diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
index adc208c2ae9c0f6c99e0f28c32a668ae0db72441..decccffb03cac60abe6e5628e2d0f3a47cc7d099 100644
--- a/arch/arm64/mm/mmap.c
+++ b/arch/arm64/mm/mmap.c
@@ -35,7 +35,7 @@
  * Leave enough space between the mmap area and the stack to honour ulimit in
  * the face of randomisation.
  */
-#define MIN_GAP (SZ_128M + ((STACK_RND_MASK << PAGE_SHIFT) + 1))
+#define MIN_GAP (SZ_128M)
 #define MAX_GAP	(STACK_TOP/6*5)
 
 static int mmap_is_legacy(void)
@@ -65,6 +65,11 @@ unsigned long arch_mmap_rnd(void)
 static unsigned long mmap_base(unsigned long rnd)
 {
 	unsigned long gap = rlimit(RLIMIT_STACK);
+	unsigned long pad = (STACK_RND_MASK << PAGE_SHIFT) + stack_guard_gap;
+
+	/* Values close to RLIM_INFINITY can overflow. */
+	if (gap + pad > gap)
+		gap += pad;
 
 	if (gap < MIN_GAP)
 		gap = MIN_GAP;