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-rw-r--r--include/linux/mmzone.h1
-rw-r--r--mm/sparse.c25
2 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 7519eb4191e7..4674145bb63d 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -509,6 +509,7 @@ static inline struct mem_section *__nr_to_section(unsigned long nr)
return NULL;
return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
}
+extern int __section_nr(struct mem_section* ms);
/*
* We use the lower bits of the mem_map pointer to store
diff --git a/mm/sparse.c b/mm/sparse.c
index 347249a4917a..0d3bd4bf3aaa 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -72,6 +72,31 @@ static inline int sparse_index_init(unsigned long section_nr, int nid)
}
#endif
+/*
+ * Although written for the SPARSEMEM_EXTREME case, this happens
+ * to also work for the flat array case becase
+ * NR_SECTION_ROOTS==NR_MEM_SECTIONS.
+ */
+int __section_nr(struct mem_section* ms)
+{
+ unsigned long root_nr;
+ struct mem_section* root;
+
+ for (root_nr = 0;
+ root_nr < NR_MEM_SECTIONS;
+ root_nr += SECTIONS_PER_ROOT) {
+ root = __nr_to_section(root_nr);
+
+ if (!root)
+ continue;
+
+ if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
+ break;
+ }
+
+ return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
+}
+
/* Record a memory area against a node. */
void memory_present(int nid, unsigned long start, unsigned long end)
{
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