| Message ID | 20211116220038.116484-2-pasha.tatashin@soleen.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | page table check | expand |
On 11/17/21 3:30 AM, Pasha Tatashin wrote: > diff --git a/Documentation/vm/arch_pgtable_helpers.rst b/Documentation/vm/arch_pgtable_helpers.rst > index 552567d863b8..fbe06ec75370 100644 > --- a/Documentation/vm/arch_pgtable_helpers.rst > +++ b/Documentation/vm/arch_pgtable_helpers.rst > @@ -66,9 +66,11 @@ PTE Page Table Helpers > +---------------------------+--------------------------------------------------+ > | pte_mknotpresent | Invalidates a mapped PTE | > +---------------------------+--------------------------------------------------+ > -| ptep_get_and_clear | Clears a PTE | > +| ptep_clear | Clears a PTE | > +---------------------------+--------------------------------------------------+ > -| ptep_get_and_clear_full | Clears a PTE | > +| ptep_get_and_clear | Clears and returns PTE | > ++---------------------------+--------------------------------------------------+ > +| ptep_get_and_clear_full | Clears and returns PTE (batched PTE unmap) | > +---------------------------+--------------------------------------------------+ > | ptep_test_and_clear_young | Clears young from a PTE | > +---------------------------+--------------------------------------------------+ Just curious. This does not have a corresponding change in mm/debug_vm_pgtable.c ?
On Wed, Nov 17, 2021 at 3:52 AM Anshuman Khandual <anshuman.khandual@arm.com> wrote: > > > > On 11/17/21 3:30 AM, Pasha Tatashin wrote: > > diff --git a/Documentation/vm/arch_pgtable_helpers.rst b/Documentation/vm/arch_pgtable_helpers.rst > > index 552567d863b8..fbe06ec75370 100644 > > --- a/Documentation/vm/arch_pgtable_helpers.rst > > +++ b/Documentation/vm/arch_pgtable_helpers.rst > > @@ -66,9 +66,11 @@ PTE Page Table Helpers > > +---------------------------+--------------------------------------------------+ > > | pte_mknotpresent | Invalidates a mapped PTE | > > +---------------------------+--------------------------------------------------+ > > -| ptep_get_and_clear | Clears a PTE | > > +| ptep_clear | Clears a PTE | > > +---------------------------+--------------------------------------------------+ > > -| ptep_get_and_clear_full | Clears a PTE | > > +| ptep_get_and_clear | Clears and returns PTE | > > ++---------------------------+--------------------------------------------------+ > > +| ptep_get_and_clear_full | Clears and returns PTE (batched PTE unmap) | > > +---------------------------+--------------------------------------------------+ > > | ptep_test_and_clear_young | Clears young from a PTE | > > +---------------------------+--------------------------------------------------+ > > Just curious. This does not have a corresponding change in mm/debug_vm_pgtable.c ? You are right, I need to replace it in mm/debug_vm_pgtable.c as well. I will do it in the next version. Thanks, Pasha
diff --git a/Documentation/vm/arch_pgtable_helpers.rst b/Documentation/vm/arch_pgtable_helpers.rst index 552567d863b8..fbe06ec75370 100644 --- a/Documentation/vm/arch_pgtable_helpers.rst +++ b/Documentation/vm/arch_pgtable_helpers.rst @@ -66,9 +66,11 @@ PTE Page Table Helpers +---------------------------+--------------------------------------------------+ | pte_mknotpresent | Invalidates a mapped PTE | +---------------------------+--------------------------------------------------+ -| ptep_get_and_clear | Clears a PTE | +| ptep_clear | Clears a PTE | +---------------------------+--------------------------------------------------+ -| ptep_get_and_clear_full | Clears a PTE | +| ptep_get_and_clear | Clears and returns PTE | ++---------------------------+--------------------------------------------------+ +| ptep_get_and_clear_full | Clears and returns PTE (batched PTE unmap) | +---------------------------+--------------------------------------------------+ | ptep_test_and_clear_young | Clears young from a PTE | +---------------------------+--------------------------------------------------+ diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index e24d2c992b11..bc8713a76e03 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -258,6 +258,14 @@ static inline int pmdp_clear_flush_young(struct vm_area_struct *vma, #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ #endif +#ifndef __HAVE_ARCH_PTEP_CLEAR +static inline void ptep_clear(struct mm_struct *mm, unsigned long addr, + pte_t *ptep) +{ + pte_clear(mm, addr, ptep); +} +#endif + #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long address, diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 5f02fda6f265..6ae659ef7e08 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -756,11 +756,7 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page, * ptl mostly unnecessary. */ spin_lock(ptl); - /* - * paravirt calls inside pte_clear here are - * superfluous. - */ - pte_clear(vma->vm_mm, address, _pte); + ptep_clear(vma->vm_mm, address, _pte); spin_unlock(ptl); } } else { @@ -774,11 +770,7 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page, * inside page_remove_rmap(). */ spin_lock(ptl); - /* - * paravirt calls inside pte_clear here are - * superfluous. - */ - pte_clear(vma->vm_mm, address, _pte); + ptep_clear(vma->vm_mm, address, _pte); page_remove_rmap(src_page, false); spin_unlock(ptl); free_page_and_swap_cache(src_page);
We have ptep_get_and_clear() and ptep_get_and_clear_full() helpers to clear PTE from user page tables, but there is no variant for simple clear of a present PTE from user page tables without using a low level pte_clear() which can be either native or para-virtualised. Add a new ptep_clear() that can be used in common code to clear PTEs from page table. We will need this call later in order to add a hook for page table check. Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> --- Documentation/vm/arch_pgtable_helpers.rst | 6 ++++-- include/linux/pgtable.h | 8 ++++++++ mm/khugepaged.c | 12 ++---------- 3 files changed, 14 insertions(+), 12 deletions(-)