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, 49 insertions, 0 deletions

diff --git a/io_uring/poll.h b/io_uring/poll.h
new file mode 100644
index 000000000..5647c5138
--- /dev/null
+++ b/io_uring/poll.h
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/io_uring_types.h>
+
+#define IO_POLL_ALLOC_CACHE_MAX 32
+
+enum {
+	IO_APOLL_OK,
+	IO_APOLL_ABORTED,
+	IO_APOLL_READY
+};
+
+struct io_poll {
+	struct file			*file;
+	struct wait_queue_head		*head;
+	__poll_t			events;
+	int				retries;
+	struct wait_queue_entry		wait;
+};
+
+struct async_poll {
+	struct io_poll		poll;
+	struct io_poll		*double_poll;
+};
+
+/*
+ * Must only be called inside issue_flags & IO_URING_F_MULTISHOT, or
+ * potentially other cases where we already "own" this poll request.
+ */
+static inline void io_poll_multishot_retry(struct io_kiocb *req)
+{
+	atomic_inc(&req->poll_refs);
+}
+
+int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_poll_add(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_poll_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_poll_remove(struct io_kiocb *req, unsigned int issue_flags);
+
+struct io_cancel_data;
+int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
+		   unsigned issue_flags);
+int io_arm_apoll(struct io_kiocb *req, unsigned issue_flags, __poll_t mask);
+int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags);
+bool io_poll_remove_all(struct io_ring_ctx *ctx, struct io_uring_task *tctx,
+			bool cancel_all);
+
+void io_poll_task_func(struct io_tw_req tw_req, io_tw_token_t tw);