5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Gerd Bayer gbayer@linux.ibm.com
[ Upstream commit 2bcae12c795f32ddfbf8c80d1b5f1d3286341c32 ]
Remove the erroneous unmap in case no DMA mapping was established
The multi-packet WQE transmit code attempts to obtain a DMA mapping for the skb. This could fail, e.g. under memory pressure, when the IOMMU driver just can't allocate more memory for page tables. While the code tries to handle this in the path below the err_unmap label it erroneously unmaps one entry from the sq's FIFO list of active mappings. Since the current map attempt failed this unmap is removing some random DMA mapping that might still be required. If the PCI function now presents that IOVA, the IOMMU may assumes a rogue DMA access and e.g. on s390 puts the PCI function in error state.
The erroneous behavior was seen in a stress-test environment that created memory pressure.
Fixes: 5af75c747e2a ("net/mlx5e: Enhanced TX MPWQE for SKBs") Signed-off-by: Gerd Bayer gbayer@linux.ibm.com Reviewed-by: Zhu Yanjun yanjun.zhu@linux.dev Acked-by: Maxim Mikityanskiy maxtram95@gmail.com Signed-off-by: Saeed Mahameed saeedm@nvidia.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/mellanox/mlx5/core/en_tx.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c index 6813279b57f89..7ec8a5ae7ea74 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c @@ -685,7 +685,6 @@ mlx5e_sq_xmit_mpwqe(struct mlx5e_txqsq *sq, struct sk_buff *skb, return;
err_unmap: - mlx5e_dma_unmap_wqe_err(sq, 1); sq->stats->dropped++; dev_kfree_skb_any(skb); mlx5e_tx_flush(sq);