| Message ID | 8352032008c7d9f1eee8d39599888a4cbe570bf7.1444995096.git.ldufour@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Fri, 2015-10-16 at 14:07 +0200, Laurent Dufour wrote: > As mentioned in the commit 56eecdb912b5 ("mm: Use > ptep/pmdp_set_numa() > for updating _PAGE_NUMA bit"), architecture like ppc64 doesn't do > tlb flush in set_pte/pmd functions. > > So when dealing with existing pte in clear_soft_dirty, the pte must > be cleared before being modified. Note that this is true of more than powerpc afaik. There's is a general rule that we don't "restrict" a PTE access permissions without first clearing it, due to various races. > Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> > CC: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> > --- > fs/proc/task_mmu.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index e2d46adb54b4..c9454ee39b28 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -753,19 +753,20 @@ static inline void clear_soft_dirty(struct > vm_area_struct *vma, > pte_t ptent = *pte; > > if (pte_present(ptent)) { > + ptent = ptep_modify_prot_start(vma->vm_mm, addr, > pte); > ptent = pte_wrprotect(ptent); > ptent = pte_clear_flags(ptent, _PAGE_SOFT_DIRTY); > + ptep_modify_prot_commit(vma->vm_mm, addr, pte, > ptent); > } else if (is_swap_pte(ptent)) { > ptent = pte_swp_clear_soft_dirty(ptent); > + set_pte_at(vma->vm_mm, addr, pte, ptent); > } > - > - set_pte_at(vma->vm_mm, addr, pte, ptent); > } > > static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma, > unsigned long addr, pmd_t *pmdp) > { > - pmd_t pmd = *pmdp; > + pmd_t pmd = pmdp_huge_get_and_clear(vma->vm_mm, addr, pmdp); > > pmd = pmd_wrprotect(pmd); > pmd = pmd_clear_flags(pmd, _PAGE_SOFT_DIRTY);
Laurent Dufour <ldufour@linux.vnet.ibm.com> writes: > As mentioned in the commit 56eecdb912b5 ("mm: Use ptep/pmdp_set_numa() > for updating _PAGE_NUMA bit"), architecture like ppc64 doesn't do > tlb flush in set_pte/pmd functions. > > So when dealing with existing pte in clear_soft_dirty, the pte must > be cleared before being modified. > > Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> > CC: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> > --- > fs/proc/task_mmu.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index e2d46adb54b4..c9454ee39b28 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -753,19 +753,20 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma, > pte_t ptent = *pte; > > if (pte_present(ptent)) { > + ptent = ptep_modify_prot_start(vma->vm_mm, addr, pte); > ptent = pte_wrprotect(ptent); > ptent = pte_clear_flags(ptent, _PAGE_SOFT_DIRTY); > + ptep_modify_prot_commit(vma->vm_mm, addr, pte, ptent); > } else if (is_swap_pte(ptent)) { > ptent = pte_swp_clear_soft_dirty(ptent); > + set_pte_at(vma->vm_mm, addr, pte, ptent); > } > - > - set_pte_at(vma->vm_mm, addr, pte, ptent); > } > > static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma, > unsigned long addr, pmd_t *pmdp) > { > - pmd_t pmd = *pmdp; > + pmd_t pmd = pmdp_huge_get_and_clear(vma->vm_mm, addr, pmdp); > > pmd = pmd_wrprotect(pmd); > pmd = pmd_clear_flags(pmd, _PAGE_SOFT_DIRTY); > -- > 1.9.1
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index e2d46adb54b4..c9454ee39b28 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -753,19 +753,20 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma, pte_t ptent = *pte; if (pte_present(ptent)) { + ptent = ptep_modify_prot_start(vma->vm_mm, addr, pte); ptent = pte_wrprotect(ptent); ptent = pte_clear_flags(ptent, _PAGE_SOFT_DIRTY); + ptep_modify_prot_commit(vma->vm_mm, addr, pte, ptent); } else if (is_swap_pte(ptent)) { ptent = pte_swp_clear_soft_dirty(ptent); + set_pte_at(vma->vm_mm, addr, pte, ptent); } - - set_pte_at(vma->vm_mm, addr, pte, ptent); } static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma, unsigned long addr, pmd_t *pmdp) { - pmd_t pmd = *pmdp; + pmd_t pmd = pmdp_huge_get_and_clear(vma->vm_mm, addr, pmdp); pmd = pmd_wrprotect(pmd); pmd = pmd_clear_flags(pmd, _PAGE_SOFT_DIRTY);
As mentioned in the commit 56eecdb912b5 ("mm: Use ptep/pmdp_set_numa() for updating _PAGE_NUMA bit"), architecture like ppc64 doesn't do tlb flush in set_pte/pmd functions. So when dealing with existing pte in clear_soft_dirty, the pte must be cleared before being modified. Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> CC: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> --- fs/proc/task_mmu.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)