vma_merge: set vma iterator to correct position.

When merging the previous value, set the vma iterator to the previous
slot.  Don't use the vma iterator to get the next/prev so that it is in
the correct position for a write.

Link: https://lkml.kernel.org/r/20230120162650.984577-50-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mmap.c b/mm/mmap.c
index 8ce4cee42dce19b2e12b390d41101edb9b92e6e7..b698a96d0511685109c055c043ae7546ff5e09e7 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -932,6 +932,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
                    && can_vma_merge_after(prev, vm_flags, anon_vma, file,
                                   pgoff, vm_userfaultfd_ctx, anon_name)) {
                        merge_prev = true;
+                       vma_prev(vmi);
                }
        }
        /* Can we merge the successor? */
@@ -1023,9 +1024,6 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
        validate_mm(mm);
        khugepaged_enter_vma(res, vm_flags);
 
-       if (res)
-               vma_iter_set(vmi, end);
-
        return res;
 }