[PATCH] mm/sparse: guard the size of mem_section is power of 2

[Wei Yang <richard.weiyang@gmail.com>]

We usually have this check, while commit 2a3cb8baef71 ("mm/sparse:
delete old sparse_init and enable new one") missed to take it.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
CC: Pavel Tatashin <pasha.tatashin@oracle.com>
---
 mm/sparse.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/sparse.c b/mm/sparse.c
index aed0951b87fa..a7d92fe7be19 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -560,6 +560,8 @@ void __init sparse_init(void)
 	unsigned long pnum_end, pnum_begin, map_count = 1;
 	int nid_begin;
 
+	/* see include/linux/mmzone.h 'struct mem_section' definition */
+	BUILD_BUG_ON(!is_power_of_2(sizeof(struct mem_section)));
 	memblocks_present();
 
 	pnum_begin = first_present_section_nr();
-- 
2.34.1