On Sun, May 28, 2023 at 2:16 PM Michael S. Tsirkin [off-list ref] wrote:

On Fri, May 26, 2023 at 01:46:17PM +0800, Liang Chen wrote:

quoted

"private" of buffer page is currently used for big mode to chain pages.
But in mergeable mode, that offset of page could mean something else,
e.g. when page_pool page is used instead. So excluding mergeable mode to
avoid such a problem.

Signed-off-by: Liang Chen <redacted>

Ugh the subject makes it looks like current code has a problem
but I don't think so because I don't think anything besides
big packets uses page->private.

The reason patch is needed is because follow up patches
use page_pool.
pls adjust commit log and subject to make all this clear.

quoted

---
 drivers/net/virtio_net.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 5a7f7a76b920..c5dca0d92e64 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -497,7 +497,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
                      return NULL;

              page = (struct page *)page->private;
-             if (page)
+             if (!vi->mergeable_rx_bufs && page)

To be safe let's limit to big packets too:

        if (!vi->mergeable_rx_bufs && vi->big_packets && page)

Sure, thanks!

quoted

                      give_pages(rq, page);
              goto ok;
      }
--
2.31.1