mm/ksm: handle protnone saved writes when making page write protect

[mirror_ubuntu-zesty-kernel.git] / mm / ksm.c

diff --git a/mm/ksm.c b/mm/ksm.c
index 9dd2e58fb6dc93184c5a9dba3347a2b06cc57c42..abc05187168a5cebdd2f6d3aca97fbe1c3fc623c 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -880,7 +880,8 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
        if (WARN_ONCE(!pvmw.pte, "Unexpected PMD mapping?"))
                goto out_unlock;
 
-       if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte)) {
+       if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte) ||
+           (pte_protnone(*pvmw.pte) && pte_savedwrite(*pvmw.pte))) {
                pte_t entry;
 
                swapped = PageSwapCache(page);
@@ -905,7 +906,11 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
                }
                if (pte_dirty(entry))
                        set_page_dirty(page);
-               entry = pte_mkclean(pte_wrprotect(entry));
+
+               if (pte_protnone(entry))
+                       entry = pte_mkclean(pte_clear_savedwrite(entry));
+               else
+                       entry = pte_mkclean(pte_wrprotect(entry));
                set_pte_at_notify(mm, pvmw.address, pvmw.pte, entry);
        }
        *orig_pte = *pvmw.pte;