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, 25 insertions, 0 deletions

diff --git a/drivers/tty/serdev/Kconfig b/drivers/tty/serdev/Kconfig
new file mode 100644
index 000000000..46ae732bf
--- /dev/null
+++ b/drivers/tty/serdev/Kconfig
@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Serial bus device driver configuration
+#
+menuconfig SERIAL_DEV_BUS
+	tristate "Serial device bus"
+	help
+	  Core support for devices connected via a serial port.
+
+	  Note that you typically also want to enable TTY port controller support.
+
+if SERIAL_DEV_BUS
+
+config SERIAL_DEV_CTRL_TTYPORT
+	bool "Serial device TTY port controller"
+	help
+	  Say Y here if you want to use the Serial device bus with common TTY
+	  drivers (e.g. serial drivers).
+
+	  If unsure, say Y.
+	depends on TTY
+	depends on SERIAL_DEV_BUS != m
+	default y
+
+endif