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Subject[PATCH v2 3/5] mm/huge_memory.c: add missing read-only THP checking in transparent_hugepage_enabled()
Date
Since commit 99cb0dbd47a1 ("mm,thp: add read-only THP support for
(non-shmem) FS"), read-only THP file mapping is supported. But it
forgot to add checking for it in transparent_hugepage_enabled().
To fix it, we add checking for read-only THP file mapping and also
introduce helper transhuge_vma_enabled() to check whether thp is
enabled for specified vma to reduce duplicated code.

Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
include/linux/huge_mm.h | 21 +++++++++++++++++----
mm/huge_memory.c | 6 ++++++
mm/khugepaged.c | 4 +---
mm/shmem.c | 3 +--
4 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 0a526f211fec..f460b74619fc 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -115,6 +115,16 @@ extern struct kobj_attribute shmem_enabled_attr;

extern unsigned long transparent_hugepage_flags;

+static inline bool transhuge_vma_enabled(struct vm_area_struct *vma,
+ unsigned long vm_flags)
+{
+ /* Explicitly disabled through madvise. */
+ if ((vm_flags & VM_NOHUGEPAGE) ||
+ test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
+ return false;
+ return true;
+}
+
/*
* to be used on vmas which are known to support THP.
* Use transparent_hugepage_enabled otherwise
@@ -128,15 +138,12 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER_DAX))
return false;

- if (vma->vm_flags & VM_NOHUGEPAGE)
+ if (!transhuge_vma_enabled(vma, vma->vm_flags))
return false;

if (vma_is_temporary_stack(vma))
return false;

- if (test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
- return false;
-
if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_FLAG))
return true;

@@ -362,6 +369,12 @@ static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
return false;
}

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

static inline bool is_transparent_hugepage(struct page *page)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 76ca1eb2a223..e24a96de2e37 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -68,12 +68,18 @@ bool transparent_hugepage_enabled(struct vm_area_struct *vma)
/* 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, vma->vm_flags))
+ return false;
if (!transhuge_vma_suitable(vma, addr))
return false;
if (vma_is_anonymous(vma))
return __transparent_hugepage_enabled(vma);
if (vma_is_shmem(vma))
return shmem_huge_enabled(vma);
+ if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && vma->vm_file &&
+ !inode_is_open_for_write(vma->vm_file->f_inode) &&
+ (vma->vm_flags & VM_EXEC))
+ return true;

return false;
}
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 6c0185fdd815..d97b20fad6e8 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -442,9 +442,7 @@ static inline int khugepaged_test_exit(struct mm_struct *mm)
static bool hugepage_vma_check(struct vm_area_struct *vma,
unsigned long vm_flags)
{
- /* Explicitly disabled through madvise. */
- if ((vm_flags & VM_NOHUGEPAGE) ||
- test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
+ if (!transhuge_vma_enabled(vma, vm_flags))
return false;

/* Enabled via shmem mount options or sysfs settings. */
diff --git a/mm/shmem.c b/mm/shmem.c
index a08cedefbfaa..1dcbec313c70 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4032,8 +4032,7 @@ bool shmem_huge_enabled(struct vm_area_struct *vma)
loff_t i_size;
pgoff_t off;

- if ((vma->vm_flags & VM_NOHUGEPAGE) ||
- test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
+ if (!transhuge_vma_enabled(vma, vma->vm_flags))
return false;
if (shmem_huge == SHMEM_HUGE_FORCE)
return true;
--
2.23.0
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