From: Hannes Frederic Sowa <han...@stressinduktion.org>
Date: Thu, 21 Apr 2016 15:49:37 +0200
> On 21.04.2016 15:31, Eric Dumazet wrote:
>> On Thu, 2016-04-21 at 05:05 -0400, valdis.kletni...@vt.edu wrote:
>>> On Thu, 21 Apr 2016 09:42:12 +0200, Hannes Frederic Sowa said:
>>>> Hi,
>>>>
>>>> On Thu, Apr 21, 2016, at 02:30, Valdis Kletnieks wrote:
>>>>> linux-next 20160420 is whining at an incredible rate - in 20 minutes of
>>>>> uptime, I piled up some 41,000 hits from all over the place (cleaned up
>>>>> to skip the CPU and PID so the list isn't quite so long):
>>>>
>>>> Thanks for the report. Can you give me some more details:
>>>>
>>>> Is this an nfs socket? Do you by accident know if this socket went
>>>> through xs_reclassify_socket at any point? We do hold the appropriate
>>>> locks at that point but I fear that the lockdep reinitialization
>>>> confused lockdep.
>>>
>>> It wasn't an NFS socket, as NFS wasn't even active at the time. I'm
>>> reasonably
>>> sure that multiple sockets were in play, given that tcp_v6_rcv and
>>> udpv6_queue_rcv_skb were both implicated. I strongly suspect that pretty
>>> much
>>> any IPv6 traffic could do it - the frequency dropped off quite a bit when I
>>> closed firefox, which is usually a heavy network hitter on my laptop.
>>
>>
>> Looks like the following patch is needed, can you try it please ?
>>
>> Thanks !
>>
>> diff --git a/include/net/sock.h b/include/net/sock.h
>> index d997ec13a643..db8301c76d50 100644
>> --- a/include/net/sock.h
>> +++ b/include/net/sock.h
>> @@ -1350,7 +1350,8 @@ static inline bool lockdep_sock_is_held(const struct
>> sock *csk)
>> {
>> struct sock *sk = (struct sock *)csk;
>>
>> - return lockdep_is_held(&sk->sk_lock) ||
>> + return !debug_locks ||
>> + lockdep_is_held(&sk->sk_lock) ||
>> lockdep_is_held(&sk->sk_lock.slock);
>> }
>> #endif
>
> I would prefer to add debug_locks at the WARN_ON level, like
> WARN_ON(debug_locks && !lockdep_sock_is_held(sk)), but I am not sure if
> this fixes the initial splat.
Can we finish this conversation out and come up with a final patch
for this soon?
Thanks.
