[PATCH 1/2] mm/memory_hotplug: introduce default dummy memory_add_physaddr_to_nid()

[Jia He <justin.he@arm.com>]

This is to introduce a general dummy helper. memory_add_physaddr_to_nid()
is a fallback option to get the nid in case NUMA_NO_NID is detected.

After this patch, arm64/sh/s390 can simply use the general dummy version.
PowerPC/x86/ia64 will still use their specific version.

This is the preparation to set a fallback value for dev_dax->target_node.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Jia He <justin.he@arm.com>
---
 arch/arm64/mm/numa.c | 10 ----------
 arch/ia64/mm/numa.c  |  2 --
 arch/sh/mm/init.c    |  9 ---------
 arch/x86/mm/numa.c   |  1 -
 mm/memory_hotplug.c  | 10 ++++++++++
 5 files changed, 10 insertions(+), 22 deletions(-)

diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
index aafcee3e3f7e..73f8b49d485c 100644
--- a/arch/arm64/mm/numa.c
+++ b/arch/arm64/mm/numa.c
@@ -461,13 +461,3 @@ void __init arm64_numa_init(void)
 
 	numa_init(dummy_numa_init);
 }
-
-/*
- * We hope that we will be hotplugging memory on nodes we already know about,
- * such that acpi_get_node() succeeds and we never fall back to this...
- */
-int memory_add_physaddr_to_nid(u64 addr)
-{
-	pr_warn("Unknown node for memory at 0x%llx, assuming node 0\n", addr);
-	return 0;
-}
diff --git a/arch/ia64/mm/numa.c b/arch/ia64/mm/numa.c
index 5e1015eb6d0d..f34964271101 100644
--- a/arch/ia64/mm/numa.c
+++ b/arch/ia64/mm/numa.c
@@ -106,7 +106,5 @@ int memory_add_physaddr_to_nid(u64 addr)
 		return 0;
 	return nid;
 }
-
-EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
 #endif
 #endif
diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
index a70ba0fdd0b3..f75932ba87a6 100644
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -430,15 +430,6 @@ int arch_add_memory(int nid, u64 start, u64 size,
 	return ret;
 }
 
-#ifdef CONFIG_NUMA
-int memory_add_physaddr_to_nid(u64 addr)
-{
-	/* Node 0 for now.. */
-	return 0;
-}
-EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
-#endif
-
 void arch_remove_memory(int nid, u64 start, u64 size,
 			struct vmem_altmap *altmap)
 {
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 8ee952038c80..2a6e62af4636 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -929,5 +929,4 @@ int memory_add_physaddr_to_nid(u64 start)
 		nid = numa_meminfo.blk[0].nid;
 	return nid;
 }
-EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
 #endif
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index da374cd3d45b..b49ab743d914 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -350,6 +350,16 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
 	return err;
 }
 
+#ifdef CONFIG_NUMA
+int __weak memory_add_physaddr_to_nid(u64 start)
+{
+	pr_info_once("Unknown target node for memory at 0x%llx, assuming node 0\n",
+			start);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
+#endif
+
 /* find the smallest valid pfn in the range [start_pfn, end_pfn) */
 static unsigned long find_smallest_section_pfn(int nid, struct zone *zone,
 				     unsigned long start_pfn,
-- 
2.17.1