[PATCH] mm/THP: Use the right function when updating access flags

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

We should use pmdp_set_access_flags to update access flags. Archs like powerpc
use extra checks(_PAGE_BUSY) when updating a hugepage PTE. A set_pmd_at doesn't
do those checks. We should use set_pmd_at only when updating a none hugepage PTE.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 mm/huge_memory.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d1cecb9..af20bb1 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1265,7 +1265,9 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
 		 * young bit, instead of the current set_pmd_at.
 		 */
 		_pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
-		set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd);
+		if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
+					  pmd, _pmd,  1))
+			update_mmu_cache_pmd(vma, addr, pmd);
 	}
 	if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
 		if (page->mapping && trylock_page(page)) {
-- 
1.8.1.2

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