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, 54 insertions, 0 deletions

diff --git a/drivers/firmware/google/memconsole.c b/drivers/firmware/google/memconsole.c
new file mode 100644
index 000000000..6138a1653
--- /dev/null
+++ b/drivers/firmware/google/memconsole.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * memconsole.c
+ *
+ * Architecture-independent parts of the memory based BIOS console.
+ *
+ * Copyright 2017 Google Inc.
+ */
+
+#include <linux/sysfs.h>
+#include <linux/kobject.h>
+#include <linux/module.h>
+
+#include "memconsole.h"
+
+static ssize_t memconsole_read(struct file *filp, struct kobject *kobp,
+			       const struct bin_attribute *bin_attr, char *buf,
+			       loff_t pos, size_t count)
+{
+	ssize_t (*memconsole_read_func)(char *, loff_t, size_t);
+
+	memconsole_read_func = bin_attr->private;
+	if (WARN_ON_ONCE(!memconsole_read_func))
+		return -EIO;
+
+	return memconsole_read_func(buf, pos, count);
+}
+
+static struct bin_attribute memconsole_bin_attr = {
+	.attr = {.name = "log", .mode = 0444},
+	.read = memconsole_read,
+};
+
+void memconsole_setup(ssize_t (*read_func)(char *, loff_t, size_t))
+{
+	memconsole_bin_attr.private = read_func;
+}
+EXPORT_SYMBOL(memconsole_setup);
+
+int memconsole_sysfs_init(void)
+{
+	return sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr);
+}
+EXPORT_SYMBOL(memconsole_sysfs_init);
+
+void memconsole_exit(void)
+{
+	sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr);
+}
+EXPORT_SYMBOL(memconsole_exit);
+
+MODULE_AUTHOR("Google, Inc.");
+MODULE_DESCRIPTION("Architecture-independent parts of the memory based BIOS console");
+MODULE_LICENSE("GPL");