Add an optional close() callback to struct vm_special_mapping. It will
be used, by powerpc at least, to handle unmapping of the VDSO.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
  include/linux/mm_types.h | 2 ++
  mm/mmap.c                | 3 +++
  2 files changed, 5 insertions(+)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 485424979254..ef32d87a3adc 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h

@@ -1313,6 +1313,8 @@ struct vm_special_mapping {
  
  	int (*mremap)(const struct vm_special_mapping *sm,
  		     struct vm_area_struct *new_vma);
+	void (*close)(const struct vm_special_mapping *sm,
+		      struct vm_area_struct *vma);
  };
  
  enum tlb_flush_reason {

diff --git a/mm/mmap.c b/mm/mmap.c
index d0dfc85b209b..24bd6aa9155c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c

@@ -3624,6 +3624,9 @@ static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
   */
  static void special_mapping_close(struct vm_area_struct *vma)
  {
+	const struct vm_special_mapping *sm = vma->vm_private_data;