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/tools/lib/slab.c b/tools/lib/slab.c
new file mode 100644
index 000000000..981a21404
--- /dev/null
+++ b/tools/lib/slab.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <stdio.h>
+#include <string.h>
+
+#include <urcu/uatomic.h>
+#include <linux/slab.h>
+#include <malloc.h>
+#include <linux/gfp.h>
+
+int kmalloc_nr_allocated;
+int kmalloc_verbose;
+
+void *kmalloc(size_t size, gfp_t gfp)
+{
+	void *ret;
+
+	if (!(gfp & __GFP_DIRECT_RECLAIM))
+		return NULL;
+
+	ret = malloc(size);
+	uatomic_inc(&kmalloc_nr_allocated);
+	if (kmalloc_verbose)
+		printf("Allocating %p from malloc\n", ret);
+	if (gfp & __GFP_ZERO)
+		memset(ret, 0, size);
+	return ret;
+}
+
+void kfree(void *p)
+{
+	if (!p)
+		return;
+	uatomic_dec(&kmalloc_nr_allocated);
+	if (kmalloc_verbose)
+		printf("Freeing %p to malloc\n", p);
+	free(p);
+}
+
+void *kmalloc_array(size_t n, size_t size, gfp_t gfp)
+{
+	void *ret;
+
+	if (!(gfp & __GFP_DIRECT_RECLAIM))
+		return NULL;
+
+	ret = calloc(n, size);
+	uatomic_inc(&kmalloc_nr_allocated);
+	if (kmalloc_verbose)
+		printf("Allocating %p from calloc\n", ret);
+	if (gfp & __GFP_ZERO)
+		memset(ret, 0, n * size);
+	return ret;
+}