[RFC PATCH 4/5] mm/hugetlb: Add prot_modify_start/commit sequence for hugetlb update

[Aneesh Kumar K.V]

Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
---
 include/linux/hugetlb.h | 18 ++++++++++++++++++
 mm/hugetlb.c            |  8 +++++---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 6b68e345f0ca..d39ba48f43b0 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -529,6 +529,24 @@ static inline void set_huge_swap_pte_at(struct mm_struct 
*mm, unsigned long addr
        set_huge_pte_at(mm, addr, ptep, pte);
 }
 #endif
+
+#ifndef huge_ptep_modify_prot_start
+static inline pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma,
+                                               unsigned long addr, pte_t *ptep)
+{
+       return huge_ptep_get_and_clear(mm, address, ptep);
+}
+#endif
+
+#ifndef huge_ptep_modify_prot_commit
+static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
+                                               unsigned long addr, pte_t *ptep,
+                                               pte_t old_pte, pte_t pte)
+{
+       set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
+}
+#endif
+
 #else  /* CONFIG_HUGETLB_PAGE */
 struct hstate {};
 #define alloc_huge_page(v, a, r) NULL
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3c21775f196b..d147662442ca 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4336,10 +4336,12 @@ unsigned long hugetlb_change_protection(struct 
vm_area_struct *vma,
                        continue;
                }
                if (!huge_pte_none(pte)) {
-                       pte = huge_ptep_get_and_clear(mm, address, ptep);
-                       pte = pte_mkhuge(huge_pte_modify(pte, newprot));
+                       pte_t old_pte;
+
+                       old_pte = huge_ptep_modify_prot_start(vma, address, 
ptep);
+                       pte = pte_mkhuge(huge_pte_modify(old_pte, newprot));
                        pte = arch_make_huge_pte(pte, vma, NULL, 0);
-                       set_huge_pte_at(mm, address, ptep, pte);
+                       huge_ptep_modify_prot_commit(vma, address, ptep, 
old_pte, pte);
                        pages++;
                }
                spin_unlock(ptl);
-- 
2.17.1