diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 63bf77dee987..35f774ed2d99 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -1111,9 +1111,6 @@ static int dmirror_migrate_to_system(struct dmirror *dmirror,
 	unsigned long *src_pfns;
 	unsigned long *dst_pfns;
 
-	src_pfns = kvcalloc(PTRS_PER_PTE, sizeof(*src_pfns), GFP_KERNEL | __GFP_NOFAIL);
-	dst_pfns = kvcalloc(PTRS_PER_PTE, sizeof(*dst_pfns), GFP_KERNEL | __GFP_NOFAIL);
-
 	start = cmd->addr;
 	end = start + size;
 	if (end < start)
@@ -1123,6 +1120,9 @@ static int dmirror_migrate_to_system(struct dmirror *dmirror,
 	if (!mmget_not_zero(mm))
 		return -EINVAL;
 
+	src_pfns = kvcalloc(PTRS_PER_PTE, sizeof(*src_pfns), GFP_KERNEL | __GFP_NOFAIL);
+	dst_pfns = kvcalloc(PTRS_PER_PTE, sizeof(*dst_pfns), GFP_KERNEL | __GFP_NOFAIL);
+
 	cmd->cpages = 0;
 	mmap_read_lock(mm);
 	for (addr = start; addr < end; addr = next) {