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, 44 insertions, 0 deletions

diff --git a/io_uring/alloc_cache.c b/io_uring/alloc_cache.c
new file mode 100644
index 000000000..58423888b
--- /dev/null
+++ b/io_uring/alloc_cache.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "alloc_cache.h"
+
+void io_alloc_cache_free(struct io_alloc_cache *cache,
+			 void (*free)(const void *))
+{
+	void *entry;
+
+	if (!cache->entries)
+		return;
+
+	while ((entry = io_alloc_cache_get(cache)) != NULL)
+		free(entry);
+
+	kvfree(cache->entries);
+	cache->entries = NULL;
+}
+
+/* returns false if the cache was initialized properly */
+bool io_alloc_cache_init(struct io_alloc_cache *cache,
+			 unsigned max_nr, unsigned int size,
+			 unsigned int init_bytes)
+{
+	cache->entries = kvmalloc_array(max_nr, sizeof(void *), GFP_KERNEL);
+	if (!cache->entries)
+		return true;
+
+	cache->nr_cached = 0;
+	cache->max_cached = max_nr;
+	cache->elem_size = size;
+	cache->init_clear = init_bytes;
+	return false;
+}
+
+void *io_cache_alloc_new(struct io_alloc_cache *cache, gfp_t gfp)
+{
+	void *obj;
+
+	obj = kmalloc(cache->elem_size, gfp);
+	if (obj && cache->init_clear)
+		memset(obj, 0, cache->init_clear);
+	return obj;
+}