From a664b2d8555c659127bf8fe049a58449d394a707 Mon Sep 17 00:00:00 2001
From: Andrea Arcangeli <aarcange@redhat.com>
Date: Thu, 13 Jan 2011 15:47:17 -0800
Subject: 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>
---
 mm/huge_memory.c | 41 ++++++++++++++++++++++++++++++-----------
 mm/madvise.c     |  4 +++-
 2 files changed, 33 insertions(+), 12 deletions(-)

(limited to 'mm')

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f4f6041176a4..fce667c0281d 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -16,6 +16,7 @@
 #include <linux/kthread.h>
 #include <linux/khugepaged.h>
 #include <linux/freezer.h>
+#include <linux/mman.h>
 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
 #include "internal.h"
@@ -1388,18 +1389,36 @@ out:
 	return ret;
 }
 
-int hugepage_madvise(unsigned long *vm_flags)
+int hugepage_madvise(unsigned long *vm_flags, int advice)
 {
-	/*
-	 * Be somewhat over-protective like KSM for now!
-	 */
-	if (*vm_flags & (VM_HUGEPAGE | VM_SHARED  | VM_MAYSHARE   |
-			 VM_PFNMAP   | VM_IO      | VM_DONTEXPAND |
-			 VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE |
-			 VM_MIXEDMAP | VM_SAO))
-		return -EINVAL;
-
-	*vm_flags |= VM_HUGEPAGE;
+	switch (advice) {
+	case MADV_HUGEPAGE:
+		/*
+		 * Be somewhat over-protective like KSM for now!
+		 */
+		if (*vm_flags & (VM_HUGEPAGE |
+				 VM_SHARED   | VM_MAYSHARE   |
+				 VM_PFNMAP   | VM_IO      | VM_DONTEXPAND |
+				 VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE |
+				 VM_MIXEDMAP | VM_SAO))
+			return -EINVAL;
+		*vm_flags &= ~VM_NOHUGEPAGE;
+		*vm_flags |= VM_HUGEPAGE;
+		break;
+	case MADV_NOHUGEPAGE:
+		/*
+		 * Be somewhat over-protective like KSM for now!
+		 */
+		if (*vm_flags & (VM_NOHUGEPAGE |
+				 VM_SHARED   | VM_MAYSHARE   |
+				 VM_PFNMAP   | VM_IO      | VM_DONTEXPAND |
+				 VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE |
+				 VM_MIXEDMAP | VM_SAO))
+			return -EINVAL;
+		*vm_flags &= ~VM_HUGEPAGE;
+		*vm_flags |= VM_NOHUGEPAGE;
+		break;
+	}
 
 	return 0;
 }
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;
 
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