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, 53 insertions, 0 deletions

diff --git a/scripts/include/xalloc.h b/scripts/include/xalloc.h
new file mode 100644
index 000000000..cdadb07d0
--- /dev/null
+++ b/scripts/include/xalloc.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef XALLOC_H
+#define XALLOC_H
+
+#include <stdlib.h>
+#include <string.h>
+
+static inline void *xmalloc(size_t size)
+{
+	void *p = malloc(size);
+
+	if (!p)
+		exit(1);
+	return p;
+}
+
+static inline void *xcalloc(size_t nmemb, size_t size)
+{
+	void *p = calloc(nmemb, size);
+
+	if (!p)
+		exit(1);
+	return p;
+}
+
+static inline void *xrealloc(void *p, size_t size)
+{
+	p = realloc(p, size);
+	if (!p)
+		exit(1);
+	return p;
+}
+
+static inline char *xstrdup(const char *s)
+{
+	char *p = strdup(s);
+
+	if (!p)
+		exit(1);
+	return p;
+}
+
+static inline char *xstrndup(const char *s, size_t n)
+{
+	char *p = strndup(s, n);
+
+	if (!p)
+		exit(1);
+	return p;
+}
+
+#endif /* XALLOC_H */