diff --git a/include/linux/mm.h b/include/linux/mm.h
index 378bcce..df17ff2 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1040,6 +1040,9 @@
 		!vma_growsup(vma->vm_next, addr);
 }
 
+extern pid_t
+vm_is_stack(struct task_struct *task, struct vm_area_struct *vma, int in_group);
+
 extern unsigned long move_page_tables(struct vm_area_struct *vma,
 		unsigned long old_addr, struct vm_area_struct *new_vma,
 		unsigned long new_addr, unsigned long len);