Pull scheduler updates from Ingo Molnar:

 - Updates to scheduler metrics:
     - PELT fixes & enhancements
     - PSI fixes & enhancements
     - Refactor cpu_util_without()

 - Updates to instrumentation/debugging:
     - Remove sched_trace_*() helper functions - can be done via debug
       info
     - Fix double update_rq_clock() warnings

 - Introduce & use "preemption model accessors" to simplify some of the
   Kconfig complexity.

 - Make softirq handling RT-safe.

 - Misc smaller fixes & cleanups.

* tag 'sched-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  topology: Remove unused cpu_cluster_mask()
  sched: Reverse sched_class layout
  sched/deadline: Remove superfluous rq clock update in push_dl_task()
  sched/core: Avoid obvious double update_rq_clock warning
  smp: Make softirq handling RT safe in flush_smp_call_function_queue()
  smp: Rename flush_smp_call_function_from_idle()
  sched: Fix missing prototype warnings
  sched/fair: Remove cfs_rq_tg_path()
  sched/fair: Remove sched_trace_*() helper functions
  sched/fair: Refactor cpu_util_without()
  sched/fair: Revise comment about lb decision matrix
  sched/psi: report zeroes for CPU full at the system level
  sched/fair: Delete useless condition in tg_unthrottle_up()
  sched/fair: Fix cfs_rq_clock_pelt() for throttled cfs_rq
  sched/fair: Move calculate of avg_load to a better location
  mailmap: Update my email address to @redhat.com
  MAINTAINERS: Add myself as scheduler topology reviewer
  psi: Fix trigger being fired unexpectedly at initial
  ftrace: Use preemption model accessors for trace header printout
  kcsan: Use preemption model accessors

Pull RCU update from Paul McKenney:

 - Documentation updates

 - Miscellaneous fixes

 - Callback-offloading updates, mainly simplifications

 - RCU-tasks updates, including some -rt fixups, handling of systems
   with sparse CPU numbering, and a fix for a boot-time race-condition
   failure

 - Put SRCU on a memory diet in order to reduce the size of the
   srcu_struct structure

 - Torture-test updates fixing some bugs in tests and closing some
   testing holes

 - Torture-test updates for the RCU tasks flavors, most notably ensuring
   that building rcutorture and friends does not change the
   RCU-tasks-related Kconfig options

 - Torture-test scripting updates

 - Expedited grace-period updates, most notably providing
   milliseconds-scale (not all that) soft real-time response from
   synchronize_rcu_expedited().

   This is also the first time in almost 30 years of RCU that someone
   other than me has pushed for a reduction in the RCU CPU stall-warning
   timeout, in this case by more than three orders of magnitude from 21
   seconds to 20 milliseconds. This tighter timeout applies only to
   expedited grace periods

* tag 'rcu.2022.05.19a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (80 commits)
  rcu: Move expedited grace period (GP) work to RT kthread_worker
  rcu: Introduce CONFIG_RCU_EXP_CPU_STALL_TIMEOUT
  srcu: Drop needless initialization of sdp in srcu_gp_start()
  srcu: Prevent expedited GPs and blocking readers from consuming CPU
  srcu: Add contention check to call_srcu() srcu_data ->lock acquisition
  srcu: Automatically determine size-transition strategy at boot
  rcutorture: Make torture.sh allow for --kasan
  rcutorture: Make torture.sh refscale and rcuscale specify Tasks Trace RCU
  rcutorture: Make kvm.sh allow more memory for --kasan runs
  torture: Save "make allmodconfig" .config file
  scftorture: Remove extraneous "scf" from per_version_boot_params
  rcutorture: Adjust scenarios' Kconfig options for CONFIG_PREEMPT_DYNAMIC
  torture: Enable CSD-lock stall reports for scftorture
  torture: Skip vmlinux check for kvm-again.sh runs
  scftorture: Adjust for TASKS_RCU Kconfig option being selected
  rcuscale: Allow rcuscale without RCU Tasks Rude/Trace
  rcuscale: Allow rcuscale without RCU Tasks
  refscale: Allow refscale without RCU Tasks Rude/Trace
  refscale: Allow refscale without RCU Tasks
  rcutorture: Allow specifying per-scenario stat_interval
  ...

 - sched/core is on a pretty old -rc1 base - refresh it to include recent fixes.
 - this also allows up to resolve a (trivial) .mailmap conflict

Conflicts:
	.mailmap

Signed-off-by: Ingo Molnar <mingo@kernel.org>

flush_smp_call_function_queue() invokes do_softirq() which is not available
on PREEMPT_RT. flush_smp_call_function_queue() is invoked from the idle
task and the migration task with preemption or interrupts disabled.

So RT kernels cannot process soft interrupts in that context as that has to
acquire 'sleeping spinlocks' which is not possible with preemption or
interrupts disabled and forbidden from the idle task anyway.

The currently known SMP function call which raises a soft interrupt is in
the block layer, but this functionality is not enabled on RT kernels due to
latency and performance reasons.

RT could wake up ksoftirqd unconditionally, but this wants to be avoided if
there were soft interrupts pending already when this is invoked in the
context of the migration task. The migration task might have preempted a
threaded interrupt handler which raised a soft interrupt, but did not reach
the local_bh_enable() to process it. The "running" ksoftirqd might prevent
the handling in the interrupt thread context which is causing latency
issues.

Add a new function which handles this case explicitely for RT and falls
back to do_softirq() on !RT kernels. In the RT case this warns when one of
the flushed SMP function calls raised a soft interrupt so this can be
investigated.

[ tglx: Moved the RT part out of SMP code ]

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/YgKgL6aPj8aBES6G@linutronix.de
Link: https://lore.kernel.org/r/20220413133024.356509586@linutronix.de

This is invoked from the stopper thread too, which is definitely not idle.
Rename it to flush_smp_call_function_queue() and fixup the callers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220413133024.305001096@linutronix.de

Debugging of problems involving insanely long-running SMI handlers
proceeds better if the CSD-lock timeout can be adjusted.  This commit
therefore provides a new smp.csd_lock_timeout kernel boot parameter
that specifies the timeout in milliseconds.  The default remains at the
previously hard-coded value of five seconds.

[ paulmck: Apply feedback from Juergen Gross. ]

Cc: Rik van Riel <riel@surriel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

The check in flush_smp_call_function_queue() for callbacks that are sent
to offline CPUs currently checks whether the queue is empty.

However, flush_smp_call_function_queue() has just deleted all the
callbacks from the queue and moved all the entries into a local list.
This checks would only be positive if some callbacks were added in the
short time after llist_del_all() was called. This does not seem to be
the intention of this check.

Change the check to look at the local list to which the entries were
moved instead of the queue from which all the callbacks were just
removed.

Fixes: 8d056c48e4862 ("CPU hotplug, smp: flush any pending IPI callbacks before CPU offline")
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220319072015.1495036-1-namit@vmware.com

As reported by syzbot and experienced by Pavel, using cpus_read_lock()
in wake_up_all_idle_cpus() generates lock inversion (against mmap_sem
and possibly others).

Instead, shrink the preempt disable region by iterating all CPUs and
checking the online status for each individual CPU while having
preemption disabled.

Fixes: 8850cb663b5c ("sched: Simplify wake_up_*idle*()")
Reported-by: syzbot+d5b23b18d2f4feae8a67@syzkaller.appspotmail.com
Reported-by: Pavel Machek <pavel@ucw.cz>
Reported-by: Qian Cai <quic_qiancai@quicinc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Qian Cai <quic_qiancai@quicinc.com>

Simplify and make wake_up_if_idle() more robust, also don't iterate
the whole machine with preempt_disable() in it's caller:
wake_up_all_idle_cpus().

This prepares for another wake_up_if_idle() user that needs a full
do_idle() cycle.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Tested-by: Vasily Gorbik <gor@linux.ibm.com> # on s390
Link: https://lkml.kernel.org/r/20210929152428.769328779@infradead.org

Fix the following warnings:

kernel/smp.c:1189: warning: cannot understand function prototype: 'struct smp_call_on_cpu_struct '
kernel/smp.c:788: warning: No description found for return value of 'smp_call_function_single_async'
kernel/smp.c:990: warning: Function parameter or member 'wait' not described in 'smp_call_function_many'
kernel/smp.c:990: warning: Excess function parameter 'flags' description in 'smp_call_function_many'
kernel/smp.c:1198: warning: Function parameter or member 'work' not described in 'smp_call_on_cpu_struct'
kernel/smp.c:1198: warning: Function parameter or member 'done' not described in 'smp_call_on_cpu_struct'
kernel/smp.c:1198: warning: Function parameter or member 'func' not described in 'smp_call_on_cpu_struct'
kernel/smp.c:1198: warning: Function parameter or member 'data' not described in 'smp_call_on_cpu_struct'
kernel/smp.c:1198: warning: Function parameter or member 'ret' not described in 'smp_call_on_cpu_struct'
kernel/smp.c:1198: warning: Function parameter or member 'cpu' not described in 'smp_call_on_cpu_struct'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210810225051.3938-1-rdunlap@infradead.org