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, 3 insertions, 1 deletions

diff --git a/mm/madvise.c b/mm/madvise.c
index ecde40a401c1..bbac126e03ed 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -72,7 +72,8 @@ static long madvise_behavior(struct vm_area_struct * vma,
                         goto out;
                 break;
         case MADV_HUGEPAGE:
-                error = hugepage_madvise(&new_flags);
+        case MADV_NOHUGEPAGE:
+                error = hugepage_madvise(&new_flags, behavior);
                 if (error)
                         goto out;
                 break;
@@ -290,6 +291,7 @@ madvise_behavior_valid(int behavior)
 #endif
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
         case MADV_HUGEPAGE:
+        case MADV_NOHUGEPAGE:
 #endif
                 return 1;