linux-kernel - [PATCH] mm/vma: small VMA lock cleanups

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Message-ID: <20251024090902.1118174-1-lorenzo.stoakes@oracle.com>
Date: Fri, 24 Oct 2025 10:09:02 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Suren Baghdasaryan <surenb@...gle.com>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Shakeel Butt <shakeel.butt@...ux.dev>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] mm/vma: small VMA lock cleanups

We declare vma_start_read() as a static function in mm/mmap_lock.c, so
there is no need to provide a stub for !CONFIG_PER_VMA_LOCK.

__is_vma_write_locked() is declared in a header and should therefore be static
inline.

Put parens around (refcnt & VMA_LOCK_OFFSET) in is_vma_writer_only() to make
precedence clear.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
---
 include/linux/mmap_lock.h | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
index 2c9fffa58714..e05da70dc0cb 100644
--- a/include/linux/mmap_lock.h
+++ b/include/linux/mmap_lock.h
@@ -130,7 +130,7 @@ static inline bool is_vma_writer_only(int refcnt)
 	 * a detached vma happens only in vma_mark_detached() and is a rare
 	 * case, therefore most of the time there will be no unnecessary wakeup.
 	 */
-	return refcnt & VMA_LOCK_OFFSET && refcnt <= VMA_LOCK_OFFSET + 1;
+	return (refcnt & VMA_LOCK_OFFSET) && refcnt <= VMA_LOCK_OFFSET + 1;
 }
 
 static inline void vma_refcount_put(struct vm_area_struct *vma)
@@ -183,7 +183,7 @@ static inline void vma_end_read(struct vm_area_struct *vma)
 }
 
 /* WARNING! Can only be used if mmap_lock is expected to be write-locked */
-static bool __is_vma_write_locked(struct vm_area_struct *vma, unsigned int *mm_lock_seq)
+static inline bool __is_vma_write_locked(struct vm_area_struct *vma, unsigned int *mm_lock_seq)
 {
 	mmap_assert_write_locked(vma->vm_mm);
 
@@ -281,9 +281,6 @@ static inline bool mmap_lock_speculate_retry(struct mm_struct *mm, unsigned int
 	return true;
 }
 static inline void vma_lock_init(struct vm_area_struct *vma, bool reset_refcnt) {}
-static inline struct vm_area_struct *vma_start_read(struct mm_struct *mm,
-						    struct vm_area_struct *vma)
-		{ return NULL; }
 static inline void vma_end_read(struct vm_area_struct *vma) {}
 static inline void vma_start_write(struct vm_area_struct *vma) {}
 static inline void vma_assert_write_locked(struct vm_area_struct *vma)
-- 
2.51.0