diff options
Diffstat (limited to 'kernel/rcu/tree.c')
| -rw-r--r-- | kernel/rcu/tree.c | 313 |
1 files changed, 174 insertions, 139 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index f12056beb916..51f24ecd94b2 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -188,6 +188,17 @@ module_param(rcu_unlock_delay, int, 0444); static int rcu_min_cached_objs = 5; module_param(rcu_min_cached_objs, int, 0444); +// A page shrinker can ask for pages to be freed to make them +// available for other parts of the system. This usually happens +// under low memory conditions, and in that case we should also +// defer page-cache filling for a short time period. +// +// The default value is 5 seconds, which is long enough to reduce +// interference with the shrinker while it asks other systems to +// drain their caches. +static int rcu_delay_page_cache_fill_msec = 5000; +module_param(rcu_delay_page_cache_fill_msec, int, 0444); + /* Retrieve RCU kthreads priority for rcutorture */ int rcu_get_gp_kthreads_prio(void) { @@ -204,7 +215,7 @@ EXPORT_SYMBOL_GPL(rcu_get_gp_kthreads_prio); * the need for long delays to increase some race probabilities with the * need for fast grace periods to increase other race probabilities. */ -#define PER_RCU_NODE_PERIOD 3 /* Number of grace periods between delays. */ +#define PER_RCU_NODE_PERIOD 3 /* Number of grace periods between delays for debugging. */ /* * Compute the mask of online CPUs for the specified rcu_node structure. @@ -244,6 +255,7 @@ void rcu_softirq_qs(void) { rcu_qs(); rcu_preempt_deferred_qs(current); + rcu_tasks_qs(current, false); } /* @@ -835,28 +847,6 @@ void noinstr rcu_irq_exit(void) rcu_nmi_exit(); } -/** - * rcu_irq_exit_preempt - Inform RCU that current CPU is exiting irq - * towards in kernel preemption - * - * Same as rcu_irq_exit() but has a sanity check that scheduling is safe - * from RCU point of view. Invoked from return from interrupt before kernel - * preemption. - */ -void rcu_irq_exit_preempt(void) -{ - lockdep_assert_irqs_disabled(); - rcu_nmi_exit(); - - RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) <= 0, - "RCU dynticks_nesting counter underflow/zero!"); - RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) != - DYNTICK_IRQ_NONIDLE, - "Bad RCU dynticks_nmi_nesting counter\n"); - RCU_LOCKDEP_WARN(rcu_dynticks_curr_cpu_in_eqs(), - "RCU in extended quiescent state!"); -} - #ifdef CONFIG_PROVE_RCU /** * rcu_irq_exit_check_preempt - Validate that scheduling is possible @@ -961,7 +951,7 @@ EXPORT_SYMBOL_GPL(rcu_idle_exit); */ void noinstr rcu_user_exit(void) { - rcu_eqs_exit(1); + rcu_eqs_exit(true); } /** @@ -1227,7 +1217,7 @@ EXPORT_SYMBOL_GPL(rcu_lockdep_current_cpu_online); #endif /* #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU) */ /* - * We are reporting a quiescent state on behalf of some other CPU, so + * When trying to report a quiescent state on behalf of some other CPU, * it is our responsibility to check for and handle potential overflow * of the rcu_node ->gp_seq counter with respect to the rcu_data counters. * After all, the CPU might be in deep idle state, and thus executing no @@ -2050,7 +2040,7 @@ static void rcu_gp_fqs_loop(void) /* * Clean up after the old grace period. */ -static void rcu_gp_cleanup(void) +static noinline void rcu_gp_cleanup(void) { int cpu; bool needgp = false; @@ -2491,7 +2481,7 @@ int rcutree_dead_cpu(unsigned int cpu) /* * Invoke any RCU callbacks that have made it to the end of their grace - * period. Thottle as specified by rdp->blimit. + * period. Throttle as specified by rdp->blimit. */ static void rcu_do_batch(struct rcu_data *rdp) { @@ -2631,7 +2621,7 @@ static void rcu_do_batch(struct rcu_data *rdp) * state, for example, user mode or idle loop. It also schedules RCU * core processing. If the current grace period has gone on too long, * it will ask the scheduler to manufacture a context switch for the sole - * purpose of providing a providing the needed quiescent state. + * purpose of providing the needed quiescent state. */ void rcu_sched_clock_irq(int user) { @@ -2913,7 +2903,6 @@ static int __init rcu_spawn_core_kthreads(void) "%s: Could not start rcuc kthread, OOM is now expected behavior\n", __func__); return 0; } -early_initcall(rcu_spawn_core_kthreads); /* * Handle any core-RCU processing required by a call_rcu() invocation. @@ -3084,12 +3073,14 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func) * period elapses, in other words after all pre-existing RCU read-side * critical sections have completed. However, the callback function * might well execute concurrently with RCU read-side critical sections - * that started after call_rcu() was invoked. RCU read-side critical - * sections are delimited by rcu_read_lock() and rcu_read_unlock(), and - * may be nested. In addition, regions of code across which interrupts, - * preemption, or softirqs have been disabled also serve as RCU read-side - * critical sections. This includes hardware interrupt handlers, softirq - * handlers, and NMI handlers. + * that started after call_rcu() was invoked. + * + * RCU read-side critical sections are delimited by rcu_read_lock() + * and rcu_read_unlock(), and may be nested. In addition, but only in + * v5.0 and later, regions of code across which interrupts, preemption, + * or softirqs have been disabled also serve as RCU read-side critical + * sections. This includes hardware interrupt handlers, softirq handlers, + * and NMI handlers. * * Note that all CPUs must agree that the grace period extended beyond * all pre-existing RCU read-side critical section. On systems with more @@ -3109,6 +3100,9 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func) * between the call to call_rcu() and the invocation of "func()" -- even * if CPU A and CPU B are the same CPU (but again only if the system has * more than one CPU). + * + * Implementation of these memory-ordering guarantees is described here: + * Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst. */ void call_rcu(struct rcu_head *head, rcu_callback_t func) { @@ -3173,6 +3167,7 @@ struct kfree_rcu_cpu_work { * Even though it is lockless an access has to be protected by the * per-cpu lock. * @page_cache_work: A work to refill the cache when it is empty + * @backoff_page_cache_fill: Delay cache refills * @work_in_progress: Indicates that page_cache_work is running * @hrtimer: A hrtimer for scheduling a page_cache_work * @nr_bkv_objs: number of allocated objects at @bkvcache. @@ -3192,7 +3187,8 @@ struct kfree_rcu_cpu { bool initialized; int count; - struct work_struct page_cache_work; + struct delayed_work page_cache_work; + atomic_t backoff_page_cache_fill; atomic_t work_in_progress; struct hrtimer hrtimer; @@ -3239,7 +3235,7 @@ get_cached_bnode(struct kfree_rcu_cpu *krcp) if (!krcp->nr_bkv_objs) return NULL; - krcp->nr_bkv_objs--; + WRITE_ONCE(krcp->nr_bkv_objs, krcp->nr_bkv_objs - 1); return (struct kvfree_rcu_bulk_data *) llist_del_first(&krcp->bkvcache); } @@ -3253,14 +3249,33 @@ put_cached_bnode(struct kfree_rcu_cpu *krcp, return false; llist_add((struct llist_node *) bnode, &krcp->bkvcache); - krcp->nr_bkv_objs++; + WRITE_ONCE(krcp->nr_bkv_objs, krcp->nr_bkv_objs + 1); return true; +} + +static int +drain_page_cache(struct kfree_rcu_cpu *krcp) +{ + unsigned long flags; + struct llist_node *page_list, *pos, *n; + int freed = 0; + raw_spin_lock_irqsave(&krcp->lock, flags); + page_list = llist_del_all(&krcp->bkvcache); + WRITE_ONCE(krcp->nr_bkv_objs, 0); + raw_spin_unlock_irqrestore(&krcp->lock, flags); + + llist_for_each_safe(pos, n, page_list) { + free_page((unsigned long)pos); + freed++; + } + + return freed; } /* * This function is invoked in workqueue context after a grace period. - * It frees all the objects queued on ->bhead_free or ->head_free. + * It frees all the objects queued on ->bkvhead_free or ->head_free. */ static void kfree_rcu_work(struct work_struct *work) { @@ -3287,7 +3302,7 @@ static void kfree_rcu_work(struct work_struct *work) krwp->head_free = NULL; raw_spin_unlock_irqrestore(&krcp->lock, flags); - // Handle two first channels. + // Handle the first two channels. for (i = 0; i < FREE_N_CHANNELS; i++) { for (; bkvhead[i]; bkvhead[i] = bnext) { bnext = bkvhead[i]->next; @@ -3325,9 +3340,11 @@ static void kfree_rcu_work(struct work_struct *work) } /* - * Emergency case only. It can happen under low memory - * condition when an allocation gets failed, so the "bulk" - * path can not be temporary maintained. + * This is used when the "bulk" path can not be used for the + * double-argument of kvfree_rcu(). This happens when the + * page-cache is empty, which means that objects are instead + * queued on a linked list through their rcu_head structures. + * This list is named "Channel 3". */ for (; head; head = next) { unsigned long offset = (unsigned long)head->func; @@ -3347,34 +3364,31 @@ static void kfree_rcu_work(struct work_struct *work) } /* - * Schedule the kfree batch RCU work to run in workqueue context after a GP. - * - * This function is invoked by kfree_rcu_monitor() when the KFREE_DRAIN_JIFFIES - * timeout has been reached. + * This function is invoked after the KFREE_DRAIN_JIFFIES timeout. */ -static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp) +static void kfree_rcu_monitor(struct work_struct *work) { - struct kfree_rcu_cpu_work *krwp; - bool repeat = false; + struct kfree_rcu_cpu *krcp = container_of(work, + struct kfree_rcu_cpu, monitor_work.work); + unsigned long flags; int i, j; - lockdep_assert_held(&krcp->lock); + raw_spin_lock_irqsave(&krcp->lock, flags); + // Attempt to start a new batch. for (i = 0; i < KFREE_N_BATCHES; i++) { - krwp = &(krcp->krw_arr[i]); + struct kfree_rcu_cpu_work *krwp = &(krcp->krw_arr[i]); - /* - * Try to detach bkvhead or head and attach it over any - * available corresponding free channel. It can be that - * a previous RCU batch is in progress, it means that - * immediately to queue another one is not possible so - * return false to tell caller to retry. - */ + // Try to detach bkvhead or head and attach it over any + // available corresponding free channel. It can be that + // a previous RCU batch is in progress, it means that + // immediately to queue another one is not possible so + // in that case the monitor work is rearmed. if ((krcp->bkvhead[0] && !krwp->bkvhead_free[0]) || (krcp->bkvhead[1] && !krwp->bkvhead_free[1]) || (krcp->head && !krwp->head_free)) { - // Channel 1 corresponds to SLAB ptrs. - // Channel 2 corresponds to vmalloc ptrs. + // Channel 1 corresponds to the SLAB-pointer bulk path. + // Channel 2 corresponds to vmalloc-pointer bulk path. for (j = 0; j < FREE_N_CHANNELS; j++) { if (!krwp->bkvhead_free[j]) { krwp->bkvhead_free[j] = krcp->bkvhead[j]; @@ -3382,7 +3396,8 @@ static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp) } } - // Channel 3 corresponds to emergency path. + // Channel 3 corresponds to both SLAB and vmalloc + // objects queued on the linked list. if (!krwp->head_free) { krwp->head_free = krcp->head; krcp->head = NULL; @@ -3390,65 +3405,35 @@ static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp) WRITE_ONCE(krcp->count, 0); - /* - * One work is per one batch, so there are three - * "free channels", the batch can handle. It can - * be that the work is in the pending state when - * channels have been detached following by each - * other. - */ + // One work is per one batch, so there are three + // "free channels", the batch can handle. It can + // be that the work is in the pending state when + // channels have been detached following by each + // other. queue_rcu_work(system_wq, &krwp->rcu_work); } - - // Repeat if any "free" corresponding channel is still busy. - if (krcp->bkvhead[0] || krcp->bkvhead[1] || krcp->head) - repeat = true; } - return !repeat; -} - -static inline void kfree_rcu_drain_unlock(struct kfree_rcu_cpu *krcp, - unsigned long flags) -{ - // Attempt to start a new batch. - krcp->monitor_todo = false; - if (queue_kfree_rcu_work(krcp)) { - // Success! Our job is done here. - raw_spin_unlock_irqrestore(&krcp->lock, flags); - return; - } + // If there is nothing to detach, it means that our job is + // successfully done here. In case of having at least one + // of the channels that is still busy we should rearm the + // work to repeat an attempt. Because previous batches are + // still in progress. + if (!krcp->bkvhead[0] && !krcp->bkvhead[1] && !krcp->head) + krcp->monitor_todo = false; + else + schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES); - // Previous RCU batch still in progress, try again later. - krcp->monitor_todo = true; - schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES); raw_spin_unlock_irqrestore(&krcp->lock, flags); } -/* - * This function is invoked after the KFREE_DRAIN_JIFFIES timeout. - * It invokes kfree_rcu_drain_unlock() to attempt to start another batch. - */ -static void kfree_rcu_monitor(struct work_struct *work) -{ - unsigned long flags; - struct kfree_rcu_cpu *krcp = container_of(work, struct kfree_rcu_cpu, - monitor_work.work); - - raw_spin_lock_irqsave(&krcp->lock, flags); - if (krcp->monitor_todo) - kfree_rcu_drain_unlock(krcp, flags); - else - raw_spin_unlock_irqrestore(&krcp->lock, flags); -} - static enum hrtimer_restart schedule_page_work_fn(struct hrtimer *t) { struct kfree_rcu_cpu *krcp = container_of(t, struct kfree_rcu_cpu, hrtimer); - queue_work(system_highpri_wq, &krcp->page_cache_work); + queue_delayed_work(system_highpri_wq, &krcp->page_cache_work, 0); return HRTIMER_NORESTART; } @@ -3457,12 +3442,16 @@ static void fill_page_cache_func(struct work_struct *work) struct kvfree_rcu_bulk_data *bnode; struct kfree_rcu_cpu *krcp = container_of(work, struct kfree_rcu_cpu, - page_cache_work); + page_cache_work.work); unsigned long flags; + int nr_pages; bool pushed; int i; - for (i = 0; i < rcu_min_cached_objs; i++) { + nr_pages = atomic_read(&krcp->backoff_page_cache_fill) ? + 1 : rcu_min_cached_objs; + + for (i = 0; i < nr_pages; i++) { bnode = (struct kvfree_rcu_bulk_data *) __get_free_page(GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); @@ -3479,6 +3468,7 @@ static void fill_page_cache_func(struct work_struct *work) } atomic_set(&krcp->work_in_progress, 0); + atomic_set(&krcp->backoff_page_cache_fill, 0); } static void @@ -3486,10 +3476,15 @@ run_page_cache_worker(struct kfree_rcu_cpu *krcp) { if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING && !atomic_xchg(&krcp->work_in_progress, 1)) { - hrtimer_init(&krcp->hrtimer, CLOCK_MONOTONIC, - HRTIMER_MODE_REL); - krcp->hrtimer.function = schedule_page_work_fn; - hrtimer_start(&krcp->hrtimer, 0, HRTIMER_MODE_REL); + if (atomic_read(&krcp->backoff_page_cache_fill)) { + queue_delayed_work(system_wq, + &krcp->page_cache_work, + msecs_to_jiffies(rcu_delay_page_cache_fill_msec)); + } else { + hrtimer_init(&krcp->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + krcp->hrtimer.function = schedule_page_work_fn; + hrtimer_start(&krcp->hrtimer, 0, HRTIMER_MODE_REL); + } } } @@ -3554,11 +3549,11 @@ add_ptr_to_bulk_krc_lock(struct kfree_rcu_cpu **krcp, } /* - * Queue a request for lazy invocation of appropriate free routine after a - * grace period. Please note there are three paths are maintained, two are the - * main ones that use array of pointers interface and third one is emergency - * one, that is used only when the main path can not be maintained temporary, - * due to memory pressure. + * Queue a request for lazy invocation of the appropriate free routine + * after a grace period. Please note that three paths are maintained, + * two for the common case using arrays of pointers and a third one that + * is used only when the main paths cannot be used, for example, due to + * memory pressure. * * Each kvfree_call_rcu() request is added to a batch. The batch will be drained * every KFREE_DRAIN_JIFFIES number of jiffies. All the objects in the batch will @@ -3647,6 +3642,8 @@ kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); count += READ_ONCE(krcp->count); + count += READ_ONCE(krcp->nr_bkv_objs); + atomic_set(&krcp->backoff_page_cache_fill, 1); } return count; @@ -3656,18 +3653,14 @@ static unsigned long kfree_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) { int cpu, freed = 0; - unsigned long flags; for_each_possible_cpu(cpu) { int count; struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); count = krcp->count; - raw_spin_lock_irqsave(&krcp->lock, flags); - if (krcp->monitor_todo) - kfree_rcu_drain_unlock(krcp, flags); - else - raw_spin_unlock_irqrestore(&krcp->lock, flags); + count += drain_page_cache(krcp); + kfree_rcu_monitor(&krcp->monitor_work.work); sc->nr_to_scan -= count; freed += count; @@ -3695,7 +3688,8 @@ void __init kfree_rcu_scheduler_running(void) struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); raw_spin_lock_irqsave(&krcp->lock, flags); - if (!krcp->head || krcp->monitor_todo) { + if ((!krcp->bkvhead[0] && !krcp->bkvhead[1] && !krcp->head) || + krcp->monitor_todo) { raw_spin_unlock_irqrestore(&krcp->lock, flags); continue; } @@ -3752,10 +3746,12 @@ static int rcu_blocking_is_gp(void) * read-side critical sections have completed. Note, however, that * upon return from synchronize_rcu(), the caller might well be executing * concurrently with new RCU read-side critical sections that began while - * synchronize_rcu() was waiting. RCU read-side critical sections are - * delimited by rcu_read_lock() and rcu_read_unlock(), and may be nested. - * In addition, regions of code across which interrupts, preemption, or - * softirqs have been disabled also serve as RCU read-side critical + * synchronize_rcu() was waiting. + * + * RCU read-side critical sections are delimited by rcu_read_lock() + * and rcu_read_unlock(), and may be nested. In addition, but only in + * v5.0 and later, regions of code across which interrupts, preemption, + * or softirqs have been disabled also serve as RCU read-side critical * sections. This includes hardware interrupt handlers, softirq handlers, * and NMI handlers. * @@ -3776,6 +3772,9 @@ static int rcu_blocking_is_gp(void) * to have executed a full memory barrier during the execution of * synchronize_rcu() -- even if CPU A and CPU B are the same CPU (but * again only if the system has more than one CPU). + * + * Implementation of these memory-ordering guarantees is described here: + * Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst. */ void synchronize_rcu(void) { @@ -3846,11 +3845,11 @@ EXPORT_SYMBOL_GPL(start_poll_synchronize_rcu); /** * poll_state_synchronize_rcu - Conditionally wait for an RCU grace period * - * @oldstate: return from call to get_state_synchronize_rcu() or start_poll_synchronize_rcu() + * @oldstate: value from get_state_synchronize_rcu() or start_poll_synchronize_rcu() * * If a full RCU grace period has elapsed since the earlier call from * which oldstate was obtained, return @true, otherwise return @false. - * If @false is returned, it is the caller's responsibilty to invoke this + * If @false is returned, it is the caller's responsibility to invoke this * function later on until it does return @true. Alternatively, the caller * can explicitly wait for a grace period, for example, by passing @oldstate * to cond_synchronize_rcu() or by directly invoking synchronize_rcu(). @@ -3862,6 +3861,11 @@ EXPORT_SYMBOL_GPL(start_poll_synchronize_rcu); * (many hours even on 32-bit systems) should check them occasionally * and either refresh them or set a flag indicating that the grace period * has completed. + * + * This function provides the same memory-ordering guarantees that + * would be provided by a synchronize_rcu() that was invoked at the call + * to the function that provided @oldstate, and that returned at the end + * of this function. */ bool poll_state_synchronize_rcu(unsigned long oldstate) { @@ -3876,7 +3880,7 @@ EXPORT_SYMBOL_GPL(poll_state_synchronize_rcu); /** * cond_synchronize_rcu - Conditionally wait for an RCU grace period * - * @oldstate: return value from earlier call to get_state_synchronize_rcu() + * @oldstate: value from get_state_synchronize_rcu() or start_poll_synchronize_rcu() * * If a full RCU grace period has elapsed since the earlier call to * get_state_synchronize_rcu() or start_poll_synchronize_rcu(), just return. @@ -3886,6 +3890,11 @@ EXPORT_SYMBOL_GPL(poll_state_synchronize_rcu); * counter wrap is harmless. If the counter wraps, we have waited for * more than 2 billion grace periods (and way more on a 64-bit system!), * so waiting for one additional grace period should be just fine. + * + * This function provides the same memory-ordering guarantees that + * would be provided by a synchronize_rcu() that was invoked at the call + * to the function that provided @oldstate, and that returned at the end + * of this function. */ void cond_synchronize_rcu(unsigned long oldstate) { @@ -3913,7 +3922,7 @@ static int rcu_pending(int user) check_cpu_stall(rdp); /* Does this CPU need a deferred NOCB wakeup? */ - if (rcu_nocb_need_deferred_wakeup(rdp)) + if (rcu_nocb_need_deferred_wakeup(rdp, RCU_NOCB_WAKE)) return 1; /* Is this a nohz_full CPU in userspace or idle? (Ignore RCU if so.) */ @@ -4096,7 +4105,7 @@ EXPORT_SYMBOL_GPL(rcu_barrier); /* * Propagate ->qsinitmask bits up the rcu_node tree to account for the * first CPU in a given leaf rcu_node structure coming online. The caller - * must hold the corresponding leaf rcu_node ->lock with interrrupts + * must hold the corresponding leaf rcu_node ->lock with interrupts * disabled. */ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf) @@ -4191,7 +4200,7 @@ int rcutree_prepare_cpu(unsigned int cpu) rdp->rcu_iw_gp_seq = rdp->gp_seq - 1; trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("cpuonl")); raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - rcu_prepare_kthreads(cpu); + rcu_spawn_one_boost_kthread(rnp); rcu_spawn_cpu_nocb_kthread(cpu); WRITE_ONCE(rcu_state.n_online_cpus, rcu_state.n_online_cpus + 1); @@ -4474,6 +4483,7 @@ static int __init rcu_spawn_gp_kthread(void) wake_up_process(t); rcu_spawn_nocb_kthreads(); rcu_spawn_boost_kthreads(); + rcu_spawn_core_kthreads(); return 0; } early_initcall(rcu_spawn_gp_kthread); @@ -4584,11 +4594,25 @@ static void __init rcu_init_one(void) * replace the definitions in tree.h because those are needed to size * the ->node array in the rcu_state structure. */ -static void __init rcu_init_geometry(void) +void rcu_init_geometry(void) { ulong d; int i; + static unsigned long old_nr_cpu_ids; int rcu_capacity[RCU_NUM_LVLS]; + static bool initialized; + + if (initialized) { + /* + * Warn if setup_nr_cpu_ids() had not yet been invoked, + * unless nr_cpus_ids == NR_CPUS, in which case who cares? + */ + WARN_ON_ONCE(old_nr_cpu_ids != nr_cpu_ids); + return; + } + + old_nr_cpu_ids = nr_cpu_ids; + initialized = true; /* * Initialize any unspecified boot parameters. @@ -4689,6 +4713,18 @@ static void __init kfree_rcu_batch_init(void) int cpu; int i; + /* Clamp it to [0:100] seconds interval. */ + if (rcu_delay_page_cache_fill_msec < 0 || + rcu_delay_page_cache_fill_msec > 100 * MSEC_PER_SEC) { + + rcu_delay_page_cache_fill_msec = + clamp(rcu_delay_page_cache_fill_msec, 0, + (int) (100 * MSEC_PER_SEC)); + + pr_info("Adjusting rcutree.rcu_delay_page_cache_fill_msec to %d ms.\n", + rcu_delay_page_cache_fill_msec); + } + for_each_possible_cpu(cpu) { struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); @@ -4698,7 +4734,7 @@ static void __init kfree_rcu_batch_init(void) } INIT_DELAYED_WORK(&krcp->monitor_work, kfree_rcu_monitor); - INIT_WORK(&krcp->page_cache_work, fill_page_cache_func); + INIT_DELAYED_WORK(&krcp->page_cache_work, fill_page_cache_func); krcp->initialized = true; } if (register_shrinker(&kfree_rcu_shrinker)) @@ -4732,12 +4768,11 @@ void __init rcu_init(void) rcutree_online_cpu(cpu); } - /* Create workqueue for expedited GPs and for Tree SRCU. */ + /* Create workqueue for Tree SRCU and for expedited GPs. */ rcu_gp_wq = alloc_workqueue("rcu_gp", WQ_MEM_RECLAIM, 0); WARN_ON(!rcu_gp_wq); rcu_par_gp_wq = alloc_workqueue("rcu_par_gp", WQ_MEM_RECLAIM, 0); WARN_ON(!rcu_par_gp_wq); - srcu_init(); /* Fill in default value for rcutree.qovld boot parameter. */ /* -After- the rcu_node ->lock fields are initialized! */ |