5.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Rafał Miłecki rafal@milecki.pl
[ Upstream commit 752e5fcc2e77358936d36ef8e522d6439372e201 ]
bgmac allocates new replacement buffer before handling each received frame. Allocating & DMA-preparing 9724 B each time consumes a lot of CPU time. Ideally bgmac should just respect currently set MTU but it isn't the case right now. For now just revert back to the old limited frame size.
This change bumps NAT masquerade speed by ~95%.
Since commit 8218f62c9c9b ("mm: page_frag: use initial zero offset for page_frag_alloc_align()"), the bgmac driver fails to open its network interface successfully and runs out of memory in the following call stack:
bgmac_open -> bgmac_dma_init -> bgmac_dma_rx_skb_for_slot -> netdev_alloc_frag
BGMAC_RX_ALLOC_SIZE = 10048 and PAGE_FRAG_CACHE_MAX_SIZE = 32768.
Eventually we land into __page_frag_alloc_align() with the following parameters across multiple successive calls:
__page_frag_alloc_align: fragsz=10048, align_mask=-1, size=32768, offset=0 __page_frag_alloc_align: fragsz=10048, align_mask=-1, size=32768, offset=10048 __page_frag_alloc_align: fragsz=10048, align_mask=-1, size=32768, offset=20096 __page_frag_alloc_align: fragsz=10048, align_mask=-1, size=32768, offset=30144
So in that case we do indeed have offset + fragsz (40192) > size (32768) and so we would eventually return NULL. Reverting to the older 1500 bytes MTU allows the network driver to be usable again.
Fixes: 8c7da63978f1 ("bgmac: configure MTU and add support for frames beyond 8192 byte size") Signed-off-by: Rafał Miłecki rafal@milecki.pl [florian: expand commit message about recent commits] Reviewed-by: Simon Horman horms@kernel.org Signed-off-by: Florian Fainelli florian.fainelli@broadcom.com Link: https://patch.msgid.link/20250127175159.1788246-1-florian.fainelli@broadcom.... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/broadcom/bgmac.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/broadcom/bgmac.h b/drivers/net/ethernet/broadcom/bgmac.h index d1200b27af1ed..51ff5aceba99e 100644 --- a/drivers/net/ethernet/broadcom/bgmac.h +++ b/drivers/net/ethernet/broadcom/bgmac.h @@ -366,8 +366,7 @@ #define BGMAC_RX_FRAME_OFFSET 30 /* There are 2 unused bytes between header and real data */ #define BGMAC_RX_BUF_OFFSET (NET_SKB_PAD + NET_IP_ALIGN - \ BGMAC_RX_FRAME_OFFSET) -/* Jumbo frame size with FCS */ -#define BGMAC_RX_MAX_FRAME_SIZE 9724 +#define BGMAC_RX_MAX_FRAME_SIZE 1536 #define BGMAC_RX_BUF_SIZE (BGMAC_RX_FRAME_OFFSET + BGMAC_RX_MAX_FRAME_SIZE) #define BGMAC_RX_ALLOC_SIZE (SKB_DATA_ALIGN(BGMAC_RX_BUF_SIZE + BGMAC_RX_BUF_OFFSET) + \ SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))