Merge tag 'locking-core-2026-02-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "Lock debugging:

   - Implement compiler-driven static analysis locking context checking,
     using the upcoming Clang 22 compiler's context analysis features
     (Marco Elver)

     We removed Sparse context analysis support, because prior to
     removal even a defconfig kernel produced 1,700+ context tracking
     Sparse warnings, the overwhelming majority of which are false
     positives. On an allmodconfig kernel the number of false positive
     context tracking Sparse warnings grows to over 5,200... On the plus
     side of the balance actual locking bugs found by Sparse context
     analysis is also rather ... sparse: I found only 3 such commits in
     the last 3 years. So the rate of false positives and the
     maintenance overhead is rather high and there appears to be no
     active policy in place to achieve a zero-warnings baseline to move
     the annotations & fixers to developers who introduce new code.

     Clang context analysis is more complete and more aggressive in
     trying to find bugs, at least in principle. Plus it has a different
     model to enabling it: it's enabled subsystem by subsystem, which
     results in zero warnings on all relevant kernel builds (as far as
     our testing managed to cover it). Which allowed us to enable it by
     default, similar to other compiler warnings, with the expectation
     that there are no warnings going forward. This enforces a
     zero-warnings baseline on clang-22+ builds (Which are still limited
     in distribution, admittedly)

     Hopefully the Clang approach can lead to a more maintainable
     zero-warnings status quo and policy, with more and more subsystems
     and drivers enabling the feature. Context tracking can be enabled
     for all kernel code via WARN_CONTEXT_ANALYSIS_ALL=y (default
     disabled), but this will generate a lot of false positives.

     ( Having said that, Sparse support could still be added back,
       if anyone is interested - the removal patch is still
       relatively straightforward to revert at this stage. )

  Rust integration updates: (Alice Ryhl, Fujita Tomonori, Boqun Feng)

    - Add support for Atomic<i8/i16/bool> and replace most Rust native
      AtomicBool usages with Atomic<bool>

    - Clean up LockClassKey and improve its documentation

    - Add missing Send and Sync trait implementation for SetOnce

    - Make ARef Unpin as it is supposed to be

    - Add __rust_helper to a few Rust helpers as a preparation for
      helper LTO

    - Inline various lock related functions to avoid additional function
      calls

  WW mutexes:

    - Extend ww_mutex tests and other test-ww_mutex updates (John
      Stultz)

  Misc fixes and cleanups:

    - rcu: Mark lockdep_assert_rcu_helper() __always_inline (Arnd
      Bergmann)

    - locking/local_lock: Include more missing headers (Peter Zijlstra)

    - seqlock: fix scoped_seqlock_read kernel-doc (Randy Dunlap)

    - rust: sync: Replace `kernel::c_str!` with C-Strings (Tamir
      Duberstein)"

* tag 'locking-core-2026-02-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (90 commits)
  locking/rwlock: Fix write_trylock_irqsave() with CONFIG_INLINE_WRITE_TRYLOCK
  rcu: Mark lockdep_assert_rcu_helper() __always_inline
  compiler-context-analysis: Remove __assume_ctx_lock from initializers
  tomoyo: Use scoped init guard
  crypto: Use scoped init guard
  kcov: Use scoped init guard
  compiler-context-analysis: Introduce scoped init guards
  cleanup: Make __DEFINE_LOCK_GUARD handle commas in initializers
  seqlock: fix scoped_seqlock_read kernel-doc
  tools: Update context analysis macros in compiler_types.h
  rust: sync: Replace `kernel::c_str!` with C-Strings
  rust: sync: Inline various lock related methods
  rust: helpers: Move #define __rust_helper out of atomic.c
  rust: wait: Add __rust_helper to helpers
  rust: time: Add __rust_helper to helpers
  rust: task: Add __rust_helper to helpers
  rust: sync: Add __rust_helper to helpers
  rust: refcount: Add __rust_helper to helpers
  rust: rcu: Add __rust_helper to helpers
  rust: processor: Add __rust_helper to helpers
  ...

1 files changed, 62 insertions, 27 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 854984967fe2..d78d7b6d30bb 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -396,6 +396,8 @@ static atomic_t sched_core_count;
 static struct cpumask sched_core_mask;
 
 static void sched_core_lock(int cpu, unsigned long *flags)
+	__context_unsafe(/* acquires multiple */)
+	__acquires(&runqueues.__lock) /* overapproximation */
 {
 	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
 	int t, i = 0;
@@ -406,6 +408,8 @@ static void sched_core_lock(int cpu, unsigned long *flags)
 }
 
 static void sched_core_unlock(int cpu, unsigned long *flags)
+	__context_unsafe(/* releases multiple */)
+	__releases(&runqueues.__lock) /* overapproximation */
 {
 	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
 	int t;
@@ -630,6 +634,7 @@ EXPORT_SYMBOL(__trace_set_current_state);
  */
 
 void raw_spin_rq_lock_nested(struct rq *rq, int subclass)
+	__context_unsafe()
 {
 	raw_spinlock_t *lock;
 
@@ -655,6 +660,7 @@ void raw_spin_rq_lock_nested(struct rq *rq, int subclass)
 }
 
 bool raw_spin_rq_trylock(struct rq *rq)
+	__context_unsafe()
 {
 	raw_spinlock_t *lock;
 	bool ret;
@@ -696,15 +702,16 @@ void double_rq_lock(struct rq *rq1, struct rq *rq2)
 	raw_spin_rq_lock(rq1);
 	if (__rq_lockp(rq1) != __rq_lockp(rq2))
 		raw_spin_rq_lock_nested(rq2, SINGLE_DEPTH_NESTING);
+	else
+		__acquire_ctx_lock(__rq_lockp(rq2)); /* fake acquire */
 
 	double_rq_clock_clear_update(rq1, rq2);
 }
 
 /*
- * __task_rq_lock - lock the rq @p resides on.
+ * ___task_rq_lock - lock the rq @p resides on.
  */
-struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
-	__acquires(rq->lock)
+struct rq *___task_rq_lock(struct task_struct *p, struct rq_flags *rf)
 {
 	struct rq *rq;
 
@@ -727,9 +734,7 @@ struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
 /*
  * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
  */
-struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
-	__acquires(p->pi_lock)
-	__acquires(rq->lock)
+struct rq *_task_rq_lock(struct task_struct *p, struct rq_flags *rf)
 {
 	struct rq *rq;
 
@@ -2431,6 +2436,7 @@ static inline bool is_cpu_allowed(struct task_struct *p, int cpu)
  */
 static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf,
 				   struct task_struct *p, int new_cpu)
+	__must_hold(__rq_lockp(rq))
 {
 	lockdep_assert_rq_held(rq);
 
@@ -2477,6 +2483,7 @@ struct set_affinity_pending {
  */
 static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,
 				 struct task_struct *p, int dest_cpu)
+	__must_hold(__rq_lockp(rq))
 {
 	/* Affinity changed (again). */
 	if (!is_cpu_allowed(p, dest_cpu))
@@ -2513,6 +2520,12 @@ static int migration_cpu_stop(void *data)
 	 */
 	flush_smp_call_function_queue();
 
+	/*
+	 * We may change the underlying rq, but the locks held will
+	 * appropriately be "transferred" when switching.
+	 */
+	context_unsafe_alias(rq);
+
 	raw_spin_lock(&p->pi_lock);
 	rq_lock(rq, &rf);
 
@@ -2624,6 +2637,8 @@ int push_cpu_stop(void *arg)
 	if (!lowest_rq)
 		goto out_unlock;
 
+	lockdep_assert_rq_held(lowest_rq);
+
 	// XXX validate p is still the highest prio task
 	if (task_rq(p) == rq) {
 		move_queued_task_locked(rq, lowest_rq, p);
@@ -2834,8 +2849,7 @@ void release_user_cpus_ptr(struct task_struct *p)
  */
 static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flags *rf,
 			    int dest_cpu, unsigned int flags)
-	__releases(rq->lock)
-	__releases(p->pi_lock)
+	__releases(__rq_lockp(rq), &p->pi_lock)
 {
 	struct set_affinity_pending my_pending = { }, *pending = NULL;
 	bool stop_pending, complete = false;
@@ -2990,8 +3004,7 @@ static int __set_cpus_allowed_ptr_locked(struct task_struct *p,
 					 struct affinity_context *ctx,
 					 struct rq *rq,
 					 struct rq_flags *rf)
-	__releases(rq->lock)
-	__releases(p->pi_lock)
+	__releases(__rq_lockp(rq), &p->pi_lock)
 {
 	const struct cpumask *cpu_allowed_mask = task_cpu_possible_mask(p);
 	const struct cpumask *cpu_valid_mask = cpu_active_mask;
@@ -4273,29 +4286,30 @@ static bool __task_needs_rq_lock(struct task_struct *p)
  */
 int task_call_func(struct task_struct *p, task_call_f func, void *arg)
 {
-	struct rq *rq = NULL;
 	struct rq_flags rf;
 	int ret;
 
 	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
 
-	if (__task_needs_rq_lock(p))
-		rq = __task_rq_lock(p, &rf);
+	if (__task_needs_rq_lock(p)) {
+		struct rq *rq = __task_rq_lock(p, &rf);
 
-	/*
-	 * At this point the task is pinned; either:
-	 *  - blocked and we're holding off wakeups	 (pi->lock)
-	 *  - woken, and we're holding off enqueue	 (rq->lock)
-	 *  - queued, and we're holding off schedule	 (rq->lock)
-	 *  - running, and we're holding off de-schedule (rq->lock)
-	 *
-	 * The called function (@func) can use: task_curr(), p->on_rq and
-	 * p->__state to differentiate between these states.
-	 */
-	ret = func(p, arg);
+		/*
+		 * At this point the task is pinned; either:
+		 *  - blocked and we're holding off wakeups	 (pi->lock)
+		 *  - woken, and we're holding off enqueue	 (rq->lock)
+		 *  - queued, and we're holding off schedule	 (rq->lock)
+		 *  - running, and we're holding off de-schedule (rq->lock)
+		 *
+		 * The called function (@func) can use: task_curr(), p->on_rq and
+		 * p->__state to differentiate between these states.
+		 */
+		ret = func(p, arg);
 
-	if (rq)
 		__task_rq_unlock(rq, p, &rf);
+	} else {
+		ret = func(p, arg);
+	}
 
 	raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags);
 	return ret;
@@ -4972,6 +4986,8 @@ void balance_callbacks(struct rq *rq, struct balance_callback *head)
 
 static inline void
 prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf)
+	__releases(__rq_lockp(rq))
+	__acquires(__rq_lockp(this_rq()))
 {
 	/*
 	 * Since the runqueue lock will be released by the next
@@ -4985,9 +5001,15 @@ prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf
 	/* this is a valid case when another task releases the spinlock */
 	rq_lockp(rq)->owner = next;
 #endif
+	/*
+	 * Model the rq reference switcheroo.
+	 */
+	__release(__rq_lockp(rq));
+	__acquire(__rq_lockp(this_rq()));
 }
 
 static inline void finish_lock_switch(struct rq *rq)
+	__releases(__rq_lockp(rq))
 {
 	/*
 	 * If we are tracking spinlock dependencies then we have to
@@ -5043,6 +5065,7 @@ static inline void kmap_local_sched_in(void)
 static inline void
 prepare_task_switch(struct rq *rq, struct task_struct *prev,
 		    struct task_struct *next)
+	__must_hold(__rq_lockp(rq))
 {
 	kcov_prepare_switch(prev);
 	sched_info_switch(rq, prev, next);
@@ -5073,7 +5096,7 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev,
  * because prev may have moved to another CPU.
  */
 static struct rq *finish_task_switch(struct task_struct *prev)
-	__releases(rq->lock)
+	__releases(__rq_lockp(this_rq()))
 {
 	struct rq *rq = this_rq();
 	struct mm_struct *mm = rq->prev_mm;
@@ -5169,7 +5192,7 @@ static struct rq *finish_task_switch(struct task_struct *prev)
  * @prev: the thread we just switched away from.
  */
 asmlinkage __visible void schedule_tail(struct task_struct *prev)
-	__releases(rq->lock)
+	__releases(__rq_lockp(this_rq()))
 {
 	/*
 	 * New tasks start with FORK_PREEMPT_COUNT, see there and
@@ -5201,6 +5224,7 @@ asmlinkage __visible void schedule_tail(struct task_struct *prev)
 static __always_inline struct rq *
 context_switch(struct rq *rq, struct task_struct *prev,
 	       struct task_struct *next, struct rq_flags *rf)
+	__releases(__rq_lockp(rq))
 {
 	prepare_task_switch(rq, prev, next);
 
@@ -5869,6 +5893,7 @@ static void prev_balance(struct rq *rq, struct task_struct *prev,
  */
 static inline struct task_struct *
 __pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+	__must_hold(__rq_lockp(rq))
 {
 	const struct sched_class *class;
 	struct task_struct *p;
@@ -5969,6 +5994,7 @@ static void queue_core_balance(struct rq *rq);
 
 static struct task_struct *
 pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+	__must_hold(__rq_lockp(rq))
 {
 	struct task_struct *next, *p, *max;
 	const struct cpumask *smt_mask;
@@ -6277,6 +6303,7 @@ static bool steal_cookie_task(int cpu, struct sched_domain *sd)
 }
 
 static void sched_core_balance(struct rq *rq)
+	__must_hold(__rq_lockp(rq))
 {
 	struct sched_domain *sd;
 	int cpu = cpu_of(rq);
@@ -6422,6 +6449,7 @@ static inline void sched_core_cpu_dying(unsigned int cpu) {}
 
 static struct task_struct *
 pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+	__must_hold(__rq_lockp(rq))
 {
 	return __pick_next_task(rq, prev, rf);
 }
@@ -8045,6 +8073,12 @@ static int __balance_push_cpu_stop(void *arg)
 	int cpu;
 
 	scoped_guard (raw_spinlock_irq, &p->pi_lock) {
+		/*
+		 * We may change the underlying rq, but the locks held will
+		 * appropriately be "transferred" when switching.
+		 */
+		context_unsafe_alias(rq);
+
 		cpu = select_fallback_rq(rq->cpu, p);
 
 		rq_lock(rq, &rf);
@@ -8068,6 +8102,7 @@ static DEFINE_PER_CPU(struct cpu_stop_work, push_work);
  * effective when the hotplug motion is down.
  */
 static void balance_push(struct rq *rq)
+	__must_hold(__rq_lockp(rq))
 {
 	struct task_struct *push_task = rq->curr;