mm/vma: move stack expansion logic to mm/vma.c

We build on previous work making expand_downwards() an entirely internal
function.

This logic is subtle and so it is highly useful to get it into vma.c so we
can then userland unit test.

We must additionally move acct_stack_growth() to vma.c as it is a helper
function used by both expand_downwards() and expand_upwards().

We are also then able to mark anon_vma_interval_tree_pre_update_vma() and
anon_vma_interval_tree_post_update_vma() static as these are no longer
used by anything else.

Link: https://lkml.kernel.org/r/0feb104eff85922019d4fb29280f3afb130c5204.1733248985.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/mm/vma.h b/mm/vma.h
index c60f37d89eb1..6c460a120f82 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -139,12 +139,6 @@ void validate_mm(struct mm_struct *mm);
 #define validate_mm(mm) do { } while (0)
 #endif
 
-/* Required for expand_downwards(). */
-void anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma);
-
-/* Required for expand_downwards(). */
-void anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma);
-
 int vma_expand(struct vma_merge_struct *vmg);
 int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	       unsigned long start, unsigned long end, pgoff_t pgoff);
@@ -478,4 +472,10 @@ static inline bool can_modify_vma_madv(struct vm_area_struct *vma, int behavior)
 
 #endif
 
+#if defined(CONFIG_STACK_GROWSUP)
+int expand_upwards(struct vm_area_struct *vma, unsigned long address);
+#endif
+
+int expand_downwards(struct vm_area_struct *vma, unsigned long address);
+
 #endif	/* __MM_VMA_H */