From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: 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. --- tools/memory-model/linux-kernel.bell | 99 ++++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 tools/memory-model/linux-kernel.bell (limited to 'tools/memory-model/linux-kernel.bell') diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell new file mode 100644 index 000000000..fe6599800 --- /dev/null +++ b/tools/memory-model/linux-kernel.bell @@ -0,0 +1,99 @@ +// SPDX-License-Identifier: GPL-2.0+ +(* + * Copyright (C) 2015 Jade Alglave , + * Copyright (C) 2016 Luc Maranget for Inria + * Copyright (C) 2017 Alan Stern , + * Andrea Parri + * + * An earlier version of this file appeared in the companion webpage for + * "Frightening small children and disconcerting grown-ups: Concurrency + * in the Linux kernel" by Alglave, Maranget, McKenney, Parri, and Stern, + * which appeared in ASPLOS 2018. + *) + +"Linux-kernel memory consistency model" + +enum Accesses = 'ONCE (*READ_ONCE,WRITE_ONCE*) || + 'RELEASE (*smp_store_release*) || + 'ACQUIRE (*smp_load_acquire*) || + 'NORETURN (* R of non-return RMW *) || + 'MB (*xchg(),cmpxchg(),...*) +instructions R[Accesses] +instructions W[Accesses] +instructions RMW[Accesses] + +enum Barriers = 'wmb (*smp_wmb*) || + 'rmb (*smp_rmb*) || + 'MB (*smp_mb*) || + 'barrier (*barrier*) || + 'rcu-lock (*rcu_read_lock*) || + 'rcu-unlock (*rcu_read_unlock*) || + 'sync-rcu (*synchronize_rcu*) || + 'before-atomic (*smp_mb__before_atomic*) || + 'after-atomic (*smp_mb__after_atomic*) || + 'after-spinlock (*smp_mb__after_spinlock*) || + 'after-unlock-lock (*smp_mb__after_unlock_lock*) || + 'after-srcu-read-unlock (*smp_mb__after_srcu_read_unlock*) +instructions F[Barriers] + + +(* + * Filter out syntactic annotations that do not provide the corresponding + * semantic ordering, such as Acquire on a store or Mb on a failed RMW. + *) +let FailedRMW = RMW \ (domain(rmw) | range(rmw)) +let Acquire = ACQUIRE \ W \ FailedRMW +let Release = RELEASE \ R \ FailedRMW +let Mb = MB \ FailedRMW +let Noreturn = NORETURN \ W + +(* SRCU *) +enum SRCU = 'srcu-lock || 'srcu-unlock || 'sync-srcu +instructions SRCU[SRCU] +(* All srcu events *) +let Srcu = Srcu-lock | Srcu-unlock | Sync-srcu + +(* Compute matching pairs of nested Rcu-lock and Rcu-unlock *) +let rcu-rscs = let rec + unmatched-locks = Rcu-lock \ domain(matched) + and unmatched-unlocks = Rcu-unlock \ range(matched) + and unmatched = unmatched-locks | unmatched-unlocks + and unmatched-po = [unmatched] ; po ; [unmatched] + and unmatched-locks-to-unlocks = + [unmatched-locks] ; po ; [unmatched-unlocks] + and matched = matched | (unmatched-locks-to-unlocks \ + (unmatched-po ; unmatched-po)) + in matched + +(* Validate nesting *) +flag ~empty Rcu-lock \ domain(rcu-rscs) as unmatched-rcu-lock +flag ~empty Rcu-unlock \ range(rcu-rscs) as unmatched-rcu-unlock + +(* Compute matching pairs of nested Srcu-lock and Srcu-unlock *) +let carry-srcu-data = (data ; [~ Srcu-unlock] ; rf)* +let srcu-rscs = ([Srcu-lock] ; carry-srcu-data ; data ; [Srcu-unlock]) & loc + +(* Validate nesting *) +flag ~empty Srcu-lock \ domain(srcu-rscs) as unmatched-srcu-lock +flag ~empty Srcu-unlock \ range(srcu-rscs) as unmatched-srcu-unlock +flag ~empty (srcu-rscs^-1 ; srcu-rscs) \ id as multiple-srcu-matches + +(* Check for use of synchronize_srcu() inside an RCU critical section *) +flag ~empty rcu-rscs & (po ; [Sync-srcu] ; po) as invalid-sleep + +(* Validate SRCU dynamic match *) +flag ~empty different-values(srcu-rscs) as srcu-bad-value-match + +(* Compute marked and plain memory accesses *) +let Marked = (~M) | IW | ONCE | RELEASE | ACQUIRE | MB | RMW | + LKR | LKW | UL | LF | RL | RU | Srcu-lock | Srcu-unlock +let Plain = M \ Marked + +(* Redefine dependencies to include those carried through plain accesses *) +let carry-dep = (data ; [~ Srcu-unlock] ; rfi)* +let addr = carry-dep ; addr +let ctrl = carry-dep ; ctrl +let data = carry-dep ; data + +flag ~empty (if "lkmmv2" then 0 else _) + as this-model-requires-variant-higher-than-lkmmv1 -- cgit v1.3.1