Merge tag 'sched-core-2025-07-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:
 "Core scheduler changes:

   - Better tracking of maximum lag of tasks in presence of different
     slices duration, for better handling of lag in the fair scheduler
     (Vincent Guittot)

   - Clean up and standardize #if/#else/#endif markers throughout the
     entire scheduler code base (Ingo Molnar)

   - Make SMP unconditional: build the SMP scheduler's data structures
     and logic on UP kernel too, even though they are not used, to
     simplify the scheduler and remove around 200 #ifdef/[#else]/#endif
     blocks from the scheduler (Ingo Molnar)

   - Reorganize cgroup bandwidth control interface handling for better
     interfacing with sched_ext (Tejun Heo)

  Balancing:

   - Bump sd->max_newidle_lb_cost when newidle balance fails (Chris
     Mason)

   - Remove sched_domain_topology_level::flags to simplify the code
     (Prateek Nayak)

   - Simplify and clean up build_sched_topology() (Li Chen)

   - Optimize build_sched_topology() on large machines (Li Chen)

  Real-time scheduling:

   - Add initial version of proxy execution: a mechanism for
     mutex-owning tasks to inherit the scheduling context of higher
     priority waiters.

     Currently limited to a single runqueue and conditional on
     CONFIG_EXPERT, and other limitations (John Stultz, Peter Zijlstra,
     Valentin Schneider)

   - Deadline scheduler (Juri Lelli):
      - Fix dl_servers initialization order (Juri Lelli)
      - Fix DL scheduler's root domain reinitialization logic (Juri
        Lelli)
      - Fix accounting bugs after global limits change (Juri Lelli)
      - Fix scalability regression by implementing less agressive
        dl_server handling (Peter Zijlstra)

  PSI:

   - Improve scalability by optimizing psi_group_change() cpu_clock()
     usage (Peter Zijlstra)

  Rust changes:

   - Make Task, CondVar and PollCondVar methods inline to avoid
     unnecessary function calls (Kunwu Chan, Panagiotis Foliadis)

   - Add might_sleep() support for Rust code: Rust's "#[track_caller]"
     mechanism is used so that Rust's might_sleep() doesn't need to be
     defined as a macro (Fujita Tomonori)

   - Introduce file_from_location() (Boqun Feng)

  Debugging & instrumentation:

   - Make clangd usable with scheduler source code files again (Peter
     Zijlstra)

   - tools: Add root_domains_dump.py which dumps root domains info (Juri
     Lelli)

   - tools: Add dl_bw_dump.py for printing bandwidth accounting info
     (Juri Lelli)

  Misc cleanups & fixes:

   - Remove play_idle() (Feng Lee)

   - Fix check_preemption_disabled() (Sebastian Andrzej Siewior)

   - Do not call __put_task_struct() on RT if pi_blocked_on is set (Luis
     Claudio R. Goncalves)

   - Correct the comment in place_entity() (wang wei)"

* tag 'sched-core-2025-07-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (84 commits)
  sched/idle: Remove play_idle()
  sched: Do not call __put_task_struct() on rt if pi_blocked_on is set
  sched: Start blocked_on chain processing in find_proxy_task()
  sched: Fix proxy/current (push,pull)ability
  sched: Add an initial sketch of the find_proxy_task() function
  sched: Fix runtime accounting w/ split exec & sched contexts
  sched: Move update_curr_task logic into update_curr_se
  locking/mutex: Add p->blocked_on wrappers for correctness checks
  locking/mutex: Rework task_struct::blocked_on
  sched: Add CONFIG_SCHED_PROXY_EXEC & boot argument to enable/disable
  sched/topology: Remove sched_domain_topology_level::flags
  x86/smpboot: avoid SMT domain attach/destroy if SMT is not enabled
  x86/smpboot: moves x86_topology to static initialize and truncate
  x86/smpboot: remove redundant CONFIG_SCHED_SMT
  smpboot: introduce SDTL_INIT() helper to tidy sched topology setup
  tools/sched: Add dl_bw_dump.py for printing bandwidth accounting info
  tools/sched: Add root_domains_dump.py which dumps root domains info
  sched/deadline: Fix accounting after global limits change
  sched/deadline: Reset extra_bw to max_bw when clearing root domains
  sched/deadline: Initialize dl_servers after SMP
  ...

1 files changed, 4 insertions, 11 deletions

diff --git a/kernel/sched/syscalls.c b/kernel/sched/syscalls.c
index 547c1f05b667e..77ae87f36e841 100644
--- a/kernel/sched/syscalls.c
+++ b/kernel/sched/syscalls.c
@@ -174,7 +174,7 @@ SYSCALL_DEFINE1(nice, int, increment)
 	return 0;
 }
 
-#endif
+#endif /* __ARCH_WANT_SYS_NICE */
 
 /**
  * task_prio - return the priority value of a given task.
@@ -209,10 +209,8 @@ int idle_cpu(int cpu)
 	if (rq->nr_running)
 		return 0;
 
-#ifdef CONFIG_SMP
 	if (rq->ttwu_pending)
 		return 0;
-#endif
 
 	return 1;
 }
@@ -255,8 +253,7 @@ int sched_core_idle_cpu(int cpu)
 
 	return idle_cpu(cpu);
 }
-
-#endif
+#endif /* CONFIG_SCHED_CORE */
 
 /**
  * find_process_by_pid - find a process with a matching PID value.
@@ -448,7 +445,7 @@ static inline int uclamp_validate(struct task_struct *p,
 }
 static void __setscheduler_uclamp(struct task_struct *p,
 				  const struct sched_attr *attr) { }
-#endif
+#endif /* !CONFIG_UCLAMP_TASK */
 
 /*
  * Allow unprivileged RT tasks to decrease priority.
@@ -642,7 +639,6 @@ change:
 			goto unlock;
 		}
 #endif /* CONFIG_RT_GROUP_SCHED */
-#ifdef CONFIG_SMP
 		if (dl_bandwidth_enabled() && dl_policy(policy) &&
 				!(attr->sched_flags & SCHED_FLAG_SUGOV)) {
 			cpumask_t *span = rq->rd->span;
@@ -658,7 +654,6 @@ change:
 				goto unlock;
 			}
 		}
-#endif
 	}
 
 	/* Re-check policy now with rq lock held: */
@@ -1120,7 +1115,6 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
 	return copy_struct_to_user(uattr, usize, &kattr, sizeof(kattr), NULL);
 }
 
-#ifdef CONFIG_SMP
 int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask)
 {
 	/*
@@ -1149,7 +1143,6 @@ int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask)
 
 	return 0;
 }
-#endif /* CONFIG_SMP */
 
 int __sched_setaffinity(struct task_struct *p, struct affinity_context *ctx)
 {
@@ -1242,7 +1235,7 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
 	user_mask = alloc_user_cpus_ptr(NUMA_NO_NODE);
 	if (user_mask) {
 		cpumask_copy(user_mask, in_mask);
-	} else if (IS_ENABLED(CONFIG_SMP)) {
+	} else {
 		return -ENOMEM;
 	}