mm: avoid taking rmap locks in move_ptes()

[karo-tx-linux.git] / mm / mmap.c

diff --git a/mm/mmap.c b/mm/mmap.c
index 81248992120d7f98d52b8914e65d21e78b041798..2d942353d681a8b4f08155eebdcfb20b088093e7 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2371,7 +2371,8 @@ int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
  * prior to moving page table entries, to effect an mremap move.
  */
 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
-       unsigned long addr, unsigned long len, pgoff_t pgoff)
+       unsigned long addr, unsigned long len, pgoff_t pgoff,
+       bool *need_rmap_locks)
 {
        struct vm_area_struct *vma = *vmap;
        unsigned long vma_start = vma->vm_start;
@@ -2413,8 +2414,9 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
                         * linear if there are no pages mapped yet.
                         */
                        VM_BUG_ON(faulted_in_anon_vma);
-                       *vmap = new_vma;
+                       *vmap = vma = new_vma;
                }
+               *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
        } else {
                new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
                if (new_vma) {
@@ -2434,6 +2436,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
                        if (new_vma->vm_ops && new_vma->vm_ops->open)
                                new_vma->vm_ops->open(new_vma);
                        vma_link(mm, new_vma, prev, rb_link, rb_parent);
+                       *need_rmap_locks = false;
                }
        }
        return new_vma;