The patch titled
Subject: mm: softdirty: addresses before VMAs in PTE holes aren't softdirty
has been added to the -mm tree. Its filename is
mm-softdirty-addresses-before-vmas-in-pte-holes-arent-softdirty.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-softdirty-addresses-before-vmas-in-pte-holes-arent-softdirty.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-softdirty-addresses-before-vmas-in-pte-holes-arent-softdirty.patch
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------------------------------------------------------
From: Peter Feiner <pfeiner@xxxxxxxxxx>
Subject: 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 68b5a652485682f67eacdee3deae640fb7845b63. The
aforementioned patch made /proc/pid/pagemap look at VM_SOFTDIRTY in PTE
holes but neglected to observe the start of VMAs returned by find_vma.
Tested:
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: Peter Feiner <pfeiner@xxxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
Cc: Jamie Liu <jamieliu@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)
diff -puN fs/proc/task_mmu.c~mm-softdirty-addresses-before-vmas-in-pte-holes-arent-softdirty fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~mm-softdirty-addresses-before-vmas-in-pte-holes-arent-softdirty
+++ a/fs/proc/task_mmu.c
@@ -931,23 +931,32 @@ static int pagemap_pte_hole(unsigned lon
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);
+ else
+ 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)
+ break;
+
+ /* 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;
}
}
-
out:
return err;
}
_
Patches currently in -mm which might be from pfeiner@xxxxxxxxxx are
mm-softdirty-addresses-before-vmas-in-pte-holes-arent-softdirty.patch
mm-softdirty-enable-write-notifications-on-vmas-after-vm_softdirty-cleared.patch
mm-softdirty-unmapped-addresses-between-vmas-are-clean.patch
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