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-rw-r--r--mm/sparse.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/mm/sparse.c b/mm/sparse.c
index 2609aba121e8..6b8b5e91ceef 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -264,7 +264,11 @@ unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
*/
static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
{
- return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
+ unsigned long coded_mem_map =
+ (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
+ BUILD_BUG_ON(SECTION_MAP_LAST_BIT > (1UL<<PFN_SECTION_SHIFT));
+ BUG_ON(coded_mem_map & ~SECTION_MAP_MASK);
+ return coded_mem_map;
}
/*