MANA passes rxq->alloc_size to napi_build_skb() for all RX buffers.
It is correct for fragment-backed RX buffers, where alloc_size matches
the actual backing allocation used for each packet buffer. However, in
the non-fragment RX path mana allocates a full page, or a higher-order
page, per RX buffer. In that case alloc_size only reflects the usable
packet area and not the actual backing memory.
This causes napi_build_skb() to underestimate the skb backing allocation
in the single-buffer RX path, so skb->truesize is derived from a value
smaller than the real RX buffer allocation.
Fix this by updating alloc_size in the non-fragment RX path to the
actual backing allocation size before it is passed to napi_build_skb().
Fixes: 730ff06d3f5c ("net: mana: Use page pool fragments for RX buffers instead
of full pages to improve memory efficiency.")
Signed-off-by: Dipayaan Roy <[email protected]>
---
drivers/net/ethernet/microsoft/mana/mana_en.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c
b/drivers/net/ethernet/microsoft/mana/mana_en.c
index ea71de39f996..884f8e548174 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -766,6 +766,13 @@ static void mana_get_rxbuf_cfg(struct mana_port_context
*apc,
}
*frag_count = 1;
+
+ /* In the single-buffer path, napi_build_skb() must see the
+ * actual backing allocation size so skb->truesize reflects
+ * the full page (or higher-order page), not just the usable
+ * packet area.
+ */
+ *alloc_size = PAGE_SIZE << get_order(*alloc_size);
return;
}
--
2.43.0
