Merge tag 'rcu.2022.07.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck...

Pull RCU updates from Paul McKenney:

 - Documentation updates

 - Miscellaneous fixes

 - Callback-offload updates, perhaps most notably a new
   RCU_NOCB_CPU_DEFAULT_ALL Kconfig option that causes all CPUs to be
   offloaded at boot time, regardless of kernel boot parameters.

   This is useful to battery-powered systems such as ChromeOS and
   Android. In addition, a new RCU_NOCB_CPU_CB_BOOST kernel boot
   parameter prevents offloaded callbacks from interfering with
   real-time workloads and with energy-efficiency mechanisms

 - Polled grace-period updates, perhaps most notably making these APIs
   account for both normal and expedited grace periods

 - Tasks RCU updates, perhaps most notably reducing the CPU overhead of
   RCU tasks trace grace periods by more than a factor of two on a
   system with 15,000 tasks.

   The reduction is expected to increase with the number of tasks, so it
   seems reasonable to hypothesize that a system with 150,000 tasks
   might see a 20-fold reduction in CPU overhead

 - Torture-test updates

 - Updates that merge RCU's dyntick-idle tracking into context tracking,
   thus reducing the overhead of transitioning to kernel mode from
   either idle or nohz_full userspace execution for kernels that track
   context independently of RCU.

   This is expected to be helpful primarily for kernels built with
   CONFIG_NO_HZ_FULL=y

* tag 'rcu.2022.07.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (98 commits)
  rcu: Add irqs-disabled indicator to expedited RCU CPU stall warnings
  rcu: Diagnose extended sync_rcu_do_polled_gp() loops
  rcu: Put panic_on_rcu_stall() after expedited RCU CPU stall warnings
  rcutorture: Test polled expedited grace-period primitives
  rcu: Add polled expedited grace-period primitives
  rcutorture: Verify that polled GP API sees synchronous grace periods
  rcu: Make Tiny RCU grace periods visible to polled APIs
  rcu: Make polled grace-period API account for expedited grace periods
  rcu: Switch polled grace-period APIs to ->gp_seq_polled
  rcu/nocb: Avoid polling when my_rdp->nocb_head_rdp list is empty
  rcu/nocb: Add option to opt rcuo kthreads out of RT priority
  rcu: Add nocb_cb_kthread check to rcu_is_callbacks_kthread()
  rcu/nocb: Add an option to offload all CPUs on boot
  rcu/nocb: Fix NOCB kthreads spawn failure with rcu_nocb_rdp_deoffload() direct call
  rcu/nocb: Invert rcu_state.barrier_mutex VS hotplug lock locking order
  rcu/nocb: Add/del rdp to iterate from rcuog itself
  rcu/tree: Add comment to describe GP-done condition in fqs loop
  rcu: Initialize first_gp_fqs at declaration in rcu_gp_fqs()
  rcu/kvfree: Remove useless monitor_todo flag
  rcu: Cleanup RCU urgency state for offline CPU
  ...

diff --cc Documentation/admin-guide/kernel-parameters.txt
Simple merge

diff --cc MAINTAINERS
Simple merge

diff --cc arch/Kconfig
Simple merge

diff --cc arch/arm/Kconfig
Simple merge

diff --cc arch/arm/kernel/entry-common.S
Simple merge

diff --cc arch/arm64/Kconfig
Simple merge

diff --cc arch/loongarch/Kconfig
index 83fe390f84496f35275ac2e534302538f6e76742,130dc65f3c858cddb79a4f9a4d5d01b91e44ac37..fc2465892a60a01406e8f3fdf6310bbc62ac99d8
--- 1/arch/loongarch/Kconfig
--- 2/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@@ -75,7 -76,8 +75,7 @@@ config LOONGARC
        select HAVE_ARCH_TRACEHOOK
        select HAVE_ARCH_TRANSPARENT_HUGEPAGE
        select HAVE_ASM_MODVERSIONS
-       select HAVE_CONTEXT_TRACKING
+       select HAVE_CONTEXT_TRACKING_USER
 -      select HAVE_COPY_THREAD_TLS
        select HAVE_DEBUG_STACKOVERFLOW
        select HAVE_DMA_CONTIGUOUS
        select HAVE_EXIT_THREAD

diff --cc arch/powerpc/Kconfig
Simple merge

diff --cc arch/riscv/Kconfig
Simple merge

diff --cc arch/sparc/Kconfig
Simple merge

diff --cc arch/x86/Kconfig
Simple merge

diff --cc arch/xtensa/kernel/entry.S
Simple merge

diff --cc drivers/acpi/processor_idle.c
Simple merge

diff --cc include/linux/sched.h
Simple merge

diff --cc init/Kconfig
Simple merge

diff --cc kernel/fork.c
Simple merge

diff --cc kernel/locking/lockdep.c
Simple merge

diff --cc kernel/rcu/tree_stall.h
Simple merge

diff --cc kernel/sched/core.c
Simple merge

diff --cc kernel/sched/sched.h
Simple merge

diff --cc kernel/time/tick-sched.c
Simple merge

diff --cc kernel/trace/trace.c
Simple merge