linux-kernel - [PATCH] mm/rmap: Move anon_vma initialization to anon_vma

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Message-Id: <20250415092548.271718-1-ye.liu@linux.dev>
Date: Tue, 15 Apr 2025 17:25:48 +0800
From: Ye Liu <ye.liu@...ux.dev>
To: akpm@...ux-foundation.org
Cc: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Ye Liu <liuye@...inos.cn>
Subject: [PATCH] mm/rmap: Move anon_vma initialization to anon_vma_ctor()

From: Ye Liu <liuye@...inos.cn>

Currently, some initialization of anon_vma is performed in
anon_vma_alloc(). Move the initialization to anon_vma_ctor()
so that all object setup is handled in one place.

Signed-off-by: Ye Liu <liuye@...inos.cn>
---
 mm/rmap.c | 27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index 67bb273dfb80..9802b1c27e4b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -89,22 +89,7 @@ static struct kmem_cache *anon_vma_chain_cachep;
 
 static inline struct anon_vma *anon_vma_alloc(void)
 {
-	struct anon_vma *anon_vma;
-
-	anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
-	if (anon_vma) {
-		atomic_set(&anon_vma->refcount, 1);
-		anon_vma->num_children = 0;
-		anon_vma->num_active_vmas = 0;
-		anon_vma->parent = anon_vma;
-		/*
-		 * Initialise the anon_vma root to point to itself. If called
-		 * from fork, the root will be reset to the parents anon_vma.
-		 */
-		anon_vma->root = anon_vma;
-	}
-
-	return anon_vma;
+	return kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
 }
 
 static inline void anon_vma_free(struct anon_vma *anon_vma)
@@ -453,8 +438,16 @@ static void anon_vma_ctor(void *data)
 	struct anon_vma *anon_vma = data;
 
 	init_rwsem(&anon_vma->rwsem);
-	atomic_set(&anon_vma->refcount, 0);
+	atomic_set(&anon_vma->refcount, 1);
 	anon_vma->rb_root = RB_ROOT_CACHED;
+	anon_vma->num_children = 0;
+	anon_vma->num_active_vmas = 0;
+	anon_vma->parent = anon_vma;
+	/*
+	 * Initialise the anon_vma root to point to itself. If called
+	 * from fork, the root will be reset to the parents anon_vma.
+	 */
+	anon_vma->root = anon_vma;
 }
 
 void __init anon_vma_init(void)
-- 
2.25.1