Merge tag 'rcu.2022.03.13a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull RCU updates from Paul McKenney:

 - Fix idle detection (Neeraj Upadhyay) and missing access marking
   detected by KCSAN.

 - Reduce coupling between rcu_barrier() and CPU-hotplug operations, so
   that rcu_barrier() no longer needs to do cpus_read_lock(). This may
   also someday allow system boot to bring CPUs online concurrently.

 - Enable more aggressive movement to per-CPU queueing when reacting to
   excessive lock contention due to workloads placing heavy update-side
   stress on RCU tasks.

 - Improvements to RCU priority boosting, including changes from Neeraj
   Upadhyay, Zqiang, and Alison Chaiken.

 - Various fixes improving test robustness and debug information.

 - Add tests for SRCU size transitions, further compress torture.sh
   build products, and improve debug output.

 - Miscellaneous fixes.

* tag 'rcu.2022.03.13a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (49 commits)
  rcu: Replace cpumask_weight with cpumask_empty where appropriate
  rcu: Remove __read_mostly annotations from rcu_scheduler_active externs
  rcu: Uninline multi-use function: finish_rcuwait()
  rcu: Mark writes to the rcu_segcblist structure's ->flags field
  kasan: Record work creation stack trace with interrupts enabled
  rcu: Inline __call_rcu() into call_rcu()
  rcu: Add mutex for rcu boost kthread spawning and affinity setting
  rcu: Fix description of kvfree_rcu()
  MAINTAINERS:  Add Frederic and Neeraj to their RCU files
  rcutorture: Provide non-power-of-two Tasks RCU scenarios
  rcutorture: Test SRCU size transitions
  torture: Make torture.sh help message match reality
  rcu-tasks: Set ->percpu_enqueue_shift to zero upon contention
  rcu-tasks: Use order_base_2() instead of ilog2()
  rcu: Create and use an rcu_rdp_cpu_online()
  rcu: Make rcu_barrier() no longer block CPU-hotplug operations
  rcu: Rework rcu_barrier() and callback-migration logic
  rcu: Refactor rcu_barrier() empty-list handling
  rcu: Kill rnp->ofl_seq and use only rcu_state.ofl_lock for exclusion
  torture: Change KVM environment variable to RCUTORTURE
  ...

1 files changed, 2 insertions, 0 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 7123524a86b8..98fa63d93ac5 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4504,6 +4504,8 @@
 			(the least-favored priority).  Otherwise, when
 			RCU_BOOST is not set, valid values are 0-99 and
 			the default is zero (non-realtime operation).
+			When RCU_NOCB_CPU is set, also adjust the
+			priority of NOCB callback kthreads.
 
 	rcutree.rcu_nocb_gp_stride= [KNL]
 			Set the number of NOCB callback kthreads in