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>

1 files changed, 35 insertions, 22 deletions

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 8a5f49abcfa2..b4e1ebaae825 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -115,9 +115,34 @@ extern struct kobj_attribute shmem_enabled_attr;
 
 extern unsigned long transparent_hugepage_flags;
 
+static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
+		unsigned long haddr)
+{
+	/* Don't have to check pgoff for anonymous vma */
+	if (!vma_is_anonymous(vma)) {
+		if (!IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
+				HPAGE_PMD_NR))
+			return false;
+	}
+
+	if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
+		return false;
+	return true;
+}
+
+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
+ * Use transparent_hugepage_active otherwise
  */
 static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
 {
@@ -128,15 +153,12 @@ 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;
 
@@ -150,22 +172,7 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
 	return false;
 }
 
-bool transparent_hugepage_enabled(struct vm_area_struct *vma);
-
-static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
-		unsigned long haddr)
-{
-	/* Don't have to check pgoff for anonymous vma */
-	if (!vma_is_anonymous(vma)) {
-		if (!IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
-				HPAGE_PMD_NR))
-			return false;
-	}
-
-	if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
-		return false;
-	return true;
-}
+bool transparent_hugepage_active(struct vm_area_struct *vma);
 
 #define transparent_hugepage_use_zero_page()				\
 	(transparent_hugepage_flags &					\
@@ -352,7 +359,7 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
 	return false;
 }
 
-static inline bool transparent_hugepage_enabled(struct vm_area_struct *vma)
+static inline bool transparent_hugepage_active(struct vm_area_struct *vma)
 {
 	return false;
 }
@@ -363,6 +370,12 @@ 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)