[2/4] mm: make vma_merge() and split_vma() internal

Commit Message

Lorenzo Stoakes Oct. 8, 2023, 8:23 p.m. UTC

Now the vma_merge()/split_vma() pattern has been abstracted, we use it
entirely internally within mm/mmap.c, so make the function static. We also
no longer need vma_merge() anywhere else except mm/mremap.c, so make it
internal.

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

Signed-off-by: Lorenzo Stoakes <[e-mail]>
---
 include/linux/mm.h | 9 ---------
 mm/internal.h      | 9 +++++++++
 mm/mmap.c          | 8 ++++----
 mm/nommu.c         | 4 ++--
 4 files changed, 15 insertions(+), 15 deletions(-)

Comments

Vlastimil Babka Oct. 9, 2023, 3:45 p.m. UTC | #1

On 10/8/23 22:23, Lorenzo Stoakes wrote:
> Now the vma_merge()/split_vma() pattern has been abstracted, we use it

"it" refers to split_vma() only so "the latter" or "split_vma()"?

> entirely internally within mm/mmap.c, so make the function static. We also
> no longer need vma_merge() anywhere else except mm/mremap.c, so make it
> internal.
> 
> In addition, the split_vma() nommu variant also need not be exported.
> 
> Signed-off-by: Lorenzo Stoakes <[e-mail]>

Reviewed-by: Vlastimil Babka <[e-mail]>

Lorenzo Stoakes Oct. 9, 2023, 6:20 p.m. UTC | #2

On Mon, Oct 09, 2023 at 05:45:26PM +0200, Vlastimil Babka wrote:
> On 10/8/23 22:23, Lorenzo Stoakes wrote:
> > Now the vma_merge()/split_vma() pattern has been abstracted, we use it
>
> "it" refers to split_vma() only so "the latter" or "split_vma()"?
>

I mean to say the pattern of attempting vma_merge(), then if that fails,
splitting as necessary. I will try to clarify the language in v2.

> > entirely internally within mm/mmap.c, so make the function static. We also
> > no longer need vma_merge() anywhere else except mm/mremap.c, so make it
> > internal.
> >
> > In addition, the split_vma() nommu variant also need not be exported.
> >
> > Signed-off-by: Lorenzo Stoakes <[e-mail]>
>
> Reviewed-by: Vlastimil Babka <[e-mail]>
>

Thanks!

Patch

diff --git a/include/linux/mm.h b/include/linux/mm.h
index c069813f215f..6aa532682094 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 8c21171b431f..58d71f84e917 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;