Re: [PATCH v11 1/3] mm: Add support to retrieve physical address range of memory from the node ID

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Tue, 12 Aug 2025 15:26:13 +0100
<shiju.jose@huawei.com> wrote:

> From: Shiju Jose <shiju.jose@huawei.com>
> 
> In the numa_memblks, a lookup facility is required to retrieve the
> physical address range of memory in a NUMA node. ACPI RAS2 memory
> features are among the use cases.
> 
> Suggested-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> Signed-off-by: Shiju Jose <shiju.jose@huawei.com>

Looks fine to me.  Mike, what do you think?

One passing comment inline.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

> ---
>  include/linux/numa.h         |  9 +++++++++
>  include/linux/numa_memblks.h |  2 ++
>  mm/numa.c                    | 10 ++++++++++
>  mm/numa_memblks.c            | 37 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 58 insertions(+)
> 
> diff --git a/include/linux/numa.h b/include/linux/numa.h
> index e6baaf6051bc..1d1aabebd26b 100644
> --- a/include/linux/numa.h
> +++ b/include/linux/numa.h
> @@ -41,6 +41,10 @@ int memory_add_physaddr_to_nid(u64 start);
>  int phys_to_target_node(u64 start);
>  #endif
>  
> +#ifndef nid_get_mem_physaddr_range
> +int nid_get_mem_physaddr_range(int nid, u64 *start, u64 *end);
> +#endif
> +
>  int numa_fill_memblks(u64 start, u64 end);
>  
>  #else /* !CONFIG_NUMA */
> @@ -63,6 +67,11 @@ static inline int phys_to_target_node(u64 start)
>  	return 0;
>  }
>  
> +static inline int nid_get_mem_physaddr_range(int nid, u64 *start, u64 *end)
> +{
> +	return 0;
> +}
> +
>  static inline void alloc_offline_node_data(int nid) {}
>  #endif
>  
> diff --git a/include/linux/numa_memblks.h b/include/linux/numa_memblks.h
> index 991076cba7c5..7b32d96d0134 100644
> --- a/include/linux/numa_memblks.h
> +++ b/include/linux/numa_memblks.h
> @@ -55,6 +55,8 @@ extern int phys_to_target_node(u64 start);
>  #define phys_to_target_node phys_to_target_node
>  extern int memory_add_physaddr_to_nid(u64 start);
>  #define memory_add_physaddr_to_nid memory_add_physaddr_to_nid
> +extern int nid_get_mem_physaddr_range(int nid, u64 *start, u64 *end);
> +#define nid_get_mem_physaddr_range nid_get_mem_physaddr_range
>  #endif /* CONFIG_NUMA_KEEP_MEMINFO */
>  
>  #endif /* CONFIG_NUMA_MEMBLKS */
> diff --git a/mm/numa.c b/mm/numa.c
> index 7d5e06fe5bd4..5335af1fefee 100644
> --- a/mm/numa.c
> +++ b/mm/numa.c
> @@ -59,3 +59,13 @@ int phys_to_target_node(u64 start)
>  }
>  EXPORT_SYMBOL_GPL(phys_to_target_node);
>  #endif
> +
> +#ifndef nid_get_mem_physaddr_range
> +int nid_get_mem_physaddr_range(int nid, u64 *start, u64 *end)
> +{
> +	pr_info_once("Unknown target phys addr range for node=%d\n", nid);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(nid_get_mem_physaddr_range);
> +#endif
> diff --git a/mm/numa_memblks.c b/mm/numa_memblks.c
> index 541a99c4071a..e1e56b7a3499 100644
> --- a/mm/numa_memblks.c
> +++ b/mm/numa_memblks.c
> @@ -590,4 +590,41 @@ int memory_add_physaddr_to_nid(u64 start)
>  }
>  EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
>  
> +/**
> + * nid_get_mem_physaddr_range - Get the physical address range
> + *				of the memblk in the NUMA node.
> + * @nid: NUMA node ID of the memblk
> + * @start: Start address of the memblk
> + * @end: End address of the memblk
> + *
> + * Find the lowest contiguous physical memory address range of the memblk
> + * in the NUMA node with the given nid and return the start and end
> + * addresses.
> + *
> + * RETURNS:
> + * 0 on success, -errno on failure.
> + */
> +int nid_get_mem_physaddr_range(int nid, u64 *start, u64 *end)
> +{
> +	struct numa_meminfo *mi = &numa_meminfo;
> +	int i;
> +
> +	if (!numa_valid_node(nid))
> +		return -EINVAL;
> +
> +	for (i = 0; i < mi->nr_blks; i++) {
> +		if (mi->blk[i].nid == nid) {
> +			*start = mi->blk[i].start;
> +			/*
> +			 * Assumption: mi->blk[i].end is the last address
> +			 * in the range + 1.

This was my fault for asking on internal review if this was documented
anywhere. It's kind of implicitly obvious when reading numa_memblk.c
because there are a bunch of end - 1 prints.
So can probably drop this comment.

> +			 */
> +			*end = mi->blk[i].end;
> +			return 0;
> +		}
> +	}
> +
> +	return -ENODEV;
> +}
> +EXPORT_SYMBOL_GPL(nid_get_mem_physaddr_range);
>  #endif /* CONFIG_NUMA_KEEP_MEMINFO */