[PATCH v5 05/11] thp: change_huge_pmd(): keep huge zero page write-protected

Kirill A. Shutemov
2012-11-07T15:01:16Z

From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

We want to get page fault on write attempt to huge zero page, so let's
keep it write-protected.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
mm/huge_memory.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d767a7c..05490b3 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1259,6 +1259,8 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
pmd_t entry;
entry = pmdp_get_and_clear(mm, addr, pmd);
entry = pmd_modify(entry, newprot);
+ if (is_huge_zero_pmd(entry))
+ entry = pmd_wrprotect(entry);
set_pmd_at(mm, addr, pmd, entry);
spin_unlock(&vma->vm_mm->page_table_lock);
ret = 1;
--
1.7.7.6