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

From: Andreas Hartmann <andihartmann@01019freenet.de>
To: Andreas Hartmann <andihartmann@01019freenet.de>, netdev@vger.kernel.org
Cc: john.fastabend@gmail.com, Michal Kubecek <mkubecek@suse.cz>
Subject: Re: Linux 4.14 - regression: broken tun/tap / bridge network with virtio - bisected
Date: Mon, 4 Dec 2017 17:28:00 +0100	[thread overview]
Message-ID: <881560f8-54ec-e946-50cb-b2e80ddb5f97@01019freenet.de> (raw)
In-Reply-To: <4efbaf24-f419-2c8e-c705-59a5242b0575@01019freenet.de>

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

Here is the same problem:
https://bugzilla.kernel.org/show_bug.cgi?id=197861

Any idea how to proceed?

Thanks,
Andreas