Commit 87e6d49a authored by Peter Feiner's avatar Peter Feiner Committed by Linus Torvalds
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mm: softdirty: addresses before VMAs in PTE holes aren't softdirty

In PTE holes that contain VM_SOFTDIRTY VMAs, unmapped addresses before
VM_SOFTDIRTY VMAs are reported as softdirty by /proc/pid/pagemap.  This
bug was introduced in commit 68b5a652

 ("mm: softdirty: respect
VM_SOFTDIRTY in PTE holes").  That commit made /proc/pid/pagemap look at
VM_SOFTDIRTY in PTE holes but neglected to observe the start of VMAs
returned by find_vma.

  Wrote a selftest that creates a PMD-sized VMA then unmaps the first
  page and asserts that the page is not softdirty. I'm going to send the
  pagemap selftest in a later commit.
Signed-off-by: default avatarPeter Feiner <>
Cc: Cyrill Gorcunov <>
Cc: Pavel Emelyanov <>
Cc: Hugh Dickins <>
Cc: Naoya Horiguchi <>
Cc: "Kirill A. Shutemov" <>
Cc: Jamie Liu <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 5760a97c
......@@ -931,23 +931,32 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end,
while (addr < end) {
struct vm_area_struct *vma = find_vma(walk->mm, addr);
pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
unsigned long vm_end;
/* End of address space hole, which we mark as non-present. */
unsigned long hole_end;
if (!vma) {
vm_end = end;
} else {
vm_end = min(end, vma->vm_end);
if (vma->vm_flags & VM_SOFTDIRTY)
pme.pme |= PM_STATUS2(pm->v2, __PM_SOFT_DIRTY);
if (vma)
hole_end = min(end, vma->vm_start);
hole_end = end;
for (; addr < hole_end; addr += PAGE_SIZE) {
err = add_to_pagemap(addr, &pme, pm);
if (err)
goto out;
for (; addr < vm_end; addr += PAGE_SIZE) {
if (!vma)
/* Addresses in the VMA. */
if (vma->vm_flags & VM_SOFTDIRTY)
pme.pme |= PM_STATUS2(pm->v2, __PM_SOFT_DIRTY);
for (; addr < min(end, vma->vm_end); addr += PAGE_SIZE) {
err = add_to_pagemap(addr, &pme, pm);
if (err)
goto out;
return err;
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