1 files changed, 12 insertions, 10 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 411144f977b1..97839f5c8c30 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3035,6 +3035,7 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
         int last_cpupid;
         int target_nid;
         bool migrated = false;
+        bool was_writable = pte_write(pte);
         int flags = 0;
 
         /* A PROT_NONE fault should not end up here */
@@ -3059,6 +3060,8 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
         /* Make it present again */
         pte = pte_modify(pte, vma->vm_page_prot);
         pte = pte_mkyoung(pte);
+        if (was_writable)
+                pte = pte_mkwrite(pte);
         set_pte_at(mm, addr, ptep, pte);
         update_mmu_cache(vma, addr, ptep);
 
@@ -3069,16 +3072,14 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
         }
 
         /*
-         * Avoid grouping on DSO/COW pages in specific and RO pages
-         * in general, RO pages shouldn't hurt as much anyway since
-         * they can be in shared cache state.
-         *
-         * FIXME! This checks "pmd_dirty()" as an approximation of
-         * "is this a read-only page", since checking "pmd_write()"
-         * is even more broken. We haven't actually turned this into
-         * a writable page, so pmd_write() will always be false.
+         * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
+         * much anyway since they can be in shared cache state. This misses
+         * the case where a mapping is writable but the process never writes
+         * to it but pte_write gets cleared during protection updates and
+         * pte_dirty has unpredictable behaviour between PTE scan updates,
+         * background writeback, dirty balancing and application behaviour.
          */
-        if (!pte_dirty(pte))
+        if (!(vma->vm_flags & VM_WRITE))
                 flags |= TNF_NO_GROUP;
 
         /*
@@ -3102,7 +3103,8 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
         if (migrated) {
                 page_nid = target_nid;
                 flags |= TNF_MIGRATED;
-        }
+        } else
+                flags |= TNF_MIGRATE_FAIL;
 
 out:
         if (page_nid != -1)