1 files changed, 48 insertions, 4 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 3efa7253523e..95264c0ef308 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -608,6 +608,9 @@ struct pagemapread {
         u64 *buffer;
 };
 
+#define PAGEMAP_WALK_SIZE       (PMD_SIZE)
+#define PAGEMAP_WALK_MASK       (PMD_MASK)
+
 #define PM_ENTRY_BYTES      sizeof(u64)
 #define PM_STATUS_BITS      3
 #define PM_STATUS_OFFSET    (64 - PM_STATUS_BITS)
@@ -666,6 +669,27 @@ static u64 pte_to_pagemap_entry(pte_t pte)
         return pme;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static u64 thp_pmd_to_pagemap_entry(pmd_t pmd, int offset)
+{
+        u64 pme = 0;
+        /*
+         * Currently pmd for thp is always present because thp can not be
+         * swapped-out, migrated, or HWPOISONed (split in such cases instead.)
+         * This if-check is just to prepare for future implementation.
+         */
+        if (pmd_present(pmd))
+                pme = PM_PFRAME(pmd_pfn(pmd) + offset)
+                        | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
+        return pme;
+}
+#else
+static inline u64 thp_pmd_to_pagemap_entry(pmd_t pmd, int offset)
+{
+        return 0;
+}
+#endif
+
 static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
                              struct mm_walk *walk)
 {
@@ -673,15 +697,37 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
         struct pagemapread *pm = walk->private;
         pte_t *pte;
         int err = 0;
+        u64 pfn = PM_NOT_PRESENT;
 
-        split_huge_page_pmd(walk->mm, pmd);
         if (pmd_trans_unstable(pmd))
                 return 0;
 
         /* find the first VMA at or above 'addr' */
         vma = find_vma(walk->mm, addr);
+        spin_lock(&walk->mm->page_table_lock);
+        if (pmd_trans_huge(*pmd)) {
+                if (pmd_trans_splitting(*pmd)) {
+                        spin_unlock(&walk->mm->page_table_lock);
+                        wait_split_huge_page(vma->anon_vma, pmd);
+                } else {
+                        for (; addr != end; addr += PAGE_SIZE) {
+                                unsigned long offset;
+
+                                offset = (addr & ~PAGEMAP_WALK_MASK) >>
+                                                PAGE_SHIFT;
+                                pfn = thp_pmd_to_pagemap_entry(*pmd, offset);
+                                err = add_to_pagemap(addr, pfn, pm);
+                                if (err)
+                                        break;
+                        }
+                        spin_unlock(&walk->mm->page_table_lock);
+                        return err;
+                }
+        } else {
+                spin_unlock(&walk->mm->page_table_lock);
+        }
+
         for (; addr != end; addr += PAGE_SIZE) {
-                u64 pfn = PM_NOT_PRESENT;
 
                 /* check to see if we've left 'vma' behind
                  * and need a new, higher one */
@@ -764,8 +810,6 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
  * determine which areas of memory are actually mapped and llseek to
  * skip over unmapped regions.
  */
-#define PAGEMAP_WALK_SIZE       (PMD_SIZE)
-#define PAGEMAP_WALK_MASK       (PMD_MASK)
 static ssize_t pagemap_read(struct file *file, char __user *buf,
                             size_t count, loff_t *ppos)
 {