-----Original Message-----
From: Mike Rapoport <rppt@kernel.org>
Sent: 05 August 2025 11:20
To: Shiju Jose <redacted>
Cc: rafael@kernel.org; bp@alien8.de; akpm@linux-foundation.org;
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Subject: Re: [PATCH v10 1/3] mm: Add node_to_range lookup facility to
numa_memblks

On Fri, Aug 01, 2025 at 06:20:27PM +0100, shiju.jose@huawei.com wrote:

quoted

From: Shiju Jose <redacted>

Lookup facility to retrieve memory phys lowest continuous range for a
NUMA node is required in the numa_memblks for the ACPI RAS2 memory
scrub use case.

If the code that needs to find the lowest contiguous range in a node runs before
we discard .init you can just use

unsigned long pfn = node_start_pfn(nid);
unsigned long start_pfn, end_pfn;

memblock_search_pfn_nid(pfn, &start_pfn, &end_pfn);

Thanks Mike for your suggestion and help.
 
With node_start_pfn(nid) and memblock_search_pfn_nid(), the 'end_pfn' return 
different value than the actual.

Found similar function get_pfn_range_for_nid(nid, &start_pfn, &end_pfn), seems more
suitable as it takes 'nid' directly and both 'start_pfn' and 'end_pfn 'return correct values. 

Thanks,
Shiju

quoted

Suggested-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Shiju Jose <redacted>
---
 include/linux/numa.h         | 10 ++++++++++
 include/linux/numa_memblks.h |  2 ++
 mm/numa.c                    | 10 ++++++++++
 mm/numa_memblks.c            | 23 +++++++++++++++++++++++
 4 files changed, 45 insertions(+)

diff --git a/include/linux/numa.h b/include/linux/numa.h index

e6baaf6051bc..d41e583a902d 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 node_to_phys_lowest_continuous_range
+int node_to_phys_lowest_continuous_range(int nid, u64 *start, u64
+*end); #endif
+
 int numa_fill_memblks(u64 start, u64 end);

 #else /* !CONFIG_NUMA */

@@ -63,6 +67,12 @@ static inline int phys_to_target_node(u64 start)
 	return 0;
 }

+static inline int node_to_phys_lowest_continuous_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..ccc53029de8b 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 node_to_phys_lowest_continuous_range(int nid, u64 *start,
+u64 *end); #define node_to_phys_lowest_continuous_range
+node_to_phys_lowest_continuous_range
 #endif /* CONFIG_NUMA_KEEP_MEMINFO */

 #endif /* CONFIG_NUMA_MEMBLKS */

diff --git a/mm/numa.c b/mm/numa.c
index 7d5e06fe5bd4..0affb56ef4f2 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 node_to_phys_lowest_continuous_range
+int node_to_phys_lowest_continuous_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(node_to_phys_lowest_continuous_range);
+#endif

diff --git a/mm/numa_memblks.c b/mm/numa_memblks.c index

541a99c4071a..9cbaa38cb92d 100644

--- a/mm/numa_memblks.c
+++ b/mm/numa_memblks.c

@@ -590,4 +590,27 @@ int memory_add_physaddr_to_nid(u64 start)  }

EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);

+static int nid_to_meminfo(struct numa_meminfo *mi, int nid, u64
+*start, u64 *end) {
+	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;
+			*end = mi->blk[i].end;
+			return 0;
+		}
+	}
+
+	return -ENODEV;
+}
+
+int node_to_phys_lowest_continuous_range(int nid, u64 *start, u64
+*end) {
+	return nid_to_meminfo(&numa_meminfo, nid, start, end); }
+EXPORT_SYMBOL_GPL(node_to_phys_lowest_continuous_range);
 #endif /* CONFIG_NUMA_KEEP_MEMINFO */
--
2.43.0

--
Sincerely yours,
Mike.