[RFC PATCH 2/6] mm: change the condition of identifying hugetlb vm

Wenwei Tao
2015-06-10T06:33:05Z

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 <wenweitaowenwei@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