mm/huge_memory.c: add missing read-only THP checking in transparent_hugepage_enabled()

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.  We rename transparent_hugepage_enabled to
transparent_hugepage_active to make the code easier to follow as suggested
by David Hildenbrand.

[linmiaohe@huawei.com: define transhuge_vma_enabled next to transhuge_vma_suitable]
  Link: https://lkml.kernel.org/r/20210514093007.4117906-1-linmiaohe@huawei.com

Link: https://lkml.kernel.org/r/20210511134857.1581273-4-linmiaohe@huawei.com
Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 12 insertions, 6 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a76b3835251d..8529ba6af151 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -64,7 +64,14 @@ static atomic_t huge_zero_refcount;
 struct page *huge_zero_page __read_mostly;
 unsigned long huge_zero_pfn __read_mostly = ~0UL;
 
-bool transparent_hugepage_enabled(struct vm_area_struct *vma)
+static inline bool file_thp_enabled(struct vm_area_struct *vma)
+{
+	return transhuge_vma_enabled(vma, vma->vm_flags) && vma->vm_file &&
+	       !inode_is_open_for_write(vma->vm_file->f_inode) &&
+	       (vma->vm_flags & VM_EXEC);
+}
+
+bool transparent_hugepage_active(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;
@@ -75,6 +82,8 @@ bool transparent_hugepage_enabled(struct vm_area_struct *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))
+		return file_thp_enabled(vma);
 
 	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 e72931b9246c..1155279a6276 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4040,8 +4040,7 @@ 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;