1 files changed, 30 insertions, 9 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index f0df3109343..ab8ccc9d14f 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;