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-rw-r--r--mm/sparse.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/mm/sparse.c b/mm/sparse.c
index b3c82ba..158d6a2 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -24,6 +24,25 @@ struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
#endif
EXPORT_SYMBOL(mem_section);
+#ifdef NODE_NOT_IN_PAGE_FLAGS
+/*
+ * If we did not store the node number in the page then we have to
+ * do a lookup in the section_to_node_table in order to find which
+ * node the page belongs to.
+ */
+#if MAX_NUMNODES <= 256
+static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
+#else
+static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
+#endif
+
+unsigned long page_to_nid(struct page *page)
+{
+ return section_to_node_table[page_to_section(page)];
+}
+EXPORT_SYMBOL(page_to_nid);
+#endif
+
#ifdef CONFIG_SPARSEMEM_EXTREME
static struct mem_section *sparse_index_alloc(int nid)
{
@@ -49,6 +68,10 @@ static int sparse_index_init(unsigned long section_nr, int nid)
struct mem_section *section;
int ret = 0;
+#ifdef NODE_NOT_IN_PAGE_FLAGS
+ section_to_node_table[section_nr] = nid;
+#endif
+
if (mem_section[root])
return -EEXIST;
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