Re: [PATCH 04/11] dma-contiguous: pass the NUMA node to dma_alloc_contiguous()

[Paolo Abeni <pabeni@redhat.com>]

On 11/6/26 19:44, Jakub Kicinski wrote:
> --- a/kernel/dma/mapping.c
> +++ b/kernel/dma/mapping.c
> @@ -642,6 +642,13 @@ EXPORT_SYMBOL_GPL(dma_get_required_mask);
>    * Same as dma_alloc_attrs() but places the memory on @node rather than on the
>    * node of @dev. Like with kmalloc_node() the node is only a preference,
>    * the page allocator may fall back to other nodes if @node is out of memory.
> + * The contiguous memory allocator (CMA) does not: only the CMA area of @node
> + * and the global CMA area are tried. The allocation may fail even though the
> + * CMA area of another node, e.g. that of @dev, still has free space.
> + *
> + * Allocations served from per-device or global coherent pools, per-device CMA
> + * areas, restricted or atomic pools, arch_dma_alloc() or dma_map_ops
> + * implementations do not take @node into account.
I'm possibly over-thinking here, but AFAICS there are a bunch of dma_map_ops that
are using dev_to_node():

dma_iommu_alloc_coherent() in arch/powerpc/kernel/dma-iommu.c
vio_dma_iommu_alloc_coherent() in arch/powerpc/platforms/pseries/vio.c
gart_alloc_coherent() in arch/x86/kernel/amd_gart_64.c

With this series they will stop using the driver provided numa node.
Probably not a blocker but possibly worth to call out?

/P