From 78d12c19e02d8151b1c82228ae6bb10f174a68e2 Mon Sep 17 00:00:00 2001
From: Yang Shi <shy828301@gmail.com>
Date: Thu, 19 May 2022 14:08:49 -0700
Subject: [PATCH] mm: thp: only regular file could be THP eligible

Since commit a4aeaa06d45e ("mm: khugepaged: skip huge page collapse for
special files"), khugepaged just collapses THP for regular file which is
the intended usecase for readonly fs THP.  Only show regular file as THP
eligible accordingly.

And make file_thp_enabled() available for khugepaged too in order to
remove duplicate code.

Link: https://lkml.kernel.org/r/20220510203222.24246-5-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Vlastmil Babka <vbabka@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/huge_mm.h | 14 ++++++++++++++
 mm/huge_memory.c        | 11 ++---------
 mm/khugepaged.c         |  9 ++-------
 3 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index fbf36bb1be22..de29821231c9 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -173,6 +173,20 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
 	return false;
 }
 
+static inline bool file_thp_enabled(struct vm_area_struct *vma)
+{
+	struct inode *inode;
+
+	if (!vma->vm_file)
+		return false;
+
+	inode = vma->vm_file->f_inode;
+
+	return (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) &&
+	       (vma->vm_flags & VM_EXEC) &&
+	       !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);
+}
+
 bool transparent_hugepage_active(struct vm_area_struct *vma);
 
 #define transparent_hugepage_use_zero_page()				\
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c37c870c526f..1a00bdf0f1e8 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -69,13 +69,6 @@ static atomic_t huge_zero_refcount;
 struct page *huge_zero_page __read_mostly;
 unsigned long huge_zero_pfn __read_mostly = ~0UL;
 
-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 */
@@ -87,8 +80,8 @@ bool transparent_hugepage_active(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);
+	if (transhuge_vma_enabled(vma, vma->vm_flags) && file_thp_enabled(vma))
+		return true;
 
 	return false;
 }
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 647efd46b369..1f4822dcc970 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -464,13 +464,8 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
 		return false;
 
 	/* Only regular file is valid */
-	if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && vma->vm_file &&
-	    (vm_flags & VM_EXEC)) {
-		struct inode *inode = vma->vm_file->f_inode;
-
-		return !inode_is_open_for_write(inode) &&
-			S_ISREG(inode->i_mode);
-	}
+	if (file_thp_enabled(vma))
+		return true;
 
 	if (!vma->anon_vma || !vma_is_anonymous(vma))
 		return false;