Merge tag 'rcu.2023.08.21a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull RCU updates from Paul McKenney:

 - Documentation updates

 - Miscellaneous fixes, perhaps most notably simplifying
   SRCU_NOTIFIER_INIT() as suggested

 - RCU Tasks updates, most notably treating Tasks RCU callbacks as lazy
   while still treating synchronous grace periods as urgent. Also fixes
   one bug that restores the ability to apply debug-objects to RCU Tasks
   and another that fixes a race condition that could result in
   false-positive failures of the boot-time self-test code

 - RCU-scalability performance-test updates, most notably adding the
   ability to measure the RCU-Tasks's grace-period kthread's CPU
   consumption. This proved quite useful for the RCU Tasks work

 - Reference-acquisition/release performance-test updates, including a
   fix for an uninitialized wait_queue_head_t

 - Miscellaneous torture-test updates

 - Torture-test scripting updates, including removal of the
   non-longer-functional formal-verification scripts, test builds of
   individual RCU Tasks flavors, better diagnostics for loss of
   connectivity for distributed rcutorture tests, disabling of reboot
   loops in qemu/KVM-based rcutorture testing, and passing of init
   parameters to rcutorture's init program

* tag 'rcu.2023.08.21a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (64 commits)
  rcu: Use WRITE_ONCE() for assignments to ->next for rculist_nulls
  rcu: Make the rcu_nocb_poll boot parameter usable via boot config
  rcu: Mark __rcu_irq_enter_check_tick() ->rcu_urgent_qs load
  srcu,notifier: Remove #ifdefs in favor of SRCU Tiny srcu_usage
  rcutorture: Stop right-shifting torture_random() return values
  torture: Stop right-shifting torture_random() return values
  torture: Move stutter_wait() timeouts to hrtimers
  torture: Move torture_shuffle() timeouts to hrtimers
  torture: Move torture_onoff() timeouts to hrtimers
  torture: Make torture_hrtimeout_*() use TASK_IDLE
  torture: Add lock_torture writer_fifo module parameter
  torture: Add a kthread-creation callback to _torture_create_kthread()
  rcu-tasks: Fix boot-time RCU tasks debug-only deadlock
  rcu-tasks: Permit use of debug-objects with RCU Tasks flavors
  checkpatch: Complain about unexpected uses of RCU Tasks Trace
  torture: Cause mkinitrd.sh to indicate failure on compile errors
  torture: Make init program dump command-line arguments
  torture: Switch qemu from -nographic to -display none
  torture: Add init-program support for loongarch
  torture: Avoid torture-test reboot loops
  ...

1 files changed, 55 insertions, 1 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 6ff63638ed82..77bda843df34 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2938,6 +2938,10 @@
 	locktorture.torture_type= [KNL]
 			Specify the locking implementation to test.
 
+	locktorture.writer_fifo= [KNL]
+			Run the write-side locktorture kthreads at
+			sched_set_fifo() real-time priority.
+
 	locktorture.verbose= [KNL]
 			Enable additional printk() statements.
 
@@ -4949,6 +4953,15 @@
 			test until boot completes in order to avoid
 			interference.
 
+	rcuscale.kfree_by_call_rcu= [KNL]
+			In kernels built with CONFIG_RCU_LAZY=y, test
+			call_rcu() instead of kfree_rcu().
+
+	rcuscale.kfree_mult= [KNL]
+			Instead of allocating an object of size kfree_obj,
+			allocate one of kfree_mult * sizeof(kfree_obj).
+			Defaults to 1.
+
 	rcuscale.kfree_rcu_test= [KNL]
 			Set to measure performance of kfree_rcu() flooding.
 
@@ -4974,6 +4987,12 @@
 			Number of loops doing rcuscale.kfree_alloc_num number
 			of allocations and frees.
 
+	rcuscale.minruntime= [KNL]
+			Set the minimum test run time in seconds.  This
+			does not affect the data-collection interval,
+			but instead allows better measurement of things
+			like CPU consumption.
+
 	rcuscale.nreaders= [KNL]
 			Set number of RCU readers.  The value -1 selects
 			N, where N is the number of CPUs.  A value
@@ -4988,7 +5007,7 @@
 			the same as for rcuscale.nreaders.
 			N, where N is the number of CPUs
 
-	rcuscale.perf_type= [KNL]
+	rcuscale.scale_type= [KNL]
 			Specify the RCU implementation to test.
 
 	rcuscale.shutdown= [KNL]
@@ -5004,6 +5023,11 @@
 			in microseconds.  The default of zero says
 			no holdoff.
 
+	rcuscale.writer_holdoff_jiffies= [KNL]
+			Additional write-side holdoff between grace
+			periods, but in jiffies.  The default of zero
+			says no holdoff.
+
 	rcutorture.fqs_duration= [KNL]
 			Set duration of force_quiescent_state bursts
 			in microseconds.
@@ -5285,6 +5309,13 @@
 			number avoids disturbing real-time workloads,
 			but lengthens grace periods.
 
+	rcupdate.rcu_task_lazy_lim= [KNL]
+			Number of callbacks on a given CPU that will
+			cancel laziness on that CPU.  Use -1 to disable
+			cancellation of laziness, but be advised that
+			doing so increases the danger of OOM due to
+			callback flooding.
+
 	rcupdate.rcu_task_stall_info= [KNL]
 			Set initial timeout in jiffies for RCU task stall
 			informational messages, which give some indication
@@ -5314,6 +5345,29 @@
 			A change in value does not take effect until
 			the beginning of the next grace period.
 
+	rcupdate.rcu_tasks_lazy_ms= [KNL]
+			Set timeout in milliseconds RCU Tasks asynchronous
+			callback batching for call_rcu_tasks().
+			A negative value will take the default.  A value
+			of zero will disable batching.	Batching is
+			always disabled for synchronize_rcu_tasks().
+
+	rcupdate.rcu_tasks_rude_lazy_ms= [KNL]
+			Set timeout in milliseconds RCU Tasks
+			Rude asynchronous callback batching for
+			call_rcu_tasks_rude().	A negative value
+			will take the default.	A value of zero will
+			disable batching.  Batching is always disabled
+			for synchronize_rcu_tasks_rude().
+
+	rcupdate.rcu_tasks_trace_lazy_ms= [KNL]
+			Set timeout in milliseconds RCU Tasks
+			Trace asynchronous callback batching for
+			call_rcu_tasks_trace().  A negative value
+			will take the default.	A value of zero will
+			disable batching.  Batching is always disabled
+			for synchronize_rcu_tasks_trace().
+
 	rcupdate.rcu_self_test= [KNL]
 			Run the RCU early boot self tests