1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index e82fc1a52cd0..d6120fa69116 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -509,6 +509,10 @@ struct mem_section {
          * pages.  However, it is stored with some other magic.
          * (see sparse.c::sparse_init_one_section())
          *
+         * Additionally during early boot we encode node id of
+         * the location of the section here to guide allocation.
+         * (see sparse.c::memory_present())
+         *
          * Making it a UL at least makes someone do a cast
          * before using it wrong.
          */
@@ -548,6 +552,7 @@ extern int __section_nr(struct mem_section* ms);
 #define SECTION_HAS_MEM_MAP     (1UL<<1)
 #define SECTION_MAP_LAST_BIT    (1UL<<2)
 #define SECTION_MAP_MASK        (~(SECTION_MAP_LAST_BIT-1))
+#define SECTION_NID_SHIFT       2
 
 static inline struct page *__section_mem_map_addr(struct mem_section *section)
 {