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From: Sumanth Korikkar <sumanthk@linux.ibm.com>
To: akpm@linux-foundation.org, linux-mm@kvack.org
Cc: hughd@google.com, hca@linux.ibm.com, gor@linux.ibm.com,
        agordeev@linux.ibm.com, iii@linux.ibm.com, linux-s390@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Sumanth Korikkar <sumanthk@linux.ibm.com>
Subject: [PATCH] mm/shmem: Inline shmem_is_huge() for disabled transparent hugepages
Date: Tue,  9 Apr 2024 17:54:07 +0200
Message-Id: <20240409155407.2322714-1-sumanthk@linux.ibm.com>
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In order to  minimize code size (CONFIG_CC_OPTIMIZE_FOR_SIZE=y),
compiler might choose to make a regular function call (out-of-line) for
shmem_is_huge() instead of inlining it. When transparent hugepages are
disabled (CONFIG_TRANSPARENT_HUGEPAGE=n), it can cause compilation
error.

mm/shmem.c: In function ‘shmem_getattr’:
/include/linux/huge_mm.h:383:27: note: in expansion of macro ‘BUILD_BUG’
  383 | #define HPAGE_PMD_SIZE ({ BUILD_BUG(); 0; })
      |                           ^~~~~~~~~
mm/shmem.c:1148:33: note: in expansion of macro ‘HPAGE_PMD_SIZE’
 1148 |                 stat->blksize = HPAGE_PMD_SIZE;

To prevent the possible error, always inline shmem_is_huge() when
transparent hugepages are disabled.

Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
---
 include/linux/shmem_fs.h | 9 +++++++++
 mm/shmem.c               | 6 ------
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index a4c15db2f5e5..3fb18f7eb73e 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -110,8 +110,17 @@ extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
 extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
 int shmem_unuse(unsigned int type);
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 extern bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
 			  struct mm_struct *mm, unsigned long vm_flags);
+#else
+static __always_inline bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
+					  struct mm_struct *mm, unsigned long vm_flags)
+{
+	return false;
+}
+#endif
+
 #ifdef CONFIG_SHMEM
 extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
 #else
diff --git a/mm/shmem.c b/mm/shmem.c
index 0aad0d9a621b..94ab99b6b574 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -748,12 +748,6 @@ static long shmem_unused_huge_count(struct super_block *sb,
 
 #define shmem_huge SHMEM_HUGE_DENY
 
-bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
-		   struct mm_struct *mm, unsigned long vm_flags)
-{
-	return false;
-}
-
 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
 		struct shrink_control *sc, unsigned long nr_to_split)
 {
-- 
2.40.1