Re: [PATCH net-next v11] virtio_net: add page_pool support for buffer allocation

[Vishwanath Seshagiri <vishs@meta.com>]

On 3/13/26 1:21 PM, Jason Wang wrote:
>> -static void put_xdp_frags(struct xdp_buff *xdp)
>> +static void put_xdp_frags(struct receive_queue *rq, struct xdp_buff *xdp)
>>   {
>>          struct skb_shared_info *shinfo;
>>          struct page *xdp_page;
>> @@ -1781,7 +1660,7 @@ static void put_xdp_frags(struct xdp_buff *xdp)
>>                  shinfo = xdp_get_shared_info_from_buff(xdp);
>>                  for (i = 0; i < shinfo->nr_frags; i++) {
>>                          xdp_page = skb_frag_page(&shinfo->frags[i]);
>> -                       put_page(xdp_page);
>> +                       page_pool_put_page(rq->page_pool, xdp_page, -1, true);
>>                  }
>>          }
>>   }
>> @@ -1873,7 +1752,7 @@ static struct page *xdp_linearize_page(struct net_device *dev,
>>          if (page_off + *len + tailroom > PAGE_SIZE)
>>                  return NULL;
>>
>> -       page = alloc_page(GFP_ATOMIC);
>> +       page = page_pool_alloc_pages(rq->page_pool, GFP_ATOMIC);
>>          if (!page)
>>                  return NULL;
>>
>> @@ -1896,8 +1775,12 @@ static struct page *xdp_linearize_page(struct net_device *dev,
>>                  p = virt_to_head_page(buf);
>>                  off = buf - page_address(p);
>>
>> +               if (rq->use_page_pool_dma)
>> +                       page_pool_dma_sync_for_cpu(rq->page_pool, p,
>> +                                                  off, buflen);
> 
> Intresting, I think we need a patch for -stable to sync for cpu as
> well (and probably the XDP_TX path).

In the old code, I believed the sync was handled implicitly inside 
virtnet_rq_get_buf() -> virtnet_rq_unmap() before data was accessed. 
Could you point me at the specific path you're concerned about for 
-stable? I want to make sure I understand the issue correctly before 
sending a fix.

> 
> 
>> +
>>                  if (check_mergeable_len(dev, ctx, buflen)) {
>> -                       put_page(p);
>> +                       page_pool_put_page(rq->page_pool, p, -1, true);
>>                          goto err_buf;
>>                  }

Sorry for missing that comment in the earlier email