diff --git a/mm/percpu.c b/mm/percpu.c
index 7e06a1e58720..806bc16f88eb 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1328,7 +1328,7 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
 
 	/* allocate chunk */
 	alloc_size = sizeof(struct pcpu_chunk) +
-		BITS_TO_LONGS(region_size >> PAGE_SHIFT);
+		BITS_TO_LONGS(region_size >> PAGE_SHIFT) * sizeof(unsigned long);
 	chunk = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
 	if (!chunk)
 		panic("%s: Failed to allocate %zu bytes\n", __func__,