diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-03-30 15:52:00 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-03-30 15:52:00 -0700 |
commit | 7c4fa150714fb319d4e2bb2303ebbd7307b0fb6d (patch) | |
tree | 6bd36b1721ae89f410ecd002d9a80e048a76653d /kernel | |
parent | d937a6dfc9428f470c3ce4d459c390944ddef538 (diff) | |
parent | baf5fe761846815164753d1bd0638fd3696db8fd (diff) |
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar:
"The main changes in this cycle were:
- Make kfree_rcu() use kfree_bulk() for added performance
- RCU updates
- Callback-overload handling updates
- Tasks-RCU KCSAN and sparse updates
- Locking torture test and RCU torture test updates
- Documentation updates
- Miscellaneous fixes"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (74 commits)
rcu: Make rcu_barrier() account for offline no-CBs CPUs
rcu: Mark rcu_state.gp_seq to detect concurrent writes
Documentation/memory-barriers: Fix typos
doc: Add rcutorture scripting to torture.txt
doc/RCU/rcu: Use https instead of http if possible
doc/RCU/rcu: Use absolute paths for non-rst files
doc/RCU/rcu: Use ':ref:' for links to other docs
doc/RCU/listRCU: Update example function name
doc/RCU/listRCU: Fix typos in a example code snippets
doc/RCU/Design: Remove remaining HTML tags in ReST files
doc: Add some more RCU list patterns in the kernel
rcutorture: Set KCSAN Kconfig options to detect more data races
rcutorture: Manually clean up after rcu_barrier() failure
rcutorture: Make rcu_torture_barrier_cbs() post from corresponding CPU
rcuperf: Measure memory footprint during kfree_rcu() test
rcutorture: Annotation lockless accesses to rcu_torture_current
rcutorture: Add READ_ONCE() to rcu_torture_count and rcu_torture_batch
rcutorture: Fix stray access to rcu_fwd_cb_nodelay
rcutorture: Fix rcu_torture_one_read()/rcu_torture_writer() data race
rcutorture: Make kvm-find-errors.sh abort on bad directory
...
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/locking/locktorture.c | 15 | ||||
-rw-r--r-- | kernel/locking/rtmutex.c | 2 | ||||
-rw-r--r-- | kernel/rcu/Makefile | 4 | ||||
-rw-r--r-- | kernel/rcu/rcu.h | 23 | ||||
-rw-r--r-- | kernel/rcu/rcu_segcblist.c | 4 | ||||
-rw-r--r-- | kernel/rcu/rcuperf.c | 14 | ||||
-rw-r--r-- | kernel/rcu/rcutorture.c | 67 | ||||
-rw-r--r-- | kernel/rcu/srcutree.c | 18 | ||||
-rw-r--r-- | kernel/rcu/tree.c | 452 | ||||
-rw-r--r-- | kernel/rcu/tree.h | 4 | ||||
-rw-r--r-- | kernel/rcu/tree_exp.h | 13 | ||||
-rw-r--r-- | kernel/rcu/tree_plugin.h | 25 | ||||
-rw-r--r-- | kernel/rcu/tree_stall.h | 41 | ||||
-rw-r--r-- | kernel/rcu/update.c | 28 | ||||
-rw-r--r-- | kernel/time/timer.c | 7 | ||||
-rw-r--r-- | kernel/torture.c | 29 |
16 files changed, 550 insertions, 196 deletions
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index 99475a66c94f..5efbfc68ce99 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -618,7 +618,7 @@ static struct lock_torture_ops percpu_rwsem_lock_ops = { static int lock_torture_writer(void *arg) { struct lock_stress_stats *lwsp = arg; - static DEFINE_TORTURE_RANDOM(rand); + DEFINE_TORTURE_RANDOM(rand); VERBOSE_TOROUT_STRING("lock_torture_writer task started"); set_user_nice(current, MAX_NICE); @@ -655,7 +655,7 @@ static int lock_torture_writer(void *arg) static int lock_torture_reader(void *arg) { struct lock_stress_stats *lrsp = arg; - static DEFINE_TORTURE_RANDOM(rand); + DEFINE_TORTURE_RANDOM(rand); VERBOSE_TOROUT_STRING("lock_torture_reader task started"); set_user_nice(current, MAX_NICE); @@ -696,15 +696,16 @@ static void __torture_print_stats(char *page, if (statp[i].n_lock_fail) fail = true; sum += statp[i].n_lock_acquired; - if (max < statp[i].n_lock_fail) - max = statp[i].n_lock_fail; - if (min > statp[i].n_lock_fail) - min = statp[i].n_lock_fail; + if (max < statp[i].n_lock_acquired) + max = statp[i].n_lock_acquired; + if (min > statp[i].n_lock_acquired) + min = statp[i].n_lock_acquired; } page += sprintf(page, "%s: Total: %lld Max/Min: %ld/%ld %s Fail: %d %s\n", write ? "Writes" : "Reads ", - sum, max, min, max / 2 > min ? "???" : "", + sum, max, min, + !onoff_interval && max / 2 > min ? "???" : "", fail, fail ? "!!!" : ""); if (fail) atomic_inc(&cxt.n_lock_torture_errors); diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 851bbb10819d..c9f090d64f00 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -57,7 +57,7 @@ rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner) if (rt_mutex_has_waiters(lock)) val |= RT_MUTEX_HAS_WAITERS; - lock->owner = (struct task_struct *)val; + WRITE_ONCE(lock->owner, (struct task_struct *)val); } static inline void clear_rt_mutex_waiters(struct rt_mutex *lock) diff --git a/kernel/rcu/Makefile b/kernel/rcu/Makefile index 82d5fba48b2f..f91f2c2cf138 100644 --- a/kernel/rcu/Makefile +++ b/kernel/rcu/Makefile @@ -3,6 +3,10 @@ # and is generally not a function of system call inputs. KCOV_INSTRUMENT := n +ifeq ($(CONFIG_KCSAN),y) +KBUILD_CFLAGS += -g -fno-omit-frame-pointer +endif + obj-y += update.o sync.o obj-$(CONFIG_TREE_SRCU) += srcutree.o obj-$(CONFIG_TINY_SRCU) += srcutiny.o diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 05f936ed167a..00ddc92c5774 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -198,6 +198,13 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head) } #endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ +extern int rcu_cpu_stall_suppress_at_boot; + +static inline bool rcu_stall_is_suppressed_at_boot(void) +{ + return rcu_cpu_stall_suppress_at_boot && !rcu_inkernel_boot_has_ended(); +} + #ifdef CONFIG_RCU_STALL_COMMON extern int rcu_cpu_stall_ftrace_dump; @@ -205,6 +212,11 @@ extern int rcu_cpu_stall_suppress; extern int rcu_cpu_stall_timeout; int rcu_jiffies_till_stall_check(void); +static inline bool rcu_stall_is_suppressed(void) +{ + return rcu_stall_is_suppressed_at_boot() || rcu_cpu_stall_suppress; +} + #define rcu_ftrace_dump_stall_suppress() \ do { \ if (!rcu_cpu_stall_suppress) \ @@ -218,6 +230,11 @@ do { \ } while (0) #else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */ + +static inline bool rcu_stall_is_suppressed(void) +{ + return rcu_stall_is_suppressed_at_boot(); +} #define rcu_ftrace_dump_stall_suppress() #define rcu_ftrace_dump_stall_unsuppress() #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ @@ -325,7 +342,8 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) * Iterate over all possible CPUs in a leaf RCU node. */ #define for_each_leaf_node_possible_cpu(rnp, cpu) \ - for ((cpu) = cpumask_next((rnp)->grplo - 1, cpu_possible_mask); \ + for (WARN_ON_ONCE(!rcu_is_leaf_node(rnp)), \ + (cpu) = cpumask_next((rnp)->grplo - 1, cpu_possible_mask); \ (cpu) <= rnp->grphi; \ (cpu) = cpumask_next((cpu), cpu_possible_mask)) @@ -335,7 +353,8 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) #define rcu_find_next_bit(rnp, cpu, mask) \ ((rnp)->grplo + find_next_bit(&(mask), BITS_PER_LONG, (cpu))) #define for_each_leaf_node_cpu_mask(rnp, cpu, mask) \ - for ((cpu) = rcu_find_next_bit((rnp), 0, (mask)); \ + for (WARN_ON_ONCE(!rcu_is_leaf_node(rnp)), \ + (cpu) = rcu_find_next_bit((rnp), 0, (mask)); \ (cpu) <= rnp->grphi; \ (cpu) = rcu_find_next_bit((rnp), (cpu) + 1 - (rnp->grplo), (mask))) diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c index 5f4fd3b8777c..9a0f66133b4b 100644 --- a/kernel/rcu/rcu_segcblist.c +++ b/kernel/rcu/rcu_segcblist.c @@ -182,7 +182,7 @@ void rcu_segcblist_offload(struct rcu_segcblist *rsclp) bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp) { return rcu_segcblist_is_enabled(rsclp) && - &rsclp->head != rsclp->tails[RCU_DONE_TAIL]; + &rsclp->head != READ_ONCE(rsclp->tails[RCU_DONE_TAIL]); } /* @@ -381,8 +381,6 @@ void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp, return; /* Nothing to do. */ WRITE_ONCE(*rsclp->tails[RCU_NEXT_TAIL], rclp->head); WRITE_ONCE(rsclp->tails[RCU_NEXT_TAIL], rclp->tail); - rclp->head = NULL; - rclp->tail = &rclp->head; } /* diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c index da94b89cd531..a4a8d097d84d 100644 --- a/kernel/rcu/rcuperf.c +++ b/kernel/rcu/rcuperf.c @@ -12,6 +12,7 @@ #include <linux/types.h> #include <linux/kernel.h> #include <linux/init.h> +#include <linux/mm.h> #include <linux/module.h> #include <linux/kthread.h> #include <linux/err.h> @@ -611,6 +612,7 @@ kfree_perf_thread(void *arg) long me = (long)arg; struct kfree_obj *alloc_ptr; u64 start_time, end_time; + long long mem_begin, mem_during = 0; VERBOSE_PERFOUT_STRING("kfree_perf_thread task started"); set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids)); @@ -626,6 +628,12 @@ kfree_perf_thread(void *arg) } do { + if (!mem_during) { + mem_during = mem_begin = si_mem_available(); + } else if (loop % (kfree_loops / 4) == 0) { + mem_during = (mem_during + si_mem_available()) / 2; + } + for (i = 0; i < kfree_alloc_num; i++) { alloc_ptr = kmalloc(sizeof(struct kfree_obj), GFP_KERNEL); if (!alloc_ptr) @@ -645,9 +653,11 @@ kfree_perf_thread(void *arg) else b_rcu_gp_test_finished = cur_ops->get_gp_seq(); - pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld\n", + pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n", (unsigned long long)(end_time - start_time), kfree_loops, - rcuperf_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started)); + rcuperf_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started), + (mem_begin - mem_during) >> (20 - PAGE_SHIFT)); + if (shutdown) { smp_mb(); /* Assign before wake. */ wake_up(&shutdown_wq); diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 1aeecc165b21..5453bd557f43 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -339,7 +339,7 @@ rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp) * period, and we want a long delay occasionally to trigger * force_quiescent_state. */ - if (!rcu_fwd_cb_nodelay && + if (!READ_ONCE(rcu_fwd_cb_nodelay) && !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) { started = cur_ops->get_gp_seq(); ts = rcu_trace_clock_local(); @@ -375,11 +375,12 @@ rcu_torture_pipe_update_one(struct rcu_torture *rp) { int i; - i = rp->rtort_pipe_count; + i = READ_ONCE(rp->rtort_pipe_count); if (i > RCU_TORTURE_PIPE_LEN) i = RCU_TORTURE_PIPE_LEN; atomic_inc(&rcu_torture_wcount[i]); - if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) { + WRITE_ONCE(rp->rtort_pipe_count, i + 1); + if (rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) { rp->rtort_mbtest = 0; return true; } @@ -1015,7 +1016,8 @@ rcu_torture_writer(void *arg) if (i > RCU_TORTURE_PIPE_LEN) i = RCU_TORTURE_PIPE_LEN; atomic_inc(&rcu_torture_wcount[i]); - old_rp->rtort_pipe_count++; + WRITE_ONCE(old_rp->rtort_pipe_count, + old_rp->rtort_pipe_count + 1); switch (synctype[torture_random(&rand) % nsynctypes]) { case RTWS_DEF_FREE: rcu_torture_writer_state = RTWS_DEF_FREE; @@ -1067,7 +1069,8 @@ rcu_torture_writer(void *arg) if (stutter_wait("rcu_torture_writer") && !READ_ONCE(rcu_fwd_cb_nodelay) && !cur_ops->slow_gps && - !torture_must_stop()) + !torture_must_stop() && + rcu_inkernel_boot_has_ended()) for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) if (list_empty(&rcu_tortures[i].rtort_free) && rcu_access_pointer(rcu_torture_current) != @@ -1290,7 +1293,7 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp) atomic_inc(&n_rcu_torture_mberror); rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp); preempt_disable(); - pipe_count = p->rtort_pipe_count; + pipe_count = READ_ONCE(p->rtort_pipe_count); if (pipe_count > RCU_TORTURE_PIPE_LEN) { /* Should not happen, but... */ pipe_count = RCU_TORTURE_PIPE_LEN; @@ -1404,14 +1407,15 @@ rcu_torture_stats_print(void) int i; long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 }; long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 }; + struct rcu_torture *rtcp; static unsigned long rtcv_snap = ULONG_MAX; static bool splatted; struct task_struct *wtp; for_each_possible_cpu(cpu) { for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) { - pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i]; - batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i]; + pipesummary[i] += READ_ONCE(per_cpu(rcu_torture_count, cpu)[i]); + batchsummary[i] += READ_ONCE(per_cpu(rcu_torture_batch, cpu)[i]); } } for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) { @@ -1420,9 +1424,10 @@ rcu_torture_stats_print(void) } pr_alert("%s%s ", torture_type, TORTURE_FLAG); + rtcp = rcu_access_pointer(rcu_torture_current); pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ", - rcu_torture_current, - rcu_torture_current ? "ver" : "VER", + rtcp, + rtcp && !rcu_stall_is_suppressed_at_boot() ? "ver" : "VER", rcu_torture_current_version, list_empty(&rcu_torture_freelist), atomic_read(&n_rcu_torture_alloc), @@ -1478,7 +1483,8 @@ rcu_torture_stats_print(void) if (cur_ops->stats) cur_ops->stats(); if (rtcv_snap == rcu_torture_current_version && - rcu_torture_current != NULL) { + rcu_access_pointer(rcu_torture_current) && + !rcu_stall_is_suppressed()) { int __maybe_unused flags = 0; unsigned long __maybe_unused gp_seq = 0; @@ -1993,8 +1999,11 @@ static int rcu_torture_fwd_prog(void *args) schedule_timeout_interruptible(fwd_progress_holdoff * HZ); WRITE_ONCE(rcu_fwd_emergency_stop, false); register_oom_notifier(&rcutorture_oom_nb); - rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries); - rcu_torture_fwd_prog_cr(rfp); + if (!IS_ENABLED(CONFIG_TINY_RCU) || + rcu_inkernel_boot_has_ended()) + rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries); + if (rcu_inkernel_boot_has_ended()) + rcu_torture_fwd_prog_cr(rfp); unregister_oom_notifier(&rcutorture_oom_nb); /* Avoid slow periods, better to test when busy. */ @@ -2044,6 +2053,14 @@ static void rcu_torture_barrier_cbf(struct rcu_head *rcu) atomic_inc(&barrier_cbs_invoked); } +/* IPI handler to get callback posted on desired CPU, if online. */ +static void rcu_torture_barrier1cb(void *rcu_void) +{ + struct rcu_head *rhp = rcu_void; + + cur_ops->call(rhp, rcu_torture_barrier_cbf); +} + /* kthread function to register callbacks used to test RCU barriers. */ static int rcu_torture_barrier_cbs(void *arg) { @@ -2067,9 +2084,11 @@ static int rcu_torture_barrier_cbs(void *arg) * The above smp_load_acquire() ensures barrier_phase load * is ordered before the following ->call(). */ - local_irq_disable(); /* Just to test no-irq call_rcu(). */ - cur_ops->call(&rcu, rcu_torture_barrier_cbf); - local_irq_enable(); + if (smp_call_function_single(myid, rcu_torture_barrier1cb, + &rcu, 1)) { + // IPI failed, so use direct call from current CPU. + cur_ops->call(&rcu, rcu_torture_barrier_cbf); + } if (atomic_dec_and_test(&barrier_cbs_count)) wake_up(&barrier_wq); } while (!torture_must_stop()); @@ -2105,7 +2124,21 @@ static int rcu_torture_barrier(void *arg) pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n", atomic_read(&barrier_cbs_invoked), n_barrier_cbs); - WARN_ON_ONCE(1); + WARN_ON(1); + // Wait manually for the remaining callbacks + i = 0; + do { + if (WARN_ON(i++ > HZ)) + i = INT_MIN; + schedule_timeout_interruptible(1); + cur_ops->cb_barrier(); + } while (atomic_read(&barrier_cbs_invoked) != + n_barrier_cbs && + !torture_must_stop()); + smp_mb(); // Can't trust ordering if broken. + if (!torture_must_stop()) + pr_err("Recovered: barrier_cbs_invoked = %d\n", + atomic_read(&barrier_cbs_invoked)); } else { n_barrier_successes++; } diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 657e6a7d1c03..0c71505f0e19 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -5,7 +5,7 @@ * Copyright (C) IBM Corporation, 2006 * Copyright (C) Fujitsu, 2012 * - * Author: Paul McKenney <paulmck@linux.ibm.com> + * Authors: Paul McKenney <paulmck@linux.ibm.com> * Lai Jiangshan <laijs@cn.fujitsu.com> * * For detailed explanation of Read-Copy Update mechanism see - @@ -450,7 +450,7 @@ static void srcu_gp_start(struct srcu_struct *ssp) spin_unlock_rcu_node(sdp); /* Interrupts remain disabled. */ smp_mb(); /* Order prior store to ->srcu_gp_seq_needed vs. GP start. */ rcu_seq_start(&ssp->srcu_gp_seq); - state = rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)); + state = rcu_seq_state(ssp->srcu_gp_seq); WARN_ON_ONCE(state != SRCU_STATE_SCAN1); } @@ -534,7 +534,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) rcu_seq_end(&ssp->srcu_gp_seq); gpseq = rcu_seq_current(&ssp->srcu_gp_seq); if (ULONG_CMP_LT(ssp->srcu_gp_seq_needed_exp, gpseq)) - ssp->srcu_gp_seq_needed_exp = gpseq; + WRITE_ONCE(ssp->srcu_gp_seq_needed_exp, gpseq); spin_unlock_irq_rcu_node(ssp); mutex_unlock(&ssp->srcu_gp_mutex); /* A new grace period can start at this point. But only one. */ @@ -550,7 +550,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) snp->srcu_have_cbs[idx] = gpseq; rcu_seq_set_state(&snp->srcu_have_cbs[idx], 1); if (ULONG_CMP_LT(snp->srcu_gp_seq_needed_exp, gpseq)) - snp->srcu_gp_seq_needed_exp = gpseq; + WRITE_ONCE(snp->srcu_gp_seq_needed_exp, gpseq); mask = snp->srcu_data_have_cbs[idx]; snp->srcu_data_have_cbs[idx] = 0; spin_unlock_irq_rcu_node(snp); @@ -614,7 +614,7 @@ static void srcu_funnel_exp_start(struct srcu_struct *ssp, struct srcu_node *snp } spin_lock_irqsave_rcu_node(ssp, flags); if (ULONG_CMP_LT(ssp->srcu_gp_seq_needed_exp, s)) - ssp->srcu_gp_seq_needed_exp = s; + WRITE_ONCE(ssp->srcu_gp_seq_needed_exp, s); spin_unlock_irqrestore_rcu_node(ssp, flags); } @@ -660,7 +660,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp, if (snp == sdp->mynode) snp->srcu_data_have_cbs[idx] |= sdp->grpmask; if (!do_norm && ULONG_CMP_LT(snp->srcu_gp_seq_needed_exp, s)) - snp->srcu_gp_seq_needed_exp = s; + WRITE_ONCE(snp->srcu_gp_seq_needed_exp, s); spin_unlock_irqrestore_rcu_node(snp, flags); } @@ -674,7 +674,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp, smp_store_release(&ssp->srcu_gp_seq_needed, s); /*^^^*/ } if (!do_norm && ULONG_CMP_LT(ssp->srcu_gp_seq_needed_exp, s)) - ssp->srcu_gp_seq_needed_exp = s; + WRITE_ONCE(ssp->srcu_gp_seq_needed_exp, s); /* If grace period not already done and none in progress, start it. */ if (!rcu_seq_done(&ssp->srcu_gp_seq, s) && @@ -1079,7 +1079,7 @@ EXPORT_SYMBOL_GPL(srcu_barrier); */ unsigned long srcu_batches_completed(struct srcu_struct *ssp) { - return ssp->srcu_idx; + return READ_ONCE(ssp->srcu_idx); } EXPORT_SYMBOL_GPL(srcu_batches_completed); @@ -1130,7 +1130,9 @@ static void srcu_advance_state(struct srcu_struct *ssp) return; /* readers present, retry later. */ } srcu_flip(ssp); + spin_lock_irq_rcu_node(ssp); rcu_seq_set_state(&ssp->srcu_gp_seq, SRCU_STATE_SCAN2); + spin_unlock_irq_rcu_node(ssp); } if (rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)) == SRCU_STATE_SCAN2) { diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index d91c9156fab2..550193a9ce76 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1,12 +1,12 @@ // SPDX-License-Identifier: GPL-2.0+ /* - * Read-Copy Update mechanism for mutual exclusion + * Read-Copy Update mechanism for mutual exclusion (tree-based version) * * Copyright IBM Corporation, 2008 * * Authors: Dipankar Sarma <dipankar@in.ibm.com> * Manfred Spraul <manfred@colorfullife.com> - * Paul E. McKenney <paulmck@linux.ibm.com> Hierarchical version + * Paul E. McKenney <paulmck@linux.ibm.com> * * Based on the original work by Paul McKenney <paulmck@linux.ibm.com> * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. @@ -150,6 +150,7 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu) static void invoke_rcu_core(void); static void rcu_report_exp_rdp(struct rcu_data *rdp); static void sync_sched_exp_online_cleanup(int cpu); +static void check_cb_ovld_locked(struct rcu_data *rdp, struct rcu_node *rnp); /* rcuc/rcub kthread realtime priority */ static int kthread_prio = IS_ENABLED(CONFIG_RCU_BOOST) ? 1 : 0; @@ -342,14 +343,17 @@ bool rcu_eqs_special_set(int cpu) { int old; int new; + int new_old; struct rcu_data *rdp = &per_cpu(rcu_data, cpu); + new_old = atomic_read(&rdp->dynticks); do { - old = atomic_read(&rdp->dynticks); + old = new_old; if (old & RCU_DYNTICK_CTRL_CTR) return false; new = old | RCU_DYNTICK_CTRL_MASK; - } while (atomic_cmpxchg(&rdp->dynticks, old, new) != old); + new_old = atomic_cmpxchg(&rdp->dynticks, old, new); + } while (new_old != old); return true; } @@ -410,10 +414,15 @@ static long blimit = DEFAULT_RCU_BLIMIT; static long qhimark = DEFAULT_RCU_QHIMARK; #define DEFAULT_RCU_QLOMARK 100 /* Once only this many pending, use blimit. */ static long qlowmark = DEFAULT_RCU_QLOMARK; +#define DEFAULT_RCU_QOVLD_MULT 2 +#define DEFAULT_RCU_QOVLD (DEFAULT_RCU_QOVLD_MULT * DEFAULT_RCU_QHIMARK) +static long qovld = DEFAULT_RCU_QOVLD; /* If this many pending, hammer QS. */ +static long qovld_calc = -1; /* No pre-initialization lock acquisitions! */ module_param(blimit, long, 0444); module_param(qhimark, long, 0444); module_param(qlowmark, long, 0444); +module_param(qovld, long, 0444); static ulong jiffies_till_first_fqs = ULONG_MAX; static ulong jiffies_till_next_fqs = ULONG_MAX; @@ -818,11 +827,12 @@ static __always_inline void rcu_nmi_enter_common(bool irq) incby = 1; } else if (tick_nohz_full_cpu(rdp->cpu) && rdp->dynticks_nmi_nesting == DYNTICK_IRQ_NONIDLE && - READ_ONCE(rdp->rcu_urgent_qs) && !rdp->rcu_forced_tick) { + READ_ONCE(rdp->rcu_urgent_qs) && + !READ_ONCE(rdp->rcu_forced_tick)) { raw_spin_lock_rcu_node(rdp->mynode); // Recheck under lock. if (rdp->rcu_urgent_qs && !rdp->rcu_forced_tick) { - rdp->rcu_forced_tick = true; + WRITE_ONCE(rdp->rcu_forced_tick, true); tick_dep_set_cpu(rdp->cpu, TICK_DEP_BIT_RCU); } raw_spin_unlock_rcu_node(rdp->mynode); @@ -899,7 +909,7 @@ static void rcu_disable_urgency_upon_qs(struct rcu_data *rdp) WRITE_ONCE(rdp->rcu_need_heavy_qs, false); if (tick_nohz_full_cpu(rdp->cpu) && rdp->rcu_forced_tick) { tick_dep_clear_cpu(rdp->cpu, TICK_DEP_BIT_RCU); - rdp->rcu_forced_tick = false; + WRITE_ONCE(rdp->rcu_forced_tick, false); } } @@ -1072,7 +1082,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) rnhqp = &per_cpu(rcu_data.rcu_need_heavy_qs, rdp->cpu); if (!READ_ONCE(*rnhqp) && (time_after(jiffies, rcu_state.gp_start + jtsq * 2) || - time_after(jiffies, rcu_state.jiffies_resched))) { + time_after(jiffies, rcu_state.jiffies_resched) || + rcu_state.cbovld)) { WRITE_ONCE(*rnhqp, true); /* Store rcu_need_heavy_qs before rcu_urgent_qs. */ smp_store_release(ruqp, true); @@ -1089,8 +1100,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) * So hit them over the head with the resched_cpu() hammer! */ if (tick_nohz_full_cpu(rdp->cpu) && - time_after(jiffies, - READ_ONCE(rdp->last_fqs_resched) + jtsq * 3)) { + (time_after(jiffies, READ_ONCE(rdp->last_fqs_resched) + jtsq * 3) || + rcu_state.cbovld)) { WRITE_ONCE(*ruqp, true); resched_cpu(rdp->cpu); WRITE_ONCE(rdp->last_fqs_resched, jiffies); @@ -1126,8 +1137,9 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) static void trace_rcu_this_gp(struct rcu_node *rnp, struct rcu_data *rdp, unsigned long gp_seq_req, const char *s) { - trace_rcu_future_grace_period(rcu_state.name, rnp->gp_seq, gp_seq_req, - rnp->level, rnp->grplo, rnp->grphi, s); + trace_rcu_future_grace_period(rcu_state.name, READ_ONCE(rnp->gp_seq), + gp_seq_req, rnp->level, + rnp->grplo, rnp->grphi, s); } /* @@ -1174,7 +1186,7 @@ static bool rcu_start_this_gp(struct rcu_node *rnp_start, struct rcu_data *rdp, TPS("Prestarted")); goto unlock_out; } - rnp->gp_seq_needed = gp_seq_req; + WRITE_ONCE(rnp->gp_seq_needed, gp_seq_req); if (rcu_seq_state(rcu_seq_current(&rnp->gp_seq))) { /* * We just marked the leaf or internal node, and a @@ -1199,18 +1211,18 @@ static bool rcu_start_this_gp(struct rcu_node *rnp_start, struct rcu_data *rdp, } trace_rcu_this_gp(rnp, rdp, gp_seq_req, TPS("Startedroot")); WRITE_ONCE(rcu_state.gp_flags, rcu_state.gp_flags | RCU_GP_FLAG_INIT); - rcu_state.gp_req_activity = jiffies; - if (!rcu_state.gp_kthread) { + WRITE_ONCE(rcu_state.gp_req_activity, jiffies); + if (!READ_ONCE(rcu_state.gp_kthread)) { trace_rcu_this_gp(rnp, rdp, gp_seq_req, TPS("NoGPkthread")); goto unlock_out; } - trace_rcu_grace_period(rcu_state.name, READ_ONCE(rcu_state.gp_seq), TPS("newreq")); + trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("newreq")); ret = true; /* Caller must wake GP kthread. */ unlock_out: /* Push furthest requested GP to leaf node and rcu_data structure. */ if (ULONG_CMP_LT(gp_seq_req, rnp->gp_seq_needed)) { - rnp_start->gp_seq_needed = rnp->gp_seq_needed; - rdp->gp_seq_needed = rnp->gp_seq_needed; + WRITE_ONCE(rnp_start->gp_seq_needed, rnp->gp_seq_needed); + WRITE_ONCE(rdp->gp_seq_needed, rnp->gp_seq_needed); } if (rnp != rnp_start) raw_spin_unlock_rcu_node(rnp); @@ -1235,12 +1247,13 @@ static bool rcu_future_gp_cleanup(struct rcu_node *rnp) } /* - * Awaken the grace-period kthread. Don't do a self-awaken (unless in - * an interrupt or softirq handler), and don't bother awakening when there - * is nothing for the grace-period kthread to do (as in several CPUs raced - * to awaken, and we lost), and finally don't try to awaken a kthread that - * has not yet been created. If all those checks are passed, track some - * debug information and awaken. + * Awaken the grace-period kthread. Don't do a self-awaken (unless in an + * interrupt or softirq handler, in which case we just might immediately + * sleep upon return, resulting in a grace-period hang), and don't bother + * awakening when there is nothing for the grace-period kthread to do + * (as in several CPUs raced to awaken, we lost), and finally don't try + * to awaken a kthread that has not yet been created. If all those checks + * are passed, track some debug information and awaken. * * So why do the self-wakeup when in an interrupt or softirq handler * in the grace-period kthread's context? Because the kthread might have @@ -1250,10 +1263,10 @@ static bool rcu_future_gp_cleanup(struct rcu_node *rnp) */ static void rcu_gp_kthread_wake(void) { - if ((current == rcu_state.gp_kthread && - !in_irq() && !in_serving_softirq()) || - !READ_ONCE(rcu_state.gp_flags) || - !rcu_state.gp_kthread) + struct task_struct *t = READ_ONCE(rcu_state.gp_kthread); + + if ((current == t && !in_irq() && !in_serving_softirq()) || + !READ_ONCE(rcu_state.gp_flags) || !t) return; WRITE_ONCE(rcu_state.gp_wake_time, jiffies); WRITE_ONCE(rcu_state.gp_wake_seq, READ_ONCE(rcu_state.gp_seq)); @@ -1321,7 +1334,7 @@ static void rcu_accelerate_cbs_unlocked(struct rcu_node *rnp, rcu_lockdep_assert_cblist_protected(rdp); c = rcu_seq_snap(&rcu_state.gp_seq); - if (!rdp->gpwrap && ULONG_CMP_GE(rdp->gp_seq_needed, c)) { + if (!READ_ONCE(rdp->gpwrap) && ULONG_CMP_GE(rdp->gp_seq_needed, c)) { /* Old request still live, so mark recent callbacks. */ (void)rcu_segcblist_accelerate(&rdp->cblist, c); return; @@ -1386,7 +1399,7 @@ static void __maybe_unused rcu_advance_cbs_nowake(struct rcu_node *rnp, static bool __note_gp_changes(struct rcu_node *rnp, struct rcu_data *rdp) { bool ret = false; - bool need_gp; + bool need_qs; const bool offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) && rcu_segcblist_is_offloaded(&rdp->cblist); @@ -1400,10 +1413,13 @@ static bool __note_gp_changes(struct rcu_node *rnp, struct rcu_data *rdp) unlikely(READ_ONCE(rdp->gpwrap))) { if (!offloaded) ret = rcu_advance_cbs(rnp, rdp); /* Advance CBs. */ + rdp->core_needs_qs = false; trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("cpuend")); } else { if (!offloaded) ret = rcu_accelerate_cbs(rnp, rdp); /* Recent CBs. */ + if (rdp->core_needs_qs) + rdp->core_needs_qs = !!(rnp->qsmask & rdp->grpmask); } /* Now handle the beginnings of any new-to-this-CPU grace periods. */ @@ -1415,14 +1431,14 @@ static bool __note_gp_changes(struct rcu_node *rnp, struct rcu_data *rdp) * go looking for one. */ trace_rcu_grace_period(rcu_state.name, rnp->gp_seq, TPS("cpustart")); - need_gp = !!(rnp->qsmask & rdp->grpmask); - rdp->cpu_no_qs.b.norm = need_gp; - rdp->core_needs_qs = need_gp; + need_qs = !!(rnp->qsmask & rdp->grpmask); + rdp->cpu_no_qs.b.norm = need_qs; + rdp->core_needs_qs = need_qs; zero_cpu_stall_ticks(rdp); } rdp->gp_seq = rnp->gp_seq; /* Remember new grace-period state. */ if (ULONG_CMP_LT(rdp->gp_seq_needed, rnp->gp_seq_needed) || rdp->gpwrap) - rdp->gp_seq_needed = rnp->gp_seq_needed; + WRITE_ONCE(rdp->gp_seq_needed, rnp->gp_seq_needed); WRITE_ONCE(rdp->gpwrap, false); rcu_gpnum_ovf(rnp, rdp); return ret; @@ -1651,8 +1667,7 @@ static void rcu_gp_fqs_loop(void) WRITE_ONCE(rcu_state.jiffies_kick_kthreads, jiffies + (j ? 3 * j : 2)); } - trace_rcu_grace_period(rcu_state.name, - READ_ONCE(rcu_state.gp_seq), + trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("fqswait")); rcu_state.gp_state = RCU_GP_WAIT_FQS; ret = swait_event_idle_timeout_exclusive( @@ -1666,13 +1681,11 @@ static void rcu_gp_fqs_loop(void) /* If time for quiescent-state forcing, do it. */ if (ULONG_CMP_GE(jiffies, rcu_state.jiffies_force_qs) || (gf & RCU_GP_FLAG_FQS)) { - trace_rcu_grace_period(rcu_state.name, - READ_ONCE(rcu_state.gp_seq), + trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("fqsstart")); rcu_gp_fqs(first_gp_fqs); first_gp_fqs = false; - trace_rcu_grace_period(rcu_state.name, - READ_ONCE(rcu_state.gp_seq), + trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("fqsend")); cond_resched_tasks_rcu_qs(); WRITE_ONCE(rcu_state.gp_activity, jiffies); @@ -1683,8 +1696,7 @@ static void rcu_gp_fqs_loop(void) cond_resched_tasks_rcu_qs(); WRITE_ONCE(rcu_state.gp_activity, jiffies); WARN_ON(signal_pending(current)); - trace_rcu_grace_period(rcu_state.name, - READ_ONCE(rcu_state.gp_seq), + trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("fqswaitsig")); ret = 1; /* Keep old FQS timing. */ j = jiffies; @@ -1701,8 +1713,9 @@ static void rcu_gp_fqs_loop(void) */ static void rcu_gp_cleanup(void) { - unsigned long gp_duration; + int cpu; bool needgp = false; + unsigned long gp_duration; unsigned long new_gp_seq; bool offloaded; struct rcu_data *rdp; @@ -1748,6 +1761,12 @@ static void rcu_gp_cleanup(void) needgp = __note_gp_changes(rnp, rdp) || needgp; /* smp_mb() provided by prior unlock-lock pair. */ needgp = rcu_future_gp_cleanup(rnp) || needgp; + // Reset overload indication for CPUs no longer overloaded + if (rcu_is_leaf_node(rnp)) + for_each_leaf_node_cpu_mask(rnp, cpu, rnp->cbovldmask) { + rdp = per_cpu_ptr(&rcu_data, cpu); + check_cb_ovld_locked(rdp, rnp); + } sq = rcu_nocb_gp_get(rnp); raw_spin_unlock_irq_rcu_node(rnp); rcu_nocb_gp_cleanup(sq); @@ -1774,9 +1793,9 @@ static void rcu_gp_cleanup(void) rcu_segcblist_is_offloaded(&rdp->cblist); if ((offloaded || !rcu_accelerate_cbs(rnp, rdp)) && needgp) { WRITE_ONCE(rcu_state.gp_flags, RCU_GP_FLAG_INIT); - rcu_state.gp_req_activity = jiffies; + WRITE_ONCE(rcu_state.gp_req_activity, jiffies); trace_rcu_grace_period(rcu_state.name, - READ_ONCE(rcu_state.gp_seq), + rcu_state.gp_seq, TPS("newreq")); } else { WRITE_ONCE(rcu_state.gp_flags, @@ -1795,8 +1814,7 @@ static int __noreturn rcu_gp_kthread(void *unused) /* Handle grace-period start. */ for (;;) { - trace_rcu_grace_period(rcu_state.name, - READ_ONCE(rcu_state.gp_seq), + trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("reqwait")); rcu_state.gp_state = RCU_GP_WAIT_GPS; swait_event_idle_exclusive(rcu_state.gp_wq, @@ -1809,8 +1827,7 @@ static int __noreturn rcu_gp_kthread(void *unused) cond_resched_tasks_rcu_qs(); WRITE_ONCE(rcu_state.gp_activity, jiffies); WARN_ON(signal_pending(current)); - trace_rcu_grace_period(rcu_state.name, - READ_ONCE(rcu_state.gp_seq), + trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("reqwaitsig")); } @@ -1881,7 +1898,7 @@ static void rcu_report_qs_rnp(unsigned long mask, struct rcu_node *rnp, WARN_ON_ONCE(oldmask); /* Any child must be all zeroed! */ WARN_ON_ONCE(!rcu_is_leaf_node(rnp) && rcu_preempt_blocked_readers_cgp(rnp)); - rnp->qsmask &= ~mask; + WRITE_ONCE(rnp->qsmask, rnp->qsmask & ~mask); trace_rcu_quiescent_state_report(rcu_state.name, rnp->gp_seq, mask, rnp->qsmask, rnp->level, rnp->grplo, rnp->grphi, @@ -1904,7 +1921,7 @@ static void rcu_report_qs_rnp(unsigned long mask, struct rcu_node *rnp, rnp_c = rnp; rnp = rnp->parent; raw_spin_lock_irqsave_rcu_node(rnp, flags); - oldmask = rnp_c->qsmask; + oldmask = READ_ONCE(rnp_c->qsmask); } /* @@ -1987,6 +2004,8 @@ rcu_report_qs_rdp(int cpu, struct rcu_data *rdp) |