>>           Priority: P1
>>>>          Component: Other
>>>>           Assignee: stephen@...workplumber.org
>>>>           Reporter: dan@...ter.net
>>>>         Regression: No
>>>>
>>>> bond interface is being used in active/standby mode with two physical NICs
>>>> inside a network nameservice to provide switchpath redundancy.
>>>>
>>>> netns is instantiated post-boot with the following:
>>>>
>>>> ip netns add vntp
>>>> ip link set p4p1 netns vntp
>>>> ip link set p4p2 netns vntp
>>>> ip link set bond0 netns vntp
>>>> ip netns exec vntp ip link set lo up
>>>> ip netns exec vntp ip link set p4p1 up
>>>> ip netns exec vntp ip link set p4p2 up
>>>> ip netns exec vntp ip link set bond0 up
>>>> ip netns exec vntp ifenslave bond0 p4p1 p4p2
>>>
>>> This is due to the following commit:
>>>
>>> commit f9399814927ad9bb995a6e109c2a5f9d8a848209
>>> Author: Weilong Chen <chenweilong@...wei.com>
>>> Date:   Wed Jan 22 17:16:30 2014 +0800
>>>
>>>    bonding: Don't allow bond devices to change network namespaces.
>>>
>>>    Like bridge, bonding as netdevice doesn't cross netns boundaries.
>>>
>>>    Bonding ports and bonding itself live in same netns.
>>>
>>>    Signed-off-by: Weilong Chen <chenweilong@...wei.com>
>>>    Signed-off-by: David S. Miller <davem@...emloft.net>
>>>
>>>
>>> NETIF_F_NETNS_LOCAL was introduced for loopback device which
>>> is created for each netns, it is not clear why we need to add it to bond
>>> and bridge...
>> 
>> Thank you for tracking this down. Without digging through the code to figure it out, does this imply that the existence of a bond interface is not possible AT ALL within a netns or simply that it may not be "migrated" between the global scope and a netns?
>It means that the migration is not possible. I think the only reason to have
>this flag on bonding and bridge is the lack of test and fix. There is probably
>some work to be done to have this feature. But are there real use cases of
>x-netns bonding or x-netns bridge?

If that use case exists I believe it is an abuse. Soft devices that are
by definition in upper-lower relationships with other devices should not
move to other namespaces. Prevents all kinds of issues. If you need a
soft device like bridge of bond within a namespace, just create it there.