Re: [PATCH net] xen-netfront: Add missing skb_mark_for_recycle

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Wed, Mar 27, 2024 at 01:14:56PM +0100, Jesper Dangaard Brouer wrote:
> Notice that skb_mark_for_recycle() is introduced later than fixes tag in
> 6a5bcd84e886 ("page_pool: Allow drivers to hint on SKB recycling").
> 
> It is believed that fixes tag were missing a call to page_pool_release_page()
> between v5.9 to v5.14, after which is should have used skb_mark_for_recycle().
> Since v6.6 the call page_pool_release_page() were removed (in 535b9c61bdef
> ("net: page_pool: hide page_pool_release_page()") and remaining callers
> converted (in commit 6bfef2ec0172 ("Merge branch
> 'net-page_pool-remove-page_pool_release_page'")).
> 
> This leak became visible in v6.8 via commit dba1b8a7ab68 ("mm/page_pool: catch
> page_pool memory leaks").
> 
> Fixes: 6c5aa6fc4def ("xen networking: add basic XDP support for xen-netfront")
> Reported-by: Arthur Borsboom <arthurborsboom@xxxxxxxxx>
> Signed-off-by: Jesper Dangaard Brouer <hawk@xxxxxxxxxx>
> ---
> Compile tested only, can someone please test this

I've got a confirmation it fixes the issue:
https://github.com/QubesOS/qubes-linux-kernel/pull/926#issuecomment-2026226944

>  drivers/net/xen-netfront.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index ad29f370034e..8d2aee88526c 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -285,6 +285,7 @@ static struct sk_buff *xennet_alloc_one_rx_buffer(struct 
> netfront_queue *queue)
>               return NULL;
>       }
>       skb_add_rx_frag(skb, 0, page, 0, 0, PAGE_SIZE);
> +     skb_mark_for_recycle(skb);
>  
>       /* Align ip header to a 16 bytes boundary */
>       skb_reserve(skb, NET_IP_ALIGN);
> 
> 
> 

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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