---

yaml
---
r: 343299
b: refs/heads/master
c: 4a6c129
h: refs/heads/master
i:
  343297: 72527b4
  343295: 2603108
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3f7dfe24b84c0ad698c461fc9c4ba3544bbfcebf
+refs/heads/master: 4a6c1297268c917e9c50701906ba2f7e06812299

trunk/mm/huge_memory.c

@@ -47,6 +47,7 @@ static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
 /* during fragmentation poll the hugepage allocator once every minute */
 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
 static struct task_struct *khugepaged_thread __read_mostly;
+static unsigned long huge_zero_pfn __read_mostly;
 static DEFINE_MUTEX(khugepaged_mutex);
 static DEFINE_SPINLOCK(khugepaged_mm_lock);
 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
@@ -159,6 +160,29 @@ static int start_khugepaged(void)
 	return err;
 }
 
+static int __init init_huge_zero_page(void)
+{
+	struct page *hpage;
+
+	hpage = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
+			HPAGE_PMD_ORDER);
+	if (!hpage)
+		return -ENOMEM;
+
+	huge_zero_pfn = page_to_pfn(hpage);
+	return 0;
+}
+
+static inline bool is_huge_zero_pfn(unsigned long pfn)
+{
+	return pfn == huge_zero_pfn;
+}
+
+static inline bool is_huge_zero_pmd(pmd_t pmd)
+{
+	return is_huge_zero_pfn(pmd_pfn(pmd));
+}
+
 #ifdef CONFIG_SYSFS
 
 static ssize_t double_flag_show(struct kobject *kobj,
@@ -540,6 +564,10 @@ static int __init hugepage_init(void)
 	if (err)
 		return err;
 
+	err = init_huge_zero_page();
+	if (err)
+		goto out;
+
 	err = khugepaged_slab_init();
 	if (err)
 		goto out;
@@ -562,6 +590,8 @@ static int __init hugepage_init(void)
 
 	return 0;
 out:
+	if (huge_zero_pfn)
+		__free_page(pfn_to_page(huge_zero_pfn));
 	hugepage_exit_sysfs(hugepage_kobj);
 	return err;
 }