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[108.214.96.168]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2bd7dc167c8sm45956eec.26.2026.02.20.11.34.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Feb 2026 11:34:07 -0800 (PST) From: Sun Jian To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org Cc: dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, nathan@kernel.org, nick.desaulniers+lkml@gmail.com, morbo@google.com, justinstitt@google.com, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Sun Jian Subject: [PATCH v2] sched: rcu: fix rq->{curr,donor} address space annotations Date: Sat, 21 Feb 2026 03:33:53 +0800 Message-ID: <20260220193353.21870-1-sun.jian.kdev@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260214102005.1398306-1-sun.jian.kdev@gmail.com> References: <20260214102005.1398306-1-sun.jian.kdev@gmail.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit With CONFIG_SCHED_PROXY_EXEC enabled, struct rq::curr and rq::donor are annotated as __rcu. Several call sites access these pointers as plain struct task_struct * while holding rq locks, which triggers address space warnings from sparse. Fix these sites by dereferencing rq->{curr,donor} with rcu_dereference_protected() under rq locks and reusing local pointers, and by using rcu_access_pointer() for address-only comparisons. No functional change intended. Build/verify: make -j$(nproc) O=../out/full-clang-x86_64 LLVM=1 kernel/sched/core.o make -j$(nproc) O=../out/full-clang-x86_64 LLVM=1 C=2 CHECK=sparse \ kernel/sched/{core,pelt,build_policy}.o Signed-off-by: Sun Jian --- v2: - Fix sparse address space warning in core.c: __schedule() prev assignment - Fix sparse noderef dereferences in pelt.c: update_other_load_avgs() - Fix sparse noderef dereference in deadline.c: dl_server_timer() - Use rcu_dereference_protected() in sched.h: get_push_task() --- kernel/sched/core.c | 78 +++++++++++++++++++++++++++++------------ kernel/sched/deadline.c | 7 +++- kernel/sched/pelt.c | 7 +++- kernel/sched/pelt.h | 5 ++- kernel/sched/sched.h | 23 ++++++------ 5 files changed, 83 insertions(+), 37 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 759777694c78..1dd13dd5be5f 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -330,7 +330,8 @@ void sched_core_dequeue(struct rq *rq, struct task_struct *p, int flags) * and re-examine whether the core is still in forced idle state. */ if (!(flags & DEQUEUE_SAVE) && rq->nr_running == 1 && - rq->core->core_forceidle_count && rq->curr == rq->idle) + rq->core->core_forceidle_count && + rcu_access_pointer(rq->curr) == rq->idle) resched_curr(rq); } @@ -891,7 +892,12 @@ static enum hrtimer_restart hrtick(struct hrtimer *timer) rq_lock(rq, &rf); update_rq_clock(rq); - rq->donor->sched_class->task_tick(rq, rq->donor, 1); + { + bool locked = lockdep_is_held(__rq_lockp(rq)); + struct task_struct *donor = + rcu_dereference_protected(rq->donor, locked); + donor->sched_class->task_tick(rq, donor, 1); + } rq_unlock(rq, &rf); return HRTIMER_NORESTART; @@ -1111,7 +1117,9 @@ void wake_up_q(struct wake_q_head *head) */ static void __resched_curr(struct rq *rq, int tif) { - struct task_struct *curr = rq->curr; + struct task_struct *curr = + rcu_dereference_protected(rq->curr, + lockdep_is_held(__rq_lockp(rq))); struct thread_info *cti = task_thread_info(curr); int cpu; @@ -1218,7 +1226,8 @@ int get_nohz_timer_target(void) guard(rcu)(); - for_each_domain(cpu, sd) { + sd = rcu_dereference(cpu_rq(cpu)->sd); + for (; sd; sd = rcu_dereference(sd->parent)) { for_each_cpu_and(i, sched_domain_span(sd), hk_mask) { if (cpu == i) continue; @@ -2179,12 +2188,15 @@ static void block_task(struct rq *rq, struct task_struct *p, int flags) */ inline int task_curr(const struct task_struct *p) { - return cpu_curr(task_cpu(p)) == p; + return rcu_access_pointer(cpu_curr(task_cpu(p))) == p; } void wakeup_preempt(struct rq *rq, struct task_struct *p, int flags) { - struct task_struct *donor = rq->donor; + struct task_struct *donor = + rcu_dereference_protected(rq->donor, lockdep_is_held(__rq_lockp(rq))); + struct task_struct *curr = + rcu_dereference_protected(rq->curr, lockdep_is_held(__rq_lockp(rq))); if (p->sched_class == rq->next_class) { rq->next_class->wakeup_preempt(rq, p, flags); @@ -2199,7 +2211,7 @@ void wakeup_preempt(struct rq *rq, struct task_struct *p, int flags) * A queue event has occurred, and we're going to schedule. In * this case, we can save a useless back to back clock update. */ - if (task_on_rq_queued(donor) && test_tsk_need_resched(rq->curr)) + if (task_on_rq_queued(donor) && test_tsk_need_resched(curr)) rq_clock_skip_update(rq); } @@ -3604,7 +3616,9 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags) __schedstat_inc(p->stats.nr_wakeups_remote); guard(rcu)(); - for_each_domain(rq->cpu, sd) { + + sd = rcu_dereference(rq->sd); + for (; sd; sd = rcu_dereference(sd->parent)) { if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { __schedstat_inc(sd->ttwu_wake_remote); break; @@ -3809,7 +3823,9 @@ void wake_up_if_idle(int cpu) guard(rcu)(); if (is_idle_task(rcu_dereference(rq->curr))) { guard(rq_lock_irqsave)(rq); - if (is_idle_task(rq->curr)) + bool locked = lockdep_is_held(__rq_lockp(rq)); + + if (is_idle_task(rcu_dereference_protected(rq->curr, locked))) resched_curr(rq); } } @@ -5556,7 +5572,8 @@ void sched_tick(void) sched_clock_tick(); rq_lock(rq, &rf); - donor = rq->donor; + donor = rcu_dereference_protected(rq->donor, + lockdep_is_held(__rq_lockp(rq))); psi_account_irqtime(rq, donor, NULL); @@ -5644,7 +5661,10 @@ static void sched_tick_remote(struct work_struct *work) */ if (tick_nohz_tick_stopped_cpu(cpu)) { guard(rq_lock_irq)(rq); - struct task_struct *curr = rq->curr; + struct task_struct *curr = + rcu_dereference_protected(rq->curr, lockdep_is_held(__rq_lockp(rq))); + struct task_struct *donor = + rcu_dereference_protected(rq->donor, lockdep_is_held(__rq_lockp(rq))); if (cpu_online(cpu)) { /* @@ -5652,7 +5672,7 @@ static void sched_tick_remote(struct work_struct *work) * we are always sure that there is no proxy (only a * single task is running). */ - WARN_ON_ONCE(rq->curr != rq->donor); + WARN_ON_ONCE(curr != donor); update_rq_clock(rq); if (!is_idle_task(curr)) { @@ -6778,7 +6798,9 @@ static void __sched notrace __schedule(int sched_mode) cpu = smp_processor_id(); rq = cpu_rq(cpu); - prev = rq->curr; + bool locked = lockdep_is_held(__rq_lockp(rq)); + + prev = rcu_dereference_protected(rq->curr, locked); schedule_debug(prev, preempt); @@ -6845,7 +6867,12 @@ static void __sched notrace __schedule(int sched_mode) } pick_again: - next = pick_next_task(rq, rq->donor, &rf); + { + bool locked = lockdep_is_held(__rq_lockp(rq)); + struct task_struct *donor = + rcu_dereference_protected(rq->donor, locked); + next = pick_next_task(rq, donor, &rf); + } rq_set_donor(rq, next); rq->next_class = next->sched_class; if (unlikely(task_is_blocked(next))) { @@ -7352,7 +7379,7 @@ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task) * real need to boost. */ if (unlikely(p == rq->idle)) { - WARN_ON(p != rq->curr); + WARN_ON(p != rcu_access_pointer(rq->curr)); WARN_ON(p->pi_blocked_on); goto out_unlock; } @@ -8116,7 +8143,9 @@ static DEFINE_PER_CPU(struct cpu_stop_work, push_work); static void balance_push(struct rq *rq) __must_hold(__rq_lockp(rq)) { - struct task_struct *push_task = rq->curr; + struct task_struct *push_task = + rcu_dereference_protected(rq->curr, + lockdep_is_held(__rq_lockp(rq))); lockdep_assert_rq_held(rq); @@ -10272,7 +10301,7 @@ void dump_cpu_task(int cpu) return; pr_info("Task dump for CPU %d:\n", cpu); - sched_show_task(cpu_curr(cpu)); + sched_show_task(rcu_access_pointer(cpu_curr(cpu))); } /* @@ -10583,24 +10612,27 @@ static void mm_cid_fixup_cpus_to_tasks(struct mm_struct *mm) /* Remote access to mm::mm_cid::pcpu requires rq_lock */ guard(rq_lock_irq)(rq); + + struct task_struct *curr = + rcu_dereference_protected(rq->curr, lockdep_is_held(__rq_lockp(rq))); /* Is the CID still owned by the CPU? */ if (cid_on_cpu(pcp->cid)) { /* * If rq->curr has @mm, transfer it with the * transition bit set. Otherwise drop it. */ - if (rq->curr->mm == mm && rq->curr->mm_cid.active) - mm_cid_transit_to_task(rq->curr, pcp); + if (curr->mm == mm && curr->mm_cid.active) + mm_cid_transit_to_task(curr, pcp); else mm_drop_cid_on_cpu(mm, pcp); - } else if (rq->curr->mm == mm && rq->curr->mm_cid.active) { - unsigned int cid = rq->curr->mm_cid.cid; + } else if (curr->mm == mm && curr->mm_cid.active) { + unsigned int cid = curr->mm_cid.cid; /* Ensure it has the transition bit set */ if (!cid_in_transit(cid)) { cid = cid_to_transit_cid(cid); - rq->curr->mm_cid.cid = cid; + curr->mm_cid.cid = cid; pcp->cid = cid; } } @@ -10625,7 +10657,7 @@ static bool mm_cid_fixup_task_to_cpu(struct task_struct *t, struct mm_struct *mm return false; if (cid_on_task(t->mm_cid.cid)) { /* If running on the CPU, put the CID in transit mode, otherwise drop it */ - if (task_rq(t)->curr == t) + if (rcu_access_pointer(task_rq(t)->curr) == t) mm_cid_transit_to_cpu(t, per_cpu_ptr(mm->mm_cid.pcpu, task_cpu(t))); else mm_unset_cid_on_task(t); diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index d08b00429323..1376474774c3 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1166,7 +1166,12 @@ static enum hrtimer_restart dl_server_timer(struct hrtimer *timer, struct sched_ * any relevant server through calling dl_server_update() and * friends. */ - rq->donor->sched_class->update_curr(rq); + { + struct task_struct *donor = + rcu_dereference_protected(rq->donor, + lockdep_is_held(__rq_lockp(rq))); + donor->sched_class->update_curr(rq); + } if (dl_se->dl_defer_idle) { dl_server_stop(dl_se); diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c index 897790889ba3..b0ad86e8ba8b 100644 --- a/kernel/sched/pelt.c +++ b/kernel/sched/pelt.c @@ -477,11 +477,16 @@ int update_irq_load_avg(struct rq *rq, u64 running) bool update_other_load_avgs(struct rq *rq) { u64 now = rq_clock_pelt(rq); - const struct sched_class *curr_class = rq->donor->sched_class; + struct task_struct *donor; + const struct sched_class *curr_class; unsigned long hw_pressure = arch_scale_hw_pressure(cpu_of(rq)); lockdep_assert_rq_held(rq); + donor = rcu_dereference_protected(rq->donor, + lockdep_is_held(__rq_lockp(rq))); + curr_class = donor->sched_class; + /* hw_pressure doesn't care about invariance */ return update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) | update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) | diff --git a/kernel/sched/pelt.h b/kernel/sched/pelt.h index f921302dc40f..2498616fa1a9 100644 --- a/kernel/sched/pelt.h +++ b/kernel/sched/pelt.h @@ -99,7 +99,10 @@ static inline void _update_idle_rq_clock_pelt(struct rq *rq) */ static inline void update_rq_clock_pelt(struct rq *rq, s64 delta) { - if (unlikely(is_idle_task(rq->curr))) { + struct task_struct *curr = + rcu_dereference_protected(rq->curr, + lockdep_is_held(__rq_lockp(rq))); + if (unlikely(is_idle_task(curr))) { _update_idle_rq_clock_pelt(rq); return; } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index b82fb70a9d54..c1673f2baaea 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1387,12 +1387,13 @@ static __always_inline struct rq *__this_rq(void) #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu))) #define this_rq() __this_rq() #define task_rq(p) cpu_rq(task_cpu(p)) -#define cpu_curr(cpu) (cpu_rq(cpu)->curr) +#define cpu_curr(cpu) ((cpu_rq(cpu)->curr)) #define raw_rq() raw_cpu_ptr(&runqueues) static inline bool idle_rq(struct rq *rq) { - return rq->curr == rq->idle && !rq->nr_running && !rq->ttwu_pending; + return rcu_access_pointer(rq->curr) == rq->idle && + !rq->nr_running && !rq->ttwu_pending; } /** @@ -2360,7 +2361,7 @@ static inline u64 global_rt_runtime(void) */ static inline int task_current(struct rq *rq, struct task_struct *p) { - return rq->curr == p; + return rcu_access_pointer(rq->curr) == p; } /* @@ -2371,7 +2372,7 @@ static inline int task_current(struct rq *rq, struct task_struct *p) */ static inline int task_current_donor(struct rq *rq, struct task_struct *p) { - return rq->donor == p; + return rcu_access_pointer(rq->donor) == p; } static inline bool task_is_blocked(struct task_struct *p) @@ -2659,7 +2660,7 @@ struct sched_class { static inline void put_prev_task(struct rq *rq, struct task_struct *prev) { - WARN_ON_ONCE(rq->donor != prev); + WARN_ON_ONCE(rcu_access_pointer(rq->donor) != prev); prev->sched_class->put_prev_task(rq, prev, NULL); } @@ -2670,8 +2671,7 @@ static inline void set_next_task(struct rq *rq, struct task_struct *next) static inline void __put_prev_set_next_dl_server(struct rq *rq, - struct task_struct *prev, - struct task_struct *next) + struct task_struct *prev, struct task_struct *next) { prev->dl_server = NULL; next->dl_server = rq->dl_server; @@ -2679,10 +2679,9 @@ __put_prev_set_next_dl_server(struct rq *rq, } static inline void put_prev_set_next_task(struct rq *rq, - struct task_struct *prev, - struct task_struct *next) + struct task_struct *prev, struct task_struct *next) { - WARN_ON_ONCE(rq->donor != prev); + WARN_ON_ONCE(rcu_access_pointer(rq->donor) != prev); __put_prev_set_next_dl_server(rq, prev, next); @@ -2809,9 +2808,11 @@ static inline cpumask_t *alloc_user_cpus_ptr(int node) static inline struct task_struct *get_push_task(struct rq *rq) { - struct task_struct *p = rq->donor; + struct task_struct *p; lockdep_assert_rq_held(rq); + p = rcu_dereference_protected(rq->donor, + lockdep_is_held(__rq_lockp(rq))); if (rq->push_busy) return NULL; base-commit: 770aaedb461a055f79b971d538678942b6607894 -- 2.43.0