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>

5 files changed, 46 insertions, 21 deletions

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 9b48c24df260..a8b7e42d19ec 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -52,10 +52,12 @@ extern pmd_t *page_check_address_pmd(struct page *page,
 #define HPAGE_PMD_SIZE HPAGE_SIZE
 
 #define transparent_hugepage_enabled(__vma)                             \
-        (transparent_hugepage_flags & (1<<TRANSPARENT_HUGEPAGE_FLAG) || \
-         (transparent_hugepage_flags &                                  \
-          (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG) &&                    \
-          (__vma)->vm_flags & VM_HUGEPAGE))
+        ((transparent_hugepage_flags &                                  \
+          (1<<TRANSPARENT_HUGEPAGE_FLAG) ||                             \
+          (transparent_hugepage_flags &                                 \
+           (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG) &&                   \
+           ((__vma)->vm_flags & VM_HUGEPAGE))) &&                       \
+         !((__vma)->vm_flags & VM_NOHUGEPAGE))
 #define transparent_hugepage_defrag(__vma)                              \
         ((transparent_hugepage_flags &                                  \
           (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)) ||                     \
@@ -103,7 +105,7 @@ extern void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd);
 #if HPAGE_PMD_ORDER > MAX_ORDER
 #error "hugepages can't be allocated by the buddy allocator"
 #endif
-extern int hugepage_madvise(unsigned long *vm_flags);
+extern int hugepage_madvise(unsigned long *vm_flags, int advice);
 extern void __vma_adjust_trans_huge(struct vm_area_struct *vma,
                                     unsigned long start,
                                     unsigned long end,
@@ -141,7 +143,7 @@ static inline int split_huge_page(struct page *page)
         do { } while (0)
 #define wait_split_huge_page(__anon_vma, __pmd) \
         do { } while (0)
-static inline int hugepage_madvise(unsigned long *vm_flags)
+static inline int hugepage_madvise(unsigned long *vm_flags, int advice)
 {
         BUG();
         return 0;
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;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ce97a2bb0b19..956a35532f47 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -83,6 +83,7 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_GROWSUP      0x00000200
 #else
 #define VM_GROWSUP      0x00000000
+#define VM_NOHUGEPAGE   0x00000200      /* MADV_NOHUGEPAGE marked this vma */
 #endif
 #define VM_PFNMAP       0x00000400      /* Page-ranges managed without "struct page", just pure PFN */
 #define VM_DENYWRITE    0x00000800      /* ETXTBSY on write attempts.. */
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;