Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6

1 files changed, 19 insertions, 0 deletions

diff --git a/mm/mlock.c b/mm/mlock.c
index 3f82720e051..cbae7c5b956 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -135,6 +135,19 @@ void munlock_vma_page(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);
+}
+
+static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
+{
+	return (vma->vm_flags & VM_GROWSDOWN) &&
+		(vma->vm_start == addr) &&
+		!vma_stack_continue(vma->vm_prev, addr);
+}
+
 /**
  * __mlock_vma_pages_range() -  mlock a range of pages in the vma.
  * @vma:   target vma
@@ -167,6 +180,12 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma,
 	if (vma->vm_flags & VM_WRITE)
 		gup_flags |= FOLL_WRITE;
 
+	/* We don't try to access the guard page of a stack vma */
+	if (stack_guard_page(vma, start)) {
+		addr += PAGE_SIZE;
+		nr_pages--;
+	}
+
 	while (nr_pages > 0) {
 		int i;