Merge tag 'rcu.2026.08.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux

Pull RCU updates from Paul McKenney:
"Make expedited grace periods expedite normal RCU callbacks

Miscellane

Merge tag 'rcu.2026.08.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux

Pull RCU updates from Paul McKenney:
"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"

* tag 'rcu.2026.08.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (59 commits)
rcu: Add closing parenthesis in comment in rcu_read_unlock_strict()
rcutorture: Make {,s}rcu_read_delay() better handle forward-progress testing
rcutorture: Announce declining to forward-progress test
torture: Don't leak shuffle_tmp_mask when shuffler kthread fails to start
rcutorture: Use this_cpu_inc() for rcu_torture_count[] and rcu_torture_batch[]
rcutorture: Make RCU Tasks Trace track Reader Batches
rcutorture: Test RCU Tasks Trace GP implying RCU GP
rcutorture: Add a stall_only module parameter
rcutorture: Add nwriters module parameter
rcutorture: Use task_state_to_char() for task-state reporting
rcutorture: Use cpumask_next_wrap() in rcu_torture_preempt()
rcutorture: Test RCU readers from hardware interrupt handlers
rcutorture: Check for immediate deboosting at reader end
srcu: Queue sdp->work when the delay timer is successfully deleted
rcu-tasks: Convert cond_resched_tasks_rcu_qs() to static inline
rcu-tasks: Fix some comments for call_rcu_tasks() and call_rcu_tasks_rude()
rcu-tasks: Rename tasks_rcu_exit_srcu_stall_timer to tasks_rcu_exit_stall_timer
rcu: Mark interrupts-enabled accesses to rdp->cpu_no_qs.s
rcu: Reduce stack usage in show_rcu_gp_kthreads()
rcu: Mark accesses to ->rcu_urgent_qs and ->rcu_need_heavy_qs
...

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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 HEAD

Changes:

Make expedited grace periods expedite normal RCU cal

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 HEAD

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.

show more ...

rust: sync: add SRCU abstraction

Add a Rust abstraction for sleepable RCU (SRCU), backed by C srcu_struct.
Provide FFI helpers and a safe wrapper with a guard-based API for read-side
critical sectio

rust: sync: add SRCU abstraction

Add a Rust abstraction for sleepable RCU (SRCU), backed by C srcu_struct.
Provide FFI helpers and a safe wrapper with a guard-based API for read-side
critical sections.

Cleanup is handled via `PinnedDrop`. It first checks for active read-side
sections and emits a warning if any guards were leaked. In that case, it
waits in `synchronize_srcu()` rather than risking a UAF by freeing the
`srcu_struct` that is still reachable from the C side. It then uses
`srcu_barrier()` to drain pending callbacks before finally calling
`cleanup_srcu_struct()`.

Signed-off-by: Onur Özkan <work@onurozkan.dev>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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