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
  ...

rust/kernel/lib.rs

@@ -43,6 +43,10 @@
 #![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(coerce_unsized))]
 #![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(dispatch_from_dyn))]
 #![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(unsize))]
+//
+// `feature(file_with_nul)` is expected to become stable. Before Rust 1.89.0, it did not exist, so
+// enable it conditionally.
+#![cfg_attr(CONFIG_RUSTC_HAS_FILE_WITH_NUL, feature(file_with_nul))]
 
 // Ensure conditional compilation based on the kernel configuration works;
 // otherwise we may silently break things like initcall handling.
@@ -279,3 +283,47 @@ macro_rules! asm {
         ::core::arch::asm!( $($asm)*, $($rest)* )
     };
 }
+
+/// Gets the C string file name of a [`Location`].
+///
+/// If `file_with_nul()` is not available, returns a string that warns about it.
+///
+/// [`Location`]: core::panic::Location
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::file_from_location;
+///
+/// #[track_caller]
+/// fn foo() {
+///     let caller = core::panic::Location::caller();
+///
+///     // Output:
+///     // - A path like "rust/kernel/example.rs" if file_with_nul() is available.
+///     // - "<Location::file_with_nul() not supported>" otherwise.
+///     let caller_file = file_from_location(caller);
+///
+///     // Prints out the message with caller's file name.
+///     pr_info!("foo() called in file {caller_file:?}\n");
+///
+///     # if cfg!(CONFIG_RUSTC_HAS_FILE_WITH_NUL) {
+///     #     assert_eq!(Ok(caller.file()), caller_file.to_str());
+///     # }
+/// }
+///
+/// # foo();
+/// ```
+#[inline]
+pub fn file_from_location<'a>(loc: &'a core::panic::Location<'a>) -> &'a core::ffi::CStr {
+    #[cfg(CONFIG_RUSTC_HAS_FILE_WITH_NUL)]
+    {
+        loc.file_with_nul()
+    }
+
+    #[cfg(not(CONFIG_RUSTC_HAS_FILE_WITH_NUL))]
+    {
+        let _ = loc;
+        c"<Location::file_with_nul() not supported>"
+    }
+}

rust/kernel/sync/condvar.rs

@@ -216,6 +216,7 @@ impl CondVar {
     /// This method behaves like `notify_one`, except that it hints to the scheduler that the
     /// current thread is about to go to sleep, so it should schedule the target thread on the same
     /// CPU.
+    #[inline]
     pub fn notify_sync(&self) {
         // SAFETY: `wait_queue_head` points to valid memory.
         unsafe { bindings::__wake_up_sync(self.wait_queue_head.get(), TASK_NORMAL) };
@@ -225,6 +226,7 @@ impl CondVar {
     ///
     /// This is not 'sticky' in the sense that if no thread is waiting, the notification is lost
     /// completely (as opposed to automatically waking up the next waiter).
+    #[inline]
     pub fn notify_one(&self) {
         self.notify(1);
     }
@@ -233,6 +235,7 @@ impl CondVar {
     ///
     /// This is not 'sticky' in the sense that if no thread is waiting, the notification is lost
     /// completely (as opposed to automatically waking up the next waiter).
+    #[inline]
     pub fn notify_all(&self) {
         self.notify(0);
     }

rust/kernel/sync/poll.rs

@@ -91,6 +91,7 @@ impl Deref for PollCondVar {
 
 #[pinned_drop]
 impl PinnedDrop for PollCondVar {
+    #[inline]
     fn drop(self: Pin<&mut Self>) {
         // Clear anything registered using `register_wait`.
         //

rust/kernel/task.rs

@@ -173,6 +173,7 @@ impl Task {
     /// Callers must ensure that the returned object is only used to access a [`CurrentTask`]
     /// within the task context that was active when this function was called. For more details,
     /// see the invariants section for [`CurrentTask`].
+    #[inline]
     pub unsafe fn current() -> impl Deref<Target = CurrentTask> {
         struct TaskRef {
             task: *const CurrentTask,
@@ -222,24 +223,28 @@ impl Task {
     }
 
     /// Returns the UID of the given task.
+    #[inline]
     pub fn uid(&self) -> Kuid {
         // SAFETY: It's always safe to call `task_uid` on a valid task.
         Kuid::from_raw(unsafe { bindings::task_uid(self.as_ptr()) })
     }
 
     /// Returns the effective UID of the given task.
+    #[inline]
     pub fn euid(&self) -> Kuid {
         // SAFETY: It's always safe to call `task_euid` on a valid task.
         Kuid::from_raw(unsafe { bindings::task_euid(self.as_ptr()) })
     }
 
     /// Determines whether the given task has pending signals.
+    #[inline]
     pub fn signal_pending(&self) -> bool {
         // SAFETY: It's always safe to call `signal_pending` on a valid task.
         unsafe { bindings::signal_pending(self.as_ptr()) != 0 }
     }
 
     /// Returns task's pid namespace with elevated reference count
+    #[inline]
     pub fn get_pid_ns(&self) -> Option<ARef<PidNamespace>> {
         // SAFETY: By the type invariant, we know that `self.0` is valid.
         let ptr = unsafe { bindings::task_get_pid_ns(self.as_ptr()) };
@@ -255,6 +260,7 @@ impl Task {
 
     /// Returns the given task's pid in the provided pid namespace.
     #[doc(alias = "task_tgid_nr_ns")]
+    #[inline]
     pub fn tgid_nr_ns(&self, pidns: Option<&PidNamespace>) -> Pid {
         let pidns = match pidns {
             Some(pidns) => pidns.as_ptr(),
@@ -268,6 +274,7 @@ impl Task {
     }
 
     /// Wakes up the task.
+    #[inline]
     pub fn wake_up(&self) {
         // SAFETY: It's always safe to call `wake_up_process` on a valid task, even if the task
         // running.
@@ -341,11 +348,13 @@ impl CurrentTask {
 
 // SAFETY: The type invariants guarantee that `Task` is always refcounted.
 unsafe impl crate::types::AlwaysRefCounted for Task {
+    #[inline]
     fn inc_ref(&self) {
         // SAFETY: The existence of a shared reference means that the refcount is nonzero.
         unsafe { bindings::get_task_struct(self.as_ptr()) };
     }
 
+    #[inline]
     unsafe fn dec_ref(obj: ptr::NonNull<Self>) {
         // SAFETY: The safety requirements guarantee that the refcount is nonzero.
         unsafe { bindings::put_task_struct(obj.cast().as_ptr()) }
@@ -391,3 +400,27 @@ impl PartialEq for Kuid {
 }
 
 impl Eq for Kuid {}
+
+/// Annotation for functions that can sleep.
+///
+/// Equivalent to the C side [`might_sleep()`], this function serves as
+/// a debugging aid and a potential scheduling point.
+///
+/// This function can only be used in a nonatomic context.
+///
+/// [`might_sleep()`]: https://docs.kernel.org/driver-api/basics.html#c.might_sleep
+#[track_caller]
+#[inline]
+pub fn might_sleep() {
+    #[cfg(CONFIG_DEBUG_ATOMIC_SLEEP)]
+    {
+        let loc = core::panic::Location::caller();
+        let file = kernel::file_from_location(loc);
+
+        // SAFETY: `file.as_ptr()` is valid for reading and guaranteed to be nul-terminated.
+        unsafe { crate::bindings::__might_sleep(file.as_ptr().cast(), loc.line() as i32) }
+    }
+
+    // SAFETY: Always safe to call.
+    unsafe { crate::bindings::might_resched() }
+}