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

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
  ...

2 files changed, 3 insertions, 2 deletions

diff --git a/init/Kconfig b/init/Kconfig
index e70702d36180..7f75a61eb52e 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -494,11 +494,11 @@ config VIRT_CPU_ACCOUNTING_NATIVE
 
 config VIRT_CPU_ACCOUNTING_GEN
 	bool "Full dynticks CPU time accounting"
-	depends on HAVE_CONTEXT_TRACKING
+	depends on HAVE_CONTEXT_TRACKING_USER
 	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
 	depends on GENERIC_CLOCKEVENTS
 	select VIRT_CPU_ACCOUNTING
-	select CONTEXT_TRACKING
+	select CONTEXT_TRACKING_USER
 	help
 	  Select this option to enable task and CPU time accounting on full
 	  dynticks systems. This accounting is implemented by watching every
diff --git a/init/init_task.c b/init/init_task.c
index 73cc8f03511a..ff6c4b9bfe6b 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -157,6 +157,7 @@ struct task_struct init_task
 	.trc_reader_nesting = 0,
 	.trc_reader_special.s = 0,
 	.trc_holdout_list = LIST_HEAD_INIT(init_task.trc_holdout_list),
+	.trc_blkd_node = LIST_HEAD_INIT(init_task.trc_blkd_node),
 #endif
 #ifdef CONFIG_CPUSETS
 	.mems_allowed_seq = SEQCNT_SPINLOCK_ZERO(init_task.mems_allowed_seq,