netdev - Re: Linux 4.14 - regression: broken tun/tap / bridge network with virtio

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Message-ID: <401a0715-fd28-63a3-8dfd-e89835d70db0@01019freenet.de>
Date:   Tue, 5 Dec 2017 17:23:07 +0100
From:   Andreas Hartmann <andihartmann@...19freenet.de>
To:     Jason Wang <jasowang@...hat.com>
Cc:     netdev@...r.kernel.org, john.fastabend@...il.com,
        Michal Kubecek <mkubecek@...e.cz>
Subject: Re: Linux 4.14 - regression: broken tun/tap / bridge network with
 virtio - bisected

On 12/05/2017 at 04:50 AM Jason Wang wrote:
> 
> 
> On 2017年12月05日 00:28, Andreas Hartmann wrote:
>> On 12/03/2017 at 12:35 PM Andreas Hartmann wrote:
>>> On 12/01/2017 at 11:11 AM Andreas Hartmann wrote:
>>>> Hello!
>>>>
>>>> I hopefully could get rid of both of my problems (hanging network w/
>>>> virtio) and endless hanging qemu-process on VM shutdown by upgrading
>>>> qemu from 2.6.2 to 2.10.1. I hope it will persist.
>>> It didn't persist. 10h later - same problems happened again. It's just
>>> much harder to trigger the problems.
>>>
>>> I'm now trying it with
>>>
>>> CONFIG_RCU_NOCB_CPU=y and
>>> rcu_nocbs=0-15
>>>
>>> Since then, I didn't see any problem any more. But this doesn't mean
>>> anything until now ... .
>> Didn't work ether. Disabling vhost_net's zcopy hadn't any effect, too.
>>
>> => It's just finally broken since
>>
>> 2ddf71e23cc246e95af72a6deed67b4a50a7b81c
>> net: add notifier hooks for devmap bpf map
> 
> Hi:
> 
> Did you use XDP devmap in host? If not, please double check it was the
> first bad commit since the patch should only work when XDP/devmap is
> used on host.

How do I know if XDP/devmap is enabled / used? Could you please give
some hint?


Thanks,
Andreas