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, 30 insertions, 0 deletions

diff --git a/scripts/Makefile.defconf b/scripts/Makefile.defconf
new file mode 100644
index 000000000..a44307f08
--- /dev/null
+++ b/scripts/Makefile.defconf
@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: GPL-2.0
+# Configuration heplers
+
+cmd_merge_fragments = \
+	$(srctree)/scripts/kconfig/merge_config.sh \
+	$4 -m -O $(objtree) $(srctree)/arch/$(SRCARCH)/configs/$2 \
+	$(foreach config,$3,$(srctree)/arch/$(SRCARCH)/configs/$(config).config)
+
+# Creates 'merged defconfigs'
+# ---------------------------------------------------------------------------
+# Usage:
+#   $(call merge_into_defconfig,base_config,config_fragment1 config_fragment2 ...)
+#
+# Input config fragments without '.config' suffix
+define merge_into_defconfig
+	$(call cmd,merge_fragments,$1,$2)
+	+$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
+endef
+
+
+# Creates 'merged defconfigs without warning about overrides'
+# ---------------------------------------------------------------------------
+# Usage:
+#   $(call merge_into_defconfig_override,base_config,config_fragment1 config_fragment2 ...)
+#
+# Input config fragments without '.config' suffix
+define merge_into_defconfig_override
+	$(call cmd,merge_fragments,$1,$2,-Q)
+	+$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
+endef