netdev - Re: Network namespace and bonding WARNING at fs/proc/generic.c remove_proc

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Message-ID: <20120706170538.GA31679@mail.hallyn.com>
Date:	Fri, 6 Jul 2012 17:05:38 +0000
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	"Serge E. Hallyn" <serge@...lyn.com>,
	Dilip Daya <dilip.daya@...com>, linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, netdev@...r.kernel.org
Subject: Re: Network namespace and bonding WARNING at fs/proc/generic.c
 remove_proc_entry

Quoting Eric W. Biederman (ebiederm@...ssion.com):
> "Serge E. Hallyn" <serge@...lyn.com> writes:
> 
> > Quoting Dilip Daya (dilip.daya@...com):
> >> Hi,
> >> 
> >> I'd discussed the following with Serge Hallyn.
> >> 
> >> => Environment based on 3.2.18 / x86_64 kernel.
> >> => WARNING: at fs/proc/generic.c:808 remove_proc_entry+0xdb/0x21f()
> >> => WARNING: at fs/proc/generic.c:849 remove_proc_entry+0x208/0x21f()
> >
> > Hi,
> >
> > thanks much for sending this.  I'm still getting this error on
> > 3.5.0-2-generic (today's ubuntu quantal kernel)
> >
> >> network namespace and bonding
> >> -----------------------------
> >> 
> >> * Migrate two phy nics from host to netns (netns0).
> >>   - ip link set ethX netns netns0
> >> 
> >> * In host environment:
> >>   - load bonding module, /sbin/modprobe -v bonding mode=1 miimon=100
> >>   - /sys/class/net/bond0 exists.
> >>   - /proc/net/bonding/bond0 exists.
> >>   - /sys/class/net/bonding_masters has bond0.
> >> 
> >> * Migrate bond0 to netns (netns0):
> >>   - ip link set bond0 netns netns0.
> >> 
> >> * Within netns (netns0):
> >>   - /sys/class/net/bonding_masters is empty.
> >>   - /sys/class/net/bond0 exist.
> >>   - configure bond0 and ifenslave with two phy nics.
> >>   - /proc/net/bonding/bond0 does not exist within netns0, but does
> >>     exist in the host environment.
> >>   - /sys/class/net/bonding_masters is empty.
> >
> > mine is not empty, fwiw.  However
> >
> >>   - ping to remote end of bond0 works.
> >> 
> >> * Within netns (netns0), flushing ethX and bondY:
> >>   - down bond0 and its phy nic interfaces:
> >>   - ip link set ... down
> >>   - ip addr flush dev [bond0 | eth#]
> >>   - deleting bond0, /sbin/ip link del dev bond0
> >
> > Yup I still get a remove_proc_entry WARNING at fs/proc/generic.c:808,
> > which is the warning when (!de)
> 
> It looks like Dilip is running an old kernel.  There should have been
> some version of /sys/class/net/bonding_masters in every network
> namespace since sometime in 2009.
> 
> >From the warning it looks like the proc files are being added/removed
> to the wrong network namespace.  So in one namespace we get an error
> when we delete the moved device and in the other network namespace
> we get an error when we remove the /proc/directory.
> 
> An old kernel without proper network namespace support is the only
> reason I can imagine someone would be moving an existing bond device
> between network namespaces.
> 
> If there are other reasons for wanting to move a bonding device between
> network namespaces it is possible to catch the NETDEV_UNREGISTER and
> NETDEV_REGISTER events to remove/add the per device proc files at the
> appropriate time.
> 
> However since moving bonding devices appears to be an unneded operation
> let's just do things simply and forbid moving bonding devices between
> network namespaces.  Serge, Dilip can you two test the patch below
> and see if it fixes the warnings.
> 
> Eric
> 
> 
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 2ee8cf9..818ed64 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -4345,6 +4345,9 @@ static void bond_setup(struct net_device *bond_dev)
>         bond_dev->priv_flags |= IFF_BONDING;
>         bond_dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE | IFF_TX_SKB_SHARING);
>  
> +       /* Don't allow bond devices to change network namespaces. */
> +       bond_dev->features |= NETIF_F_LOCAL;

I believe this needs to be NETIF_F_NETNS_LOCAL.  Test build still going with
that change.

> +
>         /* At first, we block adding VLANs. That's the only way to
>          * prevent problems that occur when adding VLANs over an
>          * empty bond. The block will be removed once non-challenged
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