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.

2 files changed, 64 insertions, 0 deletions

diff --git a/tools/arch/xtensa/include/asm/barrier.h b/tools/arch/xtensa/include/asm/barrier.h
new file mode 100644
index 000000000..583800bd7
--- /dev/null
+++ b/tools/arch/xtensa/include/asm/barrier.h
@@ -0,0 +1,18 @@
+/*
+ * Copied from the kernel sources to tools/:
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2001 - 2012 Tensilica Inc.
+ */
+
+#ifndef _TOOLS_LINUX_XTENSA_SYSTEM_H
+#define _TOOLS_LINUX_XTENSA_SYSTEM_H
+
+#define mb()  ({ __asm__ __volatile__("memw" : : : "memory"); })
+#define rmb() barrier()
+#define wmb() mb()
+
+#endif /* _TOOLS_LINUX_XTENSA_SYSTEM_H */
diff --git a/tools/arch/xtensa/include/uapi/asm/mman.h b/tools/arch/xtensa/include/uapi/asm/mman.h
new file mode 100644
index 000000000..f2b08c990
--- /dev/null
+++ b/tools/arch/xtensa/include/uapi/asm/mman.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef TOOLS_ARCH_XTENSA_UAPI_ASM_MMAN_FIX_H
+#define TOOLS_ARCH_XTENSA_UAPI_ASM_MMAN_FIX_H
+#define MADV_DODUMP	17
+#define MADV_DOFORK	11
+#define MADV_DONTDUMP   16
+#define MADV_DONTFORK	10
+#define MADV_DONTNEED	4
+#define MADV_FREE	8
+#define MADV_HUGEPAGE	14
+#define MADV_MERGEABLE   12
+#define MADV_NOHUGEPAGE	15
+#define MADV_NORMAL	0
+#define MADV_RANDOM	1
+#define MADV_REMOVE	9
+#define MADV_SEQUENTIAL	2
+#define MADV_UNMERGEABLE 13
+#define MADV_WILLNEED	3
+#define MAP_ANONYMOUS	0x0800
+#define MAP_DENYWRITE	0x2000
+#define MAP_EXECUTABLE	0x4000
+#define MAP_FILE	0
+#define MAP_FIXED	0x010
+#define MAP_GROWSDOWN	0x1000
+#define MAP_HUGETLB	0x80000
+#define MAP_LOCKED	0x8000
+#define MAP_NONBLOCK	0x20000
+#define MAP_NORESERVE	0x0400
+#define MAP_POPULATE	0x10000
+#define MAP_STACK	0x40000
+#define PROT_EXEC	0x4
+#define PROT_GROWSDOWN	0x01000000
+#define PROT_GROWSUP	0x02000000
+#define PROT_NONE	0x0
+#define PROT_READ	0x1
+#define PROT_SEM	0x10
+#define PROT_WRITE	0x2
+/* MADV_HWPOISON is undefined on xtensa, fix it for perf */
+#define MADV_HWPOISON	100
+/* MADV_SOFT_OFFLINE is undefined on xtensa, fix it for perf */
+#define MADV_SOFT_OFFLINE 101
+/* MAP_32BIT is undefined on xtensa, fix it for perf */
+#define MAP_32BIT	0
+/* MAP_UNINITIALIZED is undefined on xtensa, fix it for perf */
+#define MAP_UNINITIALIZED	0
+#endif