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, 82 insertions, 0 deletions

diff --git a/lib/crypto/nh.c b/lib/crypto/nh.c
new file mode 100644
index 000000000..e1d0095b5
--- /dev/null
+++ b/lib/crypto/nh.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2018 Google LLC
+ */
+
+/*
+ * Implementation of the NH almost-universal hash function, specifically the
+ * variant of NH used in Adiantum.  This is *not* a cryptographic hash function.
+ *
+ * Reference: section 6.3 of "Adiantum: length-preserving encryption for
+ * entry-level processors" (https://eprint.iacr.org/2018/720.pdf).
+ */
+
+#include <crypto/nh.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/unaligned.h>
+
+#ifdef CONFIG_CRYPTO_LIB_NH_ARCH
+#include "nh.h" /* $(SRCARCH)/nh.h */
+#else
+static bool nh_arch(const u32 *key, const u8 *message, size_t message_len,
+		    __le64 hash[NH_NUM_PASSES])
+{
+	return false;
+}
+#endif
+
+void nh(const u32 *key, const u8 *message, size_t message_len,
+	__le64 hash[NH_NUM_PASSES])
+{
+	u64 sums[4] = { 0, 0, 0, 0 };
+
+	if (nh_arch(key, message, message_len, hash))
+		return;
+
+	static_assert(NH_PAIR_STRIDE == 2);
+	static_assert(NH_NUM_PASSES == 4);
+
+	while (message_len) {
+		u32 m0 = get_unaligned_le32(message + 0);
+		u32 m1 = get_unaligned_le32(message + 4);
+		u32 m2 = get_unaligned_le32(message + 8);
+		u32 m3 = get_unaligned_le32(message + 12);
+
+		sums[0] += (u64)(u32)(m0 + key[0]) * (u32)(m2 + key[2]);
+		sums[1] += (u64)(u32)(m0 + key[4]) * (u32)(m2 + key[6]);
+		sums[2] += (u64)(u32)(m0 + key[8]) * (u32)(m2 + key[10]);
+		sums[3] += (u64)(u32)(m0 + key[12]) * (u32)(m2 + key[14]);
+		sums[0] += (u64)(u32)(m1 + key[1]) * (u32)(m3 + key[3]);
+		sums[1] += (u64)(u32)(m1 + key[5]) * (u32)(m3 + key[7]);
+		sums[2] += (u64)(u32)(m1 + key[9]) * (u32)(m3 + key[11]);
+		sums[3] += (u64)(u32)(m1 + key[13]) * (u32)(m3 + key[15]);
+		key += NH_MESSAGE_UNIT / sizeof(key[0]);
+		message += NH_MESSAGE_UNIT;
+		message_len -= NH_MESSAGE_UNIT;
+	}
+
+	hash[0] = cpu_to_le64(sums[0]);
+	hash[1] = cpu_to_le64(sums[1]);
+	hash[2] = cpu_to_le64(sums[2]);
+	hash[3] = cpu_to_le64(sums[3]);
+}
+EXPORT_SYMBOL_GPL(nh);
+
+#ifdef nh_mod_init_arch
+static int __init nh_mod_init(void)
+{
+	nh_mod_init_arch();
+	return 0;
+}
+subsys_initcall(nh_mod_init);
+
+static void __exit nh_mod_exit(void)
+{
+}
+module_exit(nh_mod_exit);
+#endif
+
+MODULE_DESCRIPTION("NH almost-universal hash function");
+MODULE_LICENSE("GPL");