Merge tag 'rcu.2026.08.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux

Pull RCU updates from Paul McKenney:
 "Make expedited grace periods expedite normal RCU callbacks

  Miscellaneous fixes:
   - Improve diagnostic output with character task states
   - Mark accesses to inform KCSAN of concurrency design
   - Move from kmalloc() to kmalloc_obj()
   - Documentation updates
   - Improve handling of RCU deferred quiescent states
   - Clean up unused function arguments and structure fields
   - Reduce show_rcu_gp_kthreads() stack space

  Tasks RCU updates:
   - Clean up after SRCU re-implementation of Tasks Trace RCU
   - Mark accesses to inform KCSAN of concurrency design
   - Add ->lazy_timer status to diagnostic output
   - Remove an unnecessary memory barrier
   - Fix a data race, courtesy of KCSAN
   - Documentation updates
   - Convert cond_resched_tasks_rcu_qs() from macro to static inline
     function

  SRCU updates:
   - Add Rust helpers for SRCU
   - Avoid losing queued work at cleanup_srcu_struct() time

  Torture-test updates:
   - Preparation work for immediate RCU priority deboosting
   - Test RCU readers from real interrupt handlers (as opposed to
     softirq)
   - Simplify code through use of cpumask_next_wrap()
   - Improve diagnostic output with character task states
   - Add rcutorture.nwriters parameter to allow lightweight stall
     testing, and rcutorture.stall_only to make doing so easier
   - Test an RCU Tasks Trace grace period implying an RCU grace period
   - Make RCU Tasks Trace torturing track reader batches
   - Fix a data race, courtesy of KCSAN
   - Plug a shuffle_tmp_mask memory leak on kthread spawn failure"

* tag 'rcu.2026.08.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (59 commits)
  rcu: Add closing parenthesis in comment in rcu_read_unlock_strict()
  rcutorture: Make {,s}rcu_read_delay() better handle forward-progress testing
  rcutorture: Announce declining to forward-progress test
  torture: Don't leak shuffle_tmp_mask when shuffler kthread fails to start
  rcutorture: Use this_cpu_inc() for rcu_torture_count[] and rcu_torture_batch[]
  rcutorture: Make RCU Tasks Trace track Reader Batches
  rcutorture: Test RCU Tasks Trace GP implying RCU GP
  rcutorture: Add a stall_only module parameter
  rcutorture: Add nwriters module parameter
  rcutorture: Use task_state_to_char() for task-state reporting
  rcutorture: Use cpumask_next_wrap() in rcu_torture_preempt()
  rcutorture: Test RCU readers from hardware interrupt handlers
  rcutorture: Check for immediate deboosting at reader end
  srcu: Queue sdp->work when the delay timer is successfully deleted
  rcu-tasks: Convert cond_resched_tasks_rcu_qs() to static inline
  rcu-tasks: Fix some comments for call_rcu_tasks() and call_rcu_tasks_rude()
  rcu-tasks: Rename tasks_rcu_exit_srcu_stall_timer to tasks_rcu_exit_stall_timer
  rcu: Mark interrupts-enabled accesses to rdp->cpu_no_qs.s
  rcu: Reduce stack usage in show_rcu_gp_kthreads()
  rcu: Mark accesses to ->rcu_urgent_qs and ->rcu_need_heavy_qs
  ...

6 files changed, 20 insertions, 6 deletions

diff --git a/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst b/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst
index 414f8a201..cf0f9cdca 100644
--- a/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst
+++ b/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst
@@ -410,7 +410,7 @@ workqueues (see Documentation/core-api/workqueue.rst).
 
 The requesting task still does counter snapshotting and funnel-lock
 processing, but the task reaching the top of the funnel lock does a
-``schedule_work()`` (from ``_synchronize_rcu_expedited()`` so that a
+``schedule_work()`` (from ``_synchronize_rcu_expedited()``) so that a
 workqueue kthread does the actual grace-period processing. Because
 workqueue kthreads do not accept POSIX signals, grace-period-wait
 processing need not allow for POSIX signals. In addition, this approach
diff --git a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp.svg b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp.svg
index d05bc7b27..95a66de40 100644
--- a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp.svg
+++ b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp.svg
@@ -3933,7 +3933,7 @@
          font-style="normal"
          y="-3914.085"
          x="3745.7725"
-         xml:space="preserve">rcu__report_qs_rdp())</text>
+         xml:space="preserve">rcu__report_qs_rdp()</text>
     </g>
     <g
        id="g4504-3"
diff --git a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-qs.svg b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-qs.svg
index 7d6c5f7e5..882132680 100644
--- a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-qs.svg
+++ b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-qs.svg
@@ -815,7 +815,7 @@
          font-style="normal"
          y="-3914.085"
          x="3745.7725"
-         xml:space="preserve">rcu__report_qs_rdp())</text>
+         xml:space="preserve">rcu__report_qs_rdp()</text>
     </g>
     <g
        id="g4504-3"
diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst
index 8a216e4a4..8101fe622 100644
--- a/Documentation/RCU/Design/Requirements/Requirements.rst
+++ b/Documentation/RCU/Design/Requirements/Requirements.rst
@@ -2785,7 +2785,7 @@ both srcu_read_lock() and srcu_read_unlock().  This need is handled by
 a Tasks Trace RCU API implemented as thin wrappers around SRCU-fast,
 which avoids the read-side memory barriers, at least for architectures
 that apply noinstr to kernel entry/exit code (or that build with
-``CONFIG_TASKS_TRACE_RCU_NO_MB=y``.
+``CONFIG_TASKS_TRACE_RCU_NO_MB=y``).
 
 Now that the implementation is based on SRCU-fast, a call
 to synchronize_rcu_tasks_trace() implies at least one call to
diff --git a/Documentation/RCU/rcu_dereference.rst b/Documentation/RCU/rcu_dereference.rst
index 2524dcdad..5bc3785eb 100644
--- a/Documentation/RCU/rcu_dereference.rst
+++ b/Documentation/RCU/rcu_dereference.rst
@@ -236,7 +236,7 @@ precautions.  To see this, consider the following code fragment::
 	{
 		struct foo *p;
 
-		p = kmalloc(...);
+		p = kmalloc_obj(*p);
 		if (p == NULL)
 			deal_with_it();
 		p->a = 42;  /* Each field in its own cache line. */
@@ -293,7 +293,7 @@ Then one approach is to use locking, for example, as follows::
 	{
 		struct foo *p;
 
-		p = kmalloc(...);
+		p = kmalloc_obj(*p);
 		if (p == NULL)
 			deal_with_it();
 		spin_lock(&p->lock);
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 4a12805a5..66c1c879a 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6157,6 +6157,11 @@ Kernel parameters
 			the number of CPUs.  For example, -2 selects N
 			(the number of CPUs), -3 selects N+1, and so on.
 
+	rcutorture.nwriters= [KNL]
+			Set number of RCU writers, which must be either
+			zero or one.  For additional writers, use instead
+			the rcutorture.nfakewriters parameter.
+
 	rcutorture.object_debug= [KNL]
 			Enable debug-object double-call_rcu() testing.
 
@@ -6246,6 +6251,15 @@ Kernel parameters
 			and stall_gp_kthread are specified, the
 			kthread is starved first, then the CPU.
 
+	rcutorture.stall_only= [KNL]
+			Shut off all rcutorture kthreads other than the
+			RCU CPU stall-warning test kthreads.  The purpose
+			of this is to test production applictions'
+			reactions to CPU stalls, and with minimal
+			additional overhead.  Or you can omit the
+			stall-warning tests as well and get a heavy
+			no-op, your choice!
+
 	rcutorture.stat_interval= [KNL]
 			Time (s) between statistics printk()s.