On Thu, 2025-07-17 at 10:01 +0100, Will Deacon wrote:

-#define VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE	(1024 * 4)
+/* Dimension the RX SKB so that the entire thing fits exactly into
+ * a single 4KiB page. This avoids wasting memory due to alloc_skb()
+ * rounding up to the next page order and also means that we
+ * don't leave higher-order pages sitting around in the RX queue.
+ */
+#define
VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE	SKB_WITH_OVERHEAD(1024 * 4)

Should this be SKB_WITH_OVERHEAD()?

Or should it subtract VIRTIO_VSOCK_SKB_HEADROOM instead?

(And also, I have use cases where I want to expand this to 64KiB. Can I
make it controllable with a sockopt? module param?)