Merge tag 'locking-urgent-2026-09-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fixes from Ingo Molnar:

 - Fix a softirq processing delay bug in local_interrupt_disable(),
   which should mostly only affect the Rust runtime (Boqun Feng)

 - Remove the hardirq_disable_count() function which caused the
   previous bug and is now unused & unnecessary (Boqun Feng)

 - lockdep: Invalidate stale class_cache entries for zapped classes
   (Eric Dumazet)

 - Fix rt_mutex specific futex scheduling helpers
   (Sebastian Andrzej Siewior)

 - Fix rcuwait use-after-free race during futex requeue PI (Yao Kai)

* tag 'locking-urgent-2026-09-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Prevent rcuwait use-after-free during requeue PI
  futex: Provide rt_mutex_.*_schedule() equivalents for futex scheduling
  locking/lockdep: Invalidate stale class_cache entries for zapped classes
  preempt: Remove hardirq_disable_count()
  interrupt: Disable interrupt before modifying hardirq_disable counter

3 files changed, 13 insertions, 15 deletions

diff --git a/include/linux/interrupt_rc.h b/include/linux/interrupt_rc.h
index b9a7f05ecf42..a9ed937a80e7 100644
--- a/include/linux/interrupt_rc.h
+++ b/include/linux/interrupt_rc.h
@@ -20,11 +20,8 @@
 /* Per-CPU interrupt disabling state for local_interrupt_{disable,enable}(). */
 DECLARE_PER_CPU(unsigned long, local_interrupt_disable_state);
 
-static __always_inline void __local_interrupt_disable(void)
+static __always_inline void __local_interrupt_save_state(unsigned long flags)
 {
-	unsigned long flags;
-
-	local_irq_save(flags);
 	raw_cpu_write(local_interrupt_disable_state, flags);
 }
 
@@ -36,9 +33,9 @@ static __always_inline void __local_interrupt_enable(void)
 }
 
 #ifndef INSTANTIATE_EXPORTED_INTERRUPT_DISABLE
-static __always_inline void _local_interrupt_disable(void)
+static __always_inline void _local_interrupt_save_state(unsigned long flags)
 {
-	__local_interrupt_disable();
+	__local_interrupt_save_state(flags);
 }
 
 static __always_inline void _local_interrupt_enable(void)
@@ -46,27 +43,30 @@ static __always_inline void _local_interrupt_enable(void)
 	__local_interrupt_enable();
 }
 #else
-extern void _local_interrupt_disable(void);
+extern void _local_interrupt_save_state(unsigned long flags);
 extern void _local_interrupt_enable(void);
 #endif
 
 #else /* !MODULE */
-extern void _local_interrupt_disable(void);
+extern void _local_interrupt_save_state(unsigned long flags);
 extern void _local_interrupt_enable(void);
 #endif /* !MODULE */
 
+#define hardirq_disable_enter()	__preempt_count_add_return(HARDIRQ_DISABLE_OFFSET)
+#define hardirq_disable_exit()	__preempt_count_sub_return(HARDIRQ_DISABLE_OFFSET)
+
 static inline void local_interrupt_disable(void)
 {
 	int new_count;
+	unsigned long flags;
 
 	WARN_ON_ONCE(in_nmi());
 
+	local_irq_save(flags);
 	new_count = hardirq_disable_enter();
 
-	/* Interrupts can happen here, but it's OK, see __irq_exit_rcu(). */
-
 	if ((new_count & HARDIRQ_DISABLE_MASK) == HARDIRQ_DISABLE_OFFSET)
-		_local_interrupt_disable();
+		_local_interrupt_save_state(flags);
 }
 
 static inline void local_interrupt_enable(void)
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index 8299657f0f86..2e689de7b29a 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -168,10 +168,6 @@ static __always_inline unsigned char interrupt_context_level(void)
 #define in_softirq()		(softirq_count())
 #define in_interrupt()		(irq_count())
 
-#define hardirq_disable_count()	((preempt_count() & HARDIRQ_DISABLE_MASK) >> HARDIRQ_DISABLE_SHIFT)
-#define hardirq_disable_enter()	__preempt_count_add_return(HARDIRQ_DISABLE_OFFSET)
-#define hardirq_disable_exit()	__preempt_count_sub_return(HARDIRQ_DISABLE_OFFSET)
-
 /*
  * The preempt_count offset after preempt_disable();
  */
diff --git a/include/linux/sched/rt.h b/include/linux/sched/rt.h
index 4e3338103654..922935cc3383 100644
--- a/include/linux/sched/rt.h
+++ b/include/linux/sched/rt.h
@@ -52,8 +52,10 @@ static inline bool rt_or_dl_task_policy(struct task_struct *tsk)
 
 #ifdef CONFIG_RT_MUTEXES
 extern void rt_mutex_pre_schedule(void);
+extern void rt_mutex_futex_pre_schedule(void);
 extern void rt_mutex_schedule(void);
 extern void rt_mutex_post_schedule(void);
+extern void rt_mutex_futex_post_schedule(void);
 
 /*
  * Must hold either p->pi_lock or task_rq(p)->lock.