linux-kernel - [PATCH v4 3/5] mm: make vma_merge() and split

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Message-ID: <405f2be10e20c4e9fbcc9fe6b2dfea105f6642e0.1697043508.git.lstoakes@gmail.com>
Date:   Wed, 11 Oct 2023 18:04:29 +0100
From:   Lorenzo Stoakes <lstoakes@...il.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>
Cc:     "=Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        linux-fsdevel@...r.kernel.org, Lorenzo Stoakes <lstoakes@...il.com>
Subject: [PATCH v4 3/5] mm: make vma_merge() and split_vma() internal

Now the common pattern of - attempting a merge via vma_merge() and should
this fail splitting VMAs via split_vma() - has been abstracted, the former
can be placed into mm/internal.h and the latter made static.

In addition, the split_vma() nommu variant also need not be exported.

Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
Signed-off-by: Lorenzo Stoakes <lstoakes@...il.com>
---
 include/linux/mm.h | 9 ---------
 mm/internal.h      | 9 +++++++++
 mm/mmap.c          | 8 ++++----
 mm/nommu.c         | 4 ++--
 4 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 83ee1f35febe..74d7547ffb70 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3237,16 +3237,7 @@ extern int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
 		      struct vm_area_struct *next);
 extern int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
 		       unsigned long start, unsigned long end, pgoff_t pgoff);
-extern struct vm_area_struct *vma_merge(struct vma_iterator *vmi,
-	struct mm_struct *, struct vm_area_struct *prev, unsigned long addr,
-	unsigned long end, unsigned long vm_flags, struct anon_vma *,
-	struct file *, pgoff_t, struct mempolicy *, struct vm_userfaultfd_ctx,
-	struct anon_vma_name *);
 extern struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *);
-extern int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *,
-		       unsigned long addr, int new_below);
-extern int split_vma(struct vma_iterator *vmi, struct vm_area_struct *,
-			 unsigned long addr, int new_below);
 extern int insert_vm_struct(struct mm_struct *, struct vm_area_struct *);
 extern void unlink_file_vma(struct vm_area_struct *);
 extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
diff --git a/mm/internal.h b/mm/internal.h
index 3a72975425bb..ddaeb9f2d9d7 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1011,6 +1011,15 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
 				   unsigned long addr, pmd_t *pmd,
 				   unsigned int flags);
 
+/*
+ * mm/mmap.c
+ */
+struct vm_area_struct *vma_merge(struct vma_iterator *vmi,
+	struct mm_struct *, struct vm_area_struct *prev, unsigned long addr,
+	unsigned long end, unsigned long vm_flags, struct anon_vma *,
+	struct file *, pgoff_t, struct mempolicy *, struct vm_userfaultfd_ctx,
+	struct anon_vma_name *);
+
 enum {
 	/* mark page accessed */
 	FOLL_TOUCH = 1 << 16,
diff --git a/mm/mmap.c b/mm/mmap.c
index bca685820763..a516f2412f79 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2346,8 +2346,8 @@ static void unmap_region(struct mm_struct *mm, struct ma_state *mas,
  * has already been checked or doesn't make sense to fail.
  * VMA Iterator will point to the end VMA.
  */
-int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
-		unsigned long addr, int new_below)
+static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
+		       unsigned long addr, int new_below)
 {
 	struct vma_prepare vp;
 	struct vm_area_struct *new;
@@ -2428,8 +2428,8 @@ int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
  * Split a vma into two pieces at address 'addr', a new vma is allocated
  * either for the first part or the tail.
  */
-int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
-	      unsigned long addr, int new_below)
+static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
+		     unsigned long addr, int new_below)
 {
 	if (vma->vm_mm->map_count >= sysctl_max_map_count)
 		return -ENOMEM;
diff --git a/mm/nommu.c b/mm/nommu.c
index f9553579389b..fc4afe924ad5 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1305,8 +1305,8 @@ SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
  * split a vma into two pieces at address 'addr', a new vma is allocated either
  * for the first part or the tail.
  */
-int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
-	      unsigned long addr, int new_below)
+static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
+		     unsigned long addr, int new_below)
 {
 	struct vm_area_struct *new;
 	struct vm_region *region;
-- 
2.42.0