From 63811edf512584c946e5e96b100e9e280703bbb5 Mon Sep 17 00:00:00 2001 From: Jerome Tollet Date: Mon, 24 Aug 2026 16:16:45 +0200 Subject: [PATCH] net/mlx5e: Prevent stale XSK buffer release on MPWQE refill retry With AF_XDP on a striding RQ, mlx5e defers releasing XSK buffers until an MPWQE is refilled. If XSK allocation then returns -ENOMEM, actual_wq_head is not advanced and a later NAPI poll retries the same WQE. mlx5e_free_rx_mpwqe() leaves each released slot marked as releasable. On retry it can therefore call xsk_buff_free() again through stale pointers after the frames have returned to the XSK pool and been reallocated. Set all skip_release_bitmap bits in the common error path of mlx5e_xsk_alloc_rx_mpwqe(). This matches mlx5e_alloc_rx_mpwqe(). A successful allocation already clears the bitmap after replacing every buffer, so retries become idempotent without changing the success path. Fault injection forced three consecutive failures for one selected MPWQE. Both an early allocation failure and a partial 8-of-16-buffer unwind released the original 16 XSK buffers only once. Each error left a full bitmap, the following NAPI retry skipped the release, and a later successful allocation cleared it. A 20-second AF_XDP zero-copy pressure run exercised 1,575,262 buffer allocation failures without invalid descriptors, WQE errors, or kernel warnings. Fixes: 4c2a13236807 ("net/mlx5e: RX, Defer page release in striding rq for better recycling") Cc: stable@vger.kernel.org Signed-off-by: Jerome Tollet Reviewed-by: Dragos Tatulea Link: https://patch.msgid.link/20260824141645.23700-3-jtollet@cisco.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c index 4f984f6a2cb9..55ec6387ab28 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c @@ -3,6 +3,7 @@ #include "rx.h" #include "en/xdp.h" +#include #include #include @@ -156,6 +157,7 @@ int mlx5e_xsk_alloc_rx_mpwqe(struct mlx5e_rq *rq, u16 ix) xsk_buff_free(xsk_buffs[batch]); err: + bitmap_fill(wi->skip_release_bitmap, rq->mpwqe.pages_per_wqe); rq->stats->buff_alloc_err++; return -ENOMEM; }