linux-kernel - [PATCH 2/2] mm, rmap: handle anon_vma

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Message-ID: <20241209132549.2878604-3-ruanjinjie@huawei.com>
Date: Mon, 9 Dec 2024 21:25:49 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: <viro@...iv.linux.org.uk>, <brauner@...nel.org>, <jack@...e.cz>,
	<akpm@...ux-foundation.org>, <Liam.Howlett@...cle.com>,
	<lokeshgidra@...gle.com>, <lorenzo.stoakes@...cle.com>, <rppt@...nel.org>,
	<aarcange@...hat.com>, <ruanjinjie@...wei.com>, <Jason@...c4.com>,
	<linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-mm@...ck.org>
Subject: [PATCH 2/2] mm, rmap: handle anon_vma_fork() NULL check inline

Check the anon_vma of pvma inline so we can avoid the function call
overhead if the anon_vma is NULL.

Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
---
 include/linux/rmap.h | 12 +++++++++++-
 mm/rmap.c            |  6 +-----
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 683a04088f3f..9ddba9b23a1c 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -154,7 +154,17 @@ void anon_vma_init(void);	/* create anon_vma_cachep */
 int  __anon_vma_prepare(struct vm_area_struct *);
 void unlink_anon_vmas(struct vm_area_struct *);
 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
-int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
+
+int __anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
+static inline int anon_vma_fork(struct vm_area_struct *vma,
+				struct vm_area_struct *pvma)
+{
+	/* Don't bother if the parent process has no anon_vma here. */
+	if (!pvma->anon_vma)
+		return 0;
+
+	return __anon_vma_fork(vma, pvma);
+}
 
 static inline int anon_vma_prepare(struct vm_area_struct *vma)
 {
diff --git a/mm/rmap.c b/mm/rmap.c
index c6c4d4ea29a7..06e9b68447c2 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -331,16 +331,12 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
  * the corresponding VMA in the parent process is attached to.
  * Returns 0 on success, non-zero on failure.
  */
-int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
+int __anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
 {
 	struct anon_vma_chain *avc;
 	struct anon_vma *anon_vma;
 	int error;
 
-	/* Don't bother if the parent process has no anon_vma here. */
-	if (!pvma->anon_vma)
-		return 0;
-
 	/* Drop inherited anon_vma, we'll reuse existing or allocate new. */
 	vma->anon_vma = NULL;
 
-- 
2.34.1