Re: [PATCH net] virtio-net: fix page refcnt leaking when fail toallocate frag skb

[Eric Dumazet]

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@xxxxxxxxxx>
> Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> 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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