thp: pte alloc trans splitting

pte alloc routines must wait for split_huge_page if the pmd is not present
and not null (i.e.  pmd_trans_splitting).  The additional branches are
optimized away at compile time by pmd_trans_splitting if the config option
is off.  However we must pass the vma down in order to know the anon_vma
lock to wait for.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/mm/mremap.c b/mm/mremap.c
index 563fbdd6293a..b09eefaea0b8 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -47,7 +47,8 @@ static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
         return pmd;
 }
 
-static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr)
+static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
+                            unsigned long addr)
 {
         pgd_t *pgd;
         pud_t *pud;
@@ -62,7 +63,8 @@ static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr)
         if (!pmd)
                 return NULL;
 
-        if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr))
+        VM_BUG_ON(pmd_trans_huge(*pmd));
+        if (pmd_none(*pmd) && __pte_alloc(mm, vma, pmd, addr))
                 return NULL;
 
         return pmd;
@@ -147,7 +149,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
                 old_pmd = get_old_pmd(vma->vm_mm, old_addr);
                 if (!old_pmd)
                         continue;
-                new_pmd = alloc_new_pmd(vma->vm_mm, new_addr);
+                new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
                 if (!new_pmd)
                         break;
                 next = (new_addr + PMD_SIZE) & PMD_MASK;