Merge branch 'numa-migration-fixes' (fixes from Mel Gorman)

Merge NUMA balancing related fixlets from Mel Gorman:
 "There were a few minor changes so am resending just the two patches
  that are mostly likely to affect the bug Dave and Sasha saw and marked
  them for stable.

  I'm less confident it will address Sasha's problem because while I
  have not kept up to date, I believe he's also seeing memory corruption
  issues in next from an unknown source.  Still, it would be nice to see
  how they affect trinity testing.

  I'll send the MPOL_MF_LAZY patch separately because it's not urgent"

* emailed patches from Mel Gorman <mgorman@suse.de>:
  mm: numa: Do not mark PTEs pte_numa when splitting huge pages
  mm: migrate: Close race between migration completion and mprotect

2 files changed, 9 insertions, 3 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d9a21d06b862..f8ffd9412ec5 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1795,14 +1795,17 @@ static int __split_huge_page_map(struct page *page,
                 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
                         pte_t *pte, entry;
                         BUG_ON(PageCompound(page+i));
+                        /*
+                         * Note that pmd_numa is not transferred deliberately
+                         * to avoid any possibility that pte_numa leaks to
+                         * a PROT_NONE VMA by accident.
+                         */
                         entry = mk_pte(page + i, vma->vm_page_prot);
                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
                         if (!pmd_write(*pmd))
                                 entry = pte_wrprotect(entry);
                         if (!pmd_young(*pmd))
                                 entry = pte_mkold(entry);
-                        if (pmd_numa(*pmd))
-                                entry = pte_mknuma(entry);
                         pte = pte_offset_map(&_pmd, haddr);
                         BUG_ON(!pte_none(*pte));
                         set_pte_at(mm, haddr, pte, entry);
diff --git a/mm/migrate.c b/mm/migrate.c
index f78ec9bd454d..2740360cd216 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -146,8 +146,11 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
         pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
         if (pte_swp_soft_dirty(*ptep))
                 pte = pte_mksoft_dirty(pte);
+
+        /* Recheck VMA as permissions can change since migration started  */
         if (is_write_migration_entry(entry))
-                pte = pte_mkwrite(pte);
+                pte = maybe_mkwrite(pte, vma);
+
 #ifdef CONFIG_HUGETLB_PAGE
         if (PageHuge(new)) {
                 pte = pte_mkhuge(pte);