Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEADgrafted

Changes:

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.

2 files changed, 65 insertions, 0 deletions

diff --git a/samples/trace_printk/Makefile b/samples/trace_printk/Makefile
new file mode 100644
index 000000000..c0df36167
--- /dev/null
+++ b/samples/trace_printk/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-only
+# builds a module that calls various trace_printk routines
+# then to use one (as root):  insmod <module_name.ko>
+
+# This module can also be used to test the trace_printk code.
+
+obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace-printk.o
diff --git a/samples/trace_printk/trace-printk.c b/samples/trace_printk/trace-printk.c
new file mode 100644
index 000000000..cfc159580
--- /dev/null
+++ b/samples/trace_printk/trace-printk.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/irq_work.h>
+
+/* Must not be static to force gcc to consider these non constant */
+char *trace_printk_test_global_str =
+	"This is a dynamic string that will use trace_puts\n";
+
+char *trace_printk_test_global_str_irq =
+	"(irq) This is a dynamic string that will use trace_puts\n";
+
+char *trace_printk_test_global_str_fmt =
+	"%sThis is a %s that will use trace_printk\n";
+
+static struct irq_work irqwork;
+
+static void trace_printk_irq_work(struct irq_work *work)
+{
+	trace_printk("(irq) This is a static string that will use trace_bputs\n");
+	trace_printk(trace_printk_test_global_str_irq);
+
+	trace_printk("(irq) This is a %s that will use trace_bprintk()\n",
+		     "static string");
+
+	trace_printk(trace_printk_test_global_str_fmt,
+		     "(irq) ", "dynamic string");
+}
+
+static int __init trace_printk_init(void)
+{
+	init_irq_work(&irqwork, trace_printk_irq_work);
+
+	trace_printk("This is a static string that will use trace_bputs\n");
+	trace_printk(trace_printk_test_global_str);
+
+	/* Kick off printing in irq context */
+	irq_work_queue(&irqwork);
+	irq_work_sync(&irqwork);
+
+	trace_printk("This is a %s that will use trace_bprintk()\n",
+		     "static string");
+
+	trace_printk(trace_printk_test_global_str_fmt, "", "dynamic string");
+
+	return 0;
+}
+
+static void __exit trace_printk_exit(void)
+{
+}
+
+module_init(trace_printk_init);
+module_exit(trace_printk_exit);
+
+MODULE_AUTHOR("Steven Rostedt");
+MODULE_DESCRIPTION("trace-printk");
+MODULE_LICENSE("GPL");