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, 334 insertions, 0 deletions

diff --git a/lib/tests/randstruct_kunit.c b/lib/tests/randstruct_kunit.c
new file mode 100644
index 000000000..f3a2d63c4
--- /dev/null
+++ b/lib/tests/randstruct_kunit.c
@@ -0,0 +1,334 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Test cases for struct randomization, i.e. CONFIG_RANDSTRUCT=y.
+ *
+ * For example, see:
+ * "Running tests with kunit_tool" at Documentation/dev-tools/kunit/start.rst
+ *	./tools/testing/kunit/kunit.py run randstruct [--raw_output] \
+ *		[--make_option LLVM=1] \
+ *		--kconfig_add CONFIG_RANDSTRUCT_FULL=y
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <kunit/test.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+
+#define DO_MANY_MEMBERS(macro, args...)	\
+	macro(a, args)			\
+	macro(b, args)			\
+	macro(c, args)			\
+	macro(d, args)			\
+	macro(e, args)			\
+	macro(f, args)			\
+	macro(g, args)			\
+	macro(h, args)
+
+#define do_enum(x, ignored)	MEMBER_NAME_ ## x,
+enum randstruct_member_names {
+	DO_MANY_MEMBERS(do_enum)
+	MEMBER_NAME_MAX,
+};
+/* Make sure the macros are working: want 8 test members. */
+_Static_assert(MEMBER_NAME_MAX == 8, "Number of test members changed?!");
+
+/* This is an unsigned long member to match the function pointer size */
+#define unsigned_long_member(x, ignored)	unsigned long x;
+struct randstruct_untouched {
+	DO_MANY_MEMBERS(unsigned_long_member)
+};
+
+/* Struct explicitly marked with __randomize_layout. */
+struct randstruct_shuffled {
+	DO_MANY_MEMBERS(unsigned_long_member)
+} __randomize_layout;
+#undef unsigned_long_member
+
+/* Struct implicitly randomized from being all func ptrs. */
+#define func_member(x, ignored)	size_t (*x)(int);
+struct randstruct_funcs_untouched {
+	DO_MANY_MEMBERS(func_member)
+} __no_randomize_layout;
+
+struct randstruct_funcs_shuffled {
+	DO_MANY_MEMBERS(func_member)
+};
+
+#define func_body(x, ignored)					\
+static noinline size_t func_##x(int arg)			\
+{								\
+	return offsetof(struct randstruct_funcs_untouched, x);	\
+}
+DO_MANY_MEMBERS(func_body)
+
+/* Various mixed types. */
+#define mixed_members					\
+	bool a;						\
+	short b;					\
+	unsigned int c __aligned(16);			\
+	size_t d;					\
+	char e;						\
+	u64 f;						\
+	union {						\
+		struct randstruct_shuffled shuffled;	\
+		uintptr_t g;				\
+	};						\
+	union {						\
+		void *ptr;				\
+		char h;					\
+	};
+
+struct randstruct_mixed_untouched {
+	mixed_members
+};
+
+struct randstruct_mixed_shuffled {
+	mixed_members
+} __randomize_layout;
+#undef mixed_members
+
+struct contains_randstruct_untouched {
+	int before;
+	struct randstruct_untouched untouched;
+	int after;
+};
+
+struct contains_randstruct_shuffled {
+	int before;
+	struct randstruct_shuffled shuffled;
+	int after;
+};
+
+struct contains_func_untouched {
+	struct randstruct_funcs_shuffled inner;
+	DO_MANY_MEMBERS(func_member)
+} __no_randomize_layout;
+
+struct contains_func_shuffled {
+	struct randstruct_funcs_shuffled inner;
+	DO_MANY_MEMBERS(func_member)
+};
+#undef func_member
+
+#define check_mismatch(x, untouched, shuffled)	\
+	if (offsetof(untouched, x) != offsetof(shuffled, x))	\
+		mismatches++;					\
+	kunit_info(test, #shuffled "::" #x " @ %zu (vs %zu)\n",	\
+		   offsetof(shuffled, x),			\
+		   offsetof(untouched, x));			\
+
+#define check_pair(outcome, untouched, shuffled, checker...)	\
+	mismatches = 0;						\
+	DO_MANY_MEMBERS(checker, untouched, shuffled)	\
+	kunit_info(test, "Differing " #untouched " vs " #shuffled " member positions: %d\n", \
+		   mismatches);					\
+	KUNIT_##outcome##_MSG(test, mismatches, 0,		\
+			      #untouched " vs " #shuffled " layouts: unlucky or broken?\n");
+
+static void randstruct_layout_same(struct kunit *test)
+{
+	int mismatches;
+
+	check_pair(EXPECT_EQ, struct randstruct_untouched, struct randstruct_untouched,
+		   check_mismatch)
+	check_pair(EXPECT_GT, struct randstruct_untouched, struct randstruct_shuffled,
+		   check_mismatch)
+}
+
+static void randstruct_layout_mixed(struct kunit *test)
+{
+	int mismatches;
+
+	check_pair(EXPECT_EQ, struct randstruct_mixed_untouched, struct randstruct_mixed_untouched,
+		   check_mismatch)
+	check_pair(EXPECT_GT, struct randstruct_mixed_untouched, struct randstruct_mixed_shuffled,
+		   check_mismatch)
+}
+
+static void randstruct_layout_fptr(struct kunit *test)
+{
+	int mismatches;
+
+	check_pair(EXPECT_EQ, struct randstruct_untouched, struct randstruct_untouched,
+		   check_mismatch)
+	check_pair(EXPECT_GT, struct randstruct_untouched, struct randstruct_funcs_shuffled,
+		   check_mismatch)
+	check_pair(EXPECT_GT, struct randstruct_funcs_untouched, struct randstruct_funcs_shuffled,
+		   check_mismatch)
+}
+
+#define check_mismatch_prefixed(x, prefix, untouched, shuffled)	\
+	check_mismatch(prefix.x, untouched, shuffled)
+
+static void randstruct_layout_fptr_deep(struct kunit *test)
+{
+	int mismatches;
+
+	if (IS_ENABLED(CONFIG_CC_IS_CLANG))
+		kunit_skip(test, "Clang randstruct misses inner functions: https://github.com/llvm/llvm-project/issues/138355");
+
+	check_pair(EXPECT_EQ, struct contains_func_untouched, struct contains_func_untouched,
+			check_mismatch_prefixed, inner)
+
+	check_pair(EXPECT_GT, struct contains_func_untouched, struct contains_func_shuffled,
+			check_mismatch_prefixed, inner)
+}
+
+#undef check_pair
+#undef check_mismatch
+
+#define check_mismatch(x, ignore)				\
+	KUNIT_EXPECT_EQ_MSG(test, untouched->x, shuffled->x,	\
+			    "Mismatched member value in %s initializer\n", \
+			    name);
+
+static void test_check_init(struct kunit *test, const char *name,
+			    struct randstruct_untouched *untouched,
+			    struct randstruct_shuffled *shuffled)
+{
+	DO_MANY_MEMBERS(check_mismatch)
+}
+
+static void test_check_mixed_init(struct kunit *test, const char *name,
+				  struct randstruct_mixed_untouched *untouched,
+				  struct randstruct_mixed_shuffled *shuffled)
+{
+	DO_MANY_MEMBERS(check_mismatch)
+}
+#undef check_mismatch
+
+#define check_mismatch(x, ignore)				\
+	KUNIT_EXPECT_EQ_MSG(test, untouched->untouched.x,	\
+			    shuffled->shuffled.x,		\
+			    "Mismatched member value in %s initializer\n", \
+			    name);
+static void test_check_contained_init(struct kunit *test, const char *name,
+				      struct contains_randstruct_untouched *untouched,
+				      struct contains_randstruct_shuffled *shuffled)
+{
+	DO_MANY_MEMBERS(check_mismatch)
+}
+#undef check_mismatch
+
+#define check_mismatch(x, ignore)					\
+	KUNIT_EXPECT_PTR_EQ_MSG(test, untouched->x, shuffled->x,	\
+			    "Mismatched member value in %s initializer\n", \
+			    name);
+
+static void test_check_funcs_init(struct kunit *test, const char *name,
+				  struct randstruct_funcs_untouched *untouched,
+				  struct randstruct_funcs_shuffled *shuffled)
+{
+	DO_MANY_MEMBERS(check_mismatch)
+}
+#undef check_mismatch
+
+static void randstruct_initializers(struct kunit *test)
+{
+#define init_members		\
+		.a = 1,		\
+		.b = 3,		\
+		.c = 5,		\
+		.d = 7,		\
+		.e = 11,	\
+		.f = 13,	\
+		.g = 17,	\
+		.h = 19,
+	struct randstruct_untouched untouched = {
+		init_members
+	};
+	struct randstruct_shuffled shuffled = {
+		init_members
+	};
+	struct randstruct_mixed_untouched mixed_untouched = {
+		init_members
+	};
+	struct randstruct_mixed_shuffled mixed_shuffled = {
+		init_members
+	};
+	struct contains_randstruct_untouched contains_untouched = {
+		.untouched = {
+			init_members
+		},
+	};
+	struct contains_randstruct_shuffled contains_shuffled = {
+		.shuffled = {
+			init_members
+		},
+	};
+#define func_member(x, ignored)	\
+		.x = func_##x,
+	struct randstruct_funcs_untouched funcs_untouched = {
+		DO_MANY_MEMBERS(func_member)
+	};
+	struct randstruct_funcs_shuffled funcs_shuffled = {
+		DO_MANY_MEMBERS(func_member)
+	};
+
+	test_check_init(test, "named", &untouched, &shuffled);
+	test_check_init(test, "unnamed", &untouched,
+		&(struct randstruct_shuffled){
+			init_members
+		});
+
+	test_check_contained_init(test, "named", &contains_untouched, &contains_shuffled);
+	test_check_contained_init(test, "unnamed", &contains_untouched,
+		&(struct contains_randstruct_shuffled){
+			.shuffled = (struct randstruct_shuffled){
+				init_members
+			},
+		});
+
+	test_check_contained_init(test, "named", &contains_untouched, &contains_shuffled);
+	test_check_contained_init(test, "unnamed copy", &contains_untouched,
+		&(struct contains_randstruct_shuffled){
+			/* full struct copy initializer */
+			.shuffled = shuffled,
+		});
+
+	test_check_mixed_init(test, "named", &mixed_untouched, &mixed_shuffled);
+	test_check_mixed_init(test, "unnamed", &mixed_untouched,
+		&(struct randstruct_mixed_shuffled){
+			init_members
+		});
+
+	test_check_funcs_init(test, "named", &funcs_untouched, &funcs_shuffled);
+	test_check_funcs_init(test, "unnamed", &funcs_untouched,
+		&(struct randstruct_funcs_shuffled){
+			DO_MANY_MEMBERS(func_member)
+		});
+
+#undef func_member
+#undef init_members
+}
+
+static int randstruct_test_init(struct kunit *test)
+{
+	if (!IS_ENABLED(CONFIG_RANDSTRUCT))
+		kunit_skip(test, "Not built with CONFIG_RANDSTRUCT=y");
+
+	return 0;
+}
+
+static struct kunit_case randstruct_test_cases[] = {
+	KUNIT_CASE(randstruct_layout_same),
+	KUNIT_CASE(randstruct_layout_mixed),
+	KUNIT_CASE(randstruct_layout_fptr),
+	KUNIT_CASE(randstruct_layout_fptr_deep),
+	KUNIT_CASE(randstruct_initializers),
+	{}
+};
+
+static struct kunit_suite randstruct_test_suite = {
+	.name = "randstruct",
+	.init = randstruct_test_init,
+	.test_cases = randstruct_test_cases,
+};
+
+kunit_test_suites(&randstruct_test_suite);
+
+MODULE_DESCRIPTION("Test cases for struct randomization");
+MODULE_LICENSE("GPL");