[tip: locking/urgent] futex: Clean up the redundant exit/exec functions
From: tip-bot2 for Thomas Gleixner
Date: Mon Aug 10 2026 - 03:25:41 EST
The following commit has been merged into the locking/urgent branch of tip:
Commit-ID: 0f5c25e6e04e8c4732ed59080f3d0c664886c287
Gitweb: https://git.kernel.org/tip/0f5c25e6e04e8c4732ed59080f3d0c664886c287
Author: Thomas Gleixner <tglx@xxxxxxxxxx>
AuthorDate: Fri, 07 Aug 2026 17:07:17 +02:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxx>
CommitterDate: Mon, 10 Aug 2026 09:23:19 +02:00
futex: Clean up the redundant exit/exec functions
futex_exit_release() and futex_exec_release() are identical now. That means
also exit_mm_release() and exec_mm_release() are identical.
Consolidate the whole lot and remove the redundant copies.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxx>
Reviewed-by: Kyle Zeng <kylebot@xxxxxxxxxx>
Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
fs/exec.c | 2 +-
include/linux/futex.h | 6 ++----
include/linux/sched/mm.h | 10 ++++++----
kernel/exit.c | 2 +-
kernel/fork.c | 10 ++--------
kernel/futex/core.c | 37 +++++++++++++++++--------------------
6 files changed, 29 insertions(+), 38 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 8a91c58..74d30a3 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -856,7 +856,7 @@ static int exec_mmap(struct linux_binprm *bprm)
tsk = current;
old_mm = current->mm;
/* Clean up futexes and release the mm */
- exec_mm_release(tsk, old_mm);
+ mm_exit_exec_release(tsk, old_mm);
ret = down_write_killable(&tsk->signal->exec_update_lock);
if (ret)
diff --git a/include/linux/futex.h b/include/linux/futex.h
index 51d5faa..18ed18d 100644
--- a/include/linux/futex.h
+++ b/include/linux/futex.h
@@ -71,8 +71,7 @@ static inline void futex_init_task(struct task_struct *tsk)
}
void futex_exit_recursive(struct task_struct *tsk);
-void futex_exit_release(struct task_struct *tsk);
-void futex_exec_release(struct task_struct *tsk);
+void futex_exit_exec_release(struct task_struct *tsk);
void futex_exec_done(struct task_struct *tsk);
long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
@@ -90,8 +89,7 @@ static inline int futex_hash_free(struct mm_struct *mm) { return 0; }
#else /* CONFIG_FUTEX */
static inline void futex_init_task(struct task_struct *tsk) { }
static inline void futex_exit_recursive(struct task_struct *tsk) { }
-static inline void futex_exit_release(struct task_struct *tsk) { }
-static inline void futex_exec_release(struct task_struct *tsk) { }
+static inline void futex_exit_exec_release(struct task_struct *tsk) { }
static inline void futex_exec_done(struct task_struct *tsk) { }
static inline long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
u32 __user *uaddr2, u32 val2, u32 val3)
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 95d0040..7fe7dfd 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -155,10 +155,12 @@ extern struct mm_struct *get_task_mm(struct task_struct *task);
* succeeds.
*/
extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
-/* Remove the current tasks stale references to the old mm_struct on exit() */
-extern void exit_mm_release(struct task_struct *, struct mm_struct *);
-/* Remove the current tasks stale references to the old mm_struct on exec() */
-extern void exec_mm_release(struct task_struct *, struct mm_struct *);
+
+/*
+ * Remove the current tasks stale references to the old mm_struct on exit() and
+ * exec(). Cleans up futexes as well.
+ */
+extern void mm_exit_exec_release(struct task_struct *, struct mm_struct *);
#ifdef CONFIG_MEMCG
extern void mm_update_next_owner(struct mm_struct *mm);
diff --git a/kernel/exit.c b/kernel/exit.c
index 2c0b1c0..adf93b9 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -582,7 +582,7 @@ static void exit_mm(void)
{
struct mm_struct *mm = current->mm;
- exit_mm_release(current, mm);
+ mm_exit_exec_release(current, mm);
if (!mm)
return;
diff --git a/kernel/fork.c b/kernel/fork.c
index f0e2e13..7c6918b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1502,15 +1502,9 @@ static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
complete_vfork_done(tsk);
}
-void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
+void mm_exit_exec_release(struct task_struct *tsk, struct mm_struct *mm)
{
- futex_exit_release(tsk);
- mm_release(tsk, mm);
-}
-
-void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
-{
- futex_exec_release(tsk);
+ futex_exit_exec_release(tsk);
mm_release(tsk, mm);
}
diff --git a/kernel/futex/core.c b/kernel/futex/core.c
index 3c1562d..2d1dbde 100644
--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -1537,32 +1537,29 @@ static void futex_cleanup_end(struct task_struct *tsk)
mutex_unlock(&tsk->futex.exit_mutex);
}
-void futex_exit_release(struct task_struct *tsk)
+/*
+ * Invoked from mm_exit_exec_release() to cleanup the robust lists and pi state
+ * of the outgoing task.
+ *
+ * exec() makes it interesting for futexes because the TID of the task stays the
+ * same, but from a futex perspective the task has to be treated like an exiting
+ * task. This is especially important for the sanity check for private futexes
+ * in attach_to_pi_owner() which compares the owner's mm with the waiter's mm.
+ *
+ * That check would give the wrong answer if futex_cleanup_end() would
+ * set the state to FUTEX_STATE_OK as long as the task still has the old
+ * mm.
+ *
+ * After the task has switched to the new mm it sets it to
+ * FUTEX_STATE_OK again in futex_exec_done().
+ */
+void futex_exit_exec_release(struct task_struct *tsk)
{
futex_cleanup_begin(tsk);
futex_cleanup(tsk);
futex_cleanup_end(tsk);
}
-void futex_exec_release(struct task_struct *tsk)
-{
- /*
- * exec() makes it interesting for futexes because the TID of the task
- * stays the same, but from a futex perspective the task has to be
- * treated like an exiting task. This is especially important for the
- * sanity check for private futexes in attach_to_pi_owner() which
- * compares the owner's mm with the waiter's mm.
- *
- * That check would give the wrong answer if futex_cleanup_end() would
- * set the state to FUTEX_STATE_OK as long as the task still has the old
- * mm.
- *
- * After the task has switched to the new mm it sets it to
- * FUTEX_STATE_OK again in futex_exec_done().
- */
- futex_exit_release(tsk);
-}
-
/*
* exec() has switched to the new mm. Futex operations are safe again.
*/