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, 84 insertions, 0 deletions

diff --git a/tools/perf/util/namespaces.h b/tools/perf/util/namespaces.h
new file mode 100644
index 000000000..e95c79b80
--- /dev/null
+++ b/tools/perf/util/namespaces.h
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ *
+ * Copyright (C) 2017 Hari Bathini, IBM Corporation
+ */
+
+#ifndef __PERF_NAMESPACES_H
+#define __PERF_NAMESPACES_H
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <linux/stddef.h>
+#include <linux/perf_event.h>
+#include <linux/refcount.h>
+#include <linux/types.h>
+#include <internal/rc_check.h>
+
+#ifndef HAVE_SETNS_SUPPORT
+int setns(int fd, int nstype);
+#endif
+
+struct perf_record_namespaces;
+
+struct namespaces {
+	struct list_head list;
+	u64 end_time;
+	struct perf_ns_link_info link_info[];
+};
+
+struct namespaces *namespaces__new(struct perf_record_namespaces *event);
+void namespaces__free(struct namespaces *namespaces);
+
+DECLARE_RC_STRUCT(nsinfo) {
+	pid_t			pid;
+	pid_t			tgid;
+	pid_t			nstgid;
+	bool			need_setns;
+	bool			in_pidns;
+	char			*mntns_path;
+	refcount_t		refcnt;
+};
+
+struct nscookie {
+	int			oldns;
+	int			newns;
+	char			*oldcwd;
+};
+
+int nsinfo__init(struct nsinfo *nsi);
+struct nsinfo *nsinfo__new(pid_t pid);
+struct nsinfo *nsinfo__copy(const struct nsinfo *nsi);
+
+struct nsinfo *nsinfo__get(struct nsinfo *nsi);
+void nsinfo__put(struct nsinfo *nsi);
+
+bool nsinfo__need_setns(const struct nsinfo *nsi);
+void nsinfo__clear_need_setns(struct nsinfo *nsi);
+pid_t nsinfo__tgid(const struct nsinfo  *nsi);
+pid_t nsinfo__nstgid(const struct nsinfo  *nsi);
+pid_t nsinfo__pid(const struct nsinfo  *nsi);
+bool nsinfo__in_pidns(const struct nsinfo  *nsi);
+void nsinfo__set_in_pidns(struct nsinfo *nsi);
+
+void nsinfo__mountns_enter(struct nsinfo *nsi, struct nscookie *nc);
+void nsinfo__mountns_exit(struct nscookie *nc);
+
+char *nsinfo__realpath(const char *path, struct nsinfo *nsi);
+int nsinfo__stat(const char *filename, struct stat *st, struct nsinfo *nsi);
+
+bool nsinfo__is_in_root_namespace(void);
+
+static inline void __nsinfo__zput(struct nsinfo **nsip)
+{
+	if (nsip) {
+		nsinfo__put(*nsip);
+		*nsip = NULL;
+	}
+}
+
+#define nsinfo__zput(nsi) __nsinfo__zput(&nsi)
+
+const char *perf_ns__name(unsigned int id);
+
+#endif  /* __PERF_NAMESPACES_H */