diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cpu.c | 13 | ||||
| -rw-r--r-- | kernel/locking/locktorture.c | 214 | ||||
| -rw-r--r-- | kernel/rcu/rcu.h | 17 | ||||
| -rw-r--r-- | kernel/rcu/rcu_segcblist.c | 4 | ||||
| -rw-r--r-- | kernel/rcu/rcutorture.c | 37 | ||||
| -rw-r--r-- | kernel/rcu/refscale.c | 6 | ||||
| -rw-r--r-- | kernel/rcu/srcutiny.c | 1 | ||||
| -rw-r--r-- | kernel/rcu/srcutree.c | 74 | ||||
| -rw-r--r-- | kernel/rcu/tasks.h | 11 | ||||
| -rw-r--r-- | kernel/rcu/tiny.c | 1 | ||||
| -rw-r--r-- | kernel/rcu/tree.c | 242 | ||||
| -rw-r--r-- | kernel/rcu/tree.h | 4 | ||||
| -rw-r--r-- | kernel/rcu/tree_exp.h | 6 | ||||
| -rw-r--r-- | kernel/rcu/tree_stall.h | 135 | ||||
| -rw-r--r-- | kernel/rcu/update.c | 9 | ||||
| -rw-r--r-- | kernel/torture.c | 75 |
16 files changed, 593 insertions, 256 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 303cb0591b4b..69e92ddef5dd 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1380,7 +1380,14 @@ static int takedown_cpu(unsigned int cpu) cpuhp_bp_sync_dead(cpu); tick_cleanup_dead_cpu(cpu); + + /* + * Callbacks must be re-integrated right away to the RCU state machine. + * Otherwise an RCU callback could block a further teardown function + * waiting for its completion. + */ rcutree_migrate_callbacks(cpu); + return 0; } @@ -1396,10 +1403,10 @@ void cpuhp_report_idle_dead(void) struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); BUG_ON(st->state != CPUHP_AP_OFFLINE); - rcu_report_dead(smp_processor_id()); + rcutree_report_cpu_dead(); st->state = CPUHP_AP_IDLE_DEAD; /* - * We cannot call complete after rcu_report_dead() so we delegate it + * We cannot call complete after rcutree_report_cpu_dead() so we delegate it * to an online cpu. */ smp_call_function_single(cpumask_first(cpu_online_mask), @@ -1628,7 +1635,7 @@ void notify_cpu_starting(unsigned int cpu) struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE); - rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */ + rcutree_report_cpu_starting(cpu); /* Enables RCU usage on this CPU. */ cpumask_set_cpu(cpu, &cpus_booted_once_mask); /* diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index 270c7f80ce84..69d3cd2cfc3b 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -33,21 +33,23 @@ MODULE_LICENSE("GPL"); MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>"); -torture_param(int, nwriters_stress, -1, "Number of write-locking stress-test threads"); -torture_param(int, nreaders_stress, -1, "Number of read-locking stress-test threads"); +torture_param(int, acq_writer_lim, 0, "Write_acquisition time limit (jiffies)."); +torture_param(int, call_rcu_chains, 0, "Self-propagate call_rcu() chains during test (0=disable)."); torture_param(int, long_hold, 100, "Do occasional long hold of lock (ms), 0=disable"); +torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)"); +torture_param(int, nreaders_stress, -1, "Number of read-locking stress-test threads"); +torture_param(int, nwriters_stress, -1, "Number of write-locking stress-test threads"); torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)"); torture_param(int, onoff_interval, 0, "Time between CPU hotplugs (s), 0=disable"); +torture_param(int, rt_boost, 2, + "Do periodic rt-boost. 0=Disable, 1=Only for rt_mutex, 2=For all lock types."); +torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens."); torture_param(int, shuffle_interval, 3, "Number of jiffies between shuffles, 0=disable"); torture_param(int, shutdown_secs, 0, "Shutdown time (j), <= zero to disable."); torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s"); torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable"); -torture_param(int, rt_boost, 2, - "Do periodic rt-boost. 0=Disable, 1=Only for rt_mutex, 2=For all lock types."); -torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens."); -torture_param(int, writer_fifo, 0, "Run writers at sched_set_fifo() priority"); torture_param(int, verbose, 1, "Enable verbose debugging printk()s"); -torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)"); +torture_param(int, writer_fifo, 0, "Run writers at sched_set_fifo() priority"); /* Going much higher trips "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" errors */ #define MAX_NESTED_LOCKS 8 @@ -56,6 +58,55 @@ module_param(torture_type, charp, 0444); MODULE_PARM_DESC(torture_type, "Type of lock to torture (spin_lock, spin_lock_irq, mutex_lock, ...)"); +static cpumask_var_t bind_readers; // Bind the readers to the specified set of CPUs. +static cpumask_var_t bind_writers; // Bind the writers to the specified set of CPUs. + +// Parse a cpumask kernel parameter. If there are more users later on, +// this might need to got to a more central location. +static int param_set_cpumask(const char *val, const struct kernel_param *kp) +{ + cpumask_var_t *cm_bind = kp->arg; + int ret; + char *s; + + if (!alloc_cpumask_var(cm_bind, GFP_KERNEL)) { + s = "Out of memory"; + ret = -ENOMEM; + goto out_err; + } + ret = cpulist_parse(val, *cm_bind); + if (!ret) + return ret; + s = "Bad CPU range"; +out_err: + pr_warn("%s: %s, all CPUs set\n", kp->name, s); + cpumask_setall(*cm_bind); + return ret; +} + +// Output a cpumask kernel parameter. +static int param_get_cpumask(char *buffer, const struct kernel_param *kp) +{ + cpumask_var_t *cm_bind = kp->arg; + + return sprintf(buffer, "%*pbl", cpumask_pr_args(*cm_bind)); +} + +static bool cpumask_nonempty(cpumask_var_t mask) +{ + return cpumask_available(mask) && !cpumask_empty(mask); +} + +static const struct kernel_param_ops lt_bind_ops = { + .set = param_set_cpumask, + .get = param_get_cpumask, +}; + +module_param_cb(bind_readers, <_bind_ops, &bind_readers, 0644); +module_param_cb(bind_writers, <_bind_ops, &bind_writers, 0644); + +long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask); + static struct task_struct *stats_task; static struct task_struct **writer_tasks; static struct task_struct **reader_tasks; @@ -69,6 +120,12 @@ struct lock_stress_stats { long n_lock_acquired; }; +struct call_rcu_chain { + struct rcu_head crc_rh; + bool crc_stop; +}; +struct call_rcu_chain *call_rcu_chain; + /* Forward reference. */ static void lock_torture_cleanup(void); @@ -116,12 +173,9 @@ static int torture_lock_busted_write_lock(int tid __maybe_unused) static void torture_lock_busted_write_delay(struct torture_random_state *trsp) { - const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX; - /* We want a long delay occasionally to force massive contention. */ - if (!(torture_random(trsp) % - (cxt.nrealwriters_stress * 2000 * longdelay_ms))) - mdelay(longdelay_ms); + if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold))) + mdelay(long_hold); if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000))) torture_preempt_schedule(); /* Allow test to be preempted. */ } @@ -194,15 +248,14 @@ __acquires(torture_spinlock) static void torture_spin_lock_write_delay(struct torture_random_state *trsp) { const unsigned long shortdelay_us = 2; - const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX; unsigned long j; /* We want a short delay mostly to emulate likely code, and * we want a long delay occasionally to force massive contention. */ - if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * longdelay_ms))) { + if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold))) { j = jiffies; - mdelay(longdelay_ms); + mdelay(long_hold); pr_alert("%s: delay = %lu jiffies.\n", __func__, jiffies - j); } if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 200 * shortdelay_us))) @@ -320,14 +373,12 @@ __acquires(torture_rwlock) static void torture_rwlock_write_delay(struct torture_random_state *trsp) { const unsigned long shortdelay_us = 2; - const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX; /* We want a short delay mostly to emulate likely code, and * we want a long delay occasionally to force massive contention. */ - if (!(torture_random(trsp) % - (cxt.nrealwriters_stress * 2000 * longdelay_ms))) - mdelay(longdelay_ms); + if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold))) + mdelay(long_hold); else udelay(shortdelay_us); } @@ -348,14 +399,12 @@ __acquires(torture_rwlock) static void torture_rwlock_read_delay(struct torture_random_state *trsp) { const unsigned long shortdelay_us = 10; - const unsigned long longdelay_ms = 100; /* We want a short delay mostly to emulate likely code, and * we want a long delay occasionally to force massive contention. */ - if (!(torture_random(trsp) % - (cxt.nrealreaders_stress * 2000 * longdelay_ms))) - mdelay(longdelay_ms); + if (long_hold && !(torture_random(trsp) % (cxt.nrealreaders_stress * 2000 * long_hold))) + mdelay(long_hold); else udelay(shortdelay_us); } @@ -453,12 +502,9 @@ __acquires(torture_mutex) static void torture_mutex_delay(struct torture_random_state *trsp) { - const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX; - /* We want a long delay occasionally to force massive contention. */ - if (!(torture_random(trsp) % - (cxt.nrealwriters_stress * 2000 * longdelay_ms))) - mdelay(longdelay_ms * 5); + if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold))) + mdelay(long_hold * 5); if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000))) torture_preempt_schedule(); /* Allow test to be preempted. */ } @@ -626,15 +672,13 @@ __acquires(torture_rtmutex) static void torture_rtmutex_delay(struct torture_random_state *trsp) { const unsigned long shortdelay_us = 2; - const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX; /* * We want a short delay mostly to emulate likely code, and * we want a long delay occasionally to force massive contention. */ - if (!(torture_random(trsp) % - (cxt.nrealwriters_stress * 2000 * longdelay_ms))) - mdelay(longdelay_ms); + if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold))) + mdelay(long_hold); if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 200 * shortdelay_us))) udelay(shortdelay_us); @@ -691,12 +735,9 @@ __acquires(torture_rwsem) static void torture_rwsem_write_delay(struct torture_random_state *trsp) { - const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX; - /* We want a long delay occasionally to force massive contention. */ - if (!(torture_random(trsp) % - (cxt.nrealwriters_stress * 2000 * longdelay_ms))) - mdelay(longdelay_ms * 10); + if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold))) + mdelay(long_hold * 10); if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000))) torture_preempt_schedule(); /* Allow test to be preempted. */ } @@ -716,14 +757,11 @@ __acquires(torture_rwsem) static void torture_rwsem_read_delay(struct torture_random_state *trsp) { - const unsigned long longdelay_ms = 100; - /* We want a long delay occasionally to force massive contention. */ - if (!(torture_random(trsp) % - (cxt.nrealreaders_stress * 2000 * longdelay_ms))) - mdelay(longdelay_ms * 2); + if (long_hold && !(torture_random(trsp) % (cxt.nrealreaders_stress * 2000 * long_hold))) + mdelay(long_hold * 2); else - mdelay(longdelay_ms / 2); + mdelay(long_hold / 2); if (!(torture_random(trsp) % (cxt.nrealreaders_stress * 20000))) torture_preempt_schedule(); /* Allow test to be preempted. */ } @@ -803,11 +841,13 @@ static struct lock_torture_ops percpu_rwsem_lock_ops = { */ static int lock_torture_writer(void *arg) { + unsigned long j; + unsigned long j1; + u32 lockset_mask; struct lock_stress_stats *lwsp = arg; - int tid = lwsp - cxt.lwsa; DEFINE_TORTURE_RANDOM(rand); - u32 lockset_mask; bool skip_main_lock; + int tid = lwsp - cxt.lwsa; VERBOSE_TOROUT_STRING("lock_torture_writer task started"); if (!rt_task(current)) @@ -834,17 +874,24 @@ static int lock_torture_writer(void *arg) cxt.cur_ops->nested_lock(tid, lockset_mask); if (!skip_main_lock) { + if (acq_writer_lim > 0) + j = jiffies; cxt.cur_ops->writelock(tid); if (WARN_ON_ONCE(lock_is_write_held)) lwsp->n_lock_fail++; lock_is_write_held = true; if (WARN_ON_ONCE(atomic_read(&lock_is_read_held))) lwsp->n_lock_fail++; /* rare, but... */ - + if (acq_writer_lim > 0) { + j1 = jiffies; + WARN_ONCE(time_after(j1, j + acq_writer_lim), + "%s: Lock acquisition took %lu jiffies.\n", + __func__, j1 - j); + } lwsp->n_lock_acquired++; - } - if (!skip_main_lock) { + cxt.cur_ops->write_delay(&rand); + lock_is_write_held = false; WRITE_ONCE(last_lock_release, jiffies); cxt.cur_ops->writeunlock(tid); @@ -986,16 +1033,69 @@ static int lock_torture_stats(void *arg) return 0; } + static inline void lock_torture_print_module_parms(struct lock_torture_ops *cur_ops, const char *tag) { + static cpumask_t cpumask_all; + cpumask_t *rcmp = cpumask_nonempty(bind_readers) ? bind_readers : &cpumask_all; + cpumask_t *wcmp = cpumask_nonempty(bind_writers) ? bind_writers : &cpumask_all; + + cpumask_setall(&cpumask_all); pr_alert("%s" TORTURE_FLAG - "--- %s%s: nwriters_stress=%d nreaders_stress=%d nested_locks=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n", + "--- %s%s: acq_writer_lim=%d bind_readers=%*pbl bind_writers=%*pbl call_rcu_chains=%d long_hold=%d nested_locks=%d nreaders_stress=%d nwriters_stress=%d onoff_holdoff=%d onoff_interval=%d rt_boost=%d rt_boost_factor=%d shuffle_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d verbose=%d writer_fifo=%d\n", torture_type, tag, cxt.debug_lock ? " [debug]": "", - cxt.nrealwriters_stress, cxt.nrealreaders_stress, - nested_locks, stat_interval, verbose, shuffle_interval, - stutter, shutdown_secs, onoff_interval, onoff_holdoff); + acq_writer_lim, cpumask_pr_args(rcmp), cpumask_pr_args(wcmp), + call_rcu_chains, long_hold, nested_locks, cxt.nrealreaders_stress, + cxt.nrealwriters_stress, onoff_holdoff, onoff_interval, rt_boost, + rt_boost_factor, shuffle_interval, shutdown_secs, stat_interval, stutter, + verbose, writer_fifo); +} + +// If requested, maintain call_rcu() chains to keep a grace period always +// in flight. These increase the probability of getting an RCU CPU stall +// warning and associated diagnostics when a locking primitive stalls. + +static void call_rcu_chain_cb(struct rcu_head *rhp) +{ + struct call_rcu_chain *crcp = container_of(rhp, struct call_rcu_chain, crc_rh); + + if (!smp_load_acquire(&crcp->crc_stop)) { + (void)start_poll_synchronize_rcu(); // Start one grace period... + call_rcu(&crcp->crc_rh, call_rcu_chain_cb); // ... and later start another. + } +} + +// Start the requested number of call_rcu() chains. +static int call_rcu_chain_init(void) +{ + int i; + + if (call_rcu_chains <= 0) + return 0; + call_rcu_chain = kcalloc(call_rcu_chains, sizeof(*call_rcu_chain), GFP_KERNEL); + if (!call_rcu_chain) + return -ENOMEM; + for (i = 0; i < call_rcu_chains; i++) { + call_rcu_chain[i].crc_stop = false; + call_rcu(&call_rcu_chain[i].crc_rh, call_rcu_chain_cb); + } + return 0; +} + +// Stop all of the call_rcu() chains. +static void call_rcu_chain_cleanup(void) +{ + int i; + + if (!call_rcu_chain) + return; + for (i = 0; i < call_rcu_chains; i++) + smp_store_release(&call_rcu_chain[i].crc_stop, true); + rcu_barrier(); + kfree(call_rcu_chain); + call_rcu_chain = NULL; } static void lock_torture_cleanup(void) @@ -1048,6 +1148,8 @@ static void lock_torture_cleanup(void) kfree(cxt.lrsa); cxt.lrsa = NULL; + call_rcu_chain_cleanup(); + end: if (cxt.init_called) { if (cxt.cur_ops->exit) @@ -1177,6 +1279,10 @@ static int __init lock_torture_init(void) } } + firsterr = call_rcu_chain_init(); + if (torture_init_error(firsterr)) + goto unwind; + lock_torture_print_module_parms(cxt.cur_ops, "Start of test"); /* Prepare torture context. */ @@ -1250,6 +1356,8 @@ static int __init lock_torture_init(void) writer_fifo ? sched_set_fifo : NULL); if (torture_init_error(firsterr)) goto unwind; + if (cpumask_nonempty(bind_writers)) + torture_sched_setaffinity(writer_tasks[i]->pid, bind_writers); create_reader: if (cxt.cur_ops->readlock == NULL || (j >= cxt.nrealreaders_stress)) @@ -1259,6 +1367,8 @@ static int __init lock_torture_init(void) reader_tasks[j]); if (torture_init_error(firsterr)) goto unwind; + if (cpumask_nonempty(bind_readers)) + torture_sched_setaffinity(reader_tasks[j]->pid, bind_readers); } if (stat_interval > 0) { firsterr = torture_create_kthread(lock_torture_stats, NULL, diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 98e13be411af..0d866eaa4cc8 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -10,6 +10,7 @@ #ifndef __LINUX_RCU_H #define __LINUX_RCU_H +#include <linux/slab.h> #include <trace/events/rcu.h> /* @@ -248,6 +249,12 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head) } #endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ +static inline void debug_rcu_head_callback(struct rcu_head *rhp) +{ + if (unlikely(!rhp->func)) + kmem_dump_obj(rhp); +} + extern int rcu_cpu_stall_suppress_at_boot; static inline bool rcu_stall_is_suppressed_at_boot(void) @@ -568,10 +575,6 @@ void do_trace_rcu_torture_read(const char *rcutorturename, static inline void rcu_gp_set_torture_wait(int duration) { } #endif -#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) -long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask); -#endif - #ifdef CONFIG_TINY_SRCU static inline void srcutorture_get_gp_data(enum rcutorture_type test_type, @@ -654,4 +657,10 @@ static inline bool rcu_cpu_beenfullyonline(int cpu) { return true; } bool rcu_cpu_beenfullyonline(int cpu); #endif +#ifdef CONFIG_RCU_STALL_COMMON +int rcu_stall_notifier_call_chain(unsigned long val, void *v); +#else // #ifdef CONFIG_RCU_STALL_COMMON +static inline int rcu_stall_notifier_call_chain(unsigned long val, void *v) { return NOTIFY_DONE; } +#endif // #else // #ifdef CONFIG_RCU_STALL_COMMON + #endif /* __LINUX_RCU_H */ diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c index f71fac422c8f..1693ea22ef1b 100644 --- a/kernel/rcu/rcu_segcblist.c +++ b/kernel/rcu/rcu_segcblist.c @@ -368,7 +368,7 @@ bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, smp_mb(); /* Ensure counts are updated before callback is entrained. */ rhp->next = NULL; for (i = RCU_NEXT_TAIL; i > RCU_DONE_TAIL; i--) - if (rsclp->tails[i] != rsclp->tails[i - 1]) + if (!rcu_segcblist_segempty(rsclp, i)) break; rcu_segcblist_inc_seglen(rsclp, i); WRITE_ONCE(*rsclp->tails[i], rhp); @@ -551,7 +551,7 @@ bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq) * as their ->gp_seq[] grace-period completion sequence number. */ for (i = RCU_NEXT_READY_TAIL; i > RCU_DONE_TAIL; i--) - if (rsclp->tails[i] != rsclp->tails[i - 1] && + if (!rcu_segcblist_segempty(rsclp, i) && ULONG_CMP_LT(rsclp->gp_seq[i], seq)) break; diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index ade42d6a9d9b..30fc9d34e329 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -21,6 +21,7 @@ #include <linux/spinlock.h> #include <linux/smp.h> #include <linux/rcupdate_wait.h> +#include <linux/rcu_notifier.h> #include <linux/interrupt.h> #include <linux/sched/signal.h> #include <uapi/linux/sched/types.h> @@ -810,7 +811,7 @@ static void synchronize_rcu_trivial(void) int cpu; for_each_online_cpu(cpu) { - rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu)); + torture_sched_setaffinity(current->pid, cpumask_of(cpu)); WARN_ON_ONCE(raw_smp_processor_id() != cpu); } } @@ -1149,7 +1150,7 @@ static int rcu_torture_boost(void *arg) mutex_unlock(&boost_mutex); break; } - schedule_timeout_uninterruptible(1); + schedule_timeout_uninterruptible(HZ / 20); } /* Go do the stutter. */ @@ -1160,7 +1161,7 @@ checkwait: if (stutter_wait("rcu_torture_boost")) /* Clean up and exit. */ while (!kthread_should_stop()) { torture_shutdown_absorb("rcu_torture_boost"); - schedule_timeout_uninterruptible(1); + schedule_timeout_uninterruptible(HZ / 20); } torture_kthread_stopping("rcu_torture_boost"); return 0; @@ -1183,7 +1184,7 @@ rcu_torture_fqs(void *arg) fqs_resume_time = jiffies + fqs_stutter * HZ; while (time_before(jiffies, fqs_resume_time) && !kthread_should_stop()) { - schedule_timeout_interruptible(1); + schedule_timeout_interruptible(HZ / 20); } fqs_burst_remaining = fqs_duration; while (fqs_burst_remaining > 0 && @@ -2126,7 +2127,7 @@ static int rcu_nocb_toggle(void *arg) VERBOSE_TOROUT_STRING("rcu_nocb_toggle task started"); while (!rcu_inkernel_boot_has_ended()) schedule_timeout_interruptible(HZ / 10); - for_each_online_cpu(cpu) + for_each_possible_cpu(cpu) maxcpu = cpu; WARN_ON(maxcpu < 0); if (toggle_interval > ULONG_MAX) @@ -2428,6 +2429,16 @@ static int rcutorture_booster_init(unsigned int cpu) return 0; } +static int rcu_torture_stall_nf(struct notifier_block *nb, unsigned long v, void *ptr) +{ + pr_info("%s: v=%lu, duration=%lu.\n", __func__, v, (unsigned long)ptr); + return NOTIFY_OK; +} + +static struct notifier_block rcu_torture_stall_block = { + .notifier_call = rcu_torture_stall_nf, +}; + /* * CPU-stall kthread. It waits as specified by stall_cpu_holdoff, then * induces a CPU stall for the time specified by stall_cpu. @@ -2435,9 +2446,14 @@ static int rcutorture_booster_init(unsigned int cpu) static int rcu_torture_stall(void *args) { int idx; + int ret; unsigned long stop_at; VERBOSE_TOROUT_STRING("rcu_torture_stall task started"); + ret = rcu_stall_chain_notifier_register(&rcu_torture_stall_block); + if (ret) + pr_info("%s: rcu_stall_chain_notifier_register() returned %d, %sexpected.\n", + __func__, ret, !IS_ENABLED(CONFIG_RCU_STALL_COMMON) ? "un" : ""); if (stall_cpu_holdoff > 0) { VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff"); schedule_timeout_interruptible(stall_cpu_holdoff * HZ); @@ -2481,6 +2497,11 @@ static int rcu_torture_stall(void *args) cur_ops->readunlock(idx); } pr_alert("%s end.\n", __func__); + if (!ret) { + ret = rcu_stall_chain_notifier_unregister(&rcu_torture_stall_block); + if (ret) + pr_info("%s: rcu_stall_chain_notifier_unregister() returned %d.\n", __func__, ret); + } torture_shutdown_absorb("rcu_torture_stall"); while (!kthread_should_stop()) schedule_timeout_interruptible(10 * HZ); @@ -2899,7 +2920,7 @@ static int rcu_torture_fwd_prog(void *args) WRITE_ONCE(rcu_fwd_seq, rcu_fwd_seq + 1); } else { while (READ_ONCE(rcu_fwd_seq) == oldseq && !torture_must_stop()) - schedule_timeout_interruptible(1); + schedule_timeout_interruptible(HZ / 20); oldseq = READ_ONCE(rcu_fwd_seq); } pr_alert("%s: Starting forward-progress test %d\n", __func__, rfp->rcu_fwd_id); @@ -3200,7 +3221,7 @@ static int rcu_torture_read_exit_child(void *trsp_in) set_user_nice(current, MAX_NICE); // Minimize time between reading and exiting. while (!kthread_should_stop()) - schedule_timeout_uninterruptible(1); + schedule_timeout_uninterruptible(HZ / 20); (void)rcu_torture_one_read(trsp, -1); return 0; } @@ -3248,7 +3269,7 @@ static int rcu_torture_read_exit(void *unused) smp_mb(); // Store before wakeup. wake_up(&read_exit_wq); while (!torture_must_stop()) - schedule_timeout_uninterruptible(1); + schedule_timeout_uninterruptible(HZ / 20); torture_kthread_stopping("rcu_torture_read_exit"); return 0; } diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c index 91a0fd0d4d9a..2c2648a3ad30 100644 --- a/kernel/rcu/refscale.c +++ b/kernel/rcu/refscale.c @@ -655,12 +655,12 @@ retry: goto retry; } un_delay(udl, ndl); + b = READ_ONCE(rtsp->a); // Remember, seqlock read-side release can fail. if (!rts_release(rtsp, start)) { rcu_read_unlock(); goto retry; } - b = READ_ONCE(rtsp->a); WARN_ONCE(a != b, "Re-read of ->a changed from %u to %u.\n", a, b); b = rtsp->b; rcu_read_unlock(); @@ -1025,8 +1025,8 @@ static void ref_scale_print_module_parms(struct ref_scale_ops *cur_ops, const char *tag) { pr_alert("%s" SCALE_FLAG - "--- %s: verbose=%d shutdown=%d holdoff=%d loops=%ld nreaders=%d nruns=%d readdelay=%d\n", scale_type, tag, - verbose, shutdown, holdoff, loops, nreaders, nruns, readdelay); + "--- %s: verbose=%d verbose_batched=%d shutdown=%d holdoff=%d lookup_instances=%ld loops=%ld nreaders=%d nruns=%d readdelay=%d\n", scale_type, tag, + verbose, verbose_batched, shutdown, holdoff, lookup_instances, loops, nreaders, nruns, readdelay); } static void diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c index 336af24e0fe3..c38e5933a5d6 100644 --- a/kernel/rcu/srcutiny.c +++ b/kernel/rcu/srcutiny.c @@ -138,6 +138,7 @@ void srcu_drive_gp(struct work_struct *wp) while (lh) { rhp = lh; lh = lh->next; + debug_rcu_head_callback(rhp); local_bh_disable(); rhp->func(rhp); local_bh_enable(); diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 20d7a238d675..560e99ec5333 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -223,7 +223,7 @@ static bool init_srcu_struct_nodes(struct srcu_struct *ssp, gfp_t gfp_flags) snp->grplo = cpu; snp->grphi = cpu; } - sdp->grpmask = 1 << (cpu - sdp->mynode->grplo); + sdp->grpmask = 1UL << (cpu - sdp->mynode->grplo); } smp_store_release(&ssp->srcu_sup->srcu_size_state, SRCU_SIZE_WAIT_BARRIER); return true; @@ -255,29 +255,31 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) ssp->srcu_sup->sda_is_static = is_static; if (!is_static) ssp->sda = alloc_percpu(struct srcu_data); - if (!ssp->sda) { - if (!is_static) - kfree(ssp->srcu_sup); - return -ENOMEM; - } + if (!ssp->sda) + goto err_free_sup; init_srcu_struct_data(ssp); ssp->srcu_sup->srcu_gp_seq_needed_exp = 0; ssp->srcu_sup->srcu_last_gp_end = ktime_get_mono_fast_ns(); if (READ_ONCE(ssp->srcu_sup->srcu_size_state) == SRCU_SIZE_SMALL && SRCU_SIZING_IS_INIT()) { - if (!init_srcu_struct_nodes(ssp, GFP_ATOMIC)) { - if (!ssp->srcu_sup->sda_is_static) { - free_percpu(ssp->sda); - ssp->sda = NULL; - kfree(ssp->srcu_sup); - return -ENOMEM; - } - } else { - WRITE_ONCE(ssp->srcu_sup->srcu_size_state, SRCU_SIZE_BIG); - } + if (!init_srcu_struct_nodes(ssp, GFP_ATOMIC)) + goto err_free_sda; + WRITE_ONCE(ssp->srcu_sup->srcu_size_state, SRCU_SIZE_BIG); } ssp->srcu_sup->srcu_ssp = ssp; smp_store_release(&ssp->srcu_sup->srcu_gp_seq_needed, 0); /* Init done. */ return 0; + +err_free_sda: + if (!is_static) { + free_percpu(ssp->sda); + ssp->sda = NULL; + } +err_free_sup: + if (!is_static) { + kfree(ssp->srcu_sup); + ssp->srcu_sup = NULL; + } + return -ENOMEM; } #ifdef CONFIG_DEBUG_LOCK_ALLOC @@ -782,8 +784,7 @@ static void srcu_gp_start(struct srcu_struct *ssp) spin_lock_rcu_node(sdp); /* Interrupts already disabled. */ rcu_segcblist_advance(&sdp->srcu_cblist, rcu_seq_current(&ssp->srcu_sup->srcu_gp_seq)); - (void)rcu_segcblist_accelerate(&sdp->srcu_cblist, - rcu_seq_snap(&ssp->srcu_sup->srcu_gp_seq)); + WARN_ON_ONCE(!rcu_segcblist_segempty(&sdp->srcu_cblist, RCU_NEXT_TAIL)); spin_unlock_rcu_node(sdp); /* Interrupts remain disabled. */ WRITE_ONCE(ssp->srcu_sup->srcu_gp_start, jiffies); WRITE_ONCE(ssp->srcu_sup->srcu_n_exp_nodelay, 0); @@ -833,7 +834,7 @@ static void srcu_schedule_cbs_snp(struct srcu_struct *ssp, struct srcu_node *snp int cpu; for (cpu = snp->grplo; cpu <= snp->grphi; cpu++) { - if (!(mask & (1 << (cpu - snp->grplo)))) + if (!(mask & (1UL << (cpu - snp->grplo)))) continue; srcu_schedule_cbs_sdp(per_cpu_ptr(ssp->sda, cpu), delay); } @@ -1242,10 +1243,37 @@ static unsigned long srcu_gp_start_if_needed(struct srcu_struct *ssp, spin_lock_irqsave_sdp_contention(sdp, &flags); if (rhp) rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp); + /* + * The snapshot for acceleration must be taken _before_ the read of the + * current gp sequence used for advancing, otherwise advancing may fail + * and acceleration may then fail too. + * + * This could happen if: + * + * 1) The RCU_WAIT_TAIL segment has callbacks (gp_num = X + 4) and the + * RCU_NEXT_READY_TAIL also has callbacks (gp_num = X + 8). + * + * 2) The grace period for RCU_WAIT_TAIL is seen as started but not + * completed so rcu_seq_current() returns X + SRCU_STATE_SCAN1. + * + * 3) This value is passed to rcu_segcblist_advance() which can't move + * any segment forward and fails. + * + * 4) srcu_gp_start_if_needed() still proceeds with callback acceleration. + * But then the call to rcu_seq_snap() observes the grace period for the + * RCU_WAIT_TAIL segment as completed and the subsequent one for the + * RCU_NEXT_READY_TAIL segment as started (ie: X + 4 + SRCU_STATE_SCAN1) + * so it returns a snapshot of the next grace period, which is X + 12. + * + * 5) The value of X + 12 is passed to rcu_segcblist_accelerate() but the + * freshly enqueued callback in RCU_NEXT_TAIL can't move to + * RCU_NEXT_READY_TAIL which already has callbacks for a previous grace + * period (gp_num = X + 8). So acceleration fails. + */ + s = rcu_seq_snap(&ssp->srcu_sup->srcu_gp_seq); rcu_segcblist_advance(&sdp->srcu_cblist, rcu_seq_current(&ssp->srcu_sup->srcu_gp_seq)); - s = rcu_seq_snap(&ssp->srcu_sup->srcu_gp_seq); - (void)rcu_segcblist_accelerate(&sdp->srcu_cblist, s); + WARN_ON_ONCE(!rcu_segcblist_accelerate(&sdp->srcu_cblist, s) && rhp); if (ULONG_CMP_LT(sdp->srcu_gp_seq_needed, s)) { sdp->srcu_gp_seq_needed = s; needgp = true; @@ -1692,6 +1720,7 @@ static void srcu_invoke_callbacks(struct work_struct *work) ssp = sdp->ssp; rcu_cblist_init(&ready_cbs); spin_lock_irq_rcu_node(sdp); + WARN_ON_ONCE(!rcu_segcblist_segempty(&sdp->srcu_cblist, RCU_NEXT_TAIL)); rcu_segcblist_advance(&sdp->srcu_cblist, rcu_seq_current(&ssp->srcu_sup->srcu_gp_seq)); if (sdp->srcu_cblist_invoking || @@ -1708,6 +1737,7 @@ static void srcu_invoke_callbacks(struct work_struct *work) rhp = rcu_cblist_dequeue(&ready_cbs); for (; rhp != NULL; rhp = rcu_cblist_dequeue(&ready_cbs)) { debug_rcu_head_unqueue(rhp); + debug_rcu_head_callback(rhp); local_bh_disable(); rhp->func(rhp); local_bh_enable(); @@ -1720,8 +1750,6 @@ static void srcu_invoke_callbacks(struct work_struct *work) */ spin_lock_irq_rcu_node(sdp); rcu_segcblist_add_len(&sdp->srcu_cblist, -len); - (void)rcu_segcblist_accelerate(&sdp->srcu_cblist, - rcu_seq_snap(&ssp->srcu_sup->srcu_gp_seq)); sdp->srcu_cblist_invoking = false; more = rcu_segcblist_ready_cbs(&sdp->srcu_cblist); spin_unlock_irq_rcu_node(sdp); diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 8d65f7d576a3..1fa631168594 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -432,6 +432,7 @@ static void rcu_barrier_tasks_generic(struct rcu_tasks *rtp) static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp) { int cpu; + int dequeue_limit; unsigned long flags; bool gpdone = poll_state_synchronize_rcu(rtp->percpu_dequeue_gpseq); long n; @@ -439,7 +440,8 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp) long ncbsnz = 0; int needgpcb = 0; - for (cpu = 0; cpu < smp_load_acquire(&rtp->percpu_dequeue_lim); cpu++) { + dequeue_limit = smp_load_acquire(&rtp->percpu_dequeue_lim); + for (cpu = 0; cpu < dequeue_limit; cpu++) { struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu); /* Advance and accelerate any new callbacks. */ @@ -538,6 +540,7 @@ static void rcu_tasks_invoke_cbs(struct rcu_tasks *rtp, struct rcu_tasks_percpu raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); len = rcl.len; for (rhp = rcu_cblist_dequeue(&rcl); rhp; rhp = rcu_cblist_dequeue(&rcl)) { + debug_rcu_head_callback(rhp); local_bh_disable(); rhp->func(rhp); local_bh_enable(); @@ -1084,7 +1087,7 @@ void rcu_barrier_tasks(void) } EXPORT_SYMBOL_GPL(rcu_barrier_tasks); -int rcu_tasks_lazy_ms = -1; +static int rcu_tasks_lazy_ms = -1; module_param(rcu_tasks_lazy_ms, int, 0444); static int __init rcu_spawn_tasks_kthread(void) @@ -1979,20 +1982,22 @@ static void test_rcu_tasks_callback(struct rcu_head *rhp) static void rcu_tasks_initiate_self_tests |