"Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> writes:
> This patch uses modifed pmdp_invalidate(), that return previous value of pmd,
> to transfer dirty and accessed bits.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> ---
> fs/proc/task_mmu.c | 8 ++++----
> mm/huge_memory.c | 29 ++++++++++++-----------------
> 2 files changed, 16 insertions(+), 21 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index f0c8b33d99b1..f2fc1ef5bba2 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
.....
> @@ -1965,7 +1955,6 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
> page_ref_add(page, HPAGE_PMD_NR - 1);
> write = pmd_write(*pmd);
> young = pmd_young(*pmd);
> - dirty = pmd_dirty(*pmd);
> soft_dirty = pmd_soft_dirty(*pmd);
>
> pmdp_huge_split_prepare(vma, haddr, pmd);
> @@ -1995,8 +1984,6 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
> if (soft_dirty)
> entry = pte_mksoft_dirty(entry);
> }
> - if (dirty)
> - SetPageDirty(page + i);
> pte = pte_offset_map(&_pmd, addr);
> BUG_ON(!pte_none(*pte));
> set_pte_at(mm, addr, pte, entry);
> @@ -2045,7 +2032,15 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
> * and finally we write the non-huge version of the pmd entry with
> * pmd_populate.
> */
> - pmdp_invalidate(vma, haddr, pmd);
> + old = pmdp_invalidate(vma, haddr, pmd);
> +
> + /*
> + * Transfer dirty bit using value returned by pmd_invalidate() to be
> + * sure we don't race with CPU that can set the bit under us.
> + */
> + if (pmd_dirty(old))
> + SetPageDirty(page);
> +
> pmd_populate(mm, pmd, pgtable);
>
> if (freeze) {
Can we invalidate the pmd early here ? ie, do pmdp_invalidate instead of
pmdp_huge_split_prepare() ?
-aneesh
