Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc

Pull powerpc mremap fix from Ben Herrenschmidt:
 "This is the patch that I had sent after -rc8 and which we decided to
  wait before merging.  It's based on a different tree than my -next
  branch (it needs some pre-reqs that were in -rc4 or so while my -next
  is based on -rc1) so I left it as a separate branch for your to pull.
  It's identical to the request I did 2 or 3 weeks back.

  This fixes crashes in mremap with THP on powerpc.

  The fix however requires a small change in the generic code.  It moves
  a condition into a helper we can override from the arch which is
  harmless, but it *also* slightly changes the order of the set_pmd and
  the withdraw & deposit, which should be fine according to Kirill (who
  wrote that code) but I agree -rc8 is a bit late...

  It was acked by Kirill and Andrew told me to just merge it via powerpc"

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
  powerpc/thp: Fix crash on mremap

1 files changed, 5 insertions, 9 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 65c98eb5483c..82166bf974e1 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1508,19 +1508,15 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
                         spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
                 pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
                 VM_BUG_ON(!pmd_none(*new_pmd));
-                set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
-                if (new_ptl != old_ptl) {
-                        pgtable_t pgtable;
 
-                        /*
-                         * Move preallocated PTE page table if new_pmd is on
-                         * different PMD page table.
-                         */
+                if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
+                        pgtable_t pgtable;
                         pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
                         pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
-
-                        spin_unlock(new_ptl);
                 }
+                set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
+                if (new_ptl != old_ptl)
+                        spin_unlock(new_ptl);
                 spin_unlock(old_ptl);
         }
 out: