From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Date: Fri, 23 Jan 2026 20:12:15 +0000 (+0000)
Subject: mm/vma: de-duplicate __vma_enter_locked() error path
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e5aeb75dc4049d92f6ad0da23cc6b22ffcbb9d39;p=thirdparty%2Fkernel%2Flinux.git

mm/vma: de-duplicate __vma_enter_locked() error path

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.

Link: https://lkml.kernel.org/r/c9759b593f6a158e984fa87abe2c3cbd368ef825.1769198904.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Waiman Long <longman@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c
index 85b2ae1d97208..1fabda07c922f 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)
 {