1 files changed, 30 insertions, 9 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index f0df3109343d..ab8ccc9d14ff 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -553,24 +553,45 @@ static u64 swap_pte_to_pagemap_entry(pte_t pte)
         return swp_type(e) | (swp_offset(e) << MAX_SWAPFILES_SHIFT);
 }
 
+static unsigned long pte_to_pagemap_entry(pte_t pte)
+{
+        unsigned long pme = 0;
+        if (is_swap_pte(pte))
+                pme = PM_PFRAME(swap_pte_to_pagemap_entry(pte))
+                        | PM_PSHIFT(PAGE_SHIFT) | PM_SWAP;
+        else if (pte_present(pte))
+                pme = PM_PFRAME(pte_pfn(pte))
+                        | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
+        return pme;
+}
+
 static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
                              struct mm_walk *walk)
 {
+        struct vm_area_struct *vma;
         struct pagemapread *pm = walk->private;
         pte_t *pte;
         int err = 0;
 
+        /* find the first VMA at or above 'addr' */
+        vma = find_vma(walk->mm, addr);
         for (; addr != end; addr += PAGE_SIZE) {
                 u64 pfn = PM_NOT_PRESENT;
-                pte = pte_offset_map(pmd, addr);
-                if (is_swap_pte(*pte))
-                        pfn = PM_PFRAME(swap_pte_to_pagemap_entry(*pte))
-                                | PM_PSHIFT(PAGE_SHIFT) | PM_SWAP;
-                else if (pte_present(*pte))
-                        pfn = PM_PFRAME(pte_pfn(*pte))
-                                | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
-                /* unmap so we're not in atomic when we copy to userspace */
-                pte_unmap(pte);
+
+                /* check to see if we've left 'vma' behind
+                 * and need a new, higher one */
+                if (vma && (addr >= vma->vm_end))
+                        vma = find_vma(walk->mm, addr);
+
+                /* check that 'vma' actually covers this address,
+                 * and that it isn't a huge page vma */
+                if (vma && (vma->vm_start <= addr) &&
+                    !is_vm_hugetlb_page(vma)) {
+                        pte = pte_offset_map(pmd, addr);
+                        pfn = pte_to_pagemap_entry(*pte);
+                        /* unmap before userspace copy */
+                        pte_unmap(pte);
+                }
                 err = add_to_pagemap(addr, pfn, pm);
                 if (err)
                         return err;