mm: Move vma_stack_continue into mm.h

So it can be used by all that need to check for that.

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/task_mmu.c

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 439fc1f..271afc4 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -224,7 +224,8 @@
 	/* We don't show the stack guard page in /proc/maps */
 	start = vma->vm_start;
 	if (vma->vm_flags & VM_GROWSDOWN)
-		start += PAGE_SIZE;
+		if (!vma_stack_continue(vma->vm_prev, vma->vm_start))
+			start += PAGE_SIZE;
 
 	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
 			start,

include/linux/mm.h

diff --git a/include/linux/mm.h b/include/linux/mm.h
index e6b1210..74949fb 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -864,6 +864,12 @@
 int set_page_dirty_lock(struct page *page);
 int clear_page_dirty_for_io(struct page *page);
 
+/* Is the vma a continuation of the stack vma above it? */
+static inline int vma_stack_continue(struct vm_area_struct *vma, unsigned long addr)
+{
+	return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
+}
+
 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);

mm/mlock.c

diff --git a/mm/mlock.c b/mm/mlock.c
index cbae7c5..b70919c 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -135,12 +135,6 @@
 	}
 }
 
-/* Is the vma a continuation of the stack vma above it? */
-static inline int vma_stack_continue(struct vm_area_struct *vma, unsigned long addr)
-{
-	return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
-}
-
 static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
 {
 	return (vma->vm_flags & VM_GROWSDOWN) &&