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, 281 insertions, 0 deletions

diff --git a/rust/zerocopy/src/deprecated.rs b/rust/zerocopy/src/deprecated.rs
new file mode 100644
index 000000000..24bafbf9a
--- /dev/null
+++ b/rust/zerocopy/src/deprecated.rs
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+
+// Copyright 2024 The Fuchsia Authors
+//
+// Licensed under the 2-Clause BSD License <LICENSE-BSD or
+// https://opensource.org/license/bsd-2-clause>, Apache License, Version 2.0
+// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
+// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
+// This file may not be copied, modified, or distributed except according to
+// those terms.
+
+//! Deprecated items. These are kept separate so that they don't clutter up
+//! other modules.
+
+use super::*;
+
+impl<B, T> Ref<B, T>
+where
+    B: ByteSlice,
+    T: KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(since = "0.8.0", note = "renamed to `Ref::from_bytes`")]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new(bytes: B) -> Option<Ref<B, T>> {
+        Self::from_bytes(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(since = "0.8.0", note = "renamed to `Ref::from_prefix`")]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_from_prefix(bytes: B) -> Option<(Ref<B, T>, B)> {
+        Self::from_prefix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(since = "0.8.0", note = "renamed to `Ref::from_suffix`")]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_from_suffix(bytes: B) -> Option<(B, Ref<B, T>)> {
+        Self::from_suffix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: ByteSlice,
+    T: Unaligned + KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_bytes`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_unaligned(bytes: B) -> Option<Ref<B, T>> {
+        Self::from_bytes(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: Unaligned + KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_prefix`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_unaligned_from_prefix(bytes: B) -> Option<(Ref<B, T>, B)> {
+        Self::from_prefix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: Unaligned + KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_suffix`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_unaligned_from_suffix(bytes: B) -> Option<(B, Ref<B, T>)> {
+        Self::from_suffix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: ByteSlice,
+    T: Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "`Ref::from_bytes` now supports slices")]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice(bytes: B) -> Option<Ref<B, [T]>> {
+        Self::from_bytes(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: ByteSlice,
+    T: Unaligned + Immutable,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "`Ref::from_bytes` now supports slices; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice_unaligned(bytes: B) -> Option<Ref<B, [T]>> {
+        Ref::from_bytes(bytes).ok()
+    }
+}
+
+impl<'a, B, T> Ref<B, [T]>
+where
+    B: 'a + IntoByteSlice<'a>,
+    T: FromBytes + Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "`Ref::into_ref` now supports slices")]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn into_slice(self) -> &'a [T] {
+        Ref::into_ref(self)
+    }
+}
+
+impl<'a, B, T> Ref<B, [T]>
+where
+    B: 'a + IntoByteSliceMut<'a>,
+    T: FromBytes + IntoBytes + Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "`Ref::into_mut` now supports slices")]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn into_mut_slice(self) -> &'a mut [T] {
+        Ref::into_mut(self)
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: SplitByteSlice,
+    T: Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "replaced by `Ref::from_prefix_with_elems`")]
+    #[must_use = "has no side effects"]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice_from_prefix(bytes: B, count: usize) -> Option<(Ref<B, [T]>, B)> {
+        Ref::from_prefix_with_elems(bytes, count).ok()
+    }
+
+    #[deprecated(since = "0.8.0", note = "replaced by `Ref::from_suffix_with_elems`")]
+    #[must_use = "has no side effects"]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice_from_suffix(bytes: B, count: usize) -> Option<(B, Ref<B, [T]>)> {
+        Ref::from_suffix_with_elems(bytes, count).ok()
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: SplitByteSlice,
+    T: Unaligned + Immutable,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_prefix_with_elems`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_slice_unaligned_from_prefix(bytes: B, count: usize) -> Option<(Ref<B, [T]>, B)> {
+        Ref::from_prefix_with_elems(bytes, count).ok()
+    }
+
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_suffix_with_elems`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_slice_unaligned_from_suffix(bytes: B, count: usize) -> Option<(B, Ref<B, [T]>)> {
+        Ref::from_suffix_with_elems(bytes, count).ok()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    #[allow(deprecated)]
+    fn test_deprecated_ref_methods() {
+        let bytes = &[0u8; 1][..];
+        let bytes_slice = &[0u8; 4][..];
+
+        let r: Option<Ref<&[u8], u8>> = Ref::new(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], u8>, &[u8])> = Ref::new_from_prefix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], u8>)> = Ref::new_from_suffix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<Ref<&[u8], u8>> = Ref::new_unaligned(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], u8>, &[u8])> = Ref::new_unaligned_from_prefix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], u8>)> = Ref::new_unaligned_from_suffix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<Ref<&[u8], [u8]>> = Ref::new_slice(bytes_slice);
+        assert!(r.is_some());
+
+        let r: Option<Ref<&[u8], [u8]>> = Ref::new_slice_unaligned(bytes_slice);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], [u8]>, &[u8])> = Ref::new_slice_from_prefix(bytes_slice, 1);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], [u8]>)> = Ref::new_slice_from_suffix(bytes_slice, 1);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], [u8]>, &[u8])> =
+            Ref::new_slice_unaligned_from_prefix(bytes_slice, 1);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], [u8]>)> =
+            Ref::new_slice_unaligned_from_suffix(bytes_slice, 1);
+        assert!(r.is_some());
+    }
+
+    #[test]
+    #[allow(deprecated)]
+    fn test_deprecated_into_slice() {
+        let bytes = &[0u8; 4][..];
+        let r: Ref<&[u8], [u8]> = Ref::from_bytes(bytes).unwrap();
+        let slice: &[u8] = r.into_slice();
+        assert_eq!(slice.len(), 4);
+    }
+
+    #[test]
+    #[allow(deprecated)]
+    fn test_deprecated_into_mut_slice() {
+        let mut bytes = [0u8; 4];
+        let r: Ref<&mut [u8], [u8]> = Ref::from_bytes(&mut bytes[..]).unwrap();
+        let slice: &mut [u8] = r.into_mut_slice();
+        assert_eq!(slice.len(), 4);
+    }
+}