Re: [PATCH 00/11] dma-mapping: add dma_alloc_attrs_node() and dma_alloc_coherent_node()

[Robin Murphy <robin.murphy@arm.com>]

On 2026-11-06 6:44 pm, Jakub Kicinski wrote:
> Hi!
> 
> On NUMA systems networking drivers want to allocate rings
> and buffers close to the NAPI-handling core rather than
> allocating all from where the device is connected.
> 
> Looks like we have accumulated 6 drivers which do:
> 
>         set_dev_node(dma_dev, numa_node);
>         va = dma_alloc_coherent(...);
>         set_dev_node(dma_dev, old_node);
> 
> Introduce dma_alloc_coherent_node() so that such racy
> hacks are no longer necessary.
> 
> Note that making dma_map_ops->alloc() callbacks explicit-node-aware
> is left for future work.
> 
> Stable tag on top of v7.4-rc1, so that we can also pull this into
> the networking tree:
> 
>    git://git.kernel.org/pub/scm/linux/kernel/git/kuba/linux.git tags/dma_alloc_coherent_node
> 
> v1:
>   - add the API first, then wire up the node in dma-direct, iommu-dma
>     and CMA (Robin)
>   - add dma_direct_alloc_node() and keep dma_direct_alloc() as a wrapper,
>     swiotlb-xen uses it as its ->alloc (fixes the build on arm/arm64),
>     arch/x86 no longer needs changes
>   - docs: drop the NUMA_NO_NODE suggestion from dma-api.rst (Björn)
>   - docs: document that CMA does not fall back to other nodes' areas (Björn)
>   - docs: document which allocations ignore the node
>   - explain the separate GPL-only export in the commit message (Marek)
> rfc: https://lore.kernel.org/20261027022528.633359-1-kuba@kernel.org
> 
> Jakub Kicinski (11):
>    dma-mapping: add dma_alloc_attrs_node() and dma_alloc_coherent_node()
>    dma-direct: add dma_direct_alloc_node()
>    iommu/dma: pass the NUMA node to iommu_dma_alloc()
>    dma-contiguous: pass the NUMA node to dma_alloc_contiguous()

The API side of things looks OK to me. For the DMA patches at least,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

>    eth: libwx: restore the device's NUMA node after ring allocation
>    eth: libwx: use dma_alloc_coherent_node()
>    eth: ixgbe: use dma_alloc_coherent_node()
>    eth: xgbe: use dma_alloc_coherent_node()
>    eth: fungible: use dma_alloc_coherent_node()
>    eth: mlx5: use dma_alloc_coherent_node()
>    eth: mlx4: use dma_alloc_coherent_node()
> 
>   Documentation/core-api/dma-api.rst            | 17 ++++++++
>   include/linux/dma-direct.h                    | 11 ++++-
>   include/linux/dma-map-ops.h                   |  5 ++-
>   include/linux/dma-mapping.h                   | 14 +++++++
>   include/linux/iommu-dma.h                     |  2 +-
>   include/linux/mlx4/device.h                   |  2 +-
>   include/linux/mlx5/driver.h                   |  2 -
>   drivers/iommu/dma-iommu.c                     | 30 ++++++++------
>   drivers/net/ethernet/amd/xgbe/xgbe-desc.c     |  6 +--
>   .../net/ethernet/fungible/funcore/fun_queue.c |  8 ++--
>   drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 20 +++-------
>   drivers/net/ethernet/mellanox/mlx4/alloc.c    | 12 +++---
>   drivers/net/ethernet/mellanox/mlx4/en_cq.c    |  9 +----
>   .../net/ethernet/mellanox/mlx4/en_netdev.c    |  2 +-
>   drivers/net/ethernet/mellanox/mlx4/en_rx.c    |  5 +--
>   drivers/net/ethernet/mellanox/mlx4/en_tx.c    |  5 +--
>   .../net/ethernet/mellanox/mlx5/core/alloc.c   | 24 ++---------
>   .../net/ethernet/mellanox/mlx5/core/main.c    |  4 --
>   drivers/net/ethernet/wangxun/libwx/wx_lib.c   | 22 ++++------
>   kernel/dma/contiguous.c                       | 12 +++---
>   kernel/dma/direct.c                           | 22 +++++-----
>   kernel/dma/mapping.c                          | 40 +++++++++++++++++--
>   kernel/dma/ops_helpers.c                      |  5 ++-
>   23 files changed, 152 insertions(+), 127 deletions(-)
>