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, 58 insertions, 0 deletions

diff --git a/tools/virtio/Makefile b/tools/virtio/Makefile
new file mode 100644
index 000000000..2cac5fd4b
--- /dev/null
+++ b/tools/virtio/Makefile
@@ -0,0 +1,58 @@
+# SPDX-License-Identifier: GPL-2.0
+all: test mod
+test: virtio_test vringh_test vhost_net_test
+virtio_test: virtio_ring.o virtio_test.o
+vringh_test: vringh_test.o vringh.o virtio_ring.o
+vhost_net_test: virtio_ring.o vhost_net_test.o
+
+try-run = $(shell set -e;		\
+	if ($(1)) >/dev/null 2>&1;	\
+	then echo "$(2)";		\
+	else echo "$(3)";		\
+	fi)
+
+__cc-option = $(call try-run,\
+	$(1) -Werror $(2) -c -x c /dev/null -o /dev/null,$(2),)
+cc-option = $(call __cc-option, $(CC),$(1))
+
+CFLAGS += -g -O2 -Werror -Wno-maybe-uninitialized -Wall -I. -I../include/ -I ../../usr/include/ -Wno-pointer-sign -fno-strict-overflow -fno-strict-aliasing -fno-common -MMD -U_FORTIFY_SOURCE -include ../../include/linux/kconfig.h $(call cc-option,-mfunction-return=thunk) $(call cc-option,-fcf-protection=none) $(call cc-option,-mindirect-branch-register)
+
+CFLAGS += -pthread
+LDFLAGS += -pthread
+vpath %.c ../../drivers/virtio ../../drivers/vhost
+BUILD=KCFLAGS="-I "`pwd`/../../drivers/vhost ${MAKE} -C `pwd`/../.. V=${V}
+mod:
+	${BUILD} M=`pwd`/vhost_test
+
+#oot: build vhost as an out of tree module for a distro kernel
+#no effort is taken to make it actually build or work, but tends to mostly work
+#if the distro kernel is very close to upstream
+#unsupported! this is a development tool only, don't use the
+#resulting modules in production!
+OOT_KSRC=/lib/modules/$$(uname -r)/build
+OOT_VHOST=`pwd`/../../drivers/vhost
+#Everyone depends on vhost
+#Tweak the below to enable more modules
+OOT_CONFIGS=\
+	CONFIG_VHOST=m \
+	CONFIG_VHOST_NET=n \
+	CONFIG_VHOST_SCSI=n \
+	CONFIG_VHOST_VSOCK=n \
+	CONFIG_VHOST_RING=n \
+	CONFIG_VHOST_VDPA=n
+OOT_BUILD=KCFLAGS="-include "`pwd`"/oot-stubs.h -I "${OOT_VHOST} ${MAKE} -C ${OOT_KSRC} V=${V}
+oot-build:
+	echo "UNSUPPORTED! Don't use the resulting modules in production!"
+	${OOT_BUILD} M=`pwd`/vhost_test
+	${OOT_BUILD} M=${OOT_VHOST} ${OOT_CONFIGS}
+
+oot-clean: oot-build
+oot: oot-build
+oot-clean: OOT_BUILD+=clean
+
+.PHONY: all test mod clean vhost oot oot-clean oot-build
+clean:
+	${RM} *.o vringh_test virtio_test vhost_net_test vhost_test/*.o \
+              vhost_test/.*.cmd vhost_test/Module.symvers \
+              vhost_test/modules.order *.d
+-include *.d