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Subject: Re: [PATCH v2] xen-netfront: Fix Rx stall during network stress and
 OOM
To: Juergen Gross <jgross@suse.com>, David Miller <davem@davemloft.net>,
        <boris.ostrovsky@oracle.com>, <xen-devel@lists.xenproject.org>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <0cb06b48-cb3c-47aa-2ae6-3a70197a5b64@amazon.com>
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 <ee87b2e4-de8c-7b9b-c4e5-854ffab2e554@suse.com>
CC: <kamatam@amazon.com>, <aliguori@amazon.com>, <vineethp@amazon.com>
From: Vineeth Remanan Pillai <vineethp@amazon.com>
Message-ID: <79c6ecce-bfcb-ebaa-afd2-05c1d86004d7@amazon.com>
Date: Wed, 18 Jan 2017 09:02:17 -0800
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On 01/15/2017 10:24 PM, Juergen Gross wrote:
> On 13/01/17 18:55, Remanan Pillai wrote:
>> From: Vineeth Remanan Pillai <vineethp@amazon.com>
>>
>> During an OOM scenario, request slots could not be created as skb
>> allocation fails. So the netback cannot pass in packets and netfront
>> wrongly assumes that there is no more work to be done and it disables
>> polling. This causes Rx to stall.
>>
>> The issue is with the retry logic which schedules the timer if the
>> created slots are less than NET_RX_SLOTS_MIN. The count of new request
>> slots to be pushed are calculated as a difference between new req_prod
>> and rsp_cons which could be more than the actual slots, if there are
>> unconsumed responses.
>>
>> The fix is to calculate the count of newly created slots as the
>> difference between new req_prod and old req_prod.
>>
>> Signed-off-by: Vineeth Remanan Pillai <vineethp@amazon.com>
> Reviewed-by: Juergen Gross <jgross@suse.com>
Thanks Juergen.

David,

Could you please pick up this change for net-next if there no more 
concerns..

Many Thanks,
Vineeth

>
>
> Thanks,
>
> Juergen
>