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Subject: Re: [PATCH] xen-netback: fix occasional leak of grant ref mappings
 under memory pressure
To:     Paul Durrant <Paul.Durrant@citrix.com>,
        Wei Liu <wei.liu2@citrix.com>
CC:     "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "davem@davemloft.net" <davem@davemloft.net>
References: <1551319382-32595-1-git-send-email-igor.druzhinin@citrix.com>
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 <e5ef3c0291854b67841b6c532f7651b9@AMSPEX02CL02.citrite.net>
From:   Igor Druzhinin <igor.druzhinin@citrix.com>
Message-ID: <447cd231-3ea4-e56d-29b0-6528804c9e9a@citrix.com>
Date:   Thu, 28 Feb 2019 11:43:46 +0000
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On 28/02/2019 11:21, Paul Durrant wrote:
>>> @@ -1153,6 +1152,10 @@ static int xenvif_tx_submit(struct xenvif_queue *queue)
>>>                                 kfree_skb(skb);
>>>                                 continue;
>>>                         }
>>> +
>>> +                       /* Copied all the bits from the frag list. */
>>> +                       skb_frag_list_init(skb);
>>> +                       kfree(nskb);
>>
>> I think you want kfree_skb here?
> 
> No. nskb is the frag list... it is unlinked from skb by the call to skb_frag_list_init() and then it can be freed on its own. The skb is what we need to retain, because that now contains all the data.
> 

Are you saying previous code in xenvif_handle_frag_list() incorrectly
called kfree_skb()?

Igor