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, 69 insertions, 0 deletions

diff --git a/rust/helpers/bitops.c b/rust/helpers/bitops.c
new file mode 100644
index 000000000..271b8a712
--- /dev/null
+++ b/rust/helpers/bitops.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bitops.h>
+#include <linux/find.h>
+
+__rust_helper
+void rust_helper___set_bit(unsigned long nr, unsigned long *addr)
+{
+	__set_bit(nr, addr);
+}
+
+__rust_helper
+void rust_helper___clear_bit(unsigned long nr, unsigned long *addr)
+{
+	__clear_bit(nr, addr);
+}
+
+__rust_helper
+void rust_helper_set_bit(unsigned long nr, volatile unsigned long *addr)
+{
+	set_bit(nr, addr);
+}
+
+__rust_helper
+void rust_helper_clear_bit(unsigned long nr, volatile unsigned long *addr)
+{
+	clear_bit(nr, addr);
+}
+
+/*
+ * The rust_helper_ prefix is intentionally omitted below so that the
+ * declarations in include/linux/find.h are compatible with these helpers.
+ *
+ * Note that the below #ifdefs mean that the helper is only created if C does
+ * not provide a definition.
+ */
+#ifdef find_first_zero_bit
+__rust_helper
+unsigned long _find_first_zero_bit(const unsigned long *p, unsigned long size)
+{
+	return find_first_zero_bit(p, size);
+}
+#endif /* find_first_zero_bit */
+
+#ifdef find_next_zero_bit
+__rust_helper
+unsigned long _find_next_zero_bit(const unsigned long *addr,
+				  unsigned long size, unsigned long offset)
+{
+	return find_next_zero_bit(addr, size, offset);
+}
+#endif /* find_next_zero_bit */
+
+#ifdef find_first_bit
+__rust_helper
+unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
+{
+	return find_first_bit(addr, size);
+}
+#endif /* find_first_bit */
+
+#ifdef find_next_bit
+__rust_helper
+unsigned long _find_next_bit(const unsigned long *addr, unsigned long size,
+			     unsigned long offset)
+{
+	return find_next_bit(addr, size, offset);
+}
+#endif /* find_next_bit */