Pull NOHZ updates from Thomas Gleixner:

 - Fix a long standing TOCTOU in get_cpu_sleep_time_us()

 - Make the CPU offline NOHZ handling more robust by disabling NOHZ on
   the outgoing CPU early instead of creating unneeded state which needs
   to be undone.

 - Unify idle CPU time accounting instead of having two different
   accounting mechanisms. These two different mechanisms are not really
   independent, but the different properties can in the worst case cause
   that gloabl idle time can be observed going backwards.

 - Consolidate the idle/iowait time retrieval interfaces instead of
   converting back and forth between them.

 - Make idle interrupt time accounting more robust. The original code
   assumes that interrupt time accouting is enabled and therefore stops
   elapsing idle time while an interrupt is handled in NOHZ dyntick
   state. That assumption is not correct as interrupt time accounting
   can be disabled at compile and runtime.

 - Fix an accounting error between dyntick idle time and dyntick idle
   steal time. The stolen time is not accounted and therefore idle time
   becomes inaccurate. The stolen time is now accounted after the fact
   as there is no way to predict the steal time upfront.

* tag 'timers-nohz-2026-06-13' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip:
  sched/cputime: Handle dyntick-idle steal time correctly
  sched/cputime: Handle idle irqtime gracefully
  sched/cputime: Provide get_cpu_[idle|iowait]_time_us() off-case
  tick/sched: Consolidate idle time fetching APIs
  tick/sched: Account tickless idle cputime only when tick is stopped
  tick/sched: Remove unused fields
  tick/sched: Move dyntick-idle cputime accounting to cputime code
  tick/sched: Remove nohz disabled special case in cputime fetch
  tick/sched: Unify idle cputime accounting
  s390/time: Prepare to stop elapsing in dynticks-idle
  powerpc/time: Prepare to stop elapsing in dynticks-idle
  sched/cputime: Correctly support generic vtime idle time
  sched/cputime: Remove superfluous and error prone kcpustat_field() parameter
  sched/idle: Handle offlining first in idle loop
  tick/sched: Fix TOCTOU in nohz idle time fetch

Pull RCU updates from Uladzislau Rezki:
 "Torture test updates:

   - Improve kvm-series.sh script by adding examples in its header
     comment

   - Lazy RCU is more fully tested now by replacing call_rcu_hurry()
     with call_rcu() and doing rcu_barrier() to motivate lazy callbacks
     during a stutter pause

   - Add more synonyms for the "--do-normal" group of torture.sh
     command-line arguments

  Misc changes:

   - Reduce stack usage of nocb_gp_wait() to address frame size warning
     when built with CONFIG_UBSAN_ALIGNMENT

   - The synchronize_rcu() call can detect the flood and latches a
     normal/default path temporary switching to wait_rcu_gp() path

   - Document using rcu_access_pointer() to fetch the old pointer for
     lockless cmpxchg() updates

   - Simplify some RCU code using clamp_val()

   - Fix a kerneldoc header comment typo in srcu_down_read_fast()"

* tag 'rcu.release.v7.2' of gitolite.kernel.org:pub/scm/linux/kernel/git/rcu/linux:
  rcu/nocb: reduce stack usage in nocb_gp_wait()
  rcu-tasks: Fix possible boot-time tests failed for the call_rcu_tasks()
  rcu: Latch normal synchronize_rcu() path on flood
  rcu: Document rcu_access_pointer() feeding into cmpxchg()
  rcu: Simplify param_set_next_fqs_jiffies() by applying clamp_val()
  rcu: Simplify rcu_do_batch() by applying clamp()
  checkpatch: Undeprecate rcu_read_lock_trace() and rcu_read_unlock_trace()
  srcu: Fix kerneldoc header comment typo in srcu_down_read_fast()
  torture: Allow "norm" abbreviation for "normal"
  torture: Improve kvm-series.sh header comment
  torture: Add torture_sched_set_normal() for user-specified nice values
  rcutorture: Fully test lazy RCU

The first parameter to kcpustat_field() is a pointer to the cpu kcpustat to
be fetched from. This parameter is error prone because a copy to a kcpustat
could be passed by accident instead of the original one. Also the kcpustat
structure can already be retrieved with the help of the mandatory CPU
argument.

Remove the needless parameter.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-4-frederic@kernel.org

rcutorture.2026.05.24: Torture-test updates
misc.2026.05.24: Miscellaneous RCU updates

When CONFIG_UBSAN_ALIGNMENT is enabled, the stack usage of nocb_gp_wait()
grows above typical warning limits:

In file included from kernel/rcu/tree.c:4930:
kernel/rcu/tree_nocb.h: In function 'rcu_nocb_gp_kthread':
kernel/rcu/tree_nocb.h:866:1: error: the frame size of 1968 bytes is larger than 1280 bytes [-Werror=frame-larger-than=]

Apparently, the problem is passing rcu_data from a 'void *' pointer,
which gcc assumes may be misaligned. When the function is not inlined
into rcu_nocb_gp_kthread(), that is no longer visible to gcc.

Add a 'noinline_for_stack' annotation that leads to skipping a lot of
the alignment sanitizer checks and keeps the stack usage 60% lower here.

Reviewed-by: Kunwu Chan <chentao@kylinos.cn>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

The following scenarios will cause the call_rcu_tasks() boot-time
tests failed:

                     CPU0								CPU1

rcu_init_tasks_generic()
->rcu_tasks_initiate_self_tests()
  ->call_rcu_tasks_trace(&tests[1].rh, test_rcu_tasks_callback)
    ->call_rcu_tasks_generic()
      ->havekthread = smp_load_acquire(&rtp->kthread_ptr)
       "The havekthread is false"
    ....
								       rcu_tasks_kthread()
								       ->smp_store_release(&rtp->kthread_ptr, current)
								         ->rcu_tasks_one_gp()
								           ->rcuwait_wait_event()
								             ->rcu_tasks_need_gpcb()
								               ->for (cpu = 0; cpu < dequeue_limit; cpu++)
								                 ->rcu_segcblist_n_cbs(&rtpcp->cblist) == 0
								           ->schedule()

     ->raw_spin_trylock_rcu_node()
     ->needwake = (func == wakeme_after_rcu) ||
     (rcu_segcblist_n_cbs(&rtpcp->cblist) == rcu_task_lazy_lim)

       "the rcu_task_lazy_lim default value is 32, and the
        func pointer is test_rcu_tasks_callback, lead to needwake
        is false."

     ->if (havekthread && !needwake && !timer_pending(&rtpcp->lazy_timer))
        "the havekthread is false, will not enter here."
     ....

        "the needwake is false lead to rtp_irq_work can not queue,
         even if the rtp->kthread_ptr already exists at this point."

      ->if (needwake && READ_ONCE(rtp->kthread_ptr))
        ->irq_work_queue(&rtpcp->rtp_irq_work)

For the above scenarios, if the call_rcu_tasks() is not called again
afterward, the rcu_tasks_kthread will not have a chance to be wakeup,
the test_rcu_tasks_callback() will never be called, the boot-time tests
failed can happen, this commit therefore check havekthread variable, if
it's false and the rtpcp->cblist is empty, set needwake variable is true,
if the rtp->kthread_ptr exist, the rtpcp->rtp_irq_work can be queued to
wakeup rcu_tasks_kthread.

Signed-off-by: Zqiang <qiang.zhang@linux.dev>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

Currently, rcu_normal_wake_from_gp is only enabled by default
on small systems(<= 16 CPUs) or when a user explicitly set it
enabled.

Introduce an adaptive latching mechanism:
 * Track the number of in-flight synchronize_rcu() requests
   using a new rcu_sr_normal_count counter;

 * If the count reaches/exceeds RCU_SR_NORMAL_LATCH_THR(64),
   it sets the rcu_sr_normal_latched, reverting new requests
   onto the scaled wait_rcu_gp() path;

 * The latch is cleared only when the pending requests are fully
   drained(nr == 0);

 * Enables rcu_normal_wake_from_gp by default for all systems,
   relying on this dynamic throttling instead of static CPU
   limits.

Testing(synthetic flood workload):
  * Kernel version: 6.19.0-rc6
  * Number of CPUs: 1536
  * 60K concurrent synchronize_rcu() calls

Perf(cycles, system-wide):
  total cycles: 932020263832
  rcu_sr_normal_add_req(): 2650282811 cycles(~0.28%)

Perf report excerpt:
  0.01%  0.01%  sync_test/...  [k] rcu_sr_normal_add_req

Measured overhead of rcu_sr_normal_add_req() remained ~0.28%
of total CPU cycles in this synthetic stress test.

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Tested-by: Samir M <samir@linux.ibm.com>
Suggested-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

This commit replaces a nested ?: sequence with clamp_val().  This does
not reduce the number of lines of code, but it does simplify the line
that it modifies.

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

This commit replaces a nested ?: sequence with clamp().  This does not
reduce the number of lines of code, but it does simplify the line that
it modifies.

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

Currently, rcutorture bypasses lazy RCU by using call_rcu_hurry().
This works, avoiding the dreaded rtort_pipe_count WARN(), but fails to
fully test lazy RCU.  The rtort_pipe_count WARN() splats because lazy RCU
could delay the start of an RCU grace period for a full stutter period,
which defaults to only three seconds.

This commit therefore reverts the call_rcu_hurry() instances
back to call_rcu(), but, in kernels built with CONFIG_RCU_LAZY=y,
queues a workqueue handler just before the call to stutter_wait() in
rcu_torture_writer().  This workqueue handler invokes rcu_barrier(),
which motivates any lingering lazy callbacks, thus avoiding the splat.

Reported-by: Saravana Kannan <saravanak@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>