Re: [PATCH net v2] net/mlx5: free mlx5_st_idx_data on final dealloc

[Tariq Toukan <tariqt@nvidia.com>]

On 30/06/2026 19:53, Zhiping Zhang wrote:
> Workloads that repeatedly allocate and release mkeys carrying TPH
> steering-tag hints (e.g. churning RDMA MRs) leak one
> struct mlx5_st_idx_data per cycle; kmemleak flags it as unreferenced
> and the kmalloc slab grows over time.
> 
> When the last reference to an ST table entry is dropped,
> mlx5_st_dealloc_index() removed the entry from idx_xa but the backing
> mlx5_st_idx_data allocation was never freed.
> 
> Free idx_data after the xa_erase() so the lifetime of the bookkeeping
> struct matches the lifetime of the ST entry it tracks.
> 
> Cc: stable@vger.kernel.org
> Fixes: 888a7776f4fb ("net/mlx5: Add support for device steering tag")
> Reviewed-by: Michael Gur <michaelgur@nvidia.com>
> Signed-off-by: Zhiping Zhang <zhipingz@meta.com>
> ---
> v2: respin per maintainer-netdev.rst; no code change.
> v1: https://lore.kernel.org/linux-rdma/20260612170406.3339093-1-zhipingz@meta.com/
> 
>   drivers/net/ethernet/mellanox/mlx5/core/lib/st.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/st.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/st.c
> index 997be91f0a13..7cedc348790d 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/lib/st.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/st.c
> @@ -175,6 +175,7 @@ int mlx5_st_dealloc_index(struct mlx5_core_dev *dev, u16 st_index)
>   
>   	if (refcount_dec_and_test(&idx_data->usecount)) {
>   		xa_erase(&st->idx_xa, st_index);
> +		kfree(idx_data);
>   		/* We leave PCI config space as was before, no mkey will refer to it */
>   	}
>   

Reviewed-by: Tariq Toukan <tariqt@nvidia.com>

Thanks.