[PATCH RESEND v3 05/10] mm/vma: de-duplicate __vma_enter_locked() error path

Lorenzo Stoakes
2026-01-22T13:03:55Z

We're doing precisely the same thing that __vma_exit_locked() does, so
de-duplicate this code and keep the refcount primitive in one place.

No functional change intended.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
mm/mmap_lock.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c
index 9563bfb051f4..7a0361cff6db 100644
--- a/mm/mmap_lock.c
+++ b/mm/mmap_lock.c
@@ -45,6 +45,14 @@ EXPORT_SYMBOL(__mmap_lock_do_trace_released);

#ifdef CONFIG_MMU
#ifdef CONFIG_PER_VMA_LOCK
+
+static inline void __vma_exit_locked(struct vm_area_struct *vma, bool *detached)
+{
+ *detached = refcount_sub_and_test(VM_REFCNT_EXCLUDE_READERS_FLAG,
+ &vma->vm_refcnt);
+ __vma_lockdep_release_exclusive(vma);
+}
+
/*
* __vma_enter_locked() returns 0 immediately if the vma is not
* attached, otherwise it waits for any current readers to finish and
@@ -77,7 +85,10 @@ static inline int __vma_enter_locked(struct vm_area_struct *vma,
refcount_read(&vma->vm_refcnt) == tgt_refcnt,
state);
if (err) {
- if (refcount_sub_and_test(VM_REFCNT_EXCLUDE_READERS_FLAG, &vma->vm_refcnt)) {
+ bool detached;
+
+ __vma_exit_locked(vma, &detached);
+ if (detached) {
/*
* The wait failed, but the last reader went away
* as well. Tell the caller the VMA is detached.
@@ -85,7 +96,6 @@ static inline int __vma_enter_locked(struct vm_area_struct *vma,
WARN_ON_ONCE(!detaching);
err = 0;
}
- __vma_lockdep_release_exclusive(vma);
return err;
}
__vma_lockdep_stat_mark_acquired(vma);
@@ -93,13 +103,6 @@ static inline int __vma_enter_locked(struct vm_area_struct *vma,
return 1;
}

-static inline void __vma_exit_locked(struct vm_area_struct *vma, bool *detached)
-{
- *detached = refcount_sub_and_test(VM_REFCNT_EXCLUDE_READERS_FLAG,
- &vma->vm_refcnt);
- __vma_lockdep_release_exclusive(vma);
-}
-
int __vma_start_write(struct vm_area_struct *vma, unsigned int mm_lock_seq,
int state)
{
--
2.52.0