thp: madvise(MADV_NOHUGEPAGE)

Add madvise MADV_NOHUGEPAGE to mark regions that are not important to be
hugepage backed.  Return -EINVAL if the vma is not of an anonymous type,
or the feature isn't built into the kernel.  Never silently return
success.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index 552f3184756c..6b394f0b5148 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -38,9 +38,10 @@ static inline void khugepaged_exit(struct mm_struct *mm)
 static inline int khugepaged_enter(struct vm_area_struct *vma)
 {
         if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags))
-                if (khugepaged_always() ||
-                    (khugepaged_req_madv() &&
-                     vma->vm_flags & VM_HUGEPAGE))
+                if ((khugepaged_always() ||
+                     (khugepaged_req_madv() &&
+                      vma->vm_flags & VM_HUGEPAGE)) &&
+                    !(vma->vm_flags & VM_NOHUGEPAGE))
                         if (__khugepaged_enter(vma->vm_mm))
                                 return -ENOMEM;
         return 0;