From: David Ahern <dsahern@gmail.com>
To: Xin Long <lucien.xin@gmail.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Cong Wang <xiyou.wangcong@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
David Miller <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Willem de Bruijn <willemb@google.com>,
Jakub Kicinski <jakub.kicinski@netronome.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
netdev <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
syzkaller <syzkaller@googlegroups.com>,
Dan Streetman <ddstreet@canonical.com>,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: net: hang in unregister_netdevice: waiting for lo to become free
Date: Tue, 30 Jan 2018 15:59:59 -0700 [thread overview]
Message-ID: <efa5811c-0a01-a4af-ade2-71ef5dbc4eaf@gmail.com> (raw)
In-Reply-To: <991243e2-e7c2-f2b2-72b9-d37b0d569b3b@gmail.com>
On 1/30/18 1:57 PM, David Ahern wrote:
> On 1/30/18 1:08 PM, Daniel Borkmann wrote:
>> On 01/30/2018 07:32 PM, Cong Wang wrote:
>>> On Tue, Jan 30, 2018 at 4:09 AM, Dmitry Vyukov <dvyukov@google.com> wrote:
>>>> Hello,
>>>>
>>>> The following program creates a hang in unregister_netdevice.
>>>> cleanup_net work hangs there forever periodically printing
>>>> "unregister_netdevice: waiting for lo to become free. Usage count = 3"
>>>> and creation of any new network namespaces hangs forever.
>>>
>>> Interestingly, this is not reproducible on net-next.
>>
>> The most recent change on netns refcnt was 4ee806d51176 ("net: tcp: close
>> sock if net namespace is exiting") in net/net-next from 5 days ago, maybe
>> fixed due to that?
>>
>
> This appears to be the commit introducing the refcnt leak:
>
> $ git bisect bad
> dbc2b5e9a09e9a6664679a667ff81cff6e5f2641 is the first bad commit
> commit dbc2b5e9a09e9a6664679a667ff81cff6e5f2641
> Author: Xin Long <lucien.xin@gmail.com>
> Date: Fri May 12 14:39:52 2017 +0800
>
> sctp: fix src address selection if using secondary addresses for ipv6
>
>
> v4.14 is bad. Running bisect in the background while doing other things....
>
Interesting. The commit that avoids the refcnt leak is
commit 955ec4cb3b54c7c389a9f830be7d3ae2056b9212
Author: David Ahern <dsahern@gmail.com>
Date: Wed Jan 24 19:45:29 2018 -0800
net/ipv6: Do not allow route add with a device that is down
That commit does not intentionally address the problem so it is just
masking the problematic code introduced by the commit above.
next prev parent reply other threads:[~2018-01-30 23:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-30 12:09 net: hang in unregister_netdevice: waiting for lo to become free Dmitry Vyukov
2018-01-30 18:32 ` Cong Wang
2018-01-30 20:08 ` Daniel Borkmann
2018-01-30 20:57 ` David Ahern
2018-01-30 22:59 ` David Ahern [this message]
2018-02-01 0:49 ` Xin Long
2018-02-03 12:15 ` Xin Long
2018-02-19 18:59 ` Dmitry Vyukov
2018-02-20 7:56 ` Tommi Rantala
2018-02-20 8:14 ` Dmitry Vyukov
2018-02-20 16:26 ` Neil Horman
2018-02-21 14:53 ` Tommi Rantala
2018-04-12 12:15 ` Dmitry Vyukov
2018-04-13 11:37 ` Neil Horman
2018-04-13 12:43 ` Dan Streetman
2018-04-13 15:54 ` Dmitry Vyukov
2018-04-16 7:35 ` Dmitry Vyukov
2018-04-16 19:42 ` Dan Streetman
2018-05-10 6:46 ` Dmitry Vyukov
2018-05-10 10:23 ` Dan Streetman
2018-05-11 9:19 ` Dmitry Vyukov
2018-05-11 11:40 ` Dan Streetman
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