On Fri, 18 Sep 2015 11:53:01 +0300
Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote:
> On Fri, Sep 18, 2015 at 10:20:01AM +0200, Martin Schwidefsky wrote:
> > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> > index e2d46ad..b029d42 100644
> > --- a/fs/proc/task_mmu.c
> > +++ b/fs/proc/task_mmu.c
> > @@ -754,7 +754,7 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma,
> >
> > if (pte_present(ptent)) {
> > ptent = pte_wrprotect(ptent);
> > - ptent = pte_clear_flags(ptent, _PAGE_SOFT_DIRTY);
> > + ptent = pte_clear_soft_dirty(ptent);
> > } else if (is_swap_pte(ptent)) {
> > ptent = pte_swp_clear_soft_dirty(ptent);
> > }
> > @@ -768,7 +768,7 @@ static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma,
> > pmd_t pmd = *pmdp;
> >
> > pmd = pmd_wrprotect(pmd);
> > - pmd = pmd_clear_flags(pmd, _PAGE_SOFT_DIRTY);
> > + pmd = pmd_clear_soft_dirty(pmd);
> >
>
> You know, these are only two lines where we use _PAGE_SOFT_DIRTY
> directly, so I don't see much point in adding 22 lines of code
> for that. Maybe we can leave it as is?
Only x86 has pte_clear_flags. And the two lines require that there is exactly
one bit in the PTE for soft-dirty. An alternative encoding will not be allowed.
And the current set of primitives is asymmetric, there are functions to query
and set the bit pte_soft_dirty and pte_mksoft_dirty but no function to clear
the bit.
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
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