Samuel and Alex reported regressions of the util_avg of RT rq with
commit 17e3e88ed0b6 ("sched/fair: Fix pelt lost idle time detection").
It happens that fair is updating and syncing the pelt clock with task one
when pick_next_task_fair() fails to pick a task but before the prev
scheduling class got a chance to update its pelt signals.

Move update_idle_rq_clock_pelt() in set_next_task_idle() which is called
after prev class has been called.

Fixes: 17e3e88ed0b6 ("sched/fair: Fix pelt lost idle time detection")
Closes: https://lore.kernel.org/all/CAG2KctpO6VKS6GN4QWDji0t92_gNBJ7HjjXrE+6H+RwRXt=iLg@mail.gmail.com/
Closes: https://lore.kernel.org/all/8cf19bf0e0054dcfed70e9935029201694f1bb5a.camel@mediatek.com/
Reported-by: Samuel Wu <wusamuel@google.com>
Reported-by: Alex Hoh <Alex.Hoh@mediatek.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Samuel Wu <wusamuel@google.com>
Tested-by: Alex Hoh <Alex.Hoh@mediatek.com>
Link: https://patch.msgid.link/20260121163317.505635-1-vincent.guittot@linaro.org

Pull power management updates from Rafael Wysocki:
 "There are quite a few interesting things here, including new hardware
  support, new features, some bug fixes and documentation updates. In
  addition, there are a usual bunch of minor fixes and cleanups all
  over.

  In the new hardware support category, there are intel_pstate and
  intel_rapl driver updates to support new processors, Panther Lake,
  Wildcat Lake, Noval Lake, and Diamond Rapids in the OOB mode, OPP and
  bandwidth allocation support in the tegra186 cpufreq driver, and
  JH7110S SOC support in dt-platdev cpufreq.

  The new features are the PM QoS CPU latency limit for suspend-to-idle,
  the netlink support for the energy model management, support for
  terminating system suspend via a wakeup event during the sync of file
  systems, configurable number of hibernation compression threads, the
  runtime PM auto-cleanup macros, and the "poweroff" PM event that is
  expected to be used during system shutdown.

  Bugs are mostly fixed in cpuidle governors, but there are also fixes
  elsewhere, like in the amd-pstate cpufreq driver.

  Documentation updates include, but are not limited to, a new doc on
  debugging shutdown hangs, cross-referencing fixes and cleanups in the
  intel_pstate documentation, and updates of comments in the core
  hibernation code.

  Specifics:

   - Introduce and document a QoS limit on CPU exit latency during
     wakeup from suspend-to-idle (Ulf Hansson)

   - Add support for building libcpupower statically (Zuo An)

   - Add support for sending netlink notifications to user space on
     energy model updates (Changwoo Mini, Peng Fan)

   - Minor improvements to the Rust OPP interface (Tamir Duberstein)

   - Fixes to scope-based pointers in the OPP library (Viresh Kumar)

   - Use residency threshold in polling state override decisions in the
     menu cpuidle governor (Aboorva Devarajan)

   - Add sanity check for exit latency and target residency in the
     cpufreq core (Rafael Wysocki)

   - Use this_cpu_ptr() where possible in the teo governor (Christian
     Loehle)

   - Rework the handling of tick wakeups in the teo cpuidle governor to
     increase the likelihood of stopping the scheduler tick in the cases
     when tick wakeups can be counted as non-timer ones (Rafael Wysocki)

   - Fix a reverse condition in the teo cpuidle governor and drop a
     misguided target residency check from it (Rafael Wysocki)

   - Clean up multiple minor defects in the teo cpuidle governor (Rafael
     Wysocki)

   - Update header inclusion to make it follow the Include What You Use
     principle (Andy Shevchenko)

   - Enable MSR-based RAPL PMU support in the intel_rapl power capping
     driver and arrange for using it on the Panther Lake and Wildcat
     Lake processors (Kuppuswamy Sathyanarayanan)

   - Add support for Nova Lake and Wildcat Lake processors to the
     intel_rapl power capping driver (Kaushlendra Kumar, Srinivas
     Pandruvada)

   - Add OPP and bandwidth support for Tegra186 (Aaron Kling)

   - Optimizations for parameter array handling in the amd-pstate
     cpufreq driver (Mario Limonciello)

   - Fix for mode changes with offline CPUs in the amd-pstate cpufreq
     driver (Gautham Shenoy)

   - Preserve freq_table_sorted across suspend/hibernate in the cpufreq
     core (Zihuan Zhang)

   - Adjust energy model rules for Intel hybrid platforms in the
     intel_pstate cpufreq driver and improve printing of debug messages
     in it (Rafael Wysocki)

   - Replace deprecated strcpy() in cpufreq_unregister_governor()
     (Thorsten Blum)

   - Fix duplicate hyperlink target errors in the intel_pstate cpufreq
     driver documentation and use :ref: directive for internal linking
     in it (Swaraj Gaikwad, Bagas Sanjaya)

   - Add Diamond Rapids OOB mode support to the intel_pstate cpufreq
     driver (Kuppuswamy Sathyanarayanan)

   - Use mutex guard for driver locking in the intel_pstate driver and
     eliminate some code duplication from it (Rafael Wysocki)

   - Replace udelay() with usleep_range() in ACPI cpufreq (Kaushlendra
     Kumar)

   - Minor improvements to various cpufreq drivers (Christian Marangi,
     Hal Feng, Jie Zhan, Marco Crivellari, Miaoqian Lin, and Shuhao Fu)

   - Replace snprintf() with scnprintf() in show_trace_dev_match()
     (Kaushlendra Kumar)

   - Fix memory allocation error handling in pm_vt_switch_required()
     (Malaya Kumar Rout)

   - Introduce CALL_PM_OP() macro and use it to simplify code in generic
     PM operations (Kaushlendra Kumar)

   - Add module param to backtrace all CPUs in the device power
     management watchdog (Sergey Senozhatsky)

   - Rework message printing in swsusp_save() (Rafael Wysocki)

   - Make it possible to change the number of hibernation compression
     threads (Xueqin Luo)

   - Clarify that only cgroup1 freezer uses PM freezer (Tejun Heo)

   - Add document on debugging shutdown hangs to PM documentation and
     correct a mistaken configuration option in it (Mario Limonciello)

   - Shut down wakeup source timer before removing the wakeup source
     from the list (Kaushlendra Kumar, Rafael Wysocki)

   - Introduce new PMSG_POWEROFF event for system shutdown handling with
     the help of PM device callbacks (Mario Limonciello)

   - Make pm_test delay interruptible by wakeup events (Riwen Lu)

   - Clean up kernel-doc comment style usage in the core hibernation
     code and remove unuseful comments from it (Sunday Adelodun, Rafael
     Wysocki)

   - Add support for handling wakeup events and aborting the suspend
     process while it is syncing file systems (Samuel Wu, Rafael
     Wysocki)

   - Add WQ_UNBOUND to pm_wq workqueue (Marco Crivellari)

   - Add runtime PM wrapper macros for ACQUIRE()/ACQUIRE_ERR() and use
     them in the PCI core and the ACPI TAD driver (Rafael Wysocki)

   - Improve runtime PM in the ACPI TAD driver (Rafael Wysocki)

   - Update pm_runtime_allow/forbid() documentation (Rafael Wysocki)

   - Fix typos in runtime.c comments (Malaya Kumar Rout)

   - Move governor.h from devfreq under include/linux/ and rename to
     devfreq-governor.h to allow devfreq governor definitions in out of
     drivers/devfreq/ (Dmitry Baryshkov)

   - Use min() to improve readability in tegra30-devfreq.c (Thorsten
     Blum)

   - Fix potential use-after-free issue of OPP handling in
     hisi_uncore_freq.c (Pengjie Zhang)

   - Fix typo in DFSO_DOWNDIFFERENTIAL macro name in
     governor_simpleondemand.c in devfreq (Riwen Lu)"

* tag 'pm-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (96 commits)
  PM / devfreq: Fix typo in DFSO_DOWNDIFFERENTIAL macro name
  cpuidle: Warn instead of bailing out if target residency check fails
  cpuidle: Update header inclusion
  Documentation: power/cpuidle: Document the CPU system wakeup latency QoS
  cpuidle: Respect the CPU system wakeup QoS limit for cpuidle
  sched: idle: Respect the CPU system wakeup QoS limit for s2idle
  pmdomain: Respect the CPU system wakeup QoS limit for cpuidle
  pmdomain: Respect the CPU system wakeup QoS limit for s2idle
  PM: QoS: Introduce a CPU system wakeup QoS limit
  cpuidle: governors: teo: Add missing space to the description
  PM: hibernate: Extra cleanup of comments in swap handling code
  PM / devfreq: tegra30: use min to simplify actmon_cpu_to_emc_rate
  PM / devfreq: hisi: Fix potential UAF in OPP handling
  PM / devfreq: Move governor.h to a public header location
  powercap: intel_rapl: Enable MSR-based RAPL PMU support
  powercap: intel_rapl: Prepare read_raw() interface for atomic-context callers
  cpufreq: qcom-nvmem: fix compilation warning for qcom_cpufreq_ipq806x_match_list
  PM: sleep: Call pm_sleep_fs_sync() instead of ksys_sync_helper()
  PM: sleep: Add support for wakeup during filesystem sync
  cpufreq: ACPI: Replace udelay() with usleep_range()
  ...

A CPU system wakeup QoS limit may have been requested by user space. To
avoid breaking this constraint when entering a low power state during
s2idle, let's start to take into account the QoS limit.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Reviewed-by: Kevin Hilman (TI) <khilman@baylibre.com>
Tested-by: Kevin Hilman (TI) <khilman@baylibre.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://patch.msgid.link/20251125112650.329269-5-ulf.hansson@linaro.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The dl_server time accounting code is a little odd. The normal scheduler
pattern is to update curr before doing something, such that the old state is
fully accounted before changing state.

Notably, the dl_server_timer() needs to propagate the current time accounting
since the current task could be ran by dl_server and thus this can affect
dl_se->runtime. Similarly for dl_server_start().

And since the (deferred) dl_server wants idle time accounted, rework
sched_idle_class time accounting to be more like all the others.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251020141130.GJ3245006@noisy.programming.kicks-ass.net

Some pick functions like the internal pick_next_task_fair() already take
rf but some others dont. We need this for scx's server pick function.
Prepare for this by having pick functions accept it.

[peterz: - added RETRY_TASK handling
         - removed pick_next_task_fair indirection]
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>

Have enqueue/dequeue set a per-class bit in rq->queue_mask. This then
enables easy tracking of which runqueues are modified over a
lock-break.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>

Move sched_class::prio_changed() into the change pattern.

And while there, extend it with sched_class::get_prio() in order to
fix the deadline sitation.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>

Add {DE,EN}QUEUE_CLASS and fold the sched_class::switch* methods into
the change pattern. This completes and makes the pattern more
symmetric.

This changes the order of callbacks slightly:

  OLD                              NEW
				|
				|  switching_from()
  dequeue_task();		|  dequeue_task()
  put_prev_task();		|  put_prev_task()
				|  switched_from()
				|
  ... change task ...		|  ... change task ...
				|
  switching_to();		|  switching_to()
  enqueue_task();		|  enqueue_task()
  set_next_task();		|  set_next_task()
  prev_class->switched_from()	|
  switched_to()			|  switched_to()
				|

Notably, it moves the switched_from() callback right after the
dequeue/put. Existing implementations don't appear to be affected by
this change in location -- specifically the task isn't enqueued on the
class in question in either location.

Make (CLASS)^(SAVE|MOVE), because there is nothing to save-restore
when changing scheduling classes.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>

Simplify the scheduler by making CONFIG_SMP=y code in the
idle scheduling classunconditional.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-35-mingo@kernel.org

 - Use the standard #ifdef marker format for larger blocks,
   where appropriate:

        #if CONFIG_FOO
        ...
        #else /* !CONFIG_FOO: */
        ...
        #endif /* !CONFIG_FOO */

 - Fix whitespace noise and other inconsistencies.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-11-mingo@kernel.org