[PATCH v7 10/17] mm: uninline the main body of vma_start_write()

Suren Baghdasaryan
2024-12-26T17:07:41Z

vma_start_write() is used in many places and will grow in size very soon.
It is not used in performance critical paths and uninlining it should
limit the future code size growth.
No functional changes.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
include/linux/mm.h | 12 +++---------
mm/memory.c | 14 ++++++++++++++
2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ab27de9729d8..ea4c4228b125 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -787,6 +787,8 @@ static bool __is_vma_write_locked(struct vm_area_struct *vma, unsigned int *mm_l
return (vma->vm_lock_seq == *mm_lock_seq);
}

+void __vma_start_write(struct vm_area_struct *vma, unsigned int mm_lock_seq);
+
/*
* Begin writing to a VMA.
* Exclude concurrent readers under the per-VMA lock until the currently
@@ -799,15 +801,7 @@ static inline void vma_start_write(struct vm_area_struct *vma)
if (__is_vma_write_locked(vma, &mm_lock_seq))
return;

- down_write(&vma->vm_lock.lock);
- /*
- * We should use WRITE_ONCE() here because we can have concurrent reads
- * from the early lockless pessimistic check in vma_start_read().
- * We don't really care about the correctness of that early check, but
- * we should use WRITE_ONCE() for cleanliness and to keep KCSAN happy.
- */
- WRITE_ONCE(vma->vm_lock_seq, mm_lock_seq);
- up_write(&vma->vm_lock.lock);
+ __vma_start_write(vma, mm_lock_seq);
}

static inline void vma_assert_write_locked(struct vm_area_struct *vma)
diff --git a/mm/memory.c b/mm/memory.c
index d0dee2282325..236fdecd44d6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6328,6 +6328,20 @@ struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm,
#endif

#ifdef CONFIG_PER_VMA_LOCK
+void __vma_start_write(struct vm_area_struct *vma, unsigned int mm_lock_seq)
+{
+ down_write(&vma->vm_lock.lock);
+ /*
+ * We should use WRITE_ONCE() here because we can have concurrent reads
+ * from the early lockless pessimistic check in vma_start_read().
+ * We don't really care about the correctness of that early check, but
+ * we should use WRITE_ONCE() for cleanliness and to keep KCSAN happy.
+ */
+ WRITE_ONCE(vma->vm_lock_seq, mm_lock_seq);
+ up_write(&vma->vm_lock.lock);
+}
+EXPORT_SYMBOL_GPL(__vma_start_write);
+
/*
* Lookup and lock a VMA under RCU protection. Returned VMA is guaranteed to be
* stable and not isolated. If the VMA is not found or is being modified the
--
2.47.1.613.gc27f4b7a9f-goog