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, 67 insertions, 0 deletions

diff --git a/security/landlock/object.c b/security/landlock/object.c
new file mode 100644
index 000000000..0d6e159ef
--- /dev/null
+++ b/security/landlock/object.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock LSM - Object management
+ *
+ * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2020 ANSSI
+ */
+
+#include <linux/bug.h>
+#include <linux/compiler_types.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/rcupdate.h>
+#include <linux/refcount.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "object.h"
+
+struct landlock_object *
+landlock_create_object(const struct landlock_object_underops *const underops,
+		       void *const underobj)
+{
+	struct landlock_object *new_object;
+
+	if (WARN_ON_ONCE(!underops || !underobj))
+		return ERR_PTR(-ENOENT);
+	new_object = kzalloc_obj(*new_object, GFP_KERNEL_ACCOUNT);
+	if (!new_object)
+		return ERR_PTR(-ENOMEM);
+	refcount_set(&new_object->usage, 1);
+	spin_lock_init(&new_object->lock);
+	new_object->underops = underops;
+	new_object->underobj = underobj;
+	return new_object;
+}
+
+/*
+ * The caller must own the object (i.e. thanks to object->usage) to safely put
+ * it.
+ */
+void landlock_put_object(struct landlock_object *const object)
+{
+	/*
+	 * The call to @object->underops->release(object) might sleep, e.g.
+	 * because of iput().
+	 */
+	might_sleep();
+	if (!object)
+		return;
+
+	/*
+	 * If the @object's refcount cannot drop to zero, we can just decrement
+	 * the refcount without holding a lock. Otherwise, the decrement must
+	 * happen under @object->lock for synchronization with things like
+	 * get_inode_object().
+	 */
+	if (refcount_dec_and_lock(&object->usage, &object->lock)) {
+		__acquire(&object->lock);
+		/*
+		 * With @object->lock initially held, remove the reference from
+		 * @object->underobj to @object (if it still exists).
+		 */
+		object->underops->release(object);
+		kfree_rcu(object, rcu_free);
+	}
+}