Hugetlb VMAs are not mergeable, that means a VMA couldn't have VM_HUGETLB and
VM_MERGEABLE been set in the same time. So we use VM_HUGETLB to indicate new
mergeable VMAs. Because of that a VMA which has VM_HUGETLB been set is a hugetlb
VMA only if it doesn't have VM_MERGEABLE been set in the same time.

Signed-off-by: Wenwei Tao <wenweitaowen...@gmail.com>
---
 include/linux/hugetlb_inline.h |    2 +-
 include/linux/mempolicy.h      |    2 +-
 mm/gup.c                       |    6 ++++--
 mm/huge_memory.c               |   17 ++++++++++++-----
 mm/madvise.c                   |    6 ++++--
 mm/memory.c                    |    5 +++--
 mm/mprotect.c                  |    6 ++++--
 7 files changed, 29 insertions(+), 15 deletions(-)

diff --git a/include/linux/hugetlb_inline.h b/include/linux/hugetlb_inline.h
index 2bb681f..08dff6f 100644
--- a/include/linux/hugetlb_inline.h
+++ b/include/linux/hugetlb_inline.h
@@ -7,7 +7,7 @@
 
 static inline int is_vm_hugetlb_page(struct vm_area_struct *vma)
 {
-       return !!(vma->vm_flags & VM_HUGETLB);
+       return !!((vma->vm_flags & (VM_HUGETLB | VM_MERGEABLE)) == VM_HUGETLB);
 }
 
 #else
diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 3d385c8..40ad136 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -178,7 +178,7 @@ static inline int vma_migratable(struct vm_area_struct *vma)
                return 0;
 
 #ifndef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
-       if (vma->vm_flags & VM_HUGETLB)
+       if ((vma->vm_flags & (VM_HUGETLB | VM_MERGEABLE)) == VM_HUGETLB)
                return 0;
 #endif
 
diff --git a/mm/gup.c b/mm/gup.c
index a6e24e2..5803dab 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -166,7 +166,8 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
        pud = pud_offset(pgd, address);
        if (pud_none(*pud))
                return no_page_table(vma, flags);
-       if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
+       if (pud_huge(*pud) &&
+               (vma->vm_flags & (VM_HUGETLB | VM_MERGEABLE)) == VM_HUGETLB) {
                page = follow_huge_pud(mm, address, pud, flags);
                if (page)
                        return page;
@@ -178,7 +179,8 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
        pmd = pmd_offset(pud, address);
        if (pmd_none(*pmd))
                return no_page_table(vma, flags);
-       if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
+       if (pmd_huge(*pmd) &&
+               (vma->vm_flags & (VM_HUGETLB | VM_MERGEABLE)) == VM_HUGETLB) {
                page = follow_huge_pmd(mm, address, pmd, flags);
                if (page)
                        return page;
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index fc00c8c..5a9de7f 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1910,7 +1910,6 @@ out:
        return ret;
 }
 
-#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
 
 int hugepage_madvise(struct vm_area_struct *vma,
                     unsigned long *vm_flags, int advice)
@@ -1929,7 +1928,9 @@ int hugepage_madvise(struct vm_area_struct *vma,
                /*
                 * Be somewhat over-protective like KSM for now!
                 */
-               if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
+               if (*vm_flags & (VM_HUGEPAGE | VM_SPECIAL |
+                                               VM_SHARED | VM_MAYSHARE) ||
+                       (*vm_flags & (VM_HUGETLB | VM_MERGEABLE)) == VM_HUGETLB)
                        return -EINVAL;
                *vm_flags &= ~VM_NOHUGEPAGE;
                *vm_flags |= VM_HUGEPAGE;
@@ -1945,7 +1946,9 @@ int hugepage_madvise(struct vm_area_struct *vma,
                /*
                 * Be somewhat over-protective like KSM for now!
                 */
-               if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
+               if (*vm_flags & (VM_NOHUGEPAGE | VM_SPECIAL |
+                                               VM_SHARED | VM_MAYSHARE) ||
+                       (*vm_flags & (VM_HUGETLB | VM_MERGEABLE)) == VM_HUGETLB)
                        return -EINVAL;
                *vm_flags &= ~VM_HUGEPAGE;
                *vm_flags |= VM_NOHUGEPAGE;
@@ -2052,7 +2055,8 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
        if (vma->vm_ops)
                /* khugepaged not yet working on file or special mappings */
                return 0;
-       VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma);
+       VM_BUG_ON_VMA(vm_flags & (VM_SPECIAL | VM_SHARED | VM_MAYSHARE) ||
+               (vm_flags & (VM_HUGETLB | VM_MERGEABLE)) == VM_HUGETLB, vma);
        hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
        hend = vma->vm_end & HPAGE_PMD_MASK;
        if (hstart < hend)
@@ -2396,7 +2400,10 @@ static bool hugepage_vma_check(struct vm_area_struct 
*vma)
                return false;
        if (is_vma_temporary_stack(vma))
                return false;
-       VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma);
+       VM_BUG_ON_VMA(vma->vm_flags &
+               (VM_SPECIAL | VM_SHARED | VM_MAYSHARE) ||
+               (vma->vm_flags & (VM_HUGETLB | VM_MERGEABLE)) ==
+               VM_HUGETLB, vma);
        return true;
 }
 
diff --git a/mm/madvise.c b/mm/madvise.c
index d551475..ad1081e 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -278,7 +278,8 @@ static long madvise_dontneed(struct vm_area_struct *vma,
                             unsigned long start, unsigned long end)
 {
        *prev = vma;
-       if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
+       if (vma->vm_flags & (VM_LOCKED|VM_PFNMAP) ||
+               (vma->vm_flags & (VM_HUGETLB|VM_MERGEABLE)) == VM_HUGETLB)
                return -EINVAL;
 
        zap_page_range(vma, start, end - start, NULL);
@@ -299,7 +300,8 @@ static long madvise_remove(struct vm_area_struct *vma,
 
        *prev = NULL;   /* tell sys_madvise we drop mmap_sem */
 
-       if (vma->vm_flags & (VM_LOCKED | VM_HUGETLB))
+       if (vma->vm_flags & VM_LOCKED ||
+               (vma->vm_flags & (VM_HUGETLB | VM_MERGEABLE)) == VM_HUGETLB)
                return -EINVAL;
 
        f = vma->vm_file;
diff --git a/mm/memory.c b/mm/memory.c
index 8068893..266456c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1021,8 +1021,9 @@ int copy_page_range(struct mm_struct *dst_mm, struct 
mm_struct *src_mm,
         * readonly mappings. The tradeoff is that copy_page_range is more
         * efficient than faulting.
         */
-       if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
-                       !vma->anon_vma)
+       if (!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP) ||
+               (vma->vm_flags & (VM_HUGETLB | VM_MERGEABLE)) == VM_HUGETLB) &&
+               !vma->anon_vma)
                return 0;
 
        if (is_vm_hugetlb_page(vma))
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 4472781..09cce5b 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -273,8 +273,10 @@ mprotect_fixup(struct vm_area_struct *vma, struct 
vm_area_struct **pprev,
         * even if read-only so there is no need to account for them here
         */
        if (newflags & VM_WRITE) {
-               if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
-                                               VM_SHARED|VM_NORESERVE))) {
+               if (!(oldflags &
+                       (VM_ACCOUNT|VM_WRITE|VM_SHARED|VM_NORESERVE) ||
+                       (oldflags & (VM_HUGETLB | VM_MERGEABLE)) ==
+                                                       VM_HUGETLB)) {
                        charged = nrpages;
                        if (security_vm_enough_memory_mm(mm, charged))
                                return -ENOMEM;
-- 
1.7.9.5

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