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SubjectRe: [PATCH net] virtio-net: fix page refcnt leaking when fail to allocate frag skb
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On Tue, 2013-11-19 at 16:05 +0800, Jason Wang wrote:
> We need to drop the refcnt of page when we fail to allocate an skb for frag
> list, otherwise it will be leaked. The bug was introduced by commit
> 2613af0ed18a11d5c566a81f9a6510b73180660a ("virtio_net: migrate mergeable rx
> buffers to page frag allocators").
>
> Cc: Michael Dalton <mwdalton@google.com>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Rusty Russell <rusty@rustcorp.com.au>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> The patch was needed for 3.12 stable.

Good catch, but if we return from receive_mergeable() in the 'middle'
of the frags we would need for the current skb, who will
call the virtqueue_get_buf() to flush the remaining frags ?

Don't we also need to call virtqueue_get_buf() like

while (--num_buf) {
buf = virtqueue_get_buf(rq->vq, &len);
if (!buf)
break;
put_page(virt_to_head_page(buf));
}

?






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