linux/kernel/rcu/tree_plugin.h, branch v5.19

Merge branches 'docs.2022.04.20a', 'fixes.2022.04.20a', 'nocb.2022.04.11b', 'rcu-tasks.2022.04.11b', 'srcu.2022.05.03a', 'torture.2022.04.11b', 'torture-tasks.2022.04.20a' and 'torturescript.2022.04.20a' into HEAD

2022-05-03T17:21:40Z

docs.2022.04.20a: Documentation updates. fixes.2022.04.20a: Miscellaneous fixes. nocb.2022.04.11b: Callback-offloading updates. rcu-tasks.2022.04.11b: RCU-tasks updates. srcu.2022.05.03a: Put SRCU on a memory diet. torture.2022.04.11b: Torture-test updates. torture-tasks.2022.04.20a: Avoid torture testing changing RCU configuration. torturescript.2022.04.20a: Torture-test scripting updates.

rcu: Use IRQ_WORK_INIT_HARD() to avoid rcu_read_unlock() hangs

2022-04-20T23:51:11Z

When booting kernels built with both CONFIG_RCU_STRICT_GRACE_PERIOD=y and CONFIG_PREEMPT_RT=y, the rcu_read_unlock_special() function's invocation of irq_work_queue_on() the init_irq_work() causes the rcu_preempt_deferred_qs_handler() function to work execute in SCHED_FIFO irq_work kthreads. Because rcu_read_unlock_special() is invoked on each rcu_read_unlock() in such kernels, the amount of work just keeps piling up, resulting in a boot-time hang. This commit therefore avoids this hang by using IRQ_WORK_INIT_HARD() instead of init_irq_work(), but only in kernels built with both CONFIG_PREEMPT_RT=y and CONFIG_RCU_STRICT_GRACE_PERIOD=y. Signed-off-by: Zqiang Signed-off-by: Paul E. McKenney

rcu: Check for successful spawn of ->boost_kthread_task

2022-04-20T23:51:11Z

For the spawning of the priority-boost kthreads can fail, improbable though this might seem. This commit therefore refrains from attemoting to initiate RCU priority boosting when The ->boost_kthread_task pointer is NULL. Signed-off-by: Zqiang Signed-off-by: Paul E. McKenney

rcu: Fix rcu_preempt_deferred_qs_irqrestore() strict QS reporting

2022-04-12T00:28:48Z

Suppose we have a kernel built with both CONFIG_RCU_STRICT_GRACE_PERIOD=y and CONFIG_PREEMPT=y. Suppose further that an RCU reader from which RCU core needs a quiescent state ends in rcu_preempt_deferred_qs_irqrestore(). This function will then invoke rcu_report_qs_rdp() in order to immediately report that quiescent state. Unfortunately, it will not have cleared that reader's CPU's rcu_data structure's ->cpu_no_qs.b.norm field. As a result, rcu_report_qs_rdp() will take an early exit because it will believe that this CPU has not yet encountered a quiescent state, and there will be no reporting of the current quiescent state. This commit therefore causes rcu_preempt_deferred_qs_irqrestore() to clear the ->cpu_no_qs.b.norm field before invoking rcu_report_qs_rdp(). Kudos to Boqun Feng and Neeraj Upadhyay for helping with analysis of this issue! Signed-off-by: Paul E. McKenney

rcu: Initialize boost kthread only for boot node prior SMP initialization

2022-04-12T00:05:58Z

The rcu_spawn_gp_kthread() function is called as an early initcall, which means that SMP initialization hasn't happened yet and only the boot CPU is online. Therefore, create only the boost kthread for the leaf node of the boot CPU. Signed-off-by: Frederic Weisbecker Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Signed-off-by: Paul E. McKenney

Merge tag 'sched-core-2022-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-03-22T21:39:12Z

Pull scheduler updates from Ingo Molnar: - Cleanups for SCHED_DEADLINE - Tracing updates/fixes - CPU Accounting fixes - First wave of changes to optimize the overhead of the scheduler build, from the fast-headers tree - including placeholder *_api.h headers for later header split-ups. - Preempt-dynamic using static_branch() for ARM64 - Isolation housekeeping mask rework; preperatory for further changes - NUMA-balancing: deal with CPU-less nodes - NUMA-balancing: tune systems that have multiple LLC cache domains per node (eg. AMD) - Updates to RSEQ UAPI in preparation for glibc usage - Lots of RSEQ/selftests, for same - Add Suren as PSI co-maintainer * tag 'sched-core-2022-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (81 commits) sched/headers: ARM needs asm/paravirt_api_clock.h too sched/numa: Fix boot crash on arm64 systems headers/prep: Fix header to build standalone: sched/headers: Only include when CONFIG_GENERIC_ENTRY=y cgroup: Fix suspicious rcu_dereference_check() usage warning sched/preempt: Tell about PREEMPT_DYNAMIC on kernel headers sched/topology: Remove redundant variable and fix incorrect type in build_sched_domains sched/deadline,rt: Remove unused parameter from pick_next_[rt|dl]_entity() sched/deadline,rt: Remove unused functions for !CONFIG_SMP sched/deadline: Use __node_2_[pdl|dle]() and rb_first_cached() consistently sched/deadline: Merge dl_task_can_attach() and dl_cpu_busy() sched/deadline: Move bandwidth mgmt and reclaim functions into sched class source file sched/deadline: Remove unused def_dl_bandwidth sched/tracing: Report TASK_RTLOCK_WAIT tasks as TASK_UNINTERRUPTIBLE sched/tracing: Don't re-read p->state when emitting sched_switch event sched/rt: Plug rt_mutex_setprio() vs push_rt_task() race sched/cpuacct: Remove redundant RCU read lock sched/cpuacct: Optimize away RCU read lock sched/cpuacct: Fix charge percpu cpuusage sched/headers: Reorganize, clean up and optimize kernel/sched/sched.h dependencies ...

Merge branches 'exp.2022.02.24a', 'fixes.2022.02.14a', 'rcu_barrier.2022.02.08a', 'rcu-tasks.2022.02.08a', 'rt.2022.02.01b', 'torture.2022.02.01b' and 'torturescript.2022.02.08a' into HEAD

2022-02-24T17:38:46Z

exp.2022.02.24a: Expedited grace-period updates. fixes.2022.02.14a: Miscellaneous fixes. rcu_barrier.2022.02.08a: Make rcu_barrier() no longer exclude CPU hotplug. rcu-tasks.2022.02.08a: RCU-tasks updates. rt.2022.02.01b: Real-time-related updates. torture.2022.02.01b: Torture-test updates. torturescript.2022.02.08a: Torture-test scripting updates.

sched/isolation: Use single feature type while referring to housekeeping cpumask

2022-02-16T14:57:55Z

Refer to housekeeping APIs using single feature types instead of flags. This prevents from passing multiple isolation features at once to housekeeping interfaces, which soon won't be possible anymore as each isolation features will have their own cpumask. Signed-off-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Juri Lelli Reviewed-by: Phil Auld Link: https://lore.kernel.org/r/20220207155910.527133-5-frederic@kernel.org

rcu: Replace cpumask_weight with cpumask_empty where appropriate

2022-02-14T18:36:58Z

In some places, RCU code calls cpumask_weight() to check if any bit of a given cpumask is set. We can do it more efficiently with cpumask_empty() because cpumask_empty() stops traversing the cpumask as soon as it finds first set bit, while cpumask_weight() counts all bits unconditionally. Signed-off-by: Yury Norov Acked-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney

rcu: Add mutex for rcu boost kthread spawning and affinity setting

2022-02-14T18:36:35Z

As we handle parallel CPU bringup, we will need to take care to avoid spawning multiple boost threads, or race conditions when setting their affinity. Spotted by Paul McKenney. Signed-off-by: David Woodhouse Reviewed-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney