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SubjectRE: [PATCH] xen-netback: fix occasional leak of grant ref mappings under memory pressure
Date
> -----Original Message-----
> From: Igor Druzhinin [mailto:igor.druzhinin@citrix.com]
> Sent: 28 February 2019 11:44
> To: Paul Durrant <Paul.Durrant@citrix.com>; Wei Liu <wei.liu2@citrix.com>
> Cc: xen-devel@lists.xenproject.org; netdev@vger.kernel.org; linux-kernel@vger.kernel.org;
> davem@davemloft.net
> Subject: Re: [PATCH] xen-netback: fix occasional leak of grant ref mappings under memory pressure
>
> 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()?

No, it correctly called kfree_skb() on nskb in the success case. What Wei and myself would prefer is that we have a single place that the frag list is freed in both the success and error cases.

Paul

>
> Igor
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