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, 213 insertions, 0 deletions

diff --git a/drivers/acpi/nvs.c b/drivers/acpi/nvs.c
new file mode 100644
index 000000000..6eaad7dd0
--- /dev/null
+++ b/drivers/acpi/nvs.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * nvs.c - Routines for saving and restoring ACPI NVS memory region
+ *
+ * Copyright (C) 2008-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
+ */
+
+#define pr_fmt(fmt) "ACPI: PM: " fmt
+
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/acpi.h>
+
+#include "internal.h"
+
+/* ACPI NVS regions, APEI may use it */
+
+struct nvs_region {
+	__u64 phys_start;
+	__u64 size;
+	struct list_head node;
+};
+
+static LIST_HEAD(nvs_region_list);
+
+#ifdef CONFIG_ACPI_SLEEP
+static int suspend_nvs_register(unsigned long start, unsigned long size);
+#else
+static inline int suspend_nvs_register(unsigned long a, unsigned long b)
+{
+	return 0;
+}
+#endif
+
+int acpi_nvs_register(__u64 start, __u64 size)
+{
+	struct nvs_region *region;
+
+	region = kmalloc_obj(*region);
+	if (!region)
+		return -ENOMEM;
+	region->phys_start = start;
+	region->size = size;
+	list_add_tail(&region->node, &nvs_region_list);
+
+	return suspend_nvs_register(start, size);
+}
+
+int acpi_nvs_for_each_region(int (*func)(__u64 start, __u64 size, void *data),
+			     void *data)
+{
+	int rc;
+	struct nvs_region *region;
+
+	list_for_each_entry(region, &nvs_region_list, node) {
+		rc = func(region->phys_start, region->size, data);
+		if (rc)
+			return rc;
+	}
+
+	return 0;
+}
+
+
+#ifdef CONFIG_ACPI_SLEEP
+/*
+ * Platforms, like ACPI, may want us to save some memory used by them during
+ * suspend and to restore the contents of this memory during the subsequent
+ * resume.  The code below implements a mechanism allowing us to do that.
+ */
+
+struct nvs_page {
+	unsigned long phys_start;
+	unsigned int size;
+	void *kaddr;
+	void *data;
+	bool unmap;
+	struct list_head node;
+};
+
+static LIST_HEAD(nvs_list);
+
+/**
+ * suspend_nvs_register - register platform NVS memory region to save
+ * @start: Physical address of the region.
+ * @size: Size of the region.
+ *
+ * The NVS region need not be page-aligned (both ends) and we arrange
+ * things so that the data from page-aligned addresses in this region will
+ * be copied into separate RAM pages.
+ */
+static int suspend_nvs_register(unsigned long start, unsigned long size)
+{
+	struct nvs_page *entry, *next;
+
+	pr_info("Registering ACPI NVS region [mem %#010lx-%#010lx] (%ld bytes)\n",
+		start, start + size - 1, size);
+
+	while (size > 0) {
+		unsigned int nr_bytes;
+
+		entry = kzalloc_obj(struct nvs_page);
+		if (!entry)
+			goto Error;
+
+		list_add_tail(&entry->node, &nvs_list);
+		entry->phys_start = start;
+		nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK);
+		entry->size = (size < nr_bytes) ? size : nr_bytes;
+
+		start += entry->size;
+		size -= entry->size;
+	}
+	return 0;
+
+ Error:
+	list_for_each_entry_safe(entry, next, &nvs_list, node) {
+		list_del(&entry->node);
+		kfree(entry);
+	}
+	return -ENOMEM;
+}
+
+/**
+ * suspend_nvs_free - free data pages allocated for saving NVS regions
+ */
+void suspend_nvs_free(void)
+{
+	struct nvs_page *entry;
+
+	list_for_each_entry(entry, &nvs_list, node)
+		if (entry->data) {
+			free_page((unsigned long)entry->data);
+			entry->data = NULL;
+			if (entry->kaddr) {
+				if (entry->unmap) {
+					iounmap(entry->kaddr);
+					entry->unmap = false;
+				} else {
+					acpi_os_unmap_iomem(entry->kaddr,
+							    entry->size);
+				}
+				entry->kaddr = NULL;
+			}
+		}
+}
+
+/**
+ * suspend_nvs_alloc - allocate memory necessary for saving NVS regions
+ */
+int suspend_nvs_alloc(void)
+{
+	struct nvs_page *entry;
+
+	list_for_each_entry(entry, &nvs_list, node) {
+		entry->data = (void *)__get_free_page(GFP_KERNEL);
+		if (!entry->data) {
+			suspend_nvs_free();
+			return -ENOMEM;
+		}
+	}
+	return 0;
+}
+
+/**
+ * suspend_nvs_save - save NVS memory regions
+ */
+int suspend_nvs_save(void)
+{
+	struct nvs_page *entry;
+
+	pr_info("Saving platform NVS memory\n");
+
+	list_for_each_entry(entry, &nvs_list, node)
+		if (entry->data) {
+			unsigned long phys = entry->phys_start;
+			unsigned int size = entry->size;
+
+			entry->kaddr = acpi_os_get_iomem(phys, size);
+			if (!entry->kaddr) {
+				entry->kaddr = acpi_os_ioremap(phys, size);
+				entry->unmap = !!entry->kaddr;
+			}
+			if (!entry->kaddr) {
+				suspend_nvs_free();
+				return -ENOMEM;
+			}
+			memcpy(entry->data, entry->kaddr, entry->size);
+		}
+
+	return 0;
+}
+
+/**
+ * suspend_nvs_restore - restore NVS memory regions
+ *
+ * This function is going to be called with interrupts disabled, so it
+ * cannot iounmap the virtual addresses used to access the NVS region.
+ */
+void suspend_nvs_restore(void)
+{
+	struct nvs_page *entry;
+
+	pr_info("Restoring platform NVS memory\n");
+
+	list_for_each_entry(entry, &nvs_list, node)
+		if (entry->data)
+			memcpy(entry->kaddr, entry->data, entry->size);
+}
+#endif