net: bcmgenet: allocate RX buffers as page fragments

Since the page_pool conversion every RX buffer is a whole page and the
skb truesize is the page, although the hardware writes at most 2 KiB of
it. On 64 KiB pages a packet therefore counts 65792 bytes against the
socket buffer where it used to count 2752. As a result a UDP socket
with the default buffer starts to drop after three packets, and the RX
rings pin 16 MiB for 512 KiB of buffers.

Fix this and allocate the buffers as page fragments, so the truesize is
what a packet occupies. 4 KiB pages stay one buffer per page.

Sync each buffer in the refill path, as page_pool can only sync a whole
page on recycle. On 4 KiB pages that is twice what the hardware wrote.

Fixes: 7bc054c2d4ed ("net: bcmgenet: convert RX path to page_pool")
Reported-by: Karl Mehltretter <kmehltretter@gmail.com>
Closes: https://lore.kernel.org/all/20260924065839.56793-1-kmehltretter@gmail.com/
Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260924101922.2675127-1-nb@tipi-net.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions