1 files changed, 30 insertions, 0 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 5f902e20e8c0..04eb489a6805 100644
--- a/mm/huge_memory.c
+++ b/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;
 }