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.

1 files changed, 129 insertions, 0 deletions

diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
new file mode 100644
index 000000000..53ec6c8b8
--- /dev/null
+++ b/samples/kprobes/kprobe_example.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Here's a sample kernel module showing the use of kprobes to dump a
+ * stack trace and selected registers when kernel_clone() is called.
+ *
+ * For more information on theory of operation of kprobes, see
+ * Documentation/trace/kprobes.rst
+ *
+ * You will see the trace data in /var/log/messages and on the console
+ * whenever kernel_clone() is invoked to create a new process.
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kprobes.h>
+
+static char symbol[KSYM_NAME_LEN] = "kernel_clone";
+module_param_string(symbol, symbol, KSYM_NAME_LEN, 0644);
+
+/* For each probe you need to allocate a kprobe structure */
+static struct kprobe kp = {
+	.symbol_name	= symbol,
+};
+
+/* kprobe pre_handler: called just before the probed instruction is executed */
+static int __kprobes handler_pre(struct kprobe *p, struct pt_regs *regs)
+{
+#ifdef CONFIG_X86
+	pr_info("<%s> p->addr = 0x%p, ip = %lx, flags = 0x%lx\n",
+		p->symbol_name, p->addr, regs->ip, regs->flags);
+#endif
+#ifdef CONFIG_PPC
+	pr_info("<%s> p->addr = 0x%p, nip = 0x%lx, msr = 0x%lx\n",
+		p->symbol_name, p->addr, regs->nip, regs->msr);
+#endif
+#ifdef CONFIG_MIPS
+	pr_info("<%s> p->addr = 0x%p, epc = 0x%lx, status = 0x%lx\n",
+		p->symbol_name, p->addr, regs->cp0_epc, regs->cp0_status);
+#endif
+#ifdef CONFIG_ARM64
+	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, pstate = 0x%lx\n",
+		p->symbol_name, p->addr, (long)regs->pc, (long)regs->pstate);
+#endif
+#ifdef CONFIG_ARM
+	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, cpsr = 0x%lx\n",
+		p->symbol_name, p->addr, (long)regs->ARM_pc, (long)regs->ARM_cpsr);
+#endif
+#ifdef CONFIG_RISCV
+	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, status = 0x%lx\n",
+		p->symbol_name, p->addr, regs->epc, regs->status);
+#endif
+#ifdef CONFIG_S390
+	pr_info("<%s> p->addr, 0x%p, ip = 0x%lx, flags = 0x%lx\n",
+		p->symbol_name, p->addr, regs->psw.addr, regs->flags);
+#endif
+#ifdef CONFIG_LOONGARCH
+	pr_info("<%s> p->addr = 0x%p, era = 0x%lx, estat = 0x%lx\n",
+		p->symbol_name, p->addr, regs->csr_era, regs->csr_estat);
+#endif
+
+	/* A dump_stack() here will give a stack backtrace */
+	return 0;
+}
+
+/* kprobe post_handler: called after the probed instruction is executed */
+static void __kprobes handler_post(struct kprobe *p, struct pt_regs *regs,
+				unsigned long flags)
+{
+#ifdef CONFIG_X86
+	pr_info("<%s> p->addr = 0x%p, flags = 0x%lx\n",
+		p->symbol_name, p->addr, regs->flags);
+#endif
+#ifdef CONFIG_PPC
+	pr_info("<%s> p->addr = 0x%p, msr = 0x%lx\n",
+		p->symbol_name, p->addr, regs->msr);
+#endif
+#ifdef CONFIG_MIPS
+	pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",
+		p->symbol_name, p->addr, regs->cp0_status);
+#endif
+#ifdef CONFIG_ARM64
+	pr_info("<%s> p->addr = 0x%p, pstate = 0x%lx\n",
+		p->symbol_name, p->addr, (long)regs->pstate);
+#endif
+#ifdef CONFIG_ARM
+	pr_info("<%s> p->addr = 0x%p, cpsr = 0x%lx\n",
+		p->symbol_name, p->addr, (long)regs->ARM_cpsr);
+#endif
+#ifdef CONFIG_RISCV
+	pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",
+		p->symbol_name, p->addr, regs->status);
+#endif
+#ifdef CONFIG_S390
+	pr_info("<%s> p->addr, 0x%p, flags = 0x%lx\n",
+		p->symbol_name, p->addr, regs->flags);
+#endif
+#ifdef CONFIG_LOONGARCH
+	pr_info("<%s> p->addr = 0x%p, estat = 0x%lx\n",
+		p->symbol_name, p->addr, regs->csr_estat);
+#endif
+}
+
+static int __init kprobe_init(void)
+{
+	int ret;
+	kp.pre_handler = handler_pre;
+	kp.post_handler = handler_post;
+
+	ret = register_kprobe(&kp);
+	if (ret < 0) {
+		pr_err("register_kprobe failed, returned %d\n", ret);
+		return ret;
+	}
+	pr_info("Planted kprobe at %p\n", kp.addr);
+	return 0;
+}
+
+static void __exit kprobe_exit(void)
+{
+	unregister_kprobe(&kp);
+	pr_info("kprobe at %p unregistered\n", kp.addr);
+}
+
+module_init(kprobe_init)
+module_exit(kprobe_exit)
+MODULE_DESCRIPTION("sample kernel module showing the use of kprobes");
+MODULE_LICENSE("GPL");