Re: [Xen-devel] [PATCH v3 0/3] map grant refs at pfn = mfn

[Thomas Leonard <talex5@xxxxxxxxx>]

On 6 August 2014 21:46, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> On Wed, Aug 06, 2014 at 06:50:04PM +0100, Thomas Leonard wrote:
>> On 6 August 2014 16:59, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
>> > Thomas, can you give this patch a quick try? I only compile test it
>> > because I don't have handy testing environment at the moment.
>> >
>> > Apply it to Dom0 kernel.
>> >
>> > ---8<---
>> > From b32aa53ba8b79f0006780549953510930513a3ac Mon Sep 17 00:00:00 2001
>> > From: Wei Liu <wei.liu2@xxxxxxxxxx>
>> > Date: Wed, 6 Aug 2014 16:50:06 +0100
>> > Subject: [PATCH] xen-netback: don't stop kthreads until all in-flight 
>> > packets
>> >  are processed
>> >
>> > Reference count the number of packets in host stack, so that we don't
>> > stop the deallocation thread too early. If not, we can end up with
>> > xenvif_free permanently waiting for deallocation thread to unmap grefs.
>> >
>> > Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
>>
>> That stops the errors being printed, but I still have a domain I can't 
>> destroy:
>>
>> $ xl list
>> Name                                        ID   Mem VCPUs      State   
>> Time(s)
>> Domain-0                                     0   512     2     r-----      
>> 35.6
>> (null)                                       1     0     1     --ps-d       
>> 0.1
>>
>> I do see this after a bit:
>>
>> [  240.062339] INFO: task xenwatch:18 blocked for more than 120 seconds.
>> [  240.062404]       Not tainted 3.16.0-rc7-00004-g9d89db9 #1
>> [  240.062426] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
>> disables this message.
>>
>> The load average is 1.
>>
>
> If you do "ps aux | grep vif" do you see some kthreads? If so, what is
> the status of these threads?

root@cubietruck:~# xl list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0   512     2     r-----      22.0
(null)                                       1     0     1     --ps-d       0.1

root@cubietruck:~# ps aux | grep vif
root      1189  0.0  0.0      0     0 ?        S    07:50   0:00
[vif1.0-q0-guest]
root      1190  0.0  0.0      0     0 ?        S    07:50   0:00
[vif1.0-q0-deall]
root      1242  0.0  0.2   3388  1052 pts/0    S+   07:51   0:00 grep
--color=auto vif

> What's the status of "xenwatch" thread?

root@cubietruck:~# ps aux | grep xenwatch
root        18  0.0  0.0      0     0 ?        D    07:49   0:00 [xenwatch]

root@cubietruck:~# cat /proc/18/wchan
xenvif_disconnect

>  It looks like that xenbus thread hangs waiting to be woken up, which means
> there's yet another exit point.
>
> This problem involes at least four execution entities (softirq +
> kthreads) so to be honest it's not straightforward to figure out what
> goes wrong. I will take another stab as soon as possible.
>
> Wei.



-- 
Dr Thomas Leonard        http://0install.net/
GPG: 9242 9807 C985 3C07 44A6  8B9A AE07 8280 59A5 3CC1
GPG: DA98 25AE CAD0 8975 7CDA  BD8E 0713 3F96 CA74 D8BA

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