Re: Shutting down a VM with Kernel 4.14 will sometime hang and a reboot is the only way to recover.

[David Hill <dhill@redhat.com>]

On 2017-11-29 12:15 AM, Jason Wang wrote:
>
>
> On 2017年11月29日 10:52, Dave Hill wrote:
>>>>
>>>
>>> Thanks. Zerocopy is disabled by several distribution by default. For 
>>> upstream, the only reason to let it on is to hope more developers 
>>> can help and fix the issues.
>>>
>>>
>> So I never hit this issue with previous kernel and this issue started 
>> happening with the v4.14-rc series.
>
>
> Right, this still need to be investigated if it was introduced recently.
>
> Looking at git history, the only suspected commit is for 4.14 is
>
> commit 1e6f74536de08b5e50cf0e37e735911c2cef7c62
> Author: Willem de Bruijn <willemb@google.com>
> Date:   Fri Oct 6 13:22:31 2017 -0400
>
>     vhost_net: do not stall on zerocopy depletion
>
> Maybe you can try to revert it and see.
>
> If it does not solve your issue, I suspect there's bug elsewhere that 
> cause a packet to be held for very long time.
>
>>   I'm using rawhide so perhaps this is why it isn't disabled by 
>> default but I have to mention it's an update of FC25 up to FC28 and 
>> it never got disabled.
>> Perhaps it should be disabled in Fedora too if it's not the case... 
>> I'm not sure this is the place to discuss this ... is it? 
>
> Probably not, but I guess Fedora tries to use new technology 
> aggressively.
>
> Thanks

I can revert that commit in 4.15-rc1 but I can't find it in 4.14.2 ...  
Is there another commit that could affect this ?