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-rw-r--r--kernel/locking/lockdep.c6
-rw-r--r--kernel/rcu/Kconfig.debug2
-rw-r--r--kernel/rcu/rcu.h14
-rw-r--r--kernel/rcu/rcutorture.c315
-rw-r--r--kernel/rcu/refscale.c109
-rw-r--r--kernel/rcu/srcutree.c28
-rw-r--r--kernel/rcu/sync.c4
-rw-r--r--kernel/rcu/tasks.h58
-rw-r--r--kernel/rcu/tiny.c1
-rw-r--r--kernel/rcu/tree.c313
-rw-r--r--kernel/rcu/tree.h14
-rw-r--r--kernel/rcu/tree_plugin.h239
-rw-r--r--kernel/rcu/tree_stall.h84
-rw-r--r--kernel/rcu/update.c8
-rw-r--r--kernel/time/timer.c14
15 files changed, 734 insertions, 475 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index e97d08001437..bf1c00c881e4 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -6506,6 +6506,7 @@ asmlinkage __visible void lockdep_sys_exit(void)
void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
{
struct task_struct *curr = current;
+ int dl = READ_ONCE(debug_locks);
/* Note: the following can be executed concurrently, so be careful. */
pr_warn("\n");
@@ -6515,11 +6516,12 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
pr_warn("-----------------------------\n");
pr_warn("%s:%d %s!\n", file, line, s);
pr_warn("\nother info that might help us debug this:\n\n");
- pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
+ pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n%s",
!rcu_lockdep_current_cpu_online()
? "RCU used illegally from offline CPU!\n"
: "",
- rcu_scheduler_active, debug_locks);
+ rcu_scheduler_active, dl,
+ dl ? "" : "Possible false positive due to lockdep disabling via debug_locks = 0\n");
/*
* If a CPU is in the RCU-free window in idle (ie: in the section
diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug
index 1942c1f1bb65..4fd64999300f 100644
--- a/kernel/rcu/Kconfig.debug
+++ b/kernel/rcu/Kconfig.debug
@@ -116,7 +116,7 @@ config RCU_EQS_DEBUG
config RCU_STRICT_GRACE_PERIOD
bool "Provide debug RCU implementation with short grace periods"
- depends on DEBUG_KERNEL && RCU_EXPERT
+ depends on DEBUG_KERNEL && RCU_EXPERT && NR_CPUS <= 4
default n
select PREEMPT_COUNT if PREEMPT=n
help
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index bf0827d4b659..24b5f2c2de87 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -308,6 +308,8 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
}
}
+extern void rcu_init_geometry(void);
+
/* Returns a pointer to the first leaf rcu_node structure. */
#define rcu_first_leaf_node() (rcu_state.level[rcu_num_lvls - 1])
@@ -422,12 +424,6 @@ do { \
#endif /* #if defined(CONFIG_SRCU) || !defined(CONFIG_TINY_RCU) */
-#ifdef CONFIG_SRCU
-void srcu_init(void);
-#else /* #ifdef CONFIG_SRCU */
-static inline void srcu_init(void) { }
-#endif /* #else #ifdef CONFIG_SRCU */
-
#ifdef CONFIG_TINY_RCU
/* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */
static inline bool rcu_gp_is_normal(void) { return true; }
@@ -441,7 +437,11 @@ bool rcu_gp_is_expedited(void); /* Internal RCU use. */
void rcu_expedite_gp(void);
void rcu_unexpedite_gp(void);
void rcupdate_announce_bootup_oddness(void);
+#ifdef CONFIG_TASKS_RCU_GENERIC
void show_rcu_tasks_gp_kthreads(void);
+#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
+static inline void show_rcu_tasks_gp_kthreads(void) {}
+#endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */
void rcu_request_urgent_qs_task(struct task_struct *t);
#endif /* #else #ifdef CONFIG_TINY_RCU */
@@ -519,6 +519,7 @@ static inline unsigned long rcu_exp_batches_completed(void) { return 0; }
static inline unsigned long
srcu_batches_completed(struct srcu_struct *sp) { return 0; }
static inline void rcu_force_quiescent_state(void) { }
+static inline bool rcu_check_boost_fail(unsigned long gp_state, int *cpup) { return true; }
static inline void show_rcu_gp_kthreads(void) { }
static inline int rcu_get_gp_kthreads_prio(void) { return 0; }
static inline void rcu_fwd_progress_check(unsigned long j) { }
@@ -527,6 +528,7 @@ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp);
unsigned long rcu_get_gp_seq(void);
unsigned long rcu_exp_batches_completed(void);
unsigned long srcu_batches_completed(struct srcu_struct *sp);
+bool rcu_check_boost_fail(unsigned long gp_state, int *cpup);
void show_rcu_gp_kthreads(void);
int rcu_get_gp_kthreads_prio(void);
void rcu_fwd_progress_check(unsigned long j);
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 194b9c145c40..40ef5417d954 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -245,12 +245,6 @@ static const char *rcu_torture_writer_state_getname(void)
return rcu_torture_writer_state_names[i];
}
-#if defined(CONFIG_RCU_BOOST) && defined(CONFIG_PREEMPT_RT)
-# define rcu_can_boost() 1
-#else
-# define rcu_can_boost() 0
-#endif
-
#ifdef CONFIG_RCU_TRACE
static u64 notrace rcu_trace_clock_local(void)
{
@@ -331,6 +325,7 @@ struct rcu_torture_ops {
void (*read_delay)(struct torture_random_state *rrsp,
struct rt_read_seg *rtrsp);
void (*readunlock)(int idx);
+ int (*readlock_held)(void);
unsigned long (*get_gp_seq)(void);
unsigned long (*gp_diff)(unsigned long new, unsigned long old);
void (*deferred_free)(struct rcu_torture *p);
@@ -345,6 +340,7 @@ struct rcu_torture_ops {
void (*fqs)(void);
void (*stats)(void);
void (*gp_kthread_dbg)(void);
+ bool (*check_boost_failed)(unsigned long gp_state, int *cpup);
int (*stall_dur)(void);
int irq_capable;
int can_boost;
@@ -359,6 +355,11 @@ static struct rcu_torture_ops *cur_ops;
* Definitions for rcu torture testing.
*/
+static int torture_readlock_not_held(void)
+{
+ return rcu_read_lock_bh_held() || rcu_read_lock_sched_held();
+}
+
static int rcu_torture_read_lock(void) __acquires(RCU)
{
rcu_read_lock();
@@ -483,30 +484,32 @@ static void rcu_sync_torture_init(void)
}
static struct rcu_torture_ops rcu_ops = {
- .ttype = RCU_FLAVOR,
- .init = rcu_sync_torture_init,
- .readlock = rcu_torture_read_lock,
- .read_delay = rcu_read_delay,
- .readunlock = rcu_torture_read_unlock,
- .get_gp_seq = rcu_get_gp_seq,
- .gp_diff = rcu_seq_diff,
- .deferred_free = rcu_torture_deferred_free,
- .sync = synchronize_rcu,
- .exp_sync = synchronize_rcu_expedited,
- .get_gp_state = get_state_synchronize_rcu,
- .start_gp_poll = start_poll_synchronize_rcu,
- .poll_gp_state = poll_state_synchronize_rcu,
- .cond_sync = cond_synchronize_rcu,
- .call = call_rcu,
- .cb_barrier = rcu_barrier,
- .fqs = rcu_force_quiescent_state,
- .stats = NULL,
- .gp_kthread_dbg = show_rcu_gp_kthreads,
- .stall_dur = rcu_jiffies_till_stall_check,
- .irq_capable = 1,
- .can_boost = rcu_can_boost(),
- .extendables = RCUTORTURE_MAX_EXTEND,
- .name = "rcu"
+ .ttype = RCU_FLAVOR,
+ .init = rcu_sync_torture_init,
+ .readlock = rcu_torture_read_lock,
+ .read_delay = rcu_read_delay,
+ .readunlock = rcu_torture_read_unlock,
+ .readlock_held = torture_readlock_not_held,
+ .get_gp_seq = rcu_get_gp_seq,
+ .gp_diff = rcu_seq_diff,
+ .deferred_free = rcu_torture_deferred_free,
+ .sync = synchronize_rcu,
+ .exp_sync = synchronize_rcu_expedited,
+ .get_gp_state = get_state_synchronize_rcu,
+ .start_gp_poll = start_poll_synchronize_rcu,
+ .poll_gp_state = poll_state_synchronize_rcu,
+ .cond_sync = cond_synchronize_rcu,
+ .call = call_rcu,
+ .cb_barrier = rcu_barrier,
+ .fqs = rcu_force_quiescent_state,
+ .stats = NULL,
+ .gp_kthread_dbg = show_rcu_gp_kthreads,
+ .check_boost_failed = rcu_check_boost_fail,
+ .stall_dur = rcu_jiffies_till_stall_check,
+ .irq_capable = 1,
+ .can_boost = IS_ENABLED(CONFIG_RCU_BOOST),
+ .extendables = RCUTORTURE_MAX_EXTEND,
+ .name = "rcu"
};
/*
@@ -540,6 +543,7 @@ static struct rcu_torture_ops rcu_busted_ops = {
.readlock = rcu_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_torture_read_unlock,
+ .readlock_held = torture_readlock_not_held,
.get_gp_seq = rcu_no_completed,
.deferred_free = rcu_busted_torture_deferred_free,
.sync = synchronize_rcu_busted,
@@ -589,6 +593,11 @@ static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
srcu_read_unlock(srcu_ctlp, idx);
}
+static int torture_srcu_read_lock_held(void)
+{
+ return srcu_read_lock_held(srcu_ctlp);
+}
+
static unsigned long srcu_torture_completed(void)
{
return srcu_batches_completed(srcu_ctlp);
@@ -646,6 +655,7 @@ static struct rcu_torture_ops srcu_ops = {
.readlock = srcu_torture_read_lock,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
+ .readlock_held = torture_srcu_read_lock_held,
.get_gp_seq = srcu_torture_completed,
.deferred_free = srcu_torture_deferred_free,
.sync = srcu_torture_synchronize,
@@ -681,6 +691,7 @@ static struct rcu_torture_ops srcud_ops = {
.readlock = srcu_torture_read_lock,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
+ .readlock_held = torture_srcu_read_lock_held,
.get_gp_seq = srcu_torture_completed,
.deferred_free = srcu_torture_deferred_free,
.sync = srcu_torture_synchronize,
@@ -700,6 +711,7 @@ static struct rcu_torture_ops busted_srcud_ops = {
.readlock = srcu_torture_read_lock,
.read_delay = rcu_read_delay,
.readunlock = srcu_torture_read_unlock,
+ .readlock_held = torture_srcu_read_lock_held,
.get_gp_seq = srcu_torture_completed,
.deferred_free = srcu_torture_deferred_free,
.sync = srcu_torture_synchronize,
@@ -787,6 +799,7 @@ static struct rcu_torture_ops trivial_ops = {
.readlock = rcu_torture_read_lock_trivial,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_torture_read_unlock_trivial,
+ .readlock_held = torture_readlock_not_held,
.get_gp_seq = rcu_no_completed,
.sync = synchronize_rcu_trivial,
.exp_sync = synchronize_rcu_trivial,
@@ -850,6 +863,7 @@ static struct rcu_torture_ops tasks_tracing_ops = {
.readlock = tasks_tracing_torture_read_lock,
.read_delay = srcu_read_delay, /* just reuse srcu's version. */
.readunlock = tasks_tracing_torture_read_unlock,
+ .readlock_held = rcu_read_lock_trace_held,
.get_gp_seq = rcu_no_completed,
.deferred_free = rcu_tasks_tracing_torture_deferred_free,
.sync = synchronize_rcu_tasks_trace,
@@ -871,32 +885,13 @@ static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
return cur_ops->gp_diff(new, old);
}
-static bool __maybe_unused torturing_tasks(void)
-{
- return cur_ops == &tasks_ops || cur_ops == &tasks_rude_ops;
-}
-
/*
* RCU torture priority-boost testing. Runs one real-time thread per
- * CPU for moderate bursts, repeatedly registering RCU callbacks and
- * spinning waiting for them to be invoked. If a given callback takes
- * too long to be invoked, we assume that priority inversion has occurred.
+ * CPU for moderate bursts, repeatedly starting grace periods and waiting
+ * for them to complete. If a given grace period takes too long, we assume
+ * that priority inversion has occurred.
*/
-struct rcu_boost_inflight {
- struct rcu_head rcu;
- int inflight;
-};
-
-static void rcu_torture_boost_cb(struct rcu_head *head)
-{
- struct rcu_boost_inflight *rbip =
- container_of(head, struct rcu_boost_inflight, rcu);
-
- /* Ensure RCU-core accesses precede clearing ->inflight */
- smp_store_release(&rbip->inflight, 0);
-}
-
static int old_rt_runtime = -1;
static void rcu_torture_disable_rt_throttle(void)
@@ -923,49 +918,68 @@ static void rcu_torture_enable_rt_throttle(void)
old_rt_runtime = -1;
}
-static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
+static bool rcu_torture_boost_failed(unsigned long gp_state, unsigned long *start)
{
+ int cpu;
static int dbg_done;
-
- if (end - start > test_boost_duration * HZ - HZ / 2) {
+ unsigned long end = jiffies;
+ bool gp_done;
+ unsigned long j;
+ static unsigned long last_persist;
+ unsigned long lp;
+ unsigned long mininterval = test_boost_duration * HZ - HZ / 2;
+
+ if (end - *start > mininterval) {
+ // Recheck after checking time to avoid false positives.
+ smp_mb(); // Time check before grace-period check.
+ if (cur_ops->poll_gp_state(gp_state))
+ return false; // passed, though perhaps just barely
+ if (cur_ops->check_boost_failed && !cur_ops->check_boost_failed(gp_state, &cpu)) {
+ // At most one persisted message per boost test.
+ j = jiffies;
+ lp = READ_ONCE(last_persist);
+ if (time_after(j, lp + mininterval) && cmpxchg(&last_persist, lp, j) == lp)
+ pr_info("Boost inversion persisted: No QS from CPU %d\n", cpu);
+ return false; // passed on a technicality
+ }
VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
n_rcu_torture_boost_failure++;
- if (!xchg(&dbg_done, 1) && cur_ops->gp_kthread_dbg)
+ if (!xchg(&dbg_done, 1) && cur_ops->gp_kthread_dbg) {
+ pr_info("Boost inversion thread ->rt_priority %u gp_state %lu jiffies %lu\n",
+ current->rt_priority, gp_state, end - *start);
cur_ops->gp_kthread_dbg();
+ // Recheck after print to flag grace period ending during splat.
+ gp_done = cur_ops->poll_gp_state(gp_state);
+ pr_info("Boost inversion: GP %lu %s.\n", gp_state,
+ gp_done ? "ended already" : "still pending");
- return true; /* failed */
+ }
+
+ return true; // failed
+ } else if (cur_ops->check_boost_failed && !cur_ops->check_boost_failed(gp_state, NULL)) {
+ *start = jiffies;
}
- return false; /* passed */
+ return false; // passed
}
static int rcu_torture_boost(void *arg)
{
- unsigned long call_rcu_time;
unsigned long endtime;
+ unsigned long gp_state;
+ unsigned long gp_state_time;
unsigned long oldstarttime;
- struct rcu_boost_inflight rbi = { .inflight = 0 };
VERBOSE_TOROUT_STRING("rcu_torture_boost started");
/* Set real-time priority. */
sched_set_fifo_low(current);
- init_rcu_head_on_stack(&rbi.rcu);
/* Each pass through the following loop does one boost-test cycle. */
do {
bool failed = false; // Test failed already in this test interval
- bool firsttime = true;
+ bool gp_initiated = false;
- /* Increment n_rcu_torture_boosts once per boost-test */
- while (!kthread_should_stop()) {
- if (mutex_trylock(&boost_mutex)) {
- n_rcu_torture_boosts++;
- mutex_unlock(&boost_mutex);
- break;
- }
- schedule_timeout_uninterruptible(1);
- }
if (kthread_should_stop())
goto checkwait;
@@ -979,33 +993,33 @@ static int rcu_torture_boost(void *arg)
goto checkwait;
}
- /* Do one boost-test interval. */
+ // Do one boost-test interval.
endtime = oldstarttime + test_boost_duration * HZ;
while (time_before(jiffies, endtime)) {
- /* If we don't have a callback in flight, post one. */
- if (!smp_load_acquire(&rbi.inflight)) {
- /* RCU core before ->inflight = 1. */
- smp_store_release(&rbi.inflight, 1);
- cur_ops->call(&rbi.rcu, rcu_torture_boost_cb);
- /* Check if the boost test failed */
- if (!firsttime && !failed)
- failed = rcu_torture_boost_failed(call_rcu_time, jiffies);
- call_rcu_time = jiffies;
- firsttime = false;
+ // Has current GP gone too long?
+ if (gp_initiated && !failed && !cur_ops->poll_gp_state(gp_state))
+ failed = rcu_torture_boost_failed(gp_state, &gp_state_time);
+ // If we don't have a grace period in flight, start one.
+ if (!gp_initiated || cur_ops->poll_gp_state(gp_state)) {
+ gp_state = cur_ops->start_gp_poll();
+ gp_initiated = true;
+ gp_state_time = jiffies;
}
- if (stutter_wait("rcu_torture_boost"))
+ if (stutter_wait("rcu_torture_boost")) {
sched_set_fifo_low(current);
+ // If the grace period already ended,
+ // we don't know when that happened, so
+ // start over.
+ if (cur_ops->poll_gp_state(gp_state))
+ gp_initiated = false;
+ }
if (torture_must_stop())
goto checkwait;
}
- /*
- * If boost never happened, then inflight will always be 1, in
- * this case the boost check would never happen in the above
- * loop so do another one here.
- */
- if (!firsttime && !failed && smp_load_acquire(&rbi.inflight))
- rcu_torture_boost_failed(call_rcu_time, jiffies);
+ // In case the grace period extended beyond the end of the loop.
+ if (gp_initiated && !failed && !cur_ops->poll_gp_state(gp_state))
+ rcu_torture_boost_failed(gp_state, &gp_state_time);
/*
* Set the start time of the next test interval.
@@ -1014,11 +1028,12 @@ static int rcu_torture_boost(void *arg)
* interval. Besides, we are running at RT priority,
* so delays should be relatively rare.
*/
- while (oldstarttime == boost_starttime &&
- !kthread_should_stop()) {
+ while (oldstarttime == boost_starttime && !kthread_should_stop()) {
if (mutex_trylock(&boost_mutex)) {
- boost_starttime = jiffies +
- test_boost_interval * HZ;
+ if (oldstarttime == boost_starttime) {
+ boost_starttime = jiffies + test_boost_interval * HZ;
+ n_rcu_torture_boosts++;
+ }
mutex_unlock(&boost_mutex);
break;
}
@@ -1030,15 +1045,11 @@ checkwait: if (stutter_wait("rcu_torture_boost"))
sched_set_fifo_low(current);
} while (!torture_must_stop());
- while (smp_load_acquire(&rbi.inflight))
- schedule_timeout_uninterruptible(1); // rcu_barrier() deadlocks.
-
/* Clean up and exit. */
- while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
+ while (!kthread_should_stop()) {
torture_shutdown_absorb("rcu_torture_boost");
schedule_timeout_uninterruptible(1);
}
- destroy_rcu_head_on_stack(&rbi.rcu);
torture_kthread_stopping("rcu_torture_boost");
return 0;
}
@@ -1553,11 +1564,7 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
started = cur_ops->get_gp_seq();
ts = rcu_trace_clock_local();
p = rcu_dereference_check(rcu_torture_current,
- rcu_read_lock_bh_held() ||
- rcu_read_lock_sched_held() ||
- srcu_read_lock_held(srcu_ctlp) ||
- rcu_read_lock_trace_held() ||
- torturing_tasks());
+ !cur_ops->readlock_held || cur_ops->readlock_held());
if (p == NULL) {
/* Wait for rcu_torture_writer to get underway */
rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
@@ -1861,48 +1868,49 @@ rcu_torture_stats(void *arg)
torture_shutdown_absorb("rcu_torture_stats");
} while (!torture_must_stop());
torture_kthread_stopping("rcu_torture_stats");
-
- {
- struct rcu_head *rhp;
- struct kmem_cache *kcp;
- static int z;
-
- kcp = kmem_cache_create("rcuscale", 136, 8, SLAB_STORE_USER, NULL);
- rhp = kmem_cache_alloc(kcp, GFP_KERNEL);
- pr_alert("mem_dump_obj() slab test: rcu_torture_stats = %px, &rhp = %px, rhp = %px, &z = %px\n", stats_task, &rhp, rhp, &z);
- pr_alert("mem_dump_obj(ZERO_SIZE_PTR):");
- mem_dump_obj(ZERO_SIZE_PTR);
- pr_alert("mem_dump_obj(NULL):");
- mem_dump_obj(NULL);
- pr_alert("mem_dump_obj(%px):", &rhp);
- mem_dump_obj(&rhp);
- pr_alert("mem_dump_obj(%px):", rhp);
- mem_dump_obj(rhp);
- pr_alert("mem_dump_obj(%px):", &rhp->func);
- mem_dump_obj(&rhp->func);
- pr_alert("mem_dump_obj(%px):", &z);
- mem_dump_obj(&z);
- kmem_cache_free(kcp, rhp);
- kmem_cache_destroy(kcp);
- rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
- pr_alert("mem_dump_obj() kmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
- pr_alert("mem_dump_obj(kmalloc %px):", rhp);
- mem_dump_obj(rhp);
- pr_alert("mem_dump_obj(kmalloc %px):", &rhp->func);
- mem_dump_obj(&rhp->func);
- kfree(rhp);
- rhp = vmalloc(4096);
- pr_alert("mem_dump_obj() vmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
- pr_alert("mem_dump_obj(vmalloc %px):", rhp);
- mem_dump_obj(rhp);
- pr_alert("mem_dump_obj(vmalloc %px):", &rhp->func);
- mem_dump_obj(&rhp->func);
- vfree(rhp);
- }
-
return 0;
}
+/* Test mem_dump_obj() and friends. */
+static void rcu_torture_mem_dump_obj(void)
+{
+ struct rcu_head *rhp;
+ struct kmem_cache *kcp;
+ static int z;
+
+ kcp = kmem_cache_create("rcuscale", 136, 8, SLAB_STORE_USER, NULL);
+ rhp = kmem_cache_alloc(kcp, GFP_KERNEL);
+ pr_alert("mem_dump_obj() slab test: rcu_torture_stats = %px, &rhp = %px, rhp = %px, &z = %px\n", stats_task, &rhp, rhp, &z);
+ pr_alert("mem_dump_obj(ZERO_SIZE_PTR):");
+ mem_dump_obj(ZERO_SIZE_PTR);
+ pr_alert("mem_dump_obj(NULL):");
+ mem_dump_obj(NULL);
+ pr_alert("mem_dump_obj(%px):", &rhp);
+ mem_dump_obj(&rhp);
+ pr_alert("mem_dump_obj(%px):", rhp);
+ mem_dump_obj(rhp);
+ pr_alert("mem_dump_obj(%px):", &rhp->func);
+ mem_dump_obj(&rhp->func);
+ pr_alert("mem_dump_obj(%px):", &z);
+ mem_dump_obj(&z);
+ kmem_cache_free(kcp, rhp);
+ kmem_cache_destroy(kcp);
+ rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
+ pr_alert("mem_dump_obj() kmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
+ pr_alert("mem_dump_obj(kmalloc %px):", rhp);
+ mem_dump_obj(rhp);
+ pr_alert("mem_dump_obj(kmalloc %px):", &rhp->func);
+ mem_dump_obj(&rhp->func);
+ kfree(rhp);
+ rhp = vmalloc(4096);
+ pr_alert("mem_dump_obj() vmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
+ pr_alert("mem_dump_obj(vmalloc %px):", rhp);
+ mem_dump_obj(rhp);
+ pr_alert("mem_dump_obj(vmalloc %px):", &rhp->func);
+ mem_dump_obj(&rhp->func);
+ vfree(rhp);
+}
+
static void
rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
{
@@ -2634,7 +2642,7 @@ static bool rcu_torture_can_boost(void)
if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
return false;
- if (!cur_ops->call)
+ if (!cur_ops->start_gp_poll || !cur_ops->poll_gp_state)
return false;
prio = rcu_get_gp_kthreads_prio();
@@ -2642,7 +2650,7 @@ static bool rcu_torture_can_boost(void)
return false;
if (prio < 2) {
- if (boost_warn_once == 1)
+ if (boost_warn_once == 1)
return false;
pr_alert("%s: WARN: RCU kthread priority too low to test boosting. Skipping RCU boost test. Try passing rcutree.kthread_prio > 1 on the kernel command line.\n", KBUILD_MODNAME);
@@ -2818,6 +2826,8 @@ rcu_torture_cleanup(void)
if (cur_ops->cleanup != NULL)
cur_ops->cleanup();
+ rcu_torture_mem_dump_obj();
+
rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
if (err_segs_recorded) {
@@ -3120,6 +3130,21 @@ rcu_torture_init(void)
if (firsterr < 0)
goto unwind;
rcutor_hp = firsterr;
+
+ // Testing RCU priority boosting requires rcutorture do
+ // some serious abuse. Counter this by running ksoftirqd
+ // at higher priority.
+ if (IS_BUILTIN(CONFIG_RCU_TORTURE_TEST)) {
+ for_each_online_cpu(cpu) {
+ struct sched_param sp;
+ struct task_struct *t;
+
+ t = per_cpu(ksoftirqd, cpu);
+ WARN_ON_ONCE(!t);
+ sp.sched_priority = 2;
+ sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
+ }
+ }
}
shutdown_jiffies = jiffies + shutdown_secs * HZ;
firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index 02dd9767b559..313d4547cbc7 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -362,6 +362,111 @@ static struct ref_scale_ops rwsem_ops = {
.name = "rwsem"
};
+// Definitions for global spinlock
+static DEFINE_SPINLOCK(test_lock);
+
+static void ref_lock_section(const int nloops)
+{
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ spin_lock(&test_lock);
+ spin_unlock(&test_lock);
+ }
+ preempt_enable();
+}
+
+static void ref_lock_delay_section(const int nloops, const int udl, const int ndl)
+{
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ spin_lock(&test_lock);
+ un_delay(udl, ndl);
+ spin_unlock(&test_lock);
+ }
+ preempt_enable();
+}
+
+static struct ref_scale_ops lock_ops = {
+ .readsection = ref_lock_section,
+ .delaysection = ref_lock_delay_section,
+ .name = "lock"
+};
+
+// Definitions for global irq-save spinlock
+
+static void ref_lock_irq_section(const int nloops)
+{
+ unsigned long flags;
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ spin_lock_irqsave(&test_lock, flags);
+ spin_unlock_irqrestore(&test_lock, flags);
+ }
+ preempt_enable();
+}
+
+static void ref_lock_irq_delay_section(const int nloops, const int udl, const int ndl)
+{
+ unsigned long flags;
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ spin_lock_irqsave(&test_lock, flags);
+ un_delay(udl, ndl);
+ spin_unlock_irqrestore(&test_lock, flags);
+ }
+ preempt_enable();
+}
+
+static struct ref_scale_ops lock_irq_ops = {
+ .readsection = ref_lock_irq_section,
+ .delaysection = ref_lock_irq_delay_section,
+ .name = "lock-irq"
+};
+
+// Definitions acquire-release.
+static DEFINE_PER_CPU(unsigned long, test_acqrel);
+
+static void ref_acqrel_section(const int nloops)
+{
+ unsigned long x;
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ x = smp_load_acquire(this_cpu_ptr(&test_acqrel));
+ smp_store_release(this_cpu_ptr(&test_acqrel), x + 1);
+ }
+ preempt_enable();
+}
+
+static void ref_acqrel_delay_section(const int nloops, const int udl, const int ndl)
+{
+ unsigned long x;
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ x = smp_load_acquire(this_cpu_ptr(&test_acqrel));
+ un_delay(udl, ndl);
+ smp_store_release(this_cpu_ptr(&test_acqrel), x + 1);
+ }
+ preempt_enable();
+}
+
+static struct ref_scale_ops acqrel_ops = {
+ .readsection = ref_acqrel_section,
+ .delaysection = ref_acqrel_delay_section,
+ .name = "acqrel"
+};
+
static void rcu_scale_one_reader(void)
{
if (readdelay <= 0)
@@ -653,8 +758,8 @@ ref_scale_init(void)
long i;
int firsterr = 0;
static struct ref_scale_ops *scale_ops[] = {
- &rcu_ops, &srcu_ops, &rcu_trace_ops, &rcu_tasks_ops,
- &refcnt_ops, &rwlock_ops, &rwsem_ops,
+ &rcu_ops, &srcu_ops, &rcu_trace_ops, &rcu_tasks_ops, &refcnt_ops, &rwlock_ops,
+ &rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops,
};
if (!torture_init_begin(scale_type, verbose))
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index e26547b34ad3..6833d8887181 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -80,7 +80,7 @@ do { \
* srcu_read_unlock() running against them. So if the is_static parameter
* is set, don't initialize ->srcu_lock_count[] and ->srcu_unlock_count[].
*/
-static void init_srcu_struct_nodes(struct srcu_struct *ssp, bool is_static)
+static void init_srcu_struct_nodes(struct srcu_struct *ssp)
{
int cpu;
int i;
@@ -90,6 +90,9 @@ static void init_srcu_struct_nodes(struct srcu_struct *ssp, bool is_static)
struct srcu_node *snp;
struct srcu_node *snp_first;
+ /* Initialize geometry if it has not already been initialized. */
+ rcu_init_geometry();
+
/* Work out the overall tree geometry. */
ssp->level[0] = &ssp->node[0];
for (i = 1; i < rcu_num_lvls; i++)
@@ -148,14 +151,6 @@ static void init_srcu_struct_nodes(struct srcu_struct *ssp, bool is_static)
timer_setup(&sdp->delay_work, srcu_delay_timer, 0);
sdp->ssp = ssp;
sdp->grpmask = 1 << (cpu - sdp->mynode->grplo);
- if (is_static)
- continue;
-
- /* Dynamically allocated, better be no srcu_read_locks()! */
- for (i = 0; i < ARRAY_SIZE(sdp->srcu_lock_count); i++) {
- sdp->srcu_lock_count[i] = 0;
- sdp->srcu_unlock_count[i] = 0;
- }
}
}
@@ -179,7 +174,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
ssp->sda = alloc_percpu(struct srcu_data);
if (!ssp->sda)
return -ENOMEM;
- init_srcu_struct_nodes(ssp, is_static);
+ init_srcu_struct_nodes(ssp);
ssp->srcu_gp_seq_needed_exp = 0;
ssp->srcu_last_gp_end = ktime_get_mono_fast_ns();
smp_store_release(&ssp->srcu_gp_seq_needed, 0); /* Init done. */
@@ -777,9 +772,9 @@ static bool srcu_might_be_idle(struct srcu_struct *ssp)
spin_unlock_irqrestore_rcu_node(sdp, flags);
/*
- * No local callbacks, so probabalistically probe global state.
+ * No local callbacks, so probabilistically probe global state.
* Exact information would require acquiring locks, which would
- * kill scalability, hence the probabalistic nature of the probe.
+ * kill scalability, hence the probabilistic nature of the probe.
*/
/* First, see if enough time has passed since the last GP. */
@@ -1000,6 +995,9 @@ EXPORT_SYMBOL_GPL(synchronize_srcu_expedited);
* synchronize_srcu(), srcu_read_lock(), and srcu_read_unlock() are
* passed the same srcu_struct structure.
*
+ * Implementation of these memory-ordering guarantees is similar to
+ * that of synchronize_rcu().
+ *
* If SRCU is likely idle, expedite the first request. This semantic
* was provided by Classic SRCU, and is relied upon by its users, so TREE
* SRCU must also provide it. Note that detecting idleness is heuristic
@@ -1392,11 +1390,15 @@ void __init srcu_init(void)
{
struct srcu_struct *ssp;
+ /*
+ * Once that is set, call_srcu() can follow the normal path and
+ * queue delayed work. This must follow RCU workqueues creation
+ * and timers initialization.
+ */
srcu_init_done = true;
while (!list_empty(&srcu_boot_list)) {
ssp = list_first_entry(&srcu_boot_list, struct srcu_struct,
work.work.entry);
- check_init_srcu_struct(ssp);
list_del_init(&ssp->work.work.entry);
queue_work(rcu_gp_wq, &ssp->work.work);
}
diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c
index d4558ab7a07d..33d896d85902 100644
--- a/kernel/rcu/sync.c
+++ b/kernel/rcu/sync.c
@@ -94,9 +94,9 @@ static void rcu_sync_func(struct rcu_head *rhp)
rcu_sync_call(rsp);
} else {
/*
- * We're at least a GP after the last rcu_sync_exit(); eveybody
+ * We're at least a GP after the last rcu_sync_exit(); everybody
* will now have observed the write side critical section.
- * Let 'em rip!.
+ * Let 'em rip!
*/
WRITE_ONCE(rsp->gp_state, GP_IDLE);
}
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 350ebf5051f9..03a118d1c003 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -23,7 +23,7 @@ typedef void (*postgp_func_t)(struct rcu_tasks *rtp);
* struct rcu_tasks - Definition for a Tasks-RCU-like mechanism.
* @cbs_head: Head of callback list.
* @cbs_tail: Tail pointer for callback list.
- * @cbs_wq: Wait queue allowning new callback to get kthread's attention.
+ * @cbs_wq: Wait queue allowing new callback to get kthread's attention.
* @cbs_lock: Lock protecting callback list.
* @kthread_ptr: This flavor's grace-period/callback-invocation kthread.
* @gp_func: This flavor's grace-period-wait function.
@@ -377,6 +377,46 @@ static void rcu_tasks_wait_gp(struct rcu_tasks *rtp)
// Finally, this implementation does not support high call_rcu_tasks()
// rates from multiple CPUs. If this is required, per-CPU callback lists
// will be needed.
+//
+// The implementation uses rcu_tasks_wait_gp(), which relies on function
+// pointers in the rcu_tasks structure. The rcu_spawn_tasks_kthread()
+// function sets these function pointers up so that rcu_tasks_wait_gp()
+// invokes these functions in this order:
+//
+// rcu_tasks_pregp_step():
+// Invokes synchronize_rcu() in order to wait for all in-flight
+// t->on_rq and t->nvcsw transitions to complete. This works because
+// all such transitions are carried out with interrupts disabled.
+// rcu_tasks_pertask(), invoked on every non-idle task:
+// For every runnable non-idle task other than the current one, use
+// get_task_struct() to pin down that task, snapshot that task's
+// number of voluntary context switches, and add that task to the
+// holdout list.
+// rcu_tasks_postscan():
+// Invoke synchronize_srcu() to ensure that all tasks that were
+// in the process of exiting (and which thus might not know to
+// synchronize with this RCU Tasks grace period) have completed
+// exiting.
+// check_all_holdout_tasks(), repeatedly until holdout list is empty:
+// Scans the holdout list, attempting to identify a quiescent state
+// for each task on the list. If there is a quiescent state, the
+// corresponding task is removed from the holdout list.
+// rcu_tasks_postgp():
+// Invokes synchronize_rcu() in order to ensure that all prior
+// t->on_rq and t->nvcsw transitions are seen by all CPUs and tasks
+// to have happened before the end of this RCU Tasks grace period.
+// Again, this works because all such transitions are carried out
+// with interrupts disabled.
+//
+// For each exiting task, the exit_tasks_rcu_start() and
+// exit_tasks_rcu_finish() functions begin and end, respectively, the SRCU
+// read-side critical sections waited for by rcu_tasks_postscan().
+//
+// Pre-grace-period update-side code is ordered before the grace via the
+// ->cbs_lock and the smp_mb__after_spinlock(). Pre-grace-period read-side
+// code is ordered before the grace period via synchronize_rcu() call
+// in rcu_tasks_pregp_step() and by the scheduler's locks and interrupt
+// disabling.
/* Pre-grace-period preparation. */
static void rcu_tasks_pregp_step(void)
@@ -504,7 +544,7 @@ DEFINE_RCU_TASKS(rcu_tasks, rcu_tasks_wait_gp, call_rcu_tasks, "RCU Tasks");
* or transition to usermode execution. As such, there are no read-side
* primitives analogous to rcu_read_lock() and rcu_read_unlock() because
* this primitive is intended to determine that all tasks have passed
- * through a safe state, not so much for data-strcuture synchronization.
+ * through a safe state, not so much for data-structure synchronization.
*
* See the description of call_rcu() for more detailed information on
* memory ordering guarantees.
@@ -605,8 +645,13 @@ void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
// passing an empty function to schedule_on_each_cpu(). This approach
// provides an asynchronous call_rcu_tasks_rude() API and batching
// of concurrent calls to the synchronous synchronize_rcu_rude() API.
-// This sends IPIs far and wide and induces otherwise unnecessary context
-// switches on all online CPUs, whether idle or not.
+// This invokes schedule_on_each_cpu() in order to send IPIs far and wide
+// and induces otherwise unnecessary context switches on all online CPUs,
+// whether idle or not.
+//
+// Callback handling is provided by the rcu_tasks_kthread() function.
+//
+// Ordering is provided by the scheduler's context-switch code.
// Empty function to allow workqueues to force a context switch.
static void rcu_tasks_be_rude(struct work_struct *work)
@@ -637,7 +682,7 @@ DEFINE_RCU_TASKS(rcu_tasks_rude, rcu_tasks_rude_wait_gp, call_rcu_tasks_rude,
* there are no read-side primitives analogous to rcu_read_lock() and
* rcu_read_unlock() because this primitive is intended to determine
* that all tasks have passed through a safe state, not so much for
- * data-strcuture synchronization.
+ * data-structure synchronization.
*
* See the description of call_rcu() for more detailed information on
* memory ordering guarantees.
@@ -1163,7 +1208,7 @@ static void exit_tasks_rcu_finish_trace(struct task_struct *t)
* there are no read-side primitives analogous to rcu_read_lock() and
* rcu_read_unlock() because this primitive is intended to determine
* that all tasks have passed through a safe state, not so much for
- * data-strcuture synchronization.
+ * data-structure synchronization.
*
* See the description of call_rcu() for more detailed information on
* memory ordering guarantees.
@@ -1356,5 +1401,4 @@ void __init rcu_init_tasks_generic(void)
#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
static inline void rcu_tasks_bootup_oddness(void) {}
-void show_rcu_tasks_gp_kthreads(void) {}
#endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index c8a029fbb114..340b3f8b090d 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -221,5 +221,4 @@ void __init rcu_init(void)
{
open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
rcu_early_boot_tests();
- srcu_init();
}
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! */
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 71821d59d95c..305cf6aeb408 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -115,6 +115,7 @@ struct rcu_node {
/* boosting for this rcu_node structure. */
unsigned int boost_kthread_status;
/* State of boost_kthread_task for tracing. */
+ unsigned long n_boosts; /* Number of boosts for this rcu_node structure. */
#ifdef CONFIG_RCU_NOCB_CPU
struct swait_queue_head nocb_gp_wq[2];
/* Place for rcu_nocb_kthread() to wait GP. */
@@ -153,7 +154,7 @@ struct rcu_data {
unsigned long gp_seq; /* Track rsp->gp_seq counter. */
unsigned long gp_seq_needed; /* Track furthest future GP request. */
union rcu_noqs cpu_no_qs; /* No QSes yet for this CPU. */
- bool core_needs_qs; /* Core waits for quiesc state. */
+ bool core_needs_qs; /* Core waits for quiescent state. */
bool beenonline; /* CPU online at least once. */
bool gpwrap; /* Possible ->gp_seq wrap. */
bool exp_deferred_qs; /* This CPU awaiting a deferred QS? */
@@ -218,7 +219,6 @@ struct rcu_data {
/* The following fields are used by GP kthread, hence own cacheline. */
raw_spinlock_t nocb_gp_lock ____cacheline_internodealigned_in_smp;
- struct timer_list nocb_bypass_timer; /* Force nocb_bypass flush. */
u8 nocb_gp_sleep; /* Is the nocb GP thread asleep? */
u8 nocb_gp_bypass; /* Found a bypass on last scan? */
u8 nocb_gp_gp; /* GP to wait for on last scan? */
@@ -257,10 +257,10 @@ struct rcu_data {
};
/* Values for nocb_defer_wakeup field in struct rcu_data. */
-#define RCU_NOCB_WAKE_OFF -1
#define RCU_NOCB_WAKE_NOT 0
-#define RCU_NOCB_WAKE 1
-#define RCU_NOCB_WAKE_FORCE 2
+#define RCU_NOCB_WAKE_BYPASS 1
+#define RCU_NOCB_WAKE 2
+#define RCU_NOCB_WAKE_FORCE 3
#define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500))
/* For jiffies_till_first_fqs and */
@@ -417,8 +417,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
static bool rcu_is_callbacks_kthread(void);
static void rcu_cpu_kthread_setup(unsigned int cpu);
+static void rcu_spawn_one_boost_kthread(struct rcu_node *rnp);
static void __init rcu_spawn_boost_kthreads(void);
-static void rcu_prepare_kthreads(int cpu);
static void rcu_cleanup_after_idle(void);
static void rcu_prepare_for_idle(void);
static bool rcu_preempt_has_tasks(struct rcu_node *rnp);
@@ -434,7 +434,7 @@ static bool rcu_nocb_try_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
bool *was_alldone, unsigned long flags);
static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_empty,
unsigned long flags);
-static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp);
+static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp, int level);
static bool do_nocb_deferred_wakeup(struct rcu_data *rdp);
static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp);
static void rcu_spawn_cpu_nocb_kthread(int cpu);
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 4d6962048c30..de1dc3bb7f70 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -33,10 +33,6 @@ static inline bool rcu_current_is_nocb_kthread(struct rcu_data *rdp)
return false;
}
-static inline bool rcu_running_nocb_timer(struct rcu_data *rdp)
-{
- return (timer_curr_running(&rdp->nocb_timer) && !in_irq());
-}
#else
static inline int rcu_lockdep_is_held_nocb(struct rcu_data *rdp)
{
@@ -48,11 +44,6 @@ static inline bool rcu_current_is_nocb_kthread(struct rcu_data *rdp)
return false;
}
-static inline bool rcu_running_nocb_timer(struct rcu_data *rdp)
-{
- return false;
-}
-
#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
static bool rcu_rdp_is_offloaded(struct rcu_data *rdp)
@@ -72,8 +63,7 @@ static bool rcu_rdp_is_offloaded(struct rcu_data *rdp)
rcu_lockdep_is_held_nocb(rdp) ||
(rdp == this_cpu_ptr(&rcu_data) &&
!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())) ||
- rcu_current_is_nocb_kthread(rdp) ||
- rcu_running_nocb_timer(rdp)),
+ rcu_current_is_nocb_kthread(rdp)),
"Unsafe read of RCU_NOCB offloaded state"
);
@@ -1098,6 +1088,7 @@ static int rcu_boost(struct rcu_node *rnp)
/* Lock only for side effect: boosts task t's priority. */
rt_mutex_lock(&rnp->boost_mtx);
rt_mutex_unlock(&rnp->boost_mtx); /* Then keep lockdep happy. */
+ rnp->n_boosts++;
return READ_ONCE(rnp->exp_tasks) != NULL ||
READ_ONCE(rnp->boost_tasks) != NULL;
@@ -1197,22 +1188,16 @@ static void rcu_preempt_boost_start_gp(struct rcu_node *rnp)
*/
static void rcu_spawn_one_boost_kthread(struct rcu_node *rnp)
{
- int rnp_index = rnp - rcu_get_root();
unsigned long flags;
+ int rnp_index = rnp - rcu_get_root();
struct sched_param sp;
struct task_struct *t;
- if (!IS_ENABLED(CONFIG_PREEMPT_RCU))
- return;
-
- if (!rcu_scheduler_fully_active || rcu_rnp_online_cpus(rnp) == 0)
+ if (rnp->boost_kthread_task || !rcu_scheduler_fully_active)
return;
rcu_state.boost = 1;
- if (rnp->boost_kthread_task != NULL)
- return;
-
t = kthread_create(rcu_boost_kthread, (void *)rnp,
"rcub/%d", rnp_index);
if (WARN_ON_ONCE(IS_ERR(t)))
@@ -1264,17 +1249,8 @@ static void __init rcu_spawn_boost_kthreads(void)
struct rcu_node *rnp;
rcu_for_each_leaf_node(rnp)
- rcu_spawn_one_boost_kthread(rnp);
-}
-
-static void rcu_prepare_kthreads(int cpu)
-{
- struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
- struct rcu_node *rnp = rdp->mynode;
-
- /* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */
- if (rcu_scheduler_fully_active)
- rcu_spawn_one_boost_kthread(rnp);
+ if (rcu_rnp_online_cpus(rnp))
+ rcu_spawn_one_boost_kthread(rnp);
}
#else /* #ifdef CONFIG_RCU_BOOST */
@@ -1294,15 +1270,15 @@ static void rcu_preempt_boost_start_gp(struct rcu_node *rnp)
{
}
-static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
+static void rcu_spawn_one_boost_kthread(struct rcu_node *rnp)
{
}
-static void __init rcu_spawn_boost_kthreads(void)
+static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
{
}
-static void rcu_prepare_kthreads(int cpu)
+static void __init rcu_spawn_boost_kthreads(void)
{
}
@@ -1535,13 +1511,10 @@ static void rcu_cleanup_after_idle(void)
static int __init rcu_nocb_setup(char *str)
{
alloc_bootmem_cpumask_var(&rcu_nocb_mask);
- if (!strcasecmp(str, "all")) /* legacy: use "0-N" instead */
+ if (cpulist_parse(str, rcu_nocb_mask)) {
+ pr_warn("rcu_nocbs= bad CPU range, all CPUs set\n");
cpumask_setall(rcu_nocb_mask);
- else
- if (cpulist_parse(str, rcu_nocb_mask)) {
- pr_warn("rcu_nocbs= bad CPU range, all CPUs set\n");
- cpumask_setall(rcu_nocb_mask);
- }
+ }
return 1;
}
__setup("rcu_nocbs=", rcu_nocb_setup);
@@ -1692,56 +1665,78 @@ bool rcu_is_nocb_cpu(int cpu)
return false;
}
-/*
- * Kick the GP kthread for this NOCB group. Caller holds ->nocb_lock
- * and this function releases it.
- */
-static bool wake_nocb_gp(struct rcu_data *rdp, bool force,
- unsigned long flags)
- __releases(rdp->nocb_lock)
+static bool __wake_nocb_gp(struct rcu_data *rdp_gp,
+ struct rcu_data *rdp,
+ bool force, unsigned long flags)
+ __releases(rdp_gp->nocb_gp_lock)
{
bool needwake = false;
- struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
- lockdep_assert_held(&rdp->nocb_lock);
if (!READ_ONCE(rdp_gp->nocb_gp_kthread)) {
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags);
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
TPS("AlreadyAwake"));
return false;
}
- if (READ_ONCE(rdp->nocb_defer_wakeup) > RCU_NOCB_WAKE_NOT) {
- WRITE_ONCE(rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);
- del_timer(&rdp->nocb_timer);
+ if (rdp_gp->nocb_defer_wakeup > RCU_NOCB_WAKE_NOT) {
+ WRITE_ONCE(rdp_gp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);
+ del_timer(&rdp_gp->nocb_timer);
}
- rcu_nocb_unlock_irqrestore(rdp, flags);
- raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
+
if (force || READ_ONCE(rdp_gp->nocb_gp_sleep)) {
WRITE_ONCE(rdp_gp->nocb_gp_sleep, false);
needwake = true;
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("DoWake"));
}
raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags);
- if (needwake)
+ if (needwake) {
+ trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("DoWake"));
wake_up_process(rdp_gp->nocb_gp_kthread);
+ }
return needwake;
}
/*
+ * Kick the GP kthread for this NOCB group.
+ */
+static bool wake_nocb_gp(struct rcu_data *rdp, bool force)
+{
+ unsigned long flags;
+ struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
+
+ raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
+ return __wake_nocb_gp(rdp_gp, rdp, force, flags);
+}
+
+/*
* Arrange to wake the GP kthread for this NOCB group at some future
* time when it is safe to do so.
*/
static void wake_nocb_gp_defer(struct rcu_data *rdp, int waketype,
const char *reason)
{
- if (rdp->nocb_defer_wakeup == RCU_NOCB_WAKE_OFF)
- return;
- if (rdp->nocb_defer_wakeup == RCU_NOCB_WAKE_NOT)
- mod_timer(&rdp->nocb_timer, jiffies + 1);
- if (rdp->nocb_defer_wakeup < waketype)
- WRITE_ONCE(rdp->nocb_defer_wakeup, waketype);
+ unsigned long flags;
+ struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
+
+ raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
+
+ /*
+ * Bypass wakeup overrides previous deferments. In case
+ * of callback storm, no need to wake up too early.
+ */
+ if (waketype == RCU_NOCB_WAKE_BYPASS) {
+ mod_timer(&rdp_gp->nocb_timer, jiffies + 2);
+ WRITE_ONCE(rdp_gp->nocb_defer_wakeup, waketype);
+ } else {
+ if (rdp_gp->nocb_defer_wakeup < RCU_NOCB_WAKE)
+ mod_timer(&rdp_gp->nocb_timer, jiffies + 1);
+ if (rdp_gp->nocb_defer_wakeup < waketype)
+ WRITE_ONCE(rdp_gp->nocb_defer_wakeup, waketype);
+ }
+
+ raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags);
+
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, reason);
}
@@ -1940,7 +1935,7 @@ static bool rcu_nocb_try_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
}
/*
- * Awaken the no-CBs grace-period kthead if needed, either due to it
+ * Awaken the no-CBs grace-period kthread if needed, either due to it
* legitimately being asleep or due to overload conditions.
*
* If warranted, also wake up the kthread servicing this CPUs queues.
@@ -1968,13 +1963,14 @@ static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone,
rdp->qlen_last_fqs_check = len;
if (!irqs_disabled_flags(flags)) {
/* ... if queue was empty ... */
- wake_nocb_gp(rdp, false, flags);
+ rcu_nocb_unlock_irqrestore(rdp, flags);
+ wake_nocb_gp(rdp, false);
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
TPS("WakeEmpty"));
} else {
+ rcu_nocb_unlock_irqrestore(rdp, flags);
wake_nocb_gp_defer(rdp, RCU_NOCB_WAKE,
TPS("WakeEmptyIsDeferred"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
}
} else if (len > rdp->qlen_last_fqs_check + qhimark) {
/* ... or if many callbacks queued. */
@@ -1989,10 +1985,14 @@ static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone,
smp_mb(); /* Enqueue before timer_pending(). */
if ((rdp->nocb_cb_sleep ||
!rcu_segcblist_ready_cbs(&rdp->cblist)) &&
- !timer_pending(&rdp->nocb_bypass_timer))
+ !timer_pending(&rdp->nocb_timer)) {
+ rcu_nocb_unlock_irqrestore(rdp, flags);
wake_nocb_gp_defer(rdp, RCU_NOCB_WAKE_FORCE,
TPS("WakeOvfIsDeferred"));
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ } else {
+ rcu_nocb_unlock_irqrestore(rdp, flags);
+ trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WakeNot"));
+ }
} else {
rcu_nocb_unlock_irqrestore(rdp, flags);
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WakeNot"));
@@ -2000,18 +2000,6 @@ static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone,
return;
}
-/* Wake up the no-CBs GP kthread to flush ->nocb_bypass. */
-static void do_nocb_bypass_wakeup_timer(struct timer_list *t)
-{
- unsigned long flags;
- struct rcu_data *rdp = from_timer(rdp, t, nocb_bypass_timer);
-
- trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Timer"));
- rcu_nocb_lock_irqsave(rdp, flags);
- smp_mb__after_spinlock(); /* Timer expire before wakeup. */
- __call_rcu_nocb_wake(rdp, true, flags);
-}
-
/*
* Check if we ignore this rdp.
*
@@ -2118,11 +2106,7 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
bypass = true;
}
rnp = rdp->mynode;
- if (bypass) { // Avoid race with first bypass CB.
- WRITE_ONCE(my_rdp->nocb_defer_wakeup,
- RCU_NOCB_WAKE_NOT);
- del_timer(&my_rdp->nocb_timer);
- }
+
// Advance callbacks if helpful and low contention.
needwake_gp = false;
if (!rcu_segcblist_restempty(&rdp->cblist,
@@ -2168,12 +2152,12 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
my_rdp->nocb_gp_bypass = bypass;
my_rdp->nocb_gp_gp = needwait_gp;
my_rdp->nocb_gp_seq = needwait_gp ? wait_gp_seq : 0;
+
if (bypass && !rcu_nocb_poll) {
// At least one child with non-empty ->nocb_bypass, so set
// timer in order to avoid stranding its callbacks.
- raw_spin_lock_irqsave(&my_rdp->nocb_gp_lock, flags);
- mod_timer(&my_rdp->nocb_bypass_timer, j + 2);
- raw_spin_unlock_irqrestore(&my_rdp->nocb_gp_lock, flags);
+ wake_nocb_gp_defer(my_rdp, RCU_NOCB_WAKE_BYPASS,
+ TPS("WakeBypassIsDeferred"));
}
if (rcu_nocb_poll) {
/* Polling, so trace if first poll in the series. */
@@ -2197,8 +2181,10 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
}
if (!rcu_nocb_poll) {
raw_spin_lock_irqsave(&my_rdp->nocb_gp_lock, flags);
- if (bypass)
- del_timer(&my_rdp->nocb_bypass_timer);
+ if (my_rdp->nocb_defer_wakeup > RCU_NOCB_WAKE_NOT) {
+ WRITE_ONCE(my_rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);
+ del_timer(&my_rdp->nocb_timer);
+ }
WRITE_ONCE(my_rdp->nocb_gp_sleep, true);
raw_spin_unlock_irqrestore(&my_rdp->nocb_gp_lock, flags);
}
@@ -2334,25 +2320,27 @@ static int rcu_nocb_cb_kthread(void *arg)
}
/* Is a deferred wakeup of rcu_nocb_kthread() required? */
-static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp)
+static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp, int level)
{
- return READ_ONCE(rdp->nocb_defer_wakeup) > RCU_NOCB_WAKE_NOT;
+ return READ_ONCE(rdp->nocb_defer_wakeup) >= level;
}
/* Do a deferred wakeup of rcu_nocb_kthread(). */
-static bool do_nocb_deferred_wakeup_common(struct rcu_data *rdp)
+static bool do_nocb_deferred_wakeup_common(struct rcu_data *rdp_gp,
+ struct rcu_data *rdp, int level,
+ unsigned long flags)
+ __releases(rdp_gp->nocb_gp_lock)
{
- unsigned long flags;
int ndw;
int ret;
- rcu_nocb_lock_irqsave(rdp, flags);
- if (!rcu_nocb_need_deferred_wakeup(rdp)) {
- rcu_nocb_unlock_irqrestore(rdp, flags);
+ if (!rcu_nocb_need_deferred_wakeup(rdp_gp, level)) {
+ raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags);
return false;
}
- ndw = READ_ONCE(rdp->nocb_defer_wakeup);
- ret = wake_nocb_gp(rdp, ndw == RCU_NOCB_WAKE_FORCE, flags);
+
+ ndw = rdp_gp->nocb_defer_wakeup;
+ ret = __wake_nocb_gp(rdp_gp, rdp, ndw == RCU_NOCB_WAKE_FORCE, flags);
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("DeferredWake"));
return ret;
@@ -2361,9 +2349,15 @@ static bool do_nocb_deferred_wakeup_common(struct rcu_data *rdp)
/* Do a deferred wakeup of rcu_nocb_kthread() from a timer handler. */
static void do_nocb_deferred_wakeup_timer(struct timer_list *t)
{
+ unsigned long flags;
struct rcu_data *rdp = from_timer(rdp, t, nocb_timer);
- do_nocb_deferred_wakeup_common(rdp);
+ WARN_ON_ONCE(rdp->nocb_gp_rdp != rdp);
+ trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Timer"));
+
+ raw_spin_lock_irqsave(&rdp->nocb_gp_lock, flags);
+ smp_mb__after_spinlock(); /* Timer expire before wakeup. */
+ do_nocb_deferred_wakeup_common(rdp, rdp, RCU_NOCB_WAKE_BYPASS, flags);
}
/*
@@ -2373,9 +2367,14 @@ static void do_nocb_deferred_wakeup_timer(struct timer_list *t)
*/
static bool do_nocb_deferred_wakeup(struct rcu_data *rdp)
{
- if (rcu_nocb_need_deferred_wakeup(rdp))
- return do_nocb_deferred_wakeup_common(rdp);
- return false;
+ unsigned long flags;
+ struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
+
+ if (!rdp_gp || !rcu_nocb_need_deferred_wakeup(rdp_gp, RCU_NOCB_WAKE))
+ return false;
+
+ raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
+ return do_nocb_deferred_wakeup_common(rdp_gp, rdp, RCU_NOCB_WAKE, flags);
}
void rcu_nocb_flush_deferred_wakeup(void)
@@ -2443,17 +2442,15 @@ static long rcu_nocb_rdp_deoffload(void *arg)
swait_event_exclusive(rdp->nocb_state_wq,
!rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB |
SEGCBLIST_KTHREAD_GP));
- rcu_nocb_lock_irqsave(rdp, flags);
- /* Make sure nocb timer won't stay around */
- WRITE_ONCE(rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_OFF);
- rcu_nocb_unlock_irqrestore(rdp, flags);
- del_timer_sync(&rdp->nocb_timer);
-
/*
- * Theoretically we could set SEGCBLIST_SOFTIRQ_ONLY with CB unlocked
- * and IRQs disabled but let's be paranoid.
+ * Lock one last time to acquire latest callback updates from kthreads
+ * so we can later handle callbacks locally without locking.
*/
rcu_nocb_lock_irqsave(rdp, flags);
+ /*
+ * Theoretically we could set SEGCBLIST_SOFTIRQ_ONLY after the nocb
+ * lock is released but how about being paranoid for once?
+ */
rcu_segcblist_set_flags(cblist, SEGCBLIST_SOFTIRQ_ONLY);
/*
* With SEGCBLIST_SOFTIRQ_ONLY, we can't use
@@ -2473,10 +2470,6 @@ int rcu_nocb_cpu_deoffload(int cpu)
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
int ret = 0;
- if (rdp == rdp->nocb_gp_rdp) {
- pr_info("Can't deoffload an rdp GP leader (yet)\n");
- return -EINVAL;
- }
mutex_lock(&rcu_state.barrier_mutex);
cpus_read_lock();
if (rcu_rdp_is_offloaded(rdp)) {
@@ -2517,8 +2510,7 @@ static long rcu_nocb_rdp_offload(void *arg)
* SEGCBLIST_SOFTIRQ_ONLY mode.
*/
raw_spin_lock_irqsave(&rdp->nocb_lock, flags);
- /* Re-enable nocb timer */
- WRITE_ONCE(rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);
+
/*
* We didn't take the nocb lock while working on the
* rdp->cblist in SEGCBLIST_SOFTIRQ_ONLY mode.
@@ -2626,7 +2618,6 @@ static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
raw_spin_lock_init(&rdp->nocb_bypass_lock);
raw_spin_lock_init(&rdp->nocb_gp_lock);
timer_setup(&rdp->nocb_timer, do_nocb_deferred_wakeup_timer, 0);
- timer_setup(&rdp->nocb_bypass_timer, do_nocb_bypass_wakeup_timer, 0);
rcu_cblist_init(&rdp->nocb_bypass);
}
@@ -2785,13 +2776,12 @@ static void show_rcu_nocb_gp_state(struct rcu_data *rdp)
{
struct rcu_node *rnp = rdp->mynode;
- pr_info("nocb GP %d %c%c%c%c%c%c %c[%c%c] %c%c:%ld rnp %d:%d %lu %c CPU %d%s\n",
+ pr_info("nocb GP %d %c%c%c%c%c %c[%c%c] %c%c:%ld rnp %d:%d %lu %c CPU %d%s\n",
rdp->cpu,
"kK"[!!rdp->nocb_gp_kthread],
"lL"[raw_spin_is_locked(&rdp->nocb_gp_lock)],
"dD"[!!rdp->nocb_defer_wakeup],
"tT"[timer_pending(&rdp->nocb_timer)],
- "bB"[timer_pending(&rdp->nocb_bypass_timer)],
"sS"[!!rdp->nocb_gp_sleep],
".W"[swait_active(&rdp->nocb_gp_wq)],
".W"[swait_active(&rnp->nocb_gp_wq[0])],
@@ -2812,7 +2802,6 @@ static void show_rcu_nocb_state(struct rcu_data *rdp)
char bufr[20];
struct rcu_segcblist *rsclp = &rdp->cblist;
bool waslocked;
- bool wastimer;
bool wassleep;
if (rdp->nocb_gp_rdp == rdp)
@@ -2849,15 +2838,13 @@ static void show_rcu_nocb_state(struct rcu_data *rdp)
return;
waslocked = raw_spin_is_locked(&rdp->nocb_gp_lock);
- wastimer = timer_pending(&rdp->nocb_bypass_timer);
wassleep = swait_active(&rdp->nocb_gp_wq);
- if (!rdp->nocb_gp_sleep && !waslocked && !wastimer && !wassleep)
- return; /* Nothing untowards. */
+ if (!rdp->nocb_gp_sleep && !waslocked && !wassleep)
+ return; /* Nothing untoward. */
- pr_info(" nocb GP activity on CB-only CPU!!! %c%c%c%c %c\n",
+ pr_info(" nocb GP activity on CB-only CPU!!! %c%c%c %c\n",
"lL"[waslocked],
"dD"[!!rdp->nocb_defer_wakeup],
- "tT"[wastimer],
"sS"[!!rdp->nocb_gp_sleep],
".W"[wassleep]);
}
@@ -2922,7 +2909,7 @@ static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
{
}
-static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp)
+static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp, int level)
{
return false;
}
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index acb2288063b5..3f937b20814f 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -314,6 +314,7 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp)
* tasks blocked within RCU read-side critical sections.
*/
static int rcu_print_task_stall(struct rcu_node *rnp, unsigned long flags)
+ __releases(rnp->lock)
{
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return 0;
@@ -717,6 +718,63 @@ static void check_cpu_stall(struct rcu_data *rdp)
/*
+ * Check to see if a failure to end RCU priority inversion was due to
+ * a CPU not passing through a quiescent state. When this happens, there
+ * is nothing that RCU priority boosting can do to help, so we shouldn't
+ * count this as an RCU priority boosting failure. A return of true says
+ * RCU priority boosting is to blame, and false says otherwise. If false
+ * is returned, the first of the CPUs to blame is stored through cpup.
+ * If there was no CPU blocking the current grace period, but also nothing
+ * in need of being boosted, *cpup is set to -1. This can happen in case
+ * of vCPU preemption while the last CPU is reporting its quiscent state,
+ * for example.
+ *
+ * If cpup is NULL, then a lockless quick check is carried out, suitable
+ * for high-rate usage. On the other hand, if cpup is non-NULL, each
+ * rcu_node structure's ->lock is acquired, ruling out high-rate usage.
+ */
+bool rcu_check_boost_fail(unsigned long gp_state, int *cpup)
+{
+ bool atb = false;
+ int cpu;
+ unsigned long flags;
+ struct rcu_node *rnp;
+
+ rcu_for_each_leaf_node(rnp) {
+ if (!cpup) {
+ if (READ_ONCE(rnp->qsmask)) {
+ return false;
+ } else {
+ if (READ_ONCE(rnp->gp_tasks))
+ atb = true;
+ continue;
+ }
+ }
+ *cpup = -1;
+ raw_spin_lock_irqsave_rcu_node(rnp, flags);
+ if (rnp->gp_tasks)
+ atb = true;
+ if (!rnp->qsmask) {
+ // No CPUs without quiescent states for this rnp.
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
+ continue;
+ }
+ // Find the first holdout CPU.
+ for_each_leaf_node_possible_cpu(rnp, cpu) {
+ if (rnp->qsmask & (1UL << (cpu - rnp->grplo))) {
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
+ *cpup = cpu;
+ return false;
+ }
+ }
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
+ }
+ // Can't blame CPUs, so must blame RCU priority boosting.
+ return atb;
+}
+EXPORT_SYMBOL_GPL(rcu_check_boost_fail);
+
+/*
* Show the state of the grace-period kthreads.
*/
void show_rcu_gp_kthreads(void)
@@ -726,6 +784,7 @@ void show_rcu_gp_kthreads(void)
unsigned long j;
unsigned long ja;
unsigned long jr;
+ unsigned long js;
unsigned long jw;
struct rcu_data *rdp;
struct rcu_node *rnp;
@@ -734,21 +793,30 @@ void show_rcu_gp_kthreads(void)
j = jiffies;
ja = j - data_race(rcu_state.gp_activity);
jr = j - data_race(rcu_state.gp_req_activity);
+ js = j - data_race(rcu_state.gp_start);
jw = j - data_race(rcu_state.gp_wake_time);
- pr_info("%s: wait state: %s(%d) ->state: %#x delta ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_flags %#x\n",
+ pr_info("%s: wait state: %s(%d) ->state: %#lx ->rt_priority %u delta ->gp_start %lu ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_max %lu ->gp_flags %#x\n",
rcu_state.name, gp_state_getname(rcu_state.gp_state),
- rcu_state.gp_state, t ? t->__state : 0x1ffff,
- ja, jr, jw, (long)data_race(rcu_state.gp_wake_seq),
+ rcu_state.gp_state, t ? t->__state : 0x1ffffL, t ? t->rt_priority : 0xffU,
+ js, ja, jr, jw, (long)data_race(rcu_state.gp_wake_seq),
(long)data_race(rcu_state.gp_seq),
(long)data_race(rcu_get_root()->gp_seq_needed),
+ data_race(rcu_state.gp_max),
data_race(rcu_state.gp_flags));
rcu_for_each_node_breadth_first(rnp) {
- if (ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq),
- READ_ONCE(rnp->gp_seq_needed)))
+ if (ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq), READ_ONCE(rnp->gp_seq_needed)) &&
+ !data_race(rnp->qsmask) && !data_race(rnp->boost_tasks) &&
+ !data_race(rnp->exp_tasks) && !data_race(rnp->gp_tasks))
continue;
- pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld\n",
- rnp->grplo, rnp->grphi, (long)data_race(rnp->gp_seq),
- (long)data_race(rnp->gp_seq_needed));
+ pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld ->qsmask %#lx %c%c%c%c ->n_boosts %ld\n",
+ rnp->grplo, rnp->grphi,
+ (long)data_race(rnp->gp_seq), (long)data_race(rnp->gp_seq_needed),
+ data_race(rnp->qsmask),
+ ".b"[!!data_race(rnp->boost_kthread_task)],
+ ".B"[!!data_race(rnp->boost_tasks)],
+ ".E"[!!data_race(rnp->exp_tasks)],
+ ".G"[!!data_race(rnp->gp_tasks)],
+ data_race(rnp->n_boosts));
if (!rcu_is_leaf_node(rnp))
continue;
for_each_leaf_node_possible_cpu(rnp, cpu) {
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index b95ae86c40a7..c21b38cc25e9 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -277,7 +277,7 @@ EXPORT_SYMBOL_GPL(rcu_callback_map);
noinstr int notrace debug_lockdep_rcu_enabled(void)
{
- return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && debug_locks &&
+ return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && READ_ONCE(debug_locks) &&
current->lockdep_recursion == 0;
}
EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
@@ -524,6 +524,7 @@ static void test_callback(struct rcu_head *r)
}
DEFINE_STATIC_SRCU(early_srcu);
+static unsigned long early_srcu_cookie;
struct early_boot_kfree_rcu {
struct rcu_head rh;
@@ -536,8 +537,10 @@ static void early_boot_test_call_rcu(void)
struct early_boot_kfree_rcu *rhp;
call_rcu(&head, test_callback);
- if (IS_ENABLED(CONFIG_SRCU))
+ if (IS_ENABLED(CONFIG_SRCU)) {
+ early_srcu_cookie = start_poll_synchronize_srcu(&early_srcu);
call_srcu(&early_srcu, &shead, test_callback);
+ }
rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
if (!WARN_ON_ONCE(!rhp))
kfree_rcu(rhp, rh);
@@ -563,6 +566,7 @@ static int rcu_verify_early_boot_tests(void)
if (IS_ENABLED(CONFIG_SRCU)) {
early_boot_test_counter++;
srcu_barrier(&early_srcu);
+ WARN_ON_ONCE(!poll_state_synchronize_srcu(&early_srcu, early_srcu_cookie));
}
}
if (rcu_self_test_counter != early_boot_test_counter) {
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 467087d7bdb6..3fadb58fc9d7 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1237,20 +1237,6 @@ int try_to_del_timer_sync(struct timer_list *timer)
}
EXPORT_SYMBOL(try_to_del_timer_sync);
-bool timer_curr_running(struct timer_list *timer)
-{
- int i;
-
- for (i = 0; i < NR_BASES; i++) {
- struct timer_base *base = this_cpu_ptr(&timer_bases[i]);
-
- if (base->running_timer == timer)
- return true;
- }
-
- return false;
-}
-
#ifdef CONFIG_PREEMPT_RT
static __init void timer_base_init_expiry_lock(struct timer_base *base)
{
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-30 00:43:06 +0000