[v4 PATCH 2/7] mm: thp: consolidate vma size check to transhuge_vma_suitable

Yang Shi
2022-06-15T17:29:53Z

There are couple of places that check whether the vma size is ok for
THP or whether address fits, they are open coded and duplicate, use
transhuge_vma_suitable() to do the job by passing in (vma->end -
HPAGE_PMD_SIZE).

Move vma size check into hugepage_vma_check(). This will make
khugepaged_enter() is as same as khugepaged_enter_vma(). There is just
one caller for khugepaged_enter(), replace it to khugepaged_enter_vma()
and remove khugepaged_enter().

Signed-off-by: Yang Shi <shy828301@gmail.com>
---
include/linux/huge_mm.h | 11 +++++++++++
include/linux/khugepaged.h | 14 --------------
mm/huge_memory.c | 2 +-
mm/khugepaged.c | 19 ++++++-------------
4 files changed, 18 insertions(+), 28 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 648cb3ce7099..8a5a8bfce0f5 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -116,6 +116,17 @@ extern struct kobj_attribute shmem_enabled_attr;

extern unsigned long transparent_hugepage_flags;

+/*
+ * Do the below checks:
+ * - For file vma, check if the linear page offset of vma is
+ * HPAGE_PMD_NR aligned within the file. The hugepage is
+ * guaranteed to be hugepage-aligned within the file, but we must
+ * check that the PMD-aligned addresses in the VMA map to
+ * PMD-aligned offsets within the file, else the hugepage will
+ * not be PMD-mappable.
+ * - For all vmas, check if the haddr is in an aligned HPAGE_PMD_SIZE
+ * area.
+ */
static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
unsigned long addr)
{
diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index 392d34c3c59a..31ca8a7f78f4 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -51,16 +51,6 @@ static inline void khugepaged_exit(struct mm_struct *mm)
if (test_bit(MMF_VM_HUGEPAGE, &mm->flags))
__khugepaged_exit(mm);
}
-
-static inline void khugepaged_enter(struct vm_area_struct *vma,
- unsigned long vm_flags)
-{
- if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
- khugepaged_enabled()) {
- if (hugepage_vma_check(vma, vm_flags))
- __khugepaged_enter(vma->vm_mm);
- }
-}
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
{
@@ -68,10 +58,6 @@ static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm
static inline void khugepaged_exit(struct mm_struct *mm)
{
}
-static inline void khugepaged_enter(struct vm_area_struct *vma,
- unsigned long vm_flags)
-{
-}
static inline void khugepaged_enter_vma(struct vm_area_struct *vma,
unsigned long vm_flags)
{
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4f9bbb4eab23..b530462c4493 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -726,7 +726,7 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
return VM_FAULT_FALLBACK;
if (unlikely(anon_vma_prepare(vma)))
return VM_FAULT_OOM;
- khugepaged_enter(vma, vma->vm_flags);
+ khugepaged_enter_vma(vma, vma->vm_flags);

if (!(vmf->flags & FAULT_FLAG_WRITE) &&
!mm_forbids_zeropage(vma->vm_mm) &&
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index b1dab94c0f1e..db0b334a7d1f 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -450,8 +450,8 @@ bool hugepage_vma_check(struct vm_area_struct *vma,
if (vma_is_dax(vma))
return false;

- if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) -
- vma->vm_pgoff, HPAGE_PMD_NR))
+ /* Check alignment for file vma and size for both file and anon vma */
+ if (!transhuge_vma_suitable(vma, (vma->vm_end - HPAGE_PMD_SIZE)))
return false;

/* Enabled via shmem mount options or sysfs settings. */
@@ -512,9 +512,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
unsigned long vm_flags)
{
if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
- khugepaged_enabled() &&
- (((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
- (vma->vm_end & HPAGE_PMD_MASK))) {
+ khugepaged_enabled()) {
if (hugepage_vma_check(vma, vm_flags))
__khugepaged_enter(vma->vm_mm);
}
@@ -950,7 +948,6 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
struct vm_area_struct **vmap)
{
struct vm_area_struct *vma;
- unsigned long hstart, hend;

if (unlikely(khugepaged_test_exit(mm)))
return SCAN_ANY_PROCESS;
@@ -959,9 +956,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
if (!vma)
return SCAN_VMA_NULL;

- hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
- hend = vma->vm_end & HPAGE_PMD_MASK;
- if (address < hstart || address + HPAGE_PMD_SIZE > hend)
+ if (!transhuge_vma_suitable(vma, address))
return SCAN_ADDRESS_RANGE;
if (!hugepage_vma_check(vma, vma->vm_flags))
return SCAN_VMA_CHECK;
@@ -2147,10 +2142,8 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
progress++;
continue;
}
- hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
- hend = vma->vm_end & HPAGE_PMD_MASK;
- if (hstart >= hend)
- goto skip;
+ hstart = round_up(vma->vm_start, HPAGE_PMD_SIZE);
+ hend = round_down(vma->vm_end, HPAGE_PMD_SIZE);
if (khugepaged_scan.address > hend)
goto skip;
if (khugepaged_scan.address < hstart)
--
2.26.3