---

yaml
---
r: 138495
b: refs/heads/master
c: a5adc91
h: refs/heads/master
i:
  138493: 02313e7
  138491: 3e90603
  138487: 4d12764
  138479: 761cdf7
  138463: a5c8210
  138431: c3df475
  138367: b6cfeed
  138239: d81b119
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 912f9ee21c836081e3c96dfe61025841ebeb95da
+refs/heads/master: a5adc91a4b44b5d1706b9d906cc14fe4f312afe9

trunk/arch/powerpc/mm/mmap.c

@@ -46,18 +46,26 @@ static inline int mmap_is_legacy(void)
 	return sysctl_legacy_va_layout;
 }
 
+/*
+ * Since get_random_int() returns the same value within a 1 jiffy window,
+ * we will almost always get the same randomisation for the stack and mmap
+ * region. This will mean the relative distance between stack and mmap will
+ * be the same.
+ *
+ * To avoid this we can shift the randomness by 1 bit.
+ */
 static unsigned long mmap_rnd(void)
 {
 	unsigned long rnd = 0;
 
 	if (current->flags & PF_RANDOMIZE) {
 		/* 8MB for 32bit, 1GB for 64bit */
 		if (is_32bit_task())
-			rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT)));
+			rnd = (long)(get_random_int() % (1<<(22-PAGE_SHIFT)));
 		else
-			rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT)));
+			rnd = (long)(get_random_int() % (1<<(29-PAGE_SHIFT)));
 	}
-	return rnd << PAGE_SHIFT;
+	return (rnd << PAGE_SHIFT) * 2;
 }
 
 static inline unsigned long mmap_base(void)