mm: introduce vma_init()

Not all VMAs allocated with vm_area_alloc().  Some of them allocated on
stack or in data segment.

The new helper can be use to initialize VMA properly regardless where it
was allocated.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kirill A. Shutemov <[email protected]>
Acked-by: Linus Torvalds <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

2 files changed, 8 insertions, 4 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index d3a3842316b8..31540f166987 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -452,6 +452,12 @@ struct vm_operations_struct {
 					  unsigned long addr);
 };
 
+static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm)
+{
+	vma->vm_mm = mm;
+	INIT_LIST_HEAD(&vma->anon_vma_chain);
+}
+
 struct mmu_gather;
 struct inode;
 
diff --git a/kernel/fork.c b/kernel/fork.c
index a191c05e757d..1b27babc4c78 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -312,10 +312,8 @@ struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
 {
 	struct vm_area_struct *vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 
-	if (vma) {
-		vma->vm_mm = mm;
-		INIT_LIST_HEAD(&vma->anon_vma_chain);
-	}
+	if (vma)
+		vma_init(vma, mm);
 	return vma;
 }