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net: mana: Fix RX skb truesize accounting

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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: 730ff06d3f ("net: mana: Use page pool fragments for RX buffers instead of full pages to improve memory efficiency.")
Signed-off-by: Dipayaan Roy <dipayanroy@linux.microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Link: https://patch.msgid.link/acLUhLpLum6qrD/N@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Dipayaan Roy 2026-03-24 11:14:28 -07:00 committed by Jakub Kicinski
parent 629ec78ef8
commit f73896b419
1 changed files with 7 additions and 0 deletions
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7
drivers/net/ethernet/microsoft/mana/mana_en.c
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@ -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;
}