[v4 PATCH 4/7] mm: thp: kill transparent_hugepage_active()

Yang Shi
2022-06-15T17:30:06Z

The transparent_hugepage_active() was introduced to show THP eligibility
bit in smaps in proc, smaps is the only user. But it actually does the
similar check as hugepage_vma_check() which is used by khugepaged. We
definitely don't have to maintain two similar checks, so kill
transparent_hugepage_active().

This patch also fixed the wrong behavior for VM_NO_KHUGEPAGED vmas.

Also move hugepage_vma_check() to huge_memory.c and huge_mm.h since it
is not only for khugepaged anymore.

Signed-off-by: Yang Shi <shy828301@gmail.com>
---
fs/proc/task_mmu.c | 2 +-
include/linux/huge_mm.h | 11 ++++++++-
include/linux/khugepaged.h | 2 --
mm/huge_memory.c | 50 +++++++++++++++++++++++++++++++-------
mm/khugepaged.c | 48 +++---------------------------------
5 files changed, 56 insertions(+), 57 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 37ccb5c9f4f8..39a40ec181e7 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -863,7 +863,7 @@ static int show_smap(struct seq_file *m, void *v)
__show_smap(m, &mss, false);

seq_printf(m, "THPeligible: %d\n",
- transparent_hugepage_active(vma));
+ hugepage_vma_check(vma, vma->vm_flags, true));

if (arch_pkeys_enabled())
seq_printf(m, "ProtectionKey: %8u\n", vma_pkey(vma));
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 8a5a8bfce0f5..aeb13119ee28 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -202,7 +202,9 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma)
!inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);
}

-bool transparent_hugepage_active(struct vm_area_struct *vma);
+bool hugepage_vma_check(struct vm_area_struct *vma,
+ unsigned long vm_flags,
+ bool smaps);

#define transparent_hugepage_use_zero_page() \
(transparent_hugepage_flags & \
@@ -368,6 +370,13 @@ static inline bool transhuge_vma_enabled(struct vm_area_struct *vma,
return false;
}

+static inline bool hugepage_vma_check(struct vm_area_struct *vma,
+ unsigned long vm_flags,
+ bool smaps)
+{
+ return false;
+}
+
static inline void prep_transhuge_page(struct page *page) {}

#define transparent_hugepage_flags 0UL
diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index 31ca8a7f78f4..ea5fd4c398f7 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -10,8 +10,6 @@ extern struct attribute_group khugepaged_attr_group;
extern int khugepaged_init(void);
extern void khugepaged_destroy(void);
extern int start_stop_khugepaged(void);
-extern bool hugepage_vma_check(struct vm_area_struct *vma,
- unsigned long vm_flags);
extern void __khugepaged_enter(struct mm_struct *mm);
extern void __khugepaged_exit(struct mm_struct *mm);
extern void khugepaged_enter_vma(struct vm_area_struct *vma,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b530462c4493..a28c6100b491 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -69,21 +69,53 @@ static atomic_t huge_zero_refcount;
struct page *huge_zero_page __read_mostly;
unsigned long huge_zero_pfn __read_mostly = ~0UL;

-bool transparent_hugepage_active(struct vm_area_struct *vma)
+bool hugepage_vma_check(struct vm_area_struct *vma,
+ unsigned long vm_flags,
+ bool smaps)
{
- /* The addr is used to check if the vma size fits */
- unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
+ if (!transhuge_vma_enabled(vma, vm_flags))
+ return false;
+
+ if (vm_flags & VM_NO_KHUGEPAGED)
+ return false;
+
+ /* Don't run khugepaged against DAX vma */
+ if (vma_is_dax(vma))
+ return false;

- if (!transhuge_vma_suitable(vma, addr))
+ /* 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;
- if (vma_is_anonymous(vma))
- return __transparent_hugepage_enabled(vma);
- if (vma_is_shmem(vma))
+
+ /* Enabled via shmem mount options or sysfs settings. */
+ if (shmem_file(vma->vm_file))
return shmem_huge_enabled(vma);
- if (transhuge_vma_enabled(vma, vma->vm_flags) && file_thp_enabled(vma))
+
+ if (!khugepaged_enabled())
+ return false;
+
+ /* THP settings require madvise. */
+ if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always())
+ return false;
+
+ /* Only regular file is valid */
+ if (file_thp_enabled(vma))
return true;

- return false;
+ if (!vma_is_anonymous(vma))
+ return false;
+
+ if (vma_is_temporary_stack(vma))
+ return false;
+
+ /*
+ * THPeligible bit of smaps should show 1 for proper VMAs even
+ * though anon_vma is not initialized yet.
+ */
+ if (!vma->anon_vma)
+ return smaps;
+
+ return true;
}

static bool get_huge_zero_page(void)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 5baa394e34c8..3afd87f8c0b1 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -437,46 +437,6 @@ static inline int khugepaged_test_exit(struct mm_struct *mm)
return atomic_read(&mm->mm_users) == 0;
}

-bool hugepage_vma_check(struct vm_area_struct *vma,
- unsigned long vm_flags)
-{
- if (!transhuge_vma_enabled(vma, vm_flags))
- return false;
-
- if (vm_flags & VM_NO_KHUGEPAGED)
- return false;
-
- /* Don't run khugepaged against DAX vma */
- if (vma_is_dax(vma))
- return false;
-
- /* 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. */
- if (shmem_file(vma->vm_file))
- return shmem_huge_enabled(vma);
-
- if (!khugepaged_enabled())
- return false;
-
- /* THP settings require madvise. */
- if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always())
- return false;
-
- /* Only regular file is valid */
- if (file_thp_enabled(vma))
- return true;
-
- if (!vma->anon_vma || !vma_is_anonymous(vma))
- return false;
- if (vma_is_temporary_stack(vma))
- return false;
-
- return true;
-}
-
void __khugepaged_enter(struct mm_struct *mm)
{
struct mm_slot *mm_slot;
@@ -513,7 +473,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
{
if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
khugepaged_enabled()) {
- if (hugepage_vma_check(vma, vm_flags))
+ if (hugepage_vma_check(vma, vm_flags, false))
__khugepaged_enter(vma->vm_mm);
}
}
@@ -958,7 +918,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,

if (!transhuge_vma_suitable(vma, address))
return SCAN_ADDRESS_RANGE;
- if (!hugepage_vma_check(vma, vma->vm_flags))
+ if (!hugepage_vma_check(vma, vma->vm_flags, false))
return SCAN_VMA_CHECK;
/*
* Anon VMA expected, the address may be unmapped then
@@ -1448,7 +1408,7 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
* the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check()
* will not fail the vma for missing VM_HUGEPAGE
*/
- if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE))
+ if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE, false))
return;

/* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */
@@ -2143,7 +2103,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
progress++;
break;
}
- if (!hugepage_vma_check(vma, vma->vm_flags)) {
+ if (!hugepage_vma_check(vma, vma->vm_flags, false)) {
skip:
progress++;
continue;
--
2.26.3