From f73896b4197ed53cf0894657c899265ef7c86b7a Mon Sep 17 00:00:00 2001 From: Dipayaan Roy Date: Tue, 24 Mar 2026 11:14:28 -0700 Subject: [PATCH] net: mana: Fix RX skb truesize accounting 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 Reviewed-by: Haiyang Zhang Link: https://patch.msgid.link/acLUhLpLum6qrD/N@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net Signed-off-by: Jakub Kicinski --- 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 dca62fb9a3a9..09a53c977545 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; }